JPH06163956A - Photovoltaic element and power generation system - Google Patents

Abstract

PURPOSE:To prevent the recombination of optically pumped carrier, and improve open-circuit voltage and the carrier range of positive holes, by a method wherein the band gap of an I-type layer containing silicon atoms and carbon atoms is smoothly changed in the layer thickness direction, and the minimum value is biased in the second P-type layer direction from the center position of the layer thickness. CONSTITUTION:The title photovoltaic element consists of the following; a rear electrode 101, an N-type silicon substrate 102, a first P-type layer 103, an N-type layer 104, an Si layer 105, an I-type layer 106 containing Si and C, a second P-type layer 107, a transparent electrode 108, a collecting electrode 109, etc. Since the position of the minimum value of band gap of the I-type layer is biased toward the second P-type layer side, the electric field of a conduction band is large in the vicinity of the P/I interface of the I-type layer, and therefore, electrons are effectively separated from positive holes. In the I-type layer, the electric field of a valence band is increased toward the I/Si interface, so that the recombination of electrons and holes which are optically pumped in the vicinity of the I/Si interface can be decreased, and the photoelectric conversion efficiency can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic device and a power generation system, and particularly to a pin structure made of a silicon-based non-single-crystal semiconductor material and a pn structure of microcrystalline silicon, polycrystalline silicon, or single crystal silicon. The present invention relates to a photovoltaic element formed by stacking with and a power generation system using the same.

[0002]

2. Description of the Related Art Conventionally, in a photovoltaic device having a pin structure made of a silicon-based non-single-crystal semiconductor material, the i layer contains a silicon atom and a germanium atom or a carbon atom,
Various proposals have been made for photovoltaic devices having a changed band gap. For example, (1) "Optimum position c
onions for a- (Si, Ge): H
using a triode-configura
ted rf glow discharge sys
tem ", JA Braggnolo, P. Li.
tttlefield, A.M. Mastrovit an
d G. Storeti. Conf. Rec. 19th
IEE PHOTOVOLTAIC SPECIALI
sts Conference-1987 pp. 87
8, (2) "Efficiency improv
ment in amorphous-SiGe: H
solar cells and it's application
ation to tandem type sola
r cells ”, S. Yoshida, S. Yama
naka, M .; Konagai and K.K. Taka
hash, Conf. Rec. 19th IEEE
Photovoltaic Specialists
Conference-1987 pp. 1101,
(3) “Stability and terres
trial application of a-Si
tandem type solar cells "
A. Hiroe, H .; Yamagishi, H .; Ni
shio, M .; Kondo and Y. Tawada
Conf. Rec. 19th IEEE Photo
ovoltaic Specialists Conf
erence-1987 pp. 1111, (4)
"Preparation of high qual
it a-SiGe: H Films and it
s application to the high
efficiency triple-juncti
on amorphous solar cells ”
K. Sato, K .; Kawabata, S .; Tera
ZONO, H .; Sasaki, M .; Deguchi,
T. Itagaki, H .; Morikawa, M .; Ai
ga and K.K. Fujikawa, Conf. R
ec. 20th IEEE Photovoltaic
Specialists Conference-1
988 pp. 73, (5) USP 4,816,0
82 etc. have been reported.

Further, theoretical studies on the characteristics of a photovoltaic element having a changed band gap have been carried out, for example, in (6) "A novel design for a".
morphous silicon alloy so
lar cells "S. Guha, J. Yang,
A. Pawlikiewicz, T .; Glatfelt
er, R.R. Ross, and S.M. R. Ovshins
ky, Conf. Rec. 20th IEEE Pho
tovoltaic Specialists Con
ference-1988 pp. 79, (7) "N
umerial modeling of multi
junction amorphous silico
n based PI-N solar cells "
A. H. Pawlikiewicz and S.M. G
uha, Conf. Rec. 20th IEEE Ph
OTOVOLTAIC SPECIALISTS CON
ference-1988 pp. 251, etc. have been reported.

In such a conventional photovoltaic element, p
/ I, n / i Insert a layer with a changed band gap at the interface for the purpose of preventing recombination of photoexcited carriers near the interface, increasing the open-circuit voltage, and improving the carrier range of holes. is doing. In addition, a photovoltaic element in which a pn junction formed on a polycrystalline silicon substrate and a pin junction made of amorphous silicon are stacked has been reported. For example, (8) “Amorphous Si / Polycrys
talline SiStacked Solar C
ell Having More Than 12% C
onversion efficiency ”Koj
i. Okuda, Hiroaki. Okamoto a
nd Yoshihiro. Hamakawa, Ja
panese Journal of Physics
Vol. 22 No. 9 Sep. 1983 p
p. L605, (9) "Device Physic
s and Optimum Design of a
-Si / poly Si Tandem Solar
Cells "H. Takakura, K. Miyag
i, H. Okamato, Y .; Hamakawa, P
roseceings of 4th Intenat
internal Photovoltaic Science
and Engineering Conferen
ce 1989 pp. There are 403 etc.

A photovoltaic element in which a layer containing a group III element of the periodic table as a main constituent element and a layer containing silicon and carbon as a main constituent element are stacked in the doping layer has been reported. For example, (10) "Characterization of
δ-doped a-SiC p-Layer Pre
pared by Trimethylboronand
Triethylboron and it's ap
application to Solar Cell
s ", K. Higuchi, K. Tabuchi,
S. yamanaka, M .; Konagai and
K. Takahashi, Proceedings
of 5th International Photo
ovoltaic Science and Engi
neering Conference 1990, p
p529, (11) "High Efficiency
Amourous Silicone Solar
Cells with Delta-Doped p
-Layer ", Y. Kazama, K. Seki,
W. Y. Kim. S. Yamanaka, M .; Kona
gai and K. Takahashi, Japan
nese Journal of Applied P
hysics Vol. 28, No. 7 July 1
989 pp. 1160-1164, (12) "High
h Efficiency Delta-Doped
Amourous Silicone Solar
Cells Preparedby photoche
"Malical Vapor Deposition",
K. Higuchi, K .; Tabuchi, K .; S. L
im, M.I. Konagai and K.K. Takaha
shi, Japanese Journalof A
applied Physics Vol. 30, No.
8 August 1991 pp. 1635-164
0, (13) "High Efficiency Am
ouphous Silicone Solar Ce
lls with Delta-Doped p-La
yer ”, A. Shibata, Y. Kazama,
K. Seki, W .; Y. Kim. S. Yamanak
a, M.I. Konagai and K.K. Takahas
hi, Conf. Rec. 20th IEEE Pho
tovoltaic Specialists Conf
erence-1988 pp. 317. Etc.

[0006]

The conventional photovoltaic device containing silicon atoms and carbon atoms and having a changed bandgap has further improved recombination of photoexcited carriers, open circuit voltage, and carrier range of holes. Improvement is desired. Further, the long wavelength sensitivity of 800 nm or more is poor, and further improvement is desired.

Further, the above photovoltaic element has a problem that the photoelectric conversion efficiency is lowered when the photovoltaic element is irradiated with light. Further, there is a problem that the photoelectric conversion efficiency is lowered when the i-type layer is annealed in the presence of strain and vibration. On the other hand, in the conventional pin / pn stacked photovoltaic element, there is a problem that the open circuit voltage is small, a problem that the conversion efficiency is lowered when the photovoltaic element is irradiated with light, and there is an annealing in the presence of vibration. Therefore, there is a problem that the photoelectric conversion efficiency is lowered.

An object of the present invention is to provide a photovoltaic element that solves the above-mentioned conventional problems. That is, an object of the present invention is to provide a photovoltaic device in which recombination of photoexcited carriers is prevented and an open circuit voltage and a carrier range of holes are improved. Another object of the present invention is to provide a photovoltaic element in which conversion efficiency is less likely to decrease when the photovoltaic element is irradiated with light.

A further object of the present invention is to provide a photovoltaic element in which the photoelectric conversion efficiency is less likely to decrease when annealed under vibration for a long period of time. Another object of the present invention is to provide a photovoltaic device having improved short-wavelength sensitivity and long-wavelength sensitivity and improved short-circuit current. Still another object of the present invention is to provide a system using a photovoltaic device that achieves the above object.

[0010]

[Means for Solving the Problems]
In order to achieve the object of the invention, the present inventors have conducted diligent studies.
As a result, the found photovoltaic element of the present invention is polycrystalline.
N-type substrate composed of silicon or single crystal silicon
On top of microcrystalline silicon or polycrystalline silicon or single crystal
First p-type layer composed of crystalline silicon, non-single crystal semiconductor
N-type layer made of body material, made of non-single crystal silicon material
Si layer, i-type layer made of non-single crystal semiconductor material, non-single-bonded
Light in which a second p-type layer made of a crystalline semiconductor material is sequentially stacked
In the electromotive force element, the i-type layer is composed of silicon atoms and carbon atoms.
And the band gap of the i-type layer is in the layer thickness direction.
It changes smoothly and the minimum value of the band gap is in the center of the layer thickness.
Offset from the position of the direction of the second p-type layer
Is characterized by.

Alternatively, a first n-type layer made of microcrystalline silicon, polycrystalline silicon or single crystal silicon, a non-single crystalline semiconductor material is formed on a p-type substrate made of polycrystalline silicon or single crystal silicon. A p-type layer, an i-type layer made of a non-single-crystal semiconductor material, a Si layer made of a non-single-crystal silicon material, and a second layer made of a non-single-crystal semiconductor material
In a photovoltaic device in which the n-type layers of
The type layer contains silicon atoms and carbon atoms, the band gap of the i-type layer changes smoothly in the layer thickness direction, and the minimum value of the band gap deviates from the central position of the layer thickness toward the p-type layer. It is characterized by

As a desirable mode of the photovoltaic device of the present invention, a photovoltaic device having a Si layer made of a non-single-crystal silicon material between the i-type layer and the second p-type layer or the p-type layer. It is a power device. Further, as a desirable mode of the photovoltaic element of the present invention, at least one of both ends in the layer thickness direction of the i-type layer has a maximum bandgap of the i-type layer, and the bandgap maximum value region Is 1 to 30 nm
Photovoltaic device within.

Another desirable form of the photovoltaic element of the present invention is the second p-type layer, the n-type layer, the first p-type layer (or the second n-type layer, the p-type). Layer, said l-th n
At least one layer of the type layer is composed mainly of silicon and at least one element selected from carbon, oxygen, and nitrogen, and serves as a valence electron control agent of Group III element or Group III of the periodic table. A layer containing a group V element or a group VI element (layer A) and a layer containing a group III element of the periodic table or a group V element or a group VI element as a main constituent element (B
A photovoltaic element having a laminated structure with (layer).

A desirable mode of the photovoltaic element of the present invention is that the i-type layer contains both a valence electron control agent which serves as a donor and a valence electron control agent which serves as an acceptor. Further, the valence electron control agent serving as the donor is a group V element or / VI group element of the periodic table, and the valence electron control agent serving as an acceptor is a group III element of the periodic table, and the inside of the i-type layer It is more desirable to be distributed in the layer thickness direction.

A desirable mode of the photovoltaic element of the present invention is a photovoltaic element in which the Si layer contains a group V element and / or a group VI element of the periodic table. Further, as a desirable mode of the photovoltaic element of the present invention, the S
A photovoltaic element in which an i-layer contains both a group III element of the periodic table and a group V element and / or a group VI element of the periodic table.

In addition, a desirable mode of the photovoltaic element of the present invention is a photovoltaic element in which the i-type layer contains oxygen atoms and / or nitrogen atoms. In addition, as a desirable mode of the photovoltaic element of the present invention, the above-mentioned i
In the photovoltaic element, the hydrogen content contained in the mold layer changes in accordance with the silicon atom content.

Furthermore, a desirable mode of the photovoltaic element of the present invention is that the i-type layer has a vacuum degree of 50 mTorr or less in internal pressure, which is lower than the microwave energy required to decompose 100% of the source gas for depositing the deposited film. A photovoltaic element formed by causing microwave energy to act on the source gas and at the same time to act RF energy higher than the microwave energy on the source gas, wherein the Si layer is RF.
Formed by plasma CVD method, deposition rate is 2 nm
/ Sec or less, the photovoltaic element is formed with a layer thickness of 30 nm or less.

A system using the photovoltaic element of the present invention is the photovoltaic element and the photovoltaic element for a storage battery and / or an external load, which monitors the voltage and / or current of the photovoltaic element. It is characterized by comprising a control system for controlling the supply of electric power from the element and a storage battery for accumulating the electric power from the photovoltaic element and / or supplying the electric power to an external load.

[0019]

The operation and structure of the present invention will be described in detail below with reference to the drawings. 1-a and 1-b are schematic explanatory views of the photovoltaic element of the present invention. 1A, the photovoltaic device of the present invention includes a back electrode 101, an n-type silicon substrate 102, a first p-type layer 103, and an n-type layer 10.
4, Si layer 105, i-type layer 106, second p-type layer 10
7, a transparent electrode 108, a collector electrode 109, and the like. In addition, the interface between the n-type silicon substrate and the first p-type layer is the “p / substrate interface”, the interface between the first p-type layer and the n-type layer is the “n / p interface”, and the interface between the n-type layer and the Si layer is The interface is referred to as “Si / n interface”, the interface between the Si layer and the i-type layer is referred to as “i / Si interface”, and the interface between the i-type layer and the second p-type layer is referred to as “p / i interface”.

Similarly, referring to FIG. 1-b, the photovoltaic device of the present invention comprises a back electrode 121, a p-type silicon substrate 122,
First n-type layer 123, p-type layer 124, i-type layer 125, S
The i-layer 126, the second n-type layer 127, the transparent electrode 128, and the collector electrode 129 are included. The interface between the p-type silicon substrate and the first n-type layer is “n / substrate interface”, the interface between the first n-type layer and the p-type layer is “p / n interface”,
The interface between the p-type layer and the i-type layer is the "i / p interface", and the i-type layer and Si
The interface between the layers will be referred to as “Si / i interface”, and the interface between the Si layer and the second n-type layer will be referred to as “n / Si interface”.

FIG. 19 shows the photovoltaic device of FIG. 1-a having a second Si layer between the i-type layer and the p-type layer. In the present invention, since the position of the minimum band gap value of the i-type layer is offset to the side of the second p-type layer (p-type layer), it is near the p / i interface (i / p interface) of the i-type layer. Since the electric field in the conduction band is large, the electrons and holes are efficiently separated, and the recombination of electrons and holes can be reduced.
Further, it suppresses conduction electrons from back-diffusing into the second p-type layer (p-type layer). In the i-type layer, i / S
Since the electric field in the valence band increases toward the i interface (Si / i interface), the i / Si interface (Si / i interface)
The recombination of electrons and holes photoexcited near the interface) can be reduced, the photoelectric conversion efficiency can be improved, and further, the photoelectric conversion efficiency can be reduced by irradiating the photovoltaic element with light for a long time ( (Light deterioration) can be suppressed.

Furthermore, the carrier range of electrons and holes can be lengthened by adding both a valence electron control agent that serves as a donor and a valence electron control agent that serves as an acceptor to the i-type layer. Particularly, the carrier range of electrons and holes can be effectively lengthened by containing a relatively large amount of the valence electron control agent at the maximum band gap. As a result, the high electric field in the vicinity of the i / Si interface (Si / i interface) and the high electric field in the vicinity of the p / i interface (i / p interface) can be used more effectively, and photoexcitation is performed in the i-type layer. The efficiency of collecting electrons and holes can be significantly improved. In the vicinity of the i / Si interface (Si / i interface) and p /
The defect level (so-called D ⁻ , D ⁺ ) in the vicinity of the i interface (i / p interface) is compensated by the valence electron control agent, so that the dark current (during reverse bias) due to hopping conduction through the defect level is reduced. To do. Particularly, in the vicinity of the interface, by containing a valence electron control agent in a larger amount than in the i-type layer, it is possible to reduce internal stress such as strain due to abrupt change of constituent elements peculiar to the interface. The defect level near the interface can be reduced.

As a result, the open circuit voltage and fill factor of the photovoltaic element can be improved. In addition, by incorporating both a valence electron control agent that serves as a donor and a valence electron control agent that serves as an acceptor inside the i-type layer, durability against photodegradation increases. Although the details of the mechanism are unknown, it is generally believed that the dangling bonds generated by light irradiation become the recombination centers of carriers and deteriorate the characteristics of the photovoltaic device. In the case of the present invention, both the valence electron control agent that serves as a donor and the valence electron control agent that serves as an acceptor are contained in the i-type layer.
Not activated by 0%. As a result, even if dangling bonds are generated by light irradiation, it is considered that they react with the unactivated valence electron control agent to compensate dangling bonds.

Further, even when the light intensity applied to the photovoltaic element is weak, the probability of trapping photoexcited electrons and holes decreases because the defect level is compensated by the valence electron control agent. Further, as described above, since the dark current during reverse bias is small, sufficient electromotive force can be generated. As a result, excellent photoelectric conversion efficiency is exhibited even when the intensity of light applied to the optical storage element is weak.

In addition, the photovoltaic element of the present invention is such that the photoelectric conversion efficiency is unlikely to decrease even when it is annealed under vibration for a long period of time. Although the detailed mechanism of this is not clear, the constituent elements are also changed to form the photovoltaic element in order to continuously change the band gap. Therefore, strain is accumulated inside the photovoltaic element. That is, many weak bonds exist inside the photovoltaic element. Then, the weak bond in the i-type layer is broken by the vibration and a dangling bond is formed. This is because the addition of both the valence electron control agent that serves as a donor and the valence electron control agent that serves as an acceptor increases local flexibility, and the photoelectric conversion efficiency of the photovoltaic element is improved even during annealing due to long-term vibration. It is considered that the decrease of

In the Si layer, the defect level (so-called D
^- , D ⁺ ) is compensated by the valence electron control agent added to the Si layer, so that the dark current (during reverse bias) due to hopping conduction through the defect level is reduced. In particular, i / S
In the Si layer near the i interface (Si / i interface) or near the Si / n interface (n / Si interface), the valence electron control agent is contained in a larger amount than that in the central region of the Si layer. The defect level near the interface can be reduced by, for example, abrupt change of constituent elements peculiar to the vicinity or reduction of internal stress caused by stopping plasma. This can improve the open circuit voltage and fill factor of the photovoltaic element.

Further, by stacking a pin structure made of a non-single crystal silicon semiconductor material on a pn structure made of a microcrystalline, polycrystalline or single crystal silicon semiconductor layer, short wavelength light and long wavelength light can be obtained. The sensitivity is improved, the short-circuit current is improved, and the open-circuit voltage is further improved. Further, the n (p) type layer formed on the pn junction and made of a non-single-crystal material is easily fine because the underlying layer is made of microcrystalline silicon, polycrystalline silicon, or single crystal silicon semiconductor material. Since it can be crystallized, the open circuit voltage can be improved.

By stacking the Si type layer (or i type layer) on the microcrystallized n (p) type layer, the packing density of the Si type layer (or i type layer) is improved. It is possible to reduce the decrease in the photoelectric conversion efficiency (light deterioration) particularly when the light is irradiated for a long time, and it is possible to suppress the decrease in the photoelectric conversion efficiency even in the annealing due to the vibration for a long time.

Further, before forming the p (n) type layer on the substrate, the substrate is subjected to hydrogen annealing treatment at 300 ° C. to 900 ° C.,
Alternatively, by performing hydrogen plasma treatment, hydrogen atoms can be bonded to defects in the crystal grain boundaries to compensate for the defects, and atoms in the vicinity of the crystal grain boundaries can be relaxed to reduce the defect level. The photoelectric conversion efficiency of is improved. In addition, the contact surface of the metal electrode of the pn laminated structure and the pi
The contact surface of the n structure can obtain a larger current and electromotive force by providing the degenerated semiconductor layer.

After further forming the pn structure, the substrate temperature 1
When the pin structure is formed at 50 ° C. to 400 ° C., active hydrogen atoms are formed, which act on the defects in the bulk and crystal grain boundaries of the pn structure, and the hydrogen atoms combine to compensate the defects, and the crystal. The relaxation of atoms in the vicinity of the grain boundary can be promoted to reduce the defect level, and the photoelectric conversion efficiency of the photovoltaic device can be improved. This means that the i-type layer is converted into microwave CV.
This is particularly noticeable when formed by the D method.

In the photovoltaic element of the present invention, the Si layer is deposited at a deposition rate of 2 nm / by using the RF plasma CVD method.
It is preferable that the layer is formed in a sec or less and the layer thickness is 30 nm or less. Thereby, the photoelectric conversion efficiency of the photovoltaic element can be further improved. In particular, the photovoltaic element of the present invention is such that the photoelectric conversion efficiency thereof is unlikely to change when it is used in an environment where temperature changes greatly.

The Si layer deposited by the RF plasma CVD method has a deposition rate of 2 nm / sec or less and is deposited at a low power in which a vapor phase reaction does not easily occur. As a result, the packing density of the deposited film is high, and the i / Si interface (Si / i
The interface state at the interface) is reduced, and therefore, the open circuit voltage and fill factor of the photovoltaic element can be improved. This is particularly remarkable when the i-type layer is deposited by the microwave plasma CVD method.

In the photovoltaic device having the layer structure shown in FIG. 1-a, in the vicinity of the i / Si interface of the i-type layer immediately after the start of deposition, the underlayer is formed by the RF plasma CVD method and the above-described deposited film having a slow deposition rate is formed. Therefore, the interface state of the i-type layer can be reduced under the influence of the base, and the open circuit voltage and fill factor of the photovoltaic element can be improved. This is particularly remarkable when the i-type layer is formed by the microwave plasma CVD method of the present invention.

In the photovoltaic device having the layer structure shown in FIG. 1-b, the surface level of the i-type layer immediately after the deposition is not sufficiently relaxed, so that it is considered that the surface level is very large. By forming a deposited film having a slow deposition rate on the surface of such an i-type layer by the RF plasma CVD method, the surface level of the i-type layer is controlled by the diffusion of hydrogen atoms which occurs simultaneously with the formation of the deposited film by the RF plasma CVD. It can be reduced by annealing, and the open circuit voltage and fill factor of the photovoltaic device can be improved. This is remarkable when the i-type layer is formed by the microwave plasma CVD method.

A desirable form of the photovoltaic element of the present invention is
It is a photovoltaic element in which an i-type layer is sandwiched between Si layers as shown in FIG. Further, by including a valence electron control agent (group V element and / or group VI element in the periodic table) as a donor in the Si layer, an n-type layer (second n-type layer) and an i-type layer are formed. Since the internal stress such as strain due to the abrupt change of the constituent elements in between can be reduced, the i / Si interface (Si
/ I interface) or the defect level of the Si layer in the vicinity of the Si / n interface (n / Si interface) can be reduced. This can improve the open circuit voltage and fill factor of the photovoltaic element.

In addition, a valence electron control agent (group III element of the periodic table) serving as an acceptor and a valence electron control agent (group V element and / or group VI element of the periodic table) serving as a donor are added to the Si layer. By including it, durability against light deterioration is increased. Although the details of the mechanism are unknown, it is generally believed that the dangling bonds generated by light irradiation become the recombination centers of carriers and deteriorate the characteristics of the photovoltaic device. In the case of the present invention, both the valence electron control agent that serves as a donor and the valence electron control agent that serves as an acceptor are contained in the Si layer, and they are not 100% activated. As a result, even if dangling bonds are generated by light irradiation, it is considered that they react with the unactivated valence electron control agent to compensate dangling bonds.

Further, even when the light intensity applied to the photovoltaic element is weak, the probability of trapping photoexcited electrons and holes is reduced because the defect level is compensated by the valence electron control agent. Further, as described above, since the dark current during reverse bias is small, sufficient electromotive force can be generated. As a result, excellent photoelectric conversion efficiency is exhibited even when the intensity of light applied to the photovoltaic element is weak.

In addition, the photovoltaic element of the present invention has a low photoelectric conversion efficiency even when annealed under vibration for a long time. The detailed mechanism of this is unknown, but the i / Si interface (S
In the vicinity of the (i / i interface), by adding both a valence electron control agent that serves as a donor and a valence electron control agent that serves as an acceptor, local flexibility is increased, and a photovoltaic element can be used even during annealing due to long-term vibration. It is considered that the decrease in the photoelectric conversion efficiency can be suppressed.

FIGS. 2-1 and 2-2 show changes in the band gap of the i-type layer and the Si layer of the photovoltaic element of the present invention, which is ½ of the band gap (Eg / 2). It is based on. Figure 2-1 shows RF plasma CVD
Having an Si layer 212 formed by the
The minimum position of the bandgap is p / i from the center position
It is located near the interface (i / p interface) and the maximum position of the bandgap is the i / Si interface (Si / i interface) and p / i.
It is configured to be in contact with the interface (i / p interface). 2B, as in FIG. 2A, the Si layer 2 formed by the RF plasma CVD method.
22, the minimum position of the band gap of the i-type layer 221 is closer to the p / i interface (i / p interface) than the center position, and the maximum value of the band gap is the p / i interface (i / p interface). Interface). Figure 2
-By setting the bandgap configuration like -2,
In particular, the open circuit voltage can be increased.

3-1 to 3-7 show the vicinity of the i / Si interface (Si / i interface) and / or the p / i interface (i /
It is a schematic explanatory view of a change in the bandgap of a photovoltaic device having a region where the bandgap is constant in the i-type layer near the (p interface). Each figure shows the change in the bandgap based on Eg / 2. The left side of the band diagram is the i / Si interface (Si / i interface) and the right side is the p / i interface (i / p interface). is there.

In FIG. 3A, 313 is a Si layer, and p / i
There is a region 312 with a constant band gap in the i-type layer near the interface (i / p interface), and the band gap is i / p.
This is an example having a region 311 which decreases from the Si interface (Si / i interface) side toward the p / i interface (i / p interface). The minimum value of the band gap is at the interface between the area 312 and the area 311. Further, the band is joined between the region 311 and the region 312 by discontinuously connecting the bands. By providing the region having a constant band gap in this way, it is possible to suppress the dark current due to hopping conduction via the defect level in the reverse bias of the photovoltaic element as much as possible. As a result, the open circuit voltage of the photovoltaic element increases. The layer thickness of the region 312 where the band gap is constant is a very important factor, and the preferable layer thickness range is 1 to 30 nm. When the layer thickness in the region where the band gap is constant is less than 1 nm, the dark current due to hopping conduction via the defect level cannot be suppressed, and improvement in the open circuit voltage of the photovoltaic element cannot be expected. On the other hand, the region 31 where the band gap is constant
When the layer thickness of 2 is thicker than 30 nm, photoexcited holes are likely to be accumulated in the vicinity of the interface between the region 312 where the band gap is constant and the region 311 where the band gap is changed, so that the photoexcited carriers are collected. Efficiency is reduced. That is, the short circuit photocurrent is reduced.

FIG. 3-2 shows that a region 322 having a constant band gap is provided in the i-type layer in the vicinity of the p / i interface (i / p interface) of the i-type layer, and i / of the region 321 in which the band gap changes. In this example, the band gap at the Si interface (Si / i interface) is equal to the band gap of the region 322. FIG. 3-3 shows the vicinity of the p / i interface (i / p interface) and i.
Regions 332 and 333 having a constant band gap are provided in the i-type layer near the / Si interface (Si / i interface). As a result, when a reverse bias is applied to the photovoltaic element, the dark current is further reduced and the open circuit voltage of the photovoltaic element is increased.

3-4 to 3-7 are near the i / Si interface (Si / i interface) or / and the p / i interface (i /
a region having a constant band gap in the i-type layer in the vicinity of the (p interface) and having an i / Si interface (Si / i interface) and / or p
2 is an example of the photovoltaic element of the present invention having a region where the band gap changes rapidly in the / i interface (i / p interface) direction.

FIG. 3-4 has regions 342 and 343 with constant band gaps in the i-type layer near the p / i interface (i / p interface) and near the i / Si interface (Si / i interface). There is a region 341 in which the band gap is changed, and in the region 341, the minimum band gap position is the p / i interface (i
This is an example in which the band gap of the region 341 and the band gaps of the regions 342 and 343 are continuous, which is offset to the / p interface) side. Electrons and holes photoexcited in the region where the bandgap of the i-type layer is changed by continuing the bandgap are efficiently supplied to the n-type layer (second n-type layer) and the second p-type layer (p Can be collected in each mold layer). Further, in particular, regions 342, 34 having a constant band gap
The region where the bandgap of the i-type layer is abruptly changed when 3 is 5 nm or less can reduce the dark current when a reverse bias is applied to the photovoltaic element, and thus the photovoltaic element can be reduced. The open circuit voltage can be increased.

In FIG. 3-5, the region 351 where the band gap is changed is the regions 352 and 35 where the band gap is constant.
3 is an example in which it is discontinuous and relatively loosely connected to 3.
However, since the regions where the bandgap is constant and the region where the bandgap is changing are connected gently in the direction in which the bandgap is widened, the carriers that are photoexcited in the region where the bandgap is changing have an efficient constant bandgap. Injected into the area. As a result, the collection efficiency of photoexcited carriers is increased. Whether the region where the band gap is constant and the region where the band gap is changing are connected continuously or discontinuously depends on the layer thickness between the region where the band gap is constant and the region where the band gap changes rapidly. Depends on. When the layer thickness of the region where the bandgap constant region is 5 nm or less and is thin and the bandgap changes rapidly is 10 nm or less, the bandgap constant region and the bandgap changing region are continuous. The connection increases the photoelectric conversion efficiency of the photovoltaic element, while the layer thickness in the region where the band gap is constant is thicker than 5 nm, and the layer thickness in the region where the band gap changes rapidly is 10 nm. From 30 nm to 30 nm, the conversion efficiency of the photovoltaic element is improved when the region where the band gap is constant and the region where the band gap is changed are connected discontinuously.

FIG. 3-6 shows an example in which a region having a constant band gap and a region having a changed band gap are connected in two stages. Further, it is an example in which the position where the band gap is minimum is closer to the p / i interface (i / p interface) than the center position of the i-type layer. Region 3 in which the band gap is changed by connecting to a constant region 362 having a wide band gap through a step of gradually widening the band gap from a position where the band gap is extremely small and a step of rapidly widening the band gap.
The carrier optically excited at 61 can be collected efficiently. Further, in FIG. 3-6, the i / Si interface (Si
The i-type layer near the (/ i interface) has a region in which the band gap changes rapidly toward the i / Si interface (Si / i interface).

FIG. 3-7 shows that the i-type layer near the i / Si interface (Si / i interface) and the p / i interface (i / p interface) has a region having a constant band gap, and p / Region 372 with a constant band gap near the i interface (i / p interface)
To the i / Si interface (Si /
In this example, a region 373 having a constant band gap (i interface) is connected by a rapid change in band gap.

As described above, the region where the band gap is constant and the region where the band gap changes are connected in a state where the constituent elements are similar to each other, whereby the internal strain can be reduced. As a result, even if annealed under vibration for a long period of time, the phenomenon that the weak bond in the i layer is broken, the defect level is increased, and the photoelectric conversion efficiency is lowered, is less likely to occur.
It is possible to maintain a high photoelectric conversion efficiency.

In the present invention, the preferable range of the minimum band gap value of the i-type layer containing silicon atoms and carbon atoms is selected depending on the spectrum of irradiation light, but is 1.7 to 2.0 eV. Is desirable. Further, in the photovoltaic device of the present invention in which the band gap is continuously changed, the slope of the tail state of the valence band is an important factor that influences the characteristics of the photovoltaic device. It is preferable that the slope of the tail state at the minimum value to the slope of the tail state at the maximum band gap is smoothly continuous.

The photovoltaic element having the pin / pn (nip / np) structure has been described above.
n (nipnip / np) structure or pinpinpin /
The present invention can also be applied to a photovoltaic device in which a pin structure such as a pn (nipnipnip / np) structure is laminated. FIG. 4 is a schematic explanatory view of a manufacturing apparatus suitable for forming a deposited film of the photovoltaic element of the present invention. The manufacturing apparatus includes a deposition chamber 401, a vacuum gauge 402, an RF power source 403, a substrate 404, a heater 405, a conductance valve 407, an auxiliary valve 408, a leak valve 409, and an RF.
Electrode 410, gas introduction pipe 411, microwave waveguide 41
2, dielectric window 413, shutter 415, source gas supply device 2000, mass flow controllers 2011 and 2
017, valves 2001 to 2007, 2021 to 202
7, pressure regulators 2031 to 2037, raw material gas cylinder 2
041 to 2047 and the like.

Although the details of the deposition mechanism of the microwave plasma CVD method used for forming the photovoltaic element of the present invention are unknown, it is considered as follows. Source gas 10
Microwave energy required for 0% decomposition (“MP
abbreviated as “w”) to decompose the raw material gas by causing lower microwave energy to act on the raw material gas,
It is considered that an active species suitable for forming a deposited film can be selected by causing RF energy higher than MPw to act on the source gas at the same time as microwave energy. Furthermore, the internal pressure in the deposition chamber when decomposing the source gas is 50 mTorr
In the following conditions, the gas phase reaction is considered to be suppressed as much as possible because the mean free path of the active species suitable for forming a good quality deposited film is sufficiently long. And again, the internal pressure in the deposition chamber is 50
It is considered that in the state of mTorr or less, the RF energy has almost no effect on the decomposition of the source gas and controls the potential between the plasma and the substrate in the deposition chamber. That is, in the case of the microwave plasma CVD method, the potential difference between the plasma and the substrate is small, but by introducing the RF energy at the same time as the microwave energy, the potential difference between the plasma and the substrate (+ on the plasma side and − on the substrate side). Can be large. Since the plasma potential is positively high with respect to the substrate, active species decomposed by microwave energy are deposited on the substrate, and at the same time, + ions accelerated by the plasma potential collide with the substrate and collide with the substrate surface. It is considered that the relaxation reaction is promoted and a high quality deposited film is obtained. This effect is particularly remarkable when the deposition rate is several nm / sec or more.

Since RF has a high frequency unlike DC, the difference between the plasma potential and the substrate potential is determined by the distribution of ionized ions and electrons. That is, the potential difference between the substrate and plasma is determined by the synergy of ions and electrons. Therefore, there is an effect that spark is unlikely to occur in the deposition chamber. As a result, stable glow discharge can be maintained for a long time of 10 hours or more.

In addition, when depositing a layer having a changed band gap, the flow rate and flow rate of the source gas change temporally or spatially. Therefore, in the case of DC, the DC voltage is temporally or spatially changed. It needs to be changed appropriately. On the other hand, in the above-described deposited film forming method, the ratio of ions changes due to temporal or spatial changes in the flow rate and flow rate of the source gas. Correspondingly, the RF self-bias automatically changes. As a result, when RF is applied to the RF electrode to change the raw material gas flow rate and the raw material gas flow rate ratio, D
The discharge is very stable as compared with the case of the C bias.

In addition, in the deposited film forming method of the present invention, in order to change the band gap in the i-type layer,
It is effective to temporally change the flow rate ratio of the silicon atom-containing gas and the carbon-containing gas during layer formation. At that time,
It is preferred to mix the above gases at a distance of 5 m or less from the deposition chamber. When the raw material gases are mixed at a distance of more than 5 m, the raw material gas mixing positions are far apart even if the mass flow controller is controlled in response to a desired band gap change, and therefore the raw material gas delays or the mutual change of the raw material gases is prevented. Diffusion occurs, causing a shift with respect to the desired band gap. That is, if the mixing position of the raw material gas is too far away, the controllability of the band gap is deteriorated.

Further, in order to change the hydrogen content contained in the i-type layer in the layer thickness direction, the RF energy applied to the RF electrode is increased where the hydrogen content is desired to be increased,
The RF energy applied to the RF electrode may be reduced where it is desired to reduce the hydrogen content. Although the detailed mechanism is still unknown, R applied to the RF electrode
It is considered that when the F energy is increased, the plasma potential rises and the hydrogen ions are further accelerated toward the substrate, so that more hydrogen atoms are contained in the i-type layer.

Further, in the case of applying DC energy at the same time as RF energy, it is sufficient to apply a large DC voltage applied to the RF electrode with a positive polarity in order to increase the content of hydrogen atoms. When it is desired to reduce the amount, a DC voltage applied to the RF electrode may be applied with a small voltage with positive polarity. Although the detailed mechanism is still unknown, increasing the DC energy applied to the RF electrode raises the plasma potential and causes more hydrogen ions to accelerate toward the substrate, resulting in more of the i-type layer. It is considered that hydrogen atoms are contained.

Furthermore, as another method for changing the hydrogen content contained in the i-type layer in the layer thickness direction, a gas containing silicon atoms and halogen atoms (X) (for example,
SiX ₄ , Si ₂ X ₆ , SiH _N X _4-N , Si ₃ H _N X
_6-N , etc.) and a gas containing no halogen atoms but containing silicon atoms (eg, SiH ₄ , Si ₂ H ₂ ,
Si ₃ H ₂ , SiD ₄ , SiHD ₅ , SiH ₂ D ₂ , S
iH ₃ is D, SiD ₃ H, a method of mixing a Si ₂ D ₃ H _3, etc.) to form the i-type layer. If you want to reduce the hydrogen content, increase the ratio (Y) of the gas containing both halogen atoms and silicon atoms to the total silicon atom-containing gas. If you want to decrease the hydrogen content, decrease the ratio (Y). Good. Although the detailed mechanism is still unknown, if more of the above-mentioned gas containing halogen atoms is introduced into the deposition chamber, the amount of radicals containing halogen atoms excited by microwaves in the plasma increases, It is considered that the halogen atom of the radical containing the halogen atom and the hydrogen atom existing in the i-type layer cause a substitution reaction to reduce the hydrogen content in the i-type layer.

Furthermore, as another method for changing the hydrogen content contained in the i-type layer in the layer thickness direction, a halogen lamp or a xenon lamp is provided in the deposition chamber, and i
These lamps are flashed during the mold layer formation to temporarily raise the substrate temperature. At that time, if the hydrogen content is desired to be reduced, the number of flashes per unit time is increased, the substrate temperature is temporarily raised, and if the hydrogen content is desired to be increased, the number of flushes per unit time is decreased. The substrate temperature may be temporarily lowered. By temporarily raising the substrate temperature,
It is considered that the desorption reaction of hydrogen from the surface of the i-type layer is activated.

The deposited film forming method used for producing the photovoltaic element of the present invention is performed, for example, as follows.
First, a substrate 404 for forming a deposited film is placed in the deposition chamber 401 of FIG.
Is attached, and the deposition chamber is sufficiently evacuated to 10 ⁻⁴ Torr or less. A turbo molecular pump or an oil diffusion pump is suitable for this exhaust. In the case of an oil diffusion pump, the internal pressure of the deposition chamber 401 is set to 1 so that the oil does not diffuse back into the deposition chamber.
When it becomes 0 ^-4 Torr or less, H ₂ , He, Ar, Ne,
It is preferable to introduce a gas such as Kr or Xe into the deposition chamber. After exhausting the deposition chamber sufficiently, H ₂ , He, Ar, N
Gases such as e, Kr, and Xe are introduced into the deposition chamber so that the pressure in the deposition chamber is almost the same as when the source gas for forming the deposited film is flowed. The pressure in the deposition chamber is 0.5 to 50
mTorr is the optimum range. When the internal pressure in the deposition chamber has stabilized, turn on the heater 405 and set the substrate to 1
Heat to 00-500 ° C. When the temperature of the substrate stabilizes at a predetermined temperature, the gases such as H ₂ , He, Ar, Ne, Kr, and Xe are stopped, and a predetermined amount of the raw material gas for forming the deposited film is introduced into the deposition chamber from the gas cylinder through the mass flow controller. To do.

The supply amount of the source gas for forming the deposited film introduced into the deposition chamber is appropriately determined depending on the volume of the deposition chamber. On the other hand, the internal pressure in the deposition chamber when the source gas for forming the deposited film is introduced into the deposition chamber is a very important factor in the deposited film forming method, and the optimum internal pressure in the deposition chamber is
In the case of microwave plasma CVD method, 0.5 to 50 mT
orr is preferred.

In the deposited film forming method, the microwave energy introduced into the deposition chamber for forming the deposited film is an important factor. The microwave energy is appropriately determined by the flow rate of the raw material gas introduced into the deposition chamber, but is smaller than the microwave energy (MPw) required to decompose 100% of the raw material gas, A preferable range is 0.005 to 1 W /
It is cm ³ . A preferable frequency range of microwave energy is 0.5 to 10 GHz. A frequency near 2.45 GHz is particularly suitable. Also, since a reproducible deposited film is formed by the deposited film forming method,
The frequency stability of microwave energy is very important for forming a deposited film over several hours to several tens of hours. It is preferable that the frequency fluctuation is within ± 2%. Further, the ripple of the microwave is preferably within ± 2%.

Further, in the method of forming a deposited film, the RF energy introduced into the deposition chamber at the same time as the microwave energy is a very important factor in combination with the microwave energy, and a preferable range of the RF energy. Is 0.01 to 2 W / cm ³ . RF
The preferable frequency range of energy is 1 to 100
MHz is mentioned. Particularly, 13.56 MHz is optimum. Further, it is preferable that the fluctuation of the RF frequency is within ± 2% and the waveform is smooth. When supplying the RF energy, it is appropriately selected depending on the area ratio between the area of the RF electrode for supplying the RF energy and the area of the ground, but the area of the RF electrode for supplying the RF energy is more than the area of the ground. If it is narrow, it is better to ground the self-bias (DC component) on the power supply side for RF energy supply. Furthermore, if the self-bias (DC component) on the power supply side for RF energy supply is not grounded,
It is preferable to make the area of the RF electrode for supplying the RF energy larger than the area of the earth in contact with the plasma.

In this way, microwave energy is introduced from the waveguide 412 into the deposition chamber through the dielectric window 413, and at the same time, RF energy is supplied from the RF power source 403 to the RF electrode 41.
It is introduced into the deposition chamber through 0. In this state, the source gas is decomposed for a desired time to form a deposited film having a desired layer thickness on the substrate. After that, the introduction of microwave energy and RF energy was stopped, the deposition chamber was evacuated, and H ₂ , H
After sufficiently purging with a gas such as e, Ar, Ne, Kr, or Xe, the deposited non-single-crystal semiconductor film is taken out from the deposition chamber.

In addition to the RF energy, the R
A DC voltage may be applied to the F electrode 410. Regarding the polarity of the DC voltage, it is preferable to apply the voltage so that the RF electrode becomes positive. The preferable range of the DC voltage is about 10 to 300V. In the above-described method for forming a deposited film, the following compounds are suitable as the compounds listed as the source gas for silicon deposition.

Specifically, gasification containing silicon atoms
SiH as the compound to be obtained_Four, Si ₂H₆, SiX
_Four(X: halogen atom), SiXH₂, SiX₂H₂,
SiX₃H, Si₂X₆, Si₂H₃, SiD_Four, Si
HD₃, SiH₂D₃, SiH₂D, SiFD₂, Si
X₂D₂, SiD₃H, Si₂D₃H₃Etc. (collectively
"Abbreviated as" compound (Si) ").

Examples of the gasifiable compound containing a carbon atom include CH ₄ , CD ₄ , C ₂ H _{2n + 2} (n is an integer), C
_n H _2n (n is an integer), C _n X _{2n + 2} (n is an integer, X: a halogen atom), C _n X _2n (n is an integer), C ₂ H ₂ , C ₆
H ₅ , CO ₂ , CO and the like (generally abbreviated as “compound (C)”) can be mentioned. In the present invention, as the valence electron control agent introduced into the non-single-crystal semiconductor layer for controlling the valence electrons of the non-single-crystal semiconductor layer, Group III atoms, Group V atoms and Group VI atoms of the periodic table are listed. Can be mentioned.

In the present invention, what is effectively used as a starting material for introducing a Group III atom (generally abbreviated as “compound (III)”) is specifically for introducing a boron atom. Is B ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ ,
_{B 5 H 11, B 6 H} 10, B 6 H 1 2, B 6 H 14 , etc. borohydride, BF _3, BCl _3, can be exemplified BBr _3, etc. boron halides like. In addition to this, AlCl ₃ , Al
_{(CH 3) 3, GaCl 3} , InCl 3, TlCl 3 , etc. can also be mentioned.

In the present invention, a starting point for introducing a Group V atom
Available as supplies (collectively abbreviated as “compound (V)”)
Specifically, it is used for introducing phosphorus atoms.
PH ₃, P₂H_FourPhosphorus hydride, PH, etc._FourI, PF₃, P
F_Five, PCl₃, PCl_Five, PBr₃, PBr_Five, Pl
₃Phosphorus halides such as P₂O_Five, POCl₃Oxygenation of etc.
There is a mixture. In addition, AsH₃, AsF₃, As
Cl₃, AsBr₃, AsF_Five, SbH₃, SbF₃,
SbF_Five, SbCl₃, SbCl_Five, BiCl _Five, Bi
Br₃Etc. can also be mentioned.

In the present invention, H ₂ S, SF ₄ and SF ₅ are effectively used as a starting material (generally abbreviated as “compound (VI)”) for introducing a Group VI atom. , S
O ₂ , SO ₂ F ₂ , COS, CS ₂ , H ₂ Se, SeF
₆ , TeH ₂ , TeF ₆ , (CH ₅ ) ₂ Te, (C ₂ H
₃ ) ₂ Te and the like can be mentioned. Group III atoms of the periodic table introduced into the i-type layer composed of a non-single crystal semiconductor material,
The preferable amount of introduction of the group V atom or the group VI atom is 1000 ppm or less. Further, in order to achieve the object of the present invention, in the i-type layer, a group III atom and a group V atom of the periodic table, a group III atom and a group VI atom, or a group III atom and a group V atom are included. It is preferred to add the atoms and the Group VI atoms together to compensate.

The gasifiable compound is H ₂ ,
It may be appropriately diluted with a gas such as D ₂ , He, Ne, Ar, Xe, and Kr and introduced into the deposition chamber. Particularly, the most suitable gas for diluting the gasifiable compound is H ₂ , D ₂ ,
He and Ar are mentioned. The nitrogen-containing gas introduced to contain nitrogen in the i-type layer of the non-single-crystal semiconductor layer is N ₂ , NH ₃ , ND ₃ , NO, NO ₂ , N ₂ O (collectively referred to as “compound (N)”). Abbreviated as ").

The i-type layer of the non-single crystal semiconductor layer contains oxygen.
O is used as the oxygen-containing gas introduced to induce₂, C
O, CO₂, NO, NO₂, N₂O, CH₃CH₂O
H, CH ₃OH, etc. (collectively referred to as "compound (O)"
). In the photovoltaic device of the present invention,
The second p-type layer, the n-type layer, the first p-type layer, or the second
At least one of the n-type layer, the p-type layer, and the first n-type layer of
It is preferable to have a laminated structure. In the photovoltaic element of the present invention
The laminated structure in the main constituent elements is silicon, carbon, and acid.
At least one element selected from elemental and nitrogen
As a valence electron control material.
Or a layer containing a Group V element or a Group VI element (A
Layer) and a group III element or a group V element of the periodic table or
Is a layer (B layer) containing a Group VI element as a main constituent element
To be done.

By using the laminated structure of the present invention for the doping layer, the donor concentration or the acceptor concentration of the doping layer can be improved and the open circuit voltage of the photovoltaic element can be increased. In addition, the A layer is a material that is not highly doped (lightly doped),
And by using a material with a small light absorption coefficient,
Since more light can be incident on the i-type layer or the pn junction, the short-circuit photocurrent of the photovoltaic element can be improved.

Further, the photovoltaic device having the laminated structure of the present invention can considerably suppress the decrease in photoelectric conversion efficiency even when it is annealed for a long time such as vibration. Although the detailed mechanism is still unknown, it is considered as follows. A considerable amount of strain and stress are generated inside the conventional laminated structure because the constituent elements are rapidly changed. However, since the A layer of the present invention contains carbon and / or oxygen or / and nitrogen, the generated strain and stress are relaxed inside the A layer, and therefore, even for long-time annealing such as vibration. It is considered that the decrease in photoelectric conversion efficiency can be suppressed.

Further, the photovoltaic device having the laminated structure of the present invention can considerably suppress the decrease in photoelectric conversion efficiency even when irradiated with light for a long time. Although the detailed mechanism is still unknown, it is considered as follows. Dangling bonds are generated inside the A layer when irradiated with light for a long time, but a part of the valence electron control agent contained in the A layer is inactive, and in order to compensate the generated dangling bonds, It is considered that photodegradation can be suppressed.

The A layer is an amorphous material (designated as a-), a microcrystalline material (designated as μc-), a polycrystalline material (designated as poly-) or a single crystal material (designated as c-). Composed of. Examples of the amorphous material include a-Si: H, a-Si: HX, a-SiC: H,
a-SiC: HX, a-SiO: H, a-SiO: H
X, a-SiN: H, a-SiN: HX, a-SiO
N: H, a-SiON: HX, a-SiOCN: H, a
—SiOCN: HX, (X: halogen atom) and the like.

As the microcrystalline material, for example, μc-S
i: H, μc-SiC: H, μc-Si: HX, μc-
SiC: HX, μc-SiO: H, μc-SiN: H,
μc-SiON: HX, μc-SiOCN: HX, and the like. As the polycrystalline material, for example, poly-S
i: H, poly-Si: HX, poly-SiC:
H, poly-SiC: HX, poly-Si, pol
y-SiC, etc. are mentioned.

As the single crystal material, for example, c-Si,
c-SiC etc. are mentioned. n (p) type layer, second p
When the (n) type layer has a laminated structure, a microcrystalline material, a polycrystalline material, or a single crystal material having a small absorption coefficient for short wavelength light is preferably used as the A layer. In order to form the p-type A layer, a p-type valence electron control agent (II
Group I atoms B, Al, Ga, In, Tl) are added, and n
To form a type A layer, an n-type valence electron control agent (atoms P, As, Sb, Bi of the periodic table, and / or group VI atoms S, Se, Te of the periodic table) is added. Let

The amount of the group III atom of the periodic table added to the p-type A layer, or the group V atom of the periodic table to the n-type A layer,
The optimum amount of the Group VI atom added is 10 to 10,000 ppm. Further, when the A-type layer is composed of a microcrystalline material or a polycrystalline material, hydrogen atoms (H, D) or halogen atoms contained in the A layer function to compensate dangling bonds in the A layer. , Improves the doping efficiency. The optimum amount of hydrogen atoms or halogen atoms added to the A layer is 0 to 10 at%. A preferable distribution form is one in which a large amount of hydrogen atoms and / or halogen atoms are distributed in the vicinity of the interface of the A layer. The content of hydrogen atoms and / or halogen atoms in the vicinity of the interface is A preferable range is 1.1 to 2.5 times the content. By increasing the content of hydrogen atoms or halogen atoms in the vicinity of the interface as described above, the defect level near the interface and the stress in the layer can be reduced, and the mechanical strain can be relaxed. It is possible to increase the photovoltaic power and the photocurrent of the power device. The layer thickness of the A layer is preferably 5 to 30A.

As a method of forming the A layer, plasma CVD is used.
Method, optical CVD method and the like, and the plasma CVD method is particularly preferably used. When forming the A layer by these methods,
The following gasifiable compounds and mixed gases of the compounds may be mentioned. Specific examples of the gasifiable compound containing a silicon atom include the compounds (S
i) are mentioned.

Specific examples of the gasifiable compound containing a carbon atom include the compound (C) described above.
Examples of the nitrogen-containing gas include the compound (N) described above. Examples of the oxygen-containing gas include the compound (O) described above. Examples of the substance introduced into the p-type A layer include Group III atoms of the periodic table, and examples of the atoms introduced into the n-type A layer include Group V atoms and Group VI atoms.

Compounds (II) mentioned above can be effectively used as starting materials for introducing a Group III atom.
I) can be mentioned, and B ₂ H ₆ and BF ₃ are particularly suitable, and these compounds are usually diluted with a gas such as H ₂ , He, Ar or the like to a desired concentration and stored in a high-pressure cylinder. V
Effectively used as a starting material for introducing a group atom,
The above-mentioned compound (V) can be mentioned, particularly P
H ₃ and PF ₃ are suitable, and these compounds are usually
Dilute to a desired concentration with a gas such as H ₂ , He or Ar and store in a high pressure cylinder.

Compounds (VI) mentioned above can be effectively used as starting materials for introducing a Group VI atom, and H ₂ S is particularly suitable, and these compounds are usually used.
Dilute to a desired concentration with a gas such as H ₂ , He or Ar and store in a high pressure cylinder. When the layer A is formed by the plasma CVD method, the RF plasma CVD method and the microwave plasma CVD method are suitable. When depositing by the RF plasma CVD method, the capacitively coupled RF plasma CVD method is suitable.

When depositing by the RF plasma CVD method,
The substrate temperature in the deposition chamber is 100 to 600 ° C., and the internal pressure is
0.1 to 10 Torr, RF power is 0.01 to 1W
/ Cm ², The optimum deposition rate is 0.1-1 A / sec
It is mentioned as a matter. Further, the gasifiable compound is
₂, D₂, He, Ne, Ar, Xe, Kr, etc.
It may be diluted and introduced into the deposition chamber.

In particular, when depositing an A layer made of a microcrystalline, polycrystalline, or single crystalline material, hydrogen gas is added in an amount of 2-1.
It is preferable to dilute the raw material gas to 00 times and introduce a relatively high RF power. The suitable range of RF frequency is 1 MHz to 100 MHz,
In particular, the frequency near 13.56 MHz is optimum. When depositing by the microwave plasma CVD method, the microwave plasma CVD apparatus is preferably a method in which a microwave is introduced into the deposition chamber through a dielectric window (alumina ceramics, quartz, boron nitride, etc.) 413 by a waveguide. There is. The deposition film forming method suitable for forming the i-type layer described above is also a suitable deposition method, but the deposition film applicable to the photovoltaic element can be formed under a wider deposition condition. That is, the substrate temperature in the deposition chamber is 100 to 600 ° C., and the internal pressure is 0.5 to 30 mTorr.
r, the microwave power is 0.005 to 1 W / cm ³ , and the microwave frequency is preferably 0.5 to 10 GHz.

Further, the gasifiable compound is replaced by H ₂ , D ₂ ,
It may be appropriately diluted with a gas such as He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. Especially microcrystalline, or polycrystalline,
Alternatively, when depositing an A layer made of a single crystal material, it is preferable to dilute the source gas by 2 to 100 times with hydrogen gas and introduce a relatively high microwave power.

When the layer A is deposited by the photo-CVD method, a low pressure mercury lamp is used as a light source and the substrate temperature is 100-60.
0 ° C., internal pressure 0.1 to 10 Torr, deposition rate 0.0
1 to 1 A / sec is mentioned as the optimum condition, and 1 to 100% of mercury is introduced while introducing the gasifiable compound.
About ppm may be introduced. Examples of the compound _{(Si), Si 2 H 6} , Si 2 H N X 6-N: higher silane such as (X a halogen atom) is preferably used.

Further, the gasifiable compound is replaced by H ₂ , D ₂ ,
It may be appropriately diluted with a gas such as He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. Especially microcrystalline, or polycrystalline,
Alternatively, when depositing the A layer made of a single crystal material, it is preferable to dilute the raw material gas by 2 to 100 times with hydrogen gas and introduce the diluted raw material gas.

When the main constituent atoms of the B layer are laminated with the p-type A layer, the group III atoms of the periodic table (for example, B, Al,
When laminated with an n-type A layer, which is made of Ga, In, and Tl, an atom of Group V of the periodic table (for example, P, As, Sb, B
i), or / and an atom of Group VI of the periodic table (eg, S,
Se, Te). The layer thickness of the B layer is preferably 5 to 30A.

As a method of forming the B layer, plasma CVD is used.
Method, photo CVD method, etc. are used suitably. When the B layer is formed by these methods, the following gasifiable compounds and mixed gas of the compounds can be mentioned. No. II
Compounds (III) mentioned above can be cited as examples of compounds effectively used as a starting material for introducing a Group I atom, and B ₂ H ₆ and B (CH ₃ ) ₃ are particularly suitable.

The above-mentioned compound (V) can be effectively used as a starting material for introducing a group V atom. The compound (VI) described above is effectively used as a starting material for introducing a Group VI atom.
When the B layer is formed by the plasma CVD method, the RF plasma CVD method and the microwave plasma CVD method are suitable. When depositing by the RF plasma CVD method, the capacitively coupled RF plasma CVD method is suitable.

When depositing by the RF plasma CVD method,
The substrate temperature in the deposition chamber is 100 to 600 ° C., and the internal pressure is
0.1 to 10 torr, RF power is 0.1 to 2 W /
The optimum conditions for the cm ² and the deposition rate are 0.1 to 2 A / sec. Further, the gasifiable compound may be appropriately diluted with a gas such as H ₂ , D ₂ , He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

When depositing by the microwave plasma CVD method, the microwave plasma CVD apparatus has a dielectric window (alumina ceramics, quartz, boron nitride, etc.) 41 in the deposition chamber.
A method of introducing microwaves with a waveguide via 3 is suitable. A deposition film forming method most suitable for forming an I-type layer is also a suitable deposition method, but a deposition film applicable to a photovoltaic element can be formed under wider deposition conditions. That is, the substrate temperature in the deposition chamber is 100 to 600 ° C., and the internal pressure is 0.5 to 30 m.
Torr, microwave power 0.01 to 1 W / c
The preferable range of m ³ and microwave frequency is 0.5 to 10 GHz.

Also, the gasifiable compound is replaced by H ₂ , D ₂ ,
It may be appropriately diluted with a gas such as He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. When depositing the B layer by the photo-CVD method, a low pressure mercury lamp is used as a light source, the substrate temperature is 100 to 600 ° C., the internal pressure is 0.1 to 10 torr, and the deposition rate is 0.01 to 2 A / sec. It is also possible to introduce about 1 to 100 ppm of mercury together with introducing the gasifiable compound.

Further, the gasifiable compound is replaced by H ₂ , D ₂ ,
It may be appropriately diluted with a gas such as He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. The laminated structure of the laminated structure used for the photovoltaic element of the present invention preferably starts from the A layer and ends at the A layer, for example, ABA, ABABA, ABA.
BABA etc. (AB) _n A laminated form, or _Al B
_Examples include a laminated form of (A _n B _n ) A _{n + 1} such as _l A ₂ , A _l B _l A ₂ B ₂ A _{3, and the} like. However, when a laminated structure is used for the second p-type layer, it may start from the A layer and end at the B layer. For example, a laminated form of AB, ABAB, ABABAB or the like (AB) _n , or _Al B _l , A _l B _l A ₂ B _2, etc., (A _n B _n )
The laminated form of is mentioned.

Next, the components of the photovoltaic element of the present invention will be described in detail. Substrate (102, 122) The substrate may be a polycrystal silicon substrate or a monocrystal silicon substrate, and further, a polycrystal silicon layer or monocrystal silicon on a support made of an insulating material or a conductive material. It may be a stack of layers.

When polycrystalline silicon is used as the substrate,
100 to 5 ingots produced by the casting method (Latest solar power generation technology, edited by Keihiro Hamakawa, Maki Shoten)
Either use it by slicing it to a thickness of about 00 μm, or use a ribbon-shaped silicon polycrystal produced by passing a silicon melt through a mesh of carbon fibers, or use polycrystalline silicon directly from the silicon melt. It is also possible to use one that has been gradually cooled while being pulled out. In any case,
In order to reduce many trap levels existing in the grain boundary, the substrate temperature is 500 to 900 ° C., annealing is performed in a hydrogen atmosphere, or the substrate temperature is 3
It is desirable to perform hydrogen plasma treatment at 00 to 900 ° C. or irradiate the substrate with a laser beam for annealing.

When single crystal silicon is used as the substrate,
Slice an ingot produced by the CZ (Choralski) method to a thickness of about 100 to 500 μm, or use a ribbon-shaped silicon single crystal produced by passing a carbon melt through a silicon melt. Alternatively, a single crystal silicon may be directly drawn from the silicon melt and gradually cooled while being used.

The conductive support used when laminating the polycrystalline silicon layer or the single crystal silicon layer on the support is, for example, NiCr, stainless steel, Al, Cr,
Mo, Au, Nb, Ta, V, Ti, Pt, Pb, Sn
And the like, or alloys thereof. Similarly, as the electrically insulating support, polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride,
Film of synthetic resin such as polystyrene, polyamide, etc.
Alternatively, a sheet, glass, ceramics, paper, or the like can be used. It is desirable that at least one surface of these insulating supports is subjected to a conductive treatment, and a polycrystalline silicon layer or a single crystal silicon layer is provided on the surface subjected to the conductive treatment.

For example, in the case of glass, N
iCr, Al, Cr, Mo, Ir, Nb, Ta, V, T
i, Pt, Pb, In ₂ O ₃ , ITO (In ₂ O ₃ + S
nO ₂ ) or the like to provide conductivity, or synthetic resin film such as polyester film, NiCr, Al, Ag, Pb, Zn, N
i, Au, Cr, Mo, Ir, Nb, Ta, V, Tl,
A metal thin film such as Pt is provided on the surface by vacuum vapor deposition, electron beam vapor deposition, sputtering, or the like, or the surface is laminated with the metal to impart conductivity to the surface. The shape of the support may be a sheet having a smooth surface or an uneven surface. The thickness is appropriately determined so that a desired photovoltaic element can be formed, but when flexibility as a photovoltaic element is required, it is within a range in which the function as a support is sufficiently exhibited. It can be made as thin as possible. However, it is usually 10 μm or more in terms of mechanical strength and the like in terms of manufacturing and handling of the support.

In order to form a polycrystalline silicon layer on the surface of these supports, a non-single crystal silicon layer is formed on the supports by using plasma CVD method, thermal CVD method, photo CVD method, etc. Then, there is a method of recrystallization by melting with a heater, a laser, an electron beam or the like. (SOI structure formation technology, edited by Seijiro Furukawa, Sangyo Tosho) Also, fine holes or protrusions are provided on the support, and these are used as growth nuclei for plasma CVD method, thermal CVD method, optical C method.
There is also a method of laterally growing the polycrystalline silicon layer by the VD method. Further, these methods may be used together.

In order to increase the efficiency of collecting incident light, it is desirable to make the surface of the substrate into a pyramid-shaped unevenness (texture). To perform texture processing, 1
It may be dipped in a 60% hydrazine aqueous solution at 10 ° C. for about 10 minutes, or may be dipped in a 1% NaOH aqueous solution at 100 ° C. for about 5 minutes. First p (n) type layer (103, 123) The first p (n) type layer is an important layer that influences the characteristics of the photovoltaic element. The details of the case where the first p (n) type layer has a laminated structure are as described above, but the case where the first p (n) type layer is composed of a single layer will be described below.

The first p (n) type layer is made of a microcrystalline material (μc).
-), A polycrystalline material (poly-), or a single crystal material (c-). Examples of the microcrystalline material include μc-Si: H, μc-SiC: H, μc-S.
i: HX, μc-SiC: HX, μc-SiGe: H,
μc-SiO: H, μc-SiGeC: H, μc-Si
N: H, μc-SiON: HX, μc-SiOCN: H
And the like (X: halogen atom).

Examples of the polycrystalline material include poly-S.
i: H, poly-Si: HX, poly-SiC:
H, poly-SiC: HX, poly-SiGe:
H, poly-Si, poly-SiC, poly-S
iGe etc. are mentioned. As the crystal material, for example, c-
Si, c-SiC, c-SiGe, etc. are mentioned.

To make the conductivity type p-type, a p-type valence electron control agent (group III atom B, Al, Ga, In,
Tl) is added in high concentration. To make the conductivity type n-type, an n-type valence electron control agent (group V atom P, A in the periodic table) is used.
s, Sb, Bi or / and the periodic table group VI atom
S, Se, Te) is added in high concentration. The addition amount of the group III atom of the periodic table to the first p-type layer or the addition amount of the group V and VI atoms of the periodic table to the first n-type layer is 0.1.
An optimum amount is 10 at%.

Further, the first p (n) type layer is a microcrystalline material,
Alternatively, if it is composed of a polycrystalline material, the first p
Hydrogen atoms (H, D) or halogen atoms contained in the (n) type layer act to compensate dangling bonds in the p type layer or the n type layer and improve the doping efficiency. First
The optimum amount of hydrogen atoms or halogen atoms added to the p (n) type layer is 0 to 10 at%. A preferable distribution form is one in which the content of hydrogen atoms and / or halogen atoms is largely distributed near the p / substrate interface (n / substrate interface) and near the n / p interface (p / n interface). The content of hydrogen atoms and / or halogen atoms near the interface is preferably in the range of 1.3 to 2.5 times the content in the bulk. Thus, by increasing the content of hydrogen atoms or halogen atoms near the p / substrate interface (n / substrate interface) and near the n / p interface (p / n interface), the defect level near the interface and the inside of the layer The stress can be reduced, and further, the mechanical strain can be relaxed, and the photovoltaic power and the photocurrent of the photovoltaic device of the present invention can be increased.

Regarding the electrical characteristics of the first p (n) type layer of the photovoltaic element, the activation energy is preferably 0.2 eV or less, and most preferably 0.1 eV or less. The specific resistance is preferably 100 Ωcm or less, and 1 Ωcm
The following is optimal. Further, the layer thickness of the p-type layer and the n-type layer is 5
0 to 2000 A is preferable. As a method of forming the first p (n) type layer, there are a method of depositing a thin film layer on the substrate and a method of mixing impurities from the surface of the substrate into the inside.

As a method of forming a thin film layer on a substrate, there are a plasma CVD method, a thermal CVD method, an optical CVD method, and the like.
As a method for mixing impurities into the substrate, a gas diffusion method, a solid phase diffusion method, an ion implantation method, or the like is used, and a gas diffusion method or a plasma CVD method is particularly preferably used. When the first p (n) type layer is formed by the plasma CVD method, the raw material gas is a gasifiable compound containing a silicon atom, a gasifiable compound containing a carbon atom, or the like, and a mixed gas of the compounds. Etc. can be mentioned.

Specific examples of the gasifiable compound containing a silicon atom include the compound (Si) described above. Specific examples of the gasifiable compound containing a carbon atom include the compound (C) described above. Examples of the gasifiable compound containing a germanium atom include G
Examples thereof include compounds (generally abbreviated as “compound (Ge)”) such as eH ₄ , Ge ₂ H ₆ , and GeH _N X _4-N (X: halogen).

Examples of the nitrogen-containing gas include the compound (N) described above. Examples of the oxygen-containing gas include the compound (O) described above. Examples of compounds effectively used as a starting material for introducing a Group III atom include the compound (III) described above, and particularly B ₂ H ₆ ,
BF ₃ is suitable and these compounds are usually H ₂ , H
It is preferable to use it after diluting it with a gas such as e or Ar to a desired concentration.

Compounds (V) mentioned above can be effectively used as a starting material for introducing a Group V atom, and PH ₃ and PF ₅ are particularly suitable, and these compounds are usually used. It is diluted with a gas such as H ₂ , He or Ar to a desired concentration before use. Compounds (VI) described above can be effectively used as a starting material for introducing a Group VI atom, and H ₂ S is particularly suitable, and these compounds are usually H ₂ , He, Ar and the like. Dilute to the desired concentration with the above gas before use.

When the first p (n) type layer is formed by the plasma CVD method, the RF plasma CVD method and the microwave plasma CVD method are suitable. When depositing by the RF plasma CVD method, the capacitively coupled RF plasma CVD method is suitable. When depositing by the RF plasma CVD method,
The substrate temperature in the deposition chamber is 100 to 600 ° C., and the internal pressure is
0.1 to 10 Torr, RF power is 0.01 to 5.
The optimum condition is 0 W / cm ³ and the deposition rate is 0.1 to 30 A / sec.

The gasifiable compounds are H ₂ , H
It may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. Especially μc-Si: H, μc-S
iC: H, μc-Si: HX, μc-SiC: HX, μ
c-SiO: H, μc-SiN: H, μc-SiON:
HX, μc-SiOCN: HX, poly-Si: H,
poly-Si: HX, poly-SiC: H, pol
y-SiC: HX, poly-Si, poly-SiC
In the case of depositing a layer having a small light absorption at a short wavelength such as, it is preferable to dilute the raw material gas by 2 to 100 times with hydrogen gas and introduce a relatively high RF power. A suitable range of RF frequency is from IMHz to 100 MHz, and a frequency near 13.56 MHz is particularly suitable.

When depositing by the microwave plasma CVD method, the microwave plasma CVD apparatus has a dielectric window (alumina ceramics, quartz, boron nitride, etc.) 413 in the deposition chamber.
A method of introducing microwaves through a waveguide via a is suitable. The deposition film forming method most suitable for forming the i-type layer described above is also a suitable deposition method, but a deposition film applicable to a photovoltaic element can be formed under a wider deposition condition. That is,
The substrate temperature in the deposition chamber is 100 to 600 ° C., and the internal pressure is 0.5.
~ 30mTorr, microwave power 0.005-1
W / cm ³ , microwave frequency is 0.5 to 10 GHz
Is mentioned as a preferable range.

The gasifiable compounds are H ₂ , H
It may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. Especially μc-Si: H, μc-S
iC: H, μc-Si: HX, μc-SiC: HX, μ
c-SiO: H, μc-SiN: H, μc-SiON:
HX, μc-SiOCN: HX, poly-Si: H,
poly-Si: HX, poly-SiC: H, pol
y-SiC: HX, poly-Si, poly-SiC
In the case of depositing a layer having a small light absorption at short wavelengths such as, it is preferable to dilute the raw material gas 2 to 100 times with hydrogen gas and introduce a relatively high microwave power.

When the first p-type layer is formed by the gas diffusion method, the temperature of the n-type substrate is set to 800 to 950 ° C., the diffusion gas is introduced into the deposition chamber, and the group III atom of the periodic table is added to the substrate. Diffuse near the surface. Examples of the diffusion gas include the above-mentioned compound (III), particularly BCl ₃ , BBr ₃
Is suitable. These compounds may be diluted with a gas such as H ₂ , He or Ar to a desired concentration and then introduced.

When the first n-type layer is formed by the gas diffusion method, the temperature of the p-type substrate is set to 800 to 950 ° C., the diffusion gas is introduced into the deposition chamber, and the group V atom of the periodic table, or Group VI atoms are diffused near the substrate surface. As the diffusion gas, the above-mentioned compound (V) or compound (V
I) are mentioned, and POCl ₃ and P ₂ O ₅ are particularly suitable. These compounds may be diluted with a gas such as H ₂ , He or Ar to a desired concentration and then introduced.

When the first p-type layer is formed by the ion implantation method
In this case, the group III atom of the periodic table is accelerated under a high electric field,
Irradiate the surface of the n-type substrate and inject Group III atoms into the substrate.
To enter. For example, when implanting boron, 1 to 10 ×
10¹⁵(Pieces / cm²)of¹¹B ⁺5 to 50 keV
It is recommended to use acceleration voltage. First n-type layer by ion implantation
Form a group V atom or group VI of the periodic table
Irradiate n-type substrate surface by accelerating atoms under high electric field
Then, inject the group V atom or the group VI atom into the substrate.
To enter. For example, when injecting phosphorus, 0.5 to 10
× 10¹⁵(Pieces / cm²)of³¹P⁺About 1 to 10 keV
It is recommended to use the acceleration voltage of.

N (p) type layers (104, 124) and second
P (n) type layer (107, 127) The n (p) type layer and the second p (n) type layer are important layers that influence the characteristics of the photovoltaic element. The details of the case where the n (p) type layer and the second p (n) type layer have a laminated structure are as described above, but the n (p) type layer and the second p (n) type layer are single layers. The case of being composed of is described below.

N (p) type layer made of non-single crystal material, second
Examples of the p (n) -type layer include an amorphous material, a microcrystalline material, and a polycrystalline material. Examples of the amorphous material include a-Si: H, a-Si: HX, a-SiC: H, a-.
SiC: HX, a-SiGe: H, a-SiGeC: H
X, a-SiO: H, a-SiN: H, a-SiON:
HX, a-SiOCN: HX, etc. are mentioned.

As microcrystalline material, μc-Si: H, μc
-SiC: H, μc-Si: HX, μc-SiC: H
X, μc-SiGe: H, μc-SiO: H, μc-S
iGeC: H, μc-SiN: H, μc-SiON: H
X, μc-SiOCN: HX and the like. Examples of the polycrystalline material include poly-Si: H and poly-S.
i: HX, poly-SiC: H, poly-SiC:
HX, poly-SiGe: H, poly-Si, po
Examples thereof include ly-SiC and poly-SiGe.

To make the conductivity type p-type, a p-type valence electron control agent (group III atom B, Al, Ga, In, T of the periodic table) is used.
l) is added in high concentration in the above material. To make the conductivity type n-type, an n-type valence electron control agent (group V atom P in the periodic table,
As, Sb, Bi, Periodic Table, Group VI atoms S, Se, T
e) is added in high concentration in the above material.

In particular, for the second p (n) type layer, a microcrystalline material with little light absorption or a non-single crystalline material with a wide band gap, for example, μc-Si: H, μc-Si.
C: H, μc-Si: HX, μc-SiC: HX, μc
-SiO: H, μc-SiN: H, μc-SiON: H
X, μc-SiOCN: HX, poly-Si: H, p
poly-Si: HX, poly-SiC: H, poly
-SiC: HX, poly-Si, poly-SiC,
a-SiC: H, a-SiC: HX, a-SiO: H,
a-SiN: H, a-SiON: HX, a-SiOC
N: HX and the like are suitable.

Periodic table of the p-type layer and the second p-type layer I
The amount of the group II atom added and the amount of the group V atom and the group VI added to the n-type layer and the second n-type layer are 0.1 to 0.1
The optimum amount is 50 at%. Further, hydrogen atoms (H, contained in the n (p) type layer and the second p (n) type layer are included.
D) or a halogen atom serves to compensate dangling bonds and improves the doping efficiency.
At% may be mentioned as the optimum amount. Especially n (p) type layers,
When the second p (n) type layer is made of a microcrystalline material or a polycrystalline material, the hydrogen atom or the halogen atom is 0.1 to 10 at.
% Can be mentioned as the optimum amount. Further, a preferred distribution form is one in which the content of hydrogen atoms and / or halogen atoms is distributed in the vicinity of each interface in a large amount, and the content of hydrogen atoms and / or halogen atoms in the vicinity of the interface is A preferable range is 1.1 to 2 times the amount. By increasing the content of hydrogen atoms or halogen atoms in the vicinity of each interface in this manner, the defect level and the in-film stress near the interface can be reduced and the mechanical strain can be relaxed. It is possible to increase the photovoltaic power and the photocurrent of the power device.

Regarding the electric characteristics of the n (p) type layer and the second p (n) type layer, the activation energy is preferably 0.2 eV or less, and most preferably 0.1 eV or less. The specific resistance is preferably 100 Ωcm or less, and 1 Ωcm
The following is optimal. Further, the layer thickness of the n (p) type layer is 10 to 10.
1000A is preferred, 30-300A is optimal,
The layer thickness of the second p (n) type layer is preferably 10 to 500 A, and most preferably 30 to 200 A.

As a method of forming the n (p) type layer and the second p (n) type layer, there are a plasma CVD method, a thermal CVD method and an optical CV method.
The D method or the like is used, and the plasma CVD method is particularly preferably used. N (p) type layer by plasma CVD method, second p
When forming the (n) type layer, examples of the source gas include a gasifiable compound containing a silicon atom, a gasifiable compound containing a carbon atom, and a mixed gas of the compounds.

Specific examples of the gasifiable compound containing a silicon atom include the compound (Si) described above. Specific examples of the gasifiable compound containing a carbon atom include the compound (C) described above. Examples of the gasifiable compound containing a germanium atom include the compound (Ge) described above.

As the nitrogen-containing gas, the above-mentioned compound (N) can be mentioned. Examples of the oxygen-containing gas include the compound (O) described above. Compounds (III) described above can be cited as examples of compounds effectively used as a starting material for introducing a Group III atom. Especially B
₂ H ₆ and BF ₃ are suitable.

Compounds (V) described above can be effectively used as a starting material for introducing a Group V atom. Particularly, PH ₃ and PF ₅ are suitable. The compound (VI) described above is effectively used as a starting material for introducing a Group VI atom. The deposition method preferably used as the plasma CVD method is RF plasma CVD.
Method and microwave plasma CVD method. When deposited by the RF plasma CVD method, capacitively coupled RF plasma C
The VD method is suitable.

When depositing by the RF plasma CVD method,
The substrate temperature in the deposition chamber is 100 to 450 ° C., and the internal pressure is
0.1 ~ 10Torr RF power is 0.01 ~ 5.0W
/ Cm ²The optimum deposition rate is 0.1-30 A / sec.
It is mentioned as a matter. The frequency of RF is from 1MHz
100MHz is a suitable range, especially 13.56MH
Frequencies near z are optimal.

Further, the gasifiable compound is replaced by H ₂ , H
It may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. In particular, μc-Si: H, μc-
SiC: H, μc-Si: HX, μc-SiC: HX,
μc-SiO: H, μc-SiN: H, μc-SiO
N: HX, μc-SiOCN: HX, poly-Si:
H, poly-Si: HX, poly-SiC: H, p
poly-SiC: HX, poly-Si, poly-S
iC: H, a-SiC: H, a-SiC: HX, a-S
iO: H, a-SiN: H, a-SiON: HX, a-
When depositing a microcrystalline layer such as SiOCN: HX with little light absorption, a polycrystalline layer, or an amorphous layer having a wide band gap, the raw material gas is diluted with hydrogen gas 2 to 100 times, and R
It is preferable to introduce a relatively high power as the F power.

When depositing by the microwave plasma CVD method, the microwave plasma CVD apparatus is preferably a method of introducing microwaves into the deposition chamber through a dielectric window by a waveguide. A deposition film forming method most suitable for forming the i-type layer is also a suitable deposition method, but a deposition film applicable to a photovoltaic element can be formed under a wider deposition condition. That is, the substrate temperature in the deposition chamber is 100 to 400 ° C., and the internal pressure is 0.5 to 30.
mTorr, microwave power 0.005-1 W / c
The preferable range of m ³ and microwave frequency is 0.5 to 10 GHz.

Further, the gasifiable compound is replaced by H ₂ , H
It may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. In particular, μc-Si: H, μc-
SiC: H, μc-Si: HX, μc-SiC: HX,
μc-SiO: H, μc-SiN: H, μc-SiO
N: HX, μc-SiOCN: HX, poly-Si:
H, poly-Si: HX, poly-SiC: H, p
poly-SiC: HX, poly-Si, poly-S
iC, H, a-SiC: H, a-SiC: HX, a-S
iO: H, a-SiN: H, a-SiON: HX, a-
When depositing a microcrystalline layer such as SiOCN: HX with little light absorption, a polycrystalline layer, or an amorphous layer with a wide bandgap, dilute the source gas 2 to 100 times with hydrogen gas and compare the microwave power. It is preferable to introduce an extremely high power.

I-Type Layer (106, 125) In the photovoltaic device of the present invention, the i-type layer is the most important layer for generating and transporting carriers with respect to irradiation light.
As the i-type layer, slightly p-type and slightly n-type layers can be used. The i-type layer of the photovoltaic element of the present invention contains silicon atoms and carbon atoms, and the band gap smoothly changes in the layer thickness direction of the i-type layer, and the position of the minimum value of the band gap is i-type. It is offset in the p / i interface (i / p interface) direction from the center position of the layer.
Further, it is preferable that both the valence electron control agent serving as a donor and the valence electron control agent serving as an acceptor are doped.

The hydrogen atom (H, D) or halogen atom (X) contained in the i-type layer serves to compensate dangling bonds of the i-type layer, and the mobility and life of carriers in the i-type layer. To improve the product of It also works to compensate the interface states of the p / i interface (i / p interface) and the i / Si interface (Si / i interface), and improves the photovoltaic power, photocurrent and photoresponsiveness of the photovoltaic device. It has the effect of The number of hydrogen atoms and / or halogen atoms contained in the i-type layer is 1 to 3
The optimum content is 0 at%.

Particularly, p / i interface (i / p interface), i / S
A preferable distribution form is one in which the content of hydrogen atoms and / or halogen atoms is largely distributed near the i interface (Si / i interface), and the content of hydrogen atoms and / or halogen atoms near the interface is mentioned. The preferable range is 1.1 to 2 times the content in the bulk.
Further, it is preferable that the content of hydrogen atoms and / or halogen atoms is changed contrary to the increase or decrease of the content of silicon atoms. When the content of silicon atoms is maximum, the content of hydrogen atoms or halogen atoms is 1 to
A preferable range is 10 at%, and a preferable range is 0.3 to 0.8 times the maximum region of the content of hydrogen atoms and / or halogen atoms.

In the i-type layer of the photovoltaic element of the present invention, it is desirable that the content of hydrogen atoms and / or halogen atoms is small where the number of silicon atoms is large, and is large where the number of silicon atoms is small. That is, corresponding to the band gap, the content of hydrogen atoms and / or halogen atoms is small when the band gap is narrow, and hydrogen atoms and / or where the band gap is wide.
Also, it is desirable that the content of halogen atoms is large. Although the details of the mechanism are unknown, according to the deposited film forming method of the present invention, in the deposition of the alloy-based semiconductor containing silicon atoms and carbon atoms, the difference in ionization rate between silicon atoms and carbon atoms causes It is considered that there is a difference in the RF energy acquired by the atoms, and as a result, even if the hydrogen-containing content and / or the halogen-containing content in the alloy-based semiconductor is small, the relaxation is sufficiently advanced and a good-quality alloy-based semiconductor can be deposited.

In addition, by adding a small amount of oxygen and / or nitrogen of 100 ppm or less to the i-type layer containing silicon atoms and carbon atoms, the durability of the photovoltaic element against annealing due to long-term vibration is improved. It will be. The reason for this is unknown in detail, but since the composition ratio of silicon atoms and carbon atoms changes continuously in the layer thickness direction, it is better than when silicon atoms and carbon atoms are mixed at a constant ratio. It is considered that the residual strain tends to increase. By adding oxygen atoms and / or nitrogen atoms to such a system, structural strain can be reduced, and as a result, durability of the photovoltaic element against annealing due to long-term vibration is improved. it is conceivable that. As the distribution of oxygen atoms and / or nitrogen atoms in the layer thickness direction, a distribution that increases or decreases according to the content of silicon atoms is preferable. This distribution is the opposite of the distribution of hydrogen atoms and / or halogen atoms, but it is considered that such distribution is preferable because of the effect of removing structural strain and the effect of reducing unbonded hands. .

Furthermore, by distributing such hydrogen atoms (or / and halogen atoms) and oxygen atoms (or / and nitrogen atoms), the tail states of the valence band and the conduction band are smoothly and continuously connected. Is. i
The layer thickness of the type layer largely depends on the structure of the photovoltaic element (for example, single cell, tandem cell, triple cell) and the bandgap of the i-type layer, but 0.05 to 1.0 μm is mentioned as the optimum layer thickness. To be

The i-type layer containing silicon atoms and carbon atoms formed by the above-described deposited film forming method has a deposition rate of 2.5 m.
Even if it is increased to n / sec or more, the tail state on the valence band side is small, and the tilt of the tail state is 60 m.
It is eV or less, and the density of end bonds by electron spin resonance (ESR) is 10 ¹⁷ / cm ³ or less. The band gap of the i-type layer is from the bulk toward the p / i interface (i / p interface) and / or the i / Si interface (Si / i
It is preferable to design so as to widen toward the interface). By designing in this way, the photovoltaic power and photocurrent of the photovoltaic device can be increased,
Further, it is possible to control a decrease in photoelectric conversion efficiency (photodegradation) and the like when light is irradiated for a long time.

Si layer (105, 126) In the photovoltaic element of the present invention, the Si layer is an important layer for efficiently transporting the generated carriers. As the conductivity type of the Si layer, an i-type layer, slightly p-type, and slightly n-type can be used. Si only between the n-type layer and the i-type layer or between the i-type layer and the second n-type layer as shown in FIGS. 1-a and 1-b.
If there is a layer, it may be i-type or slightly n-type. Further, as shown in FIG. 19, between the n-type layer and the i-type layer and the second
When there is a Si layer between both the p-type layer and the i-type layer, it is desirable that the conductivity type of the former Si layer (first Si layer) is i-type or slightly n-type. The conductivity type of the Si layer (second Si layer) is preferably i-type or slightly p-type.

As the Si layer of the photovoltaic element of the present invention,
Contains silicon atoms, a-Si: H, a-S
i: HX, a-SiGe: H, a-SiGe: HX, a
-SiO: H, a-SiN: H, a-SiON: HX, etc. are mentioned, and a-Si: H and a-Si: HX are most suitable. A hydrogen atom (H, D) or a halogen atom (X) contained in the Si layer serves to compensate for a dangling bond of the Si layer and improves the product of carrier mobility and lifetime in the Si layer. Is. Also, i / Si interface (Si / i interface), S
It has a function of compensating the interface order of each interface of the i / n interface (n / Si interface), and has an effect of improving the photovoltaic power, the photocurrent and the photoresponsiveness of the photovoltaic device. The hydrogen atoms and / or halogen atoms contained in the Si layer are 1 to 3
The optimum content is 0 at%.

In particular, in the Si layer near the i / Si interface (Si / i interface) and near the Si / n interface (n / Si interface), those having a large content of hydrogen atoms and / or halogen atoms are distributed. It is mentioned as a preferable distribution form, and the content of hydrogen atoms and / or halogen atoms in the vicinity of the interface is preferably in the range of 1.1 to 2 times the content of the bulk hand. Further, it is preferable that the content of hydrogen atoms and / or halogen atoms is changed contrary to the increase or decrease of the content of silicon atoms. The content of hydrogen atoms and / or halogen atoms at the maximum content of silicon atoms is preferably 1 to 10 at%,
A preferable range is 0.3 to 0.8 times the maximum region of the content of hydrogen atoms and / or halogen atoms.

In addition, 1 and oxygen and / or nitrogen are added to the Si layer.
The addition of 0.00 ppm or less improves the durability against annealing due to long-term vibration of the photovoltaic element. Although the cause thereof is not known in detail, the composition ratio of the i-type layer containing silicon atoms and carbon atoms and the second p-type layer (p-type layer) is drastically different. It is considered that the residual strain tends to increase. By adding oxygen atoms and / or nitrogen atoms to such a system, structural strain can be reduced, and as a result, durability of the photovoltaic element against annealing due to long-term vibration is improved. it is conceivable that. The distribution of oxygen atoms and / or nitrogen atoms in the layer thickness direction is from the i / Si interface (Si / i interface) to S
A distribution that decreases toward the i / n interface (n / Si interface) is preferred.

Furthermore, by distributing such hydrogen atoms (or / and halogen atoms) and oxygen atoms (or / and nitrogen atoms), the tail states of the valence band and the conduction band are smoothly and continuously connected. Is. S
The layer thickness of the i layer is a demanded factor in the photovoltaic device of the present invention, and the optimum thickness is 30 nm or less.

The deposition rate of the Si layer is an important factor in the photovoltaic device of the present invention, and the optimum deposition rate is 2 nm / sec or less. Further, the RF plasma CVD method is the most suitable method for depositing the Si layer, but an optical CVD method can also be used. When depositing the Si layer using the RF plasma CVD method, capacitively coupled RF plasma CV
Method D is suitable.

When depositing by the RF plasma CVD method,
The substrate temperature in the deposition chamber is 100 to 450 ° C., and the internal pressure is
0.1-10 Torr, RF power 0.005-
The optimum condition is 0.1 W / cm ² . The suitable range of the RF frequency is 1 MHz to 100 MHz, and a frequency near 13.56 MHz is particularly suitable.

Specific examples of the source gas include the compounds (Si) described above as the gasifiable compounds containing silicon atoms. As the gasifiable compound containing a germanium atom, the above-mentioned compound (Ge)
Is mentioned. Examples of the nitrogen-containing gas include the compound (N) described above.

As the oxygen-containing gas, the above-mentioned compound (O) can be mentioned. Examples of the substance introduced to make the conductivity type slightly p-type include Group III elements in the periodic table, and examples of the substance introduced to make the conductivity type slightly n-type are Periodic Table V Group atoms or / and Group VI atoms are included. Compounds (II) mentioned above are effectively used as starting materials for introducing a Group III atom.
I) can be mentioned. B ₂ H ₆ and BF ₃ are particularly suitable.

Compounds (V) described above can be effectively used as starting materials for introducing a Group V atom. Particularly, PH ₃ and PF ₆ are suitable. The compound (VI) described above is effectively used as a starting material for introducing a Group VI atom. Further, the gasifiable compound may be appropriately diluted with a gas such as H ₂ , He, Ne, Ar, Xe, and Kr and introduced into the deposition chamber.

When the Si layer is deposited by the photo CVD method, the substrate temperature in the deposition chamber is 100 to 450 ° C., the internal pressure is 0.1 to 10 Torr, the light source is a low pressure mercury lamp, or an ArF excimer laser. In addition, the deposition rate may be increased by introducing a very small amount of mercury (Hg) into the deposition chamber. As the raw material gas, specifically, as a gasifiable compound containing a silicon atom,
The compound (Si) mentioned above is mentioned. In this case, when a low-pressure mercury lamp is used as a light source, higher order silanes such as Si ₂ H ₆ and Si ₂ H _n X _6-n (X: halogen) are suitable.

Examples of the gasifiable compound containing a germanium atom include the compound (Ge) described above. In this case, when using a low-pressure mercury lamp as the light source,
Higher order germanes such as Ge ₂ H ₆ are suitable. Examples of the nitrogen-containing gas include the compound (N) described above. Examples of the oxygen-containing gas include the compound (O) described above.

The substance introduced to make the conductivity type slightly p-type includes a group III element atom of the periodic table, and the substance introduced to make the conductivity type slightly n-type is the periodic Table Group V atoms and / or Group VI atoms are included. The compound (III) described above is effectively used as a starting material for introducing a Group III atom.
Can be mentioned. B ₂ H ₆ and BF ₃ are particularly suitable.

Compounds (V) described above can be effectively used as a starting material for introducing a Group V atom. Particularly, PH ₃ and PF ₅ are suitable. The compound (VI) described above is effectively used as a starting material for introducing a Group VI atom. Further, the gasifiable compound may be appropriately diluted with a gas such as H ₂ , He, Ne, Ar, Xe, and Kr and introduced into the deposition chamber.

The Si layer of the present invention has a small tail state on the valence band side, and the tail state has an inclination of 5
The density is 5 mev or less, and the density of end bonds by electron spin resonance (ESR) is 10 ¹⁷ / cm ³ or less. It is preferable that the peak half-width of 2000 cm ⁻¹ , which represents the state in which one hydrogen atom is bonded to the silicon atom of the Si layer of the present invention, is small.

Transparent Electrodes (108, 128) As transparent electrodes, indium oxide and indium-tin oxide transparent electrodes are suitable. The sputtering method and the vacuum evaporation method are the most suitable deposition methods for depositing the transparent electrode.
The transparent electrode is deposited as follows.

In the sputtering apparatus, indium
When depositing a transparent electrode made of oxide on a substrate,
Get is metallic indium (In) or indium oxide
(In ₂O₃) Etc. are used. Further Inn
Deposition of transparent electrode made of di-tin oxide on the substrate
If the target is metallic tin, metallic indium or gold
Genus tin and metal indium alloy, tin oxide, indium
Target such as aluminum oxide, indium-tin oxide
Used in combination as appropriate.

When depositing by the sputtering method, the substrate temperature is an important factor, and 25 ° C. to 600 ° C. is mentioned as a preferable range. When depositing a transparent electrode by a sputtering method, as a gas for sputtering,
Examples of the inert gas include argon gas (Ar), neon gas (Ne), xenon gas (Xe), and helium gas (He), and Ar gas is most suitable. Further, it is preferable to add oxygen gas (O ₂ ) to the inert gas as needed. Especially when a metal is used as a target, oxygen gas (O ₂ ) is essential.

Further, when the target is sputtered with the inert gas or the like, the pressure in the discharge space is 0.1 to 50 mTorr in order to effectively sputter.
Is mentioned as a preferable range. In addition, a DC power supply or an RF power supply is suitable as a power supply for the sputtering method. A suitable power range for the sputtering is 10 to 1000 W.

The deposition rate of the transparent electrode depends on the pressure in the discharge space and the discharge power, and the optimum deposition rate is 0.0
It is in the range of 1 to 10 nm / sec. The layer thickness of the transparent electrode is preferably deposited under conditions that satisfy the conditions of the antireflection film. As a specific layer thickness of the transparent electrode, 50 to 300 nm is mentioned as a preferable range.

Suitable vapor deposition sources for depositing transparent electrodes in the vacuum vapor deposition method include metal tin, metal indium, and indium-tin alloy. Moreover, the range of 25 ° C. to 600 ° C. is a suitable range for the substrate temperature when depositing the transparent electrode. Further, when depositing the transparent electrode, the pressure in the deposition chamber is reduced to 10 ⁻⁶ Torr or less and then oxygen gas (O 2
It is necessary to introduce ₂ ) into the deposition chamber in the range of 5 × 10 ⁻⁵ Torr to 9 × 10 ⁻⁴ Torr.

By introducing oxygen in this range, the metal vaporized from the vapor deposition source reacts with oxygen in the vapor phase to deposit a good transparent electrode. Further, RF power may be introduced at the vacuum degree to generate plasma, and vapor deposition may be performed through the plasma. The preferable deposition rate range of the transparent electrode under the above conditions is 0.01 to 10 nm / se.
c. If the deposition rate is less than 0.01 nm / sec, the productivity will be reduced, and if it is more than 10 nm / sec, a rough film will be formed and the transmittance, the conductivity and the adhesion will be reduced.

Backside Electrodes (101, 121) The backside electrodes are Ni, Au, Ti, Pd, Ag, A.
A metal such as 1, Cu, AlSi or the like, which has a high reflectance from visible light to near infrared and can form a good ohmic contact with silicon, or an alloy thereof is suitable. These metals are preferably formed by a vacuum vapor deposition method, a sputtering method, a plating method, a printing method, or the like.

For example, when the film is formed by the vacuum evaporation method, n
Type silicon substrate, Ti-Ag or Ti-Pd
-Ag or Ti-Ni-Cu is suitable, and Al is suitable for the p-type silicon substrate. When the plating method is used, Ni, Al, or Cr is suitable. Further, by performing a sintering process at 300 ° C. to 800 ° C. after the plating process, a better ohmic contact can be obtained, The interface level existing at the interface of can be reduced. Further, Cu may be finally plated in order to reduce the series resistance of the electrodes.

In the case of forming by a printing method, an Ag paste is printed on an n-type silicon substrate and an Al paste is printed on a p-type silicon substrate by a screen printing machine, and thereafter, sintering is performed to obtain a good result. Get contacts.
The layer thickness of these metals is 10 nm to 5000 nm
Is mentioned as a suitable layer thickness. In order to make the surface of the back surface electrode uneven (textured), the temperature of the substrate at the time of deposition is set to 200 ° C. or higher in the case of the vacuum deposition method, and after the back surface electrode is deposited in the case of the plating method or the printing method. Thermal annealing may be performed by setting the substrate temperature to 200 ° C. or higher.

Collecting Electrode (109, 129) The material and forming method of the collecting electrode are basically the same as those of the back electrode. However, i, which is the photovoltaic layer
The shape of the collector electrode (the shape as viewed from the incident direction of light) and the material are important for efficiently injecting light into the mold layer and efficiently collecting the generated carriers in the electrode.

Usually, a comb-shaped collector electrode is used, and the line width and the number of wires are determined by the shape and size of the photovoltaic element viewed from the light incident direction, the size of the collector electrode, and the like. To be done. The line width is usually about 0.1 mm to 5 mm. As the material, Ag, Cu, Al, Cr or the like having a low specific resistance is usually used. Next, the power generation system of the present invention will be described with reference to the drawings.

A system using the photovoltaic element of the present invention is a photovoltaic element of the present invention and the photovoltaic element for a storage battery and / or an external load, which monitors the voltage and / or current of the photovoltaic element. It comprises a control system for controlling the supply of electric power from the electric power element, and a storage battery for accumulating electric power from the photovoltaic element and / or supplying electric power to an external load.

FIG. 18 shows an example of the power supply system of the present invention, which is a basic circuit for charging and power supply using a photovoltaic element. In this circuit, the photovoltaic element of the present invention is used as a solar cell module and a backflow prevention diode (C
D), a voltage control circuit (constant voltage circuit) that monitors the voltage and controls the voltage, a storage battery, a load, and the like.
A germanium diode, a silicon diode, a Schottky diode, or the like is suitable as the backflow prevention diode. As the storage battery, nickel cadmium battery,
Rechargeable silver oxide batteries, lead-acid batteries, flywheel energy storage units and the like can be mentioned.

The voltage control circuit is approximately equal to the output of the solar battery until the battery is fully charged, but when the battery is fully charged, the charging current is stopped by the charging control IC. Such a solar cell system using photovoltaic power can be used as a power source for a battery charging system for automobiles, a battery charging system for ships, a streetlight lighting system, an exhaust system, and the like.

As described above, the power supply system using the photovoltaic element of the present invention as a solar cell can be used stably for a long period of time, and even when the irradiation light contrasted with the solar cell varies. Since it sufficiently functions as an electromotive force element, it exhibits excellent stability.

[0171]

EXAMPLES Hereinafter, the electromotive element of the present invention will be described in detail by producing a solar cell, but the present invention is not limited thereto. (Example 1) First, n produced by the casting method
The solar cell of FIG. 1-a was produced using a mold-type polycrystalline silicon substrate.

A 50 × 50 m ² substrate having a thickness of 500 μm was dipped in an aqueous solution of HF and HNO ₃ (diluted to 10% with H ₂ O) for several seconds and washed with pure water. Next, it was ultrasonically cleaned with acetone and perisopropanol, further washed with pure water, and dried with warm air. Next, a semiconductor layer was formed on the substrate by the manufacturing apparatus using the glow discharge decomposition method including the source gas supply device 2000 and the deposition device 400 shown in FIG. The manufacturing procedure will be described below.

In the gas cylinders 2041 to 2047 in the figure
Is the source gas for producing the photovoltaic element of the present invention.
Sealed, 2041 is SiH_FourGas (purity 99.
999%) cylinder, CH 2042_FourGas (purity 99.
9999%) cylinder, 2043 is H₂Gas (purity 99.
9999%) cylinder, 2044 is H₂100pp with gas
PH diluted to m₃Gas (purity 99.99%, below
"PH₃/ H₂Cylinder, 2045 is H₂
B diluted to 100 ppm with gas₂H₆Gas (purity 9
9.99%, below "B₂H₆/ H₂Abbreviated as ") Bon
2046 is H ₂NH diluted to 1% with gas₃gas
(Purity of 99.9999%, hereinafter "NH₃/ H₂"
Cylinder, 2047 was diluted to 1% with He gas
O₂Gas (purity 99.9999%, hereinafter "O₂/ He "
It is a cylinder. Gas cylinder 2041 in advance
~ 2047 when installing each gas, valve 2
Adjust the pressure by introducing it into the gas pipe from 021 to 2027.
Each gas pressure is set to 2 Kg / cm by the vessels 2031 to 2037.
²Adjusted to.

Next, the back surface of the substrate 404 is heated by the heater 4
05, the leak valve 409 of the deposition chamber 401 is closed, the conductance valve 407 is fully opened, the inside of the deposition chamber 401 is evacuated by a vacuum pump (not shown), and the reading of the vacuum gauge 402 is about 1 × 10 ^−4. At the time of Torr, the valves 2001 to 2007 and the auxiliary valve 408 are opened to evacuate the inside of the gas pipe, and when the reading of the vacuum gauge 402 becomes about 1 × 10 ⁻⁴ Torr, the valve 200
1 to 2007 are closed, 2031 to 2037 are gradually opened, and each gas is mass flow controller 2011 to
It was introduced in 2071.

After the preparation for film formation is completed as described above, the substrate is subjected to hydrogen plasma treatment, and then the substrate 404.
A first p-type layer, an n-type layer, a Si layer, an i-type layer, and a second p-type layer were formed thereon. First, to perform the hydrogen plasma treatment, the valve 2003 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the H ₂ gas flow rate to 500 sccm. Adjusting the conductance valve while observing the vacuum gauge 402 so that the pressure in the deposition chamber becomes 2.0 Torr, and heating the heater 4 so that the temperature of the substrate 404 becomes 550 ° C.
05 is set, and it is confirmed that the shutter 415 is closed when the substrate temperature becomes stable.
W) The power supply was set to 0.20 W / cm ³ , and μW power was introduced to cause glow discharge, the shutter 415 was opened, and hydrogen plasma treatment of the substrate was started. After 10 minutes, the shutter was closed, the μW power supply was turned off, the glow discharge was stopped, and the hydrogen plasma treatment was completed. After continuously flowing H ₂ gas into the deposition chamber 401 for 5 minutes, the valve 20
03 was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, in order to form the first p-type layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller is set so that the H ₂ gas flow rate becomes 50 sccm. Adjusted in 2013. Adjusting the conductance valve while watching the vacuum gauge 402 so that the pressure in the deposition chamber becomes 2.0 Torr, and setting the heater 405 so that the temperature of the substrate 404 becomes 350 ° C., the substrate temperature is stable. Valve 200
1, 2005 gradually open, SiH ₄ gas, B ₂ H ₆
/ H ₂ gas was caused to flow into the deposition chamber 401. At this time, S
iH ₄ gas flow rate is 5 sccm, H ₂ gas flow rate is 100 s
It was adjusted with each mass flow controller so that ccm and B ₂ H ₆ / H ₂ gas became 500 sccm. The opening of the conductance valve 407 was adjusted while observing the vacuum gauge 402 so that the pressure in the deposition chamber 401 was 2.0 Torr. Make sure the shutter 415 is closed, set the RF power supply to 0.20 W / cm ³ , and
Shutter 41 is generated by introducing electric power to cause glow discharge.
5 was opened and the formation of the first p-type layer on the substrate was started. After the first p-type layer having a layer thickness of 100 nm was prepared, the shutter was closed, the RF power was turned off, the glow discharge was stopped, and the first
The formation of the p-type layer was completed. The valves 2001 and 2005 are closed, and SiH ₄ gas, B ₂ H ₆ /
Stopping the flow of H ₂ gas for 5 minutes, H ₂ into the deposition chamber 401
After continuing to flow the gas, the valve 2003 was closed and the inside of the deposition chamber 401 and the gas pipe were evacuated.

To form the n-type layer, the auxiliary valve 40
8, gradually open the valve 2003, H₂Gas to gas
It is introduced into the deposition chamber 401 through the inlet pipe 411, and H₂gas
Mass flow control so that the flow rate is 50 sccm
Ra 2013 is set and the pressure in the deposition chamber is 1.0 Tor.
Adjust the conductance valve to r
Heater 405 so that the temperature of 04 becomes 350 ° C.
It was set. When the substrate temperature is stable,
Open 2001 and 2004 gradually to SiH_FourGas, P
H₃/ H₂Gas was flowed into the deposition chamber 401. this
Sometimes SiH_FourGas flow rate is 2 sccm, H₂Gas flow rate is 1
00sccm, PH₃/ H₂Gas flow rate is 200 sccm
Adjust with each mass flow controller so that
It was The pressure in the deposition chamber 401 will be 1.0 Torr.
Thus, the opening of the conductance valve 407 was adjusted. R
The power of F power source is 0.01W / cm³ Set to RF electrode
Introduce RF power to 410 to cause glow discharge and
Open the shutter and start making the n-type layer on the first p-type layer
The n-type layer with a layer thickness of 30 nm was produced, and the shutter was released.
Closed, RF power turned off, glow discharge stopped, n-type
Finished forming layers. Close the valves 2001 and 2004
SiH into the deposition chamber 401_FourGas, PH₃/ H ₂Moth
Stop the flow of gas into the deposition chamber 401 for 5 minutes.₂Gas
After continuing the flow, the outflow valve 2003 is closed and the deposition chamber 4
The inside of 01 and the inside of the gas pipe were evacuated.

To form the Si layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401 through the introduction pipe 411, and the mass flow controller 2013 is set so that the H ₂ gas flow rate is 50 sccm. Then, the pressure inside the deposition chamber was adjusted to 1.5 Torr by a conductance valve, and the heater 405 was set so that the temperature of the substrate 404 became 270 ° C. When the substrate temperature became stable, the valve 2001 was gradually opened to allow SiH ₄ gas to flow into the deposition chamber 401. At this time, the SiH ₄ gas flow rate is ₂ sccm and the H ₂ gas flow rate is 1 sc
It was adjusted with each mass flow controller so as to be 00 sccm. The pressure in the deposition chamber 401 is 1.5 To
The opening of the conductance valve 407 was adjusted so as to be rr. The power of the RF power source was set to 0.01 W / cm ³ , RF power was introduced to the RF electrode 410 to cause glow discharge, the shutter was opened, the production of the Si layer on the n-type layer was started, and the deposition rate was 0. 0.15 nm / sec, layer thickness 10 nm
After the Si layer was produced, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the Si layer was completed. The valve 2001 is closed, and Si in the deposition chamber 401
The flow rate of H ₄ gas was stopped and H _{2 was} introduced into the deposition chamber 401 for 5 minutes.
After continuing to flow the gas, the outflow valve 2003 was closed and the inside of the deposition chamber 401 and the gas pipe were evacuated.

Next, to prepare the i-type layer, the valve 20 was used.
Open 03 gradually, H₂Introduce gas into deposition chamber 401
And H₂The mass flow should be 300sccm.
Adjusted with the low controller 2013. Deposition chamber pressure
With a conductance valve so that it becomes 0.01 Torr
Adjust and heat the substrate 404 to 350 ° C
Set the heater 405 and make sure the substrate temperature is stable.
Further, the valves 2001 and 2002 are gradually opened to set the Si
H_FourGas, CH_FourGas was flowed into the deposition chamber 401.
At this time, SiH_FourGas flow rate is 100 sccm, CH_FourBut
Flow rate 30 sccm, H₂Gas flow rate is 300sccm
Adjust with each mass flow controller so that
It was The pressure in the deposition chamber 401 will be 0.01 Torr.
Thus, the opening of the conductance valve 407 was adjusted. Next
The power of the RF power supply 403 is 0.40 W / cm³Set to
Then, it was applied to the RF electrode 403. After that, μW not shown
The power of the power supply is 0.20 W / cm³Set the dielectric window 41 to
ΜW power is introduced into the deposition 401 through
Electricity is generated, the shutter is opened, and the i-type layer on the Si layer
Production was started. Connect to mass flow controller
Flow rate change pattern shown in FIG.
According to SiH_FourGas, CH_FourChange the flow rate of gas
When an i-type layer having a layer thickness of 300 nm was produced,
And turn off the μW power to stop glow discharge,
The F power supply 403 was turned off, and the production of the i-type layer was completed. Valve 2
001 and 2002 are closed, and SiH enters the deposition chamber 401.
_FourGas, CH _FourStop gas inflow, deposit chamber 40 for 5 minutes
1 into H₂Close the valve 2003 after continuing to flow the gas.
Then, the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, in order to form the second p-type layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller is set so that the H ₂ gas flow rate becomes 50 sccm. Adjusted in 2013. The pressure in the deposition chamber was adjusted to 2.0 Torr by a conductance valve, the heater 405 was set so that the temperature of the substrate 404 was 200 ° C., and the temperature of the substrate was stabilized. 2005 is gradually opened, SiH ₄ gas, CH ₄ gas, B ₂ H ₆ / H
_Two gases were allowed to flow into the deposition chamber 401. At this time, SiH
₄ gas flow rate is 1 sccm, CH ₄ gas flow rate is 0.5 sc
cm, H ₂ gas flow rate is 100 sccm, B ₂ H ₆ / H ₂
Each mass flow controller adjusted the gas flow rate to 100 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 2.0 Torr. RF power supply 0.20 W / cm
Setting to ³ , RF power was introduced to cause glow discharge, the shutter 415 was opened, and formation of the second p-type layer on the i-type layer was started. When the second p-type layer having a layer thickness of 10 nm was produced, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the second p-type layer was completed. Valve 2
001, 2002, 2005 are closed to stop the inflow of SiH ₄ gas, CH ₄ gas, and B ₂ H ₆ / H ₂ gas into the deposition chamber 401, and continue to flow H ₂ gas into the deposition chamber 401 for 5 minutes. After that, the valve 2003 was closed, the deposition chamber 401 and the gas pipe were evacuated, the auxiliary valve 408 was closed, the leak valve 409 was opened, and the deposition chamber 401 was leaked.

Next, a transparent electrode was formed on the second p-type layer.
The thickness of the ITO (In₂O ₂+ SnO₂)
Vacuum deposition was performed by a normal vacuum deposition method. Then silver on the transparent electrode
(Ag) layer thickness 5μm current collector electrode by normal vacuum evaporation
It was vacuum-deposited by the method. Next, if the Ag-Ti alloy is
The backside electrode with a layer thickness of 3 μm consisting of
It was vapor-deposited.

This is the end of the production of this solar cell. This solar cell will be referred to as (SC Ex 1), and Table 1 shows the manufacturing conditions of the first p-type layer, the n-type layer, the Si layer, the i-type layer, and the second p-type layer. (Comparative Example 1-1) The same conditions as in Example 1 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were adjusted by the respective mass flow controllers according to the flow rate pattern shown in FIG. 6 when forming the i-type layer. A solar cell was manufactured by the same procedure. This solar cell will be referred to as (SC ratio 1-1).

(Comparative Example 2) When forming an i-type layer, μW
A solar cell was manufactured under the same conditions and the same procedure as in Example 1 except that the power was 0.5 W / cm ³ . This solar cell will be called (SC ratio 1-2). (Comparative Example 1-3) A solar cell was manufactured under the same conditions and the same procedure as in Example 1 except that the RF power was 0.15 W / cm ³ when forming the i-type layer. This solar cell will be called (SC ratio 1-3).

Comparative Example 1-4 When forming the i-type layer,
μW power 0.5 W / cm ³ , RF power 0.55 W /
A solar cell was produced under the same conditions and the same procedure as in Example 1 except that the solar cell was set to cm ³ . This solar cell (SC ratio 1-4)
I will call it. (Comparative Example 1-5) A solar cell was manufactured under the same conditions and the same procedure as in Example 1 except that the pressure in the deposition chamber was set to 0.08 Torr when forming the i-type layer. This solar cell will be called (SC ratio 1-5).

(Comparative Example 1-6) When forming a Si layer,
A solar cell was produced under the same conditions and the same procedure as in Example 1 except that the deposition rate was 3 nm / sec. This solar cell will be referred to as (SC ratio 1-6). (Comparative Example 1-7) When forming the Si layer, the layer thickness is set to 40 n.
A solar cell was manufactured under the same conditions and the same procedure as in Example 1 except that the thickness was changed to m. This solar cell will be called (SC ratio 1-7).

The produced solar cells (SC Ex 1) and (S
The initial light conversion efficiency (photovoltaic power / incident light power) and durability characteristics of C ratio 1-1) to (SC ratio 1-7) were measured.
For the measurement of the initial photoelectric conversion efficiency,
Installed under -1.5 (100 mW / cm ² ) light irradiation,
It is obtained by measuring the V-1 characteristic. As a result of the measurement, for the solar cell of (SC Ex 1), (SC ratio 1-
The initial photoelectric conversion efficiencies of 1) to (SC ratio 1-7) were as follows.

(SC ratio 1-1) 0.88 times (SC ratio 1-2) 0.63 times (SC ratio 1-3) 0.80 times (SC ratio 1-4) 0.65 times (SC ratio 1-5) 0.77 times (SC ratio 1-6) 0.70 times (SC ratio 1-7) 0.82 times The durability characteristics were measured by measuring the prepared solar cell at 70% humidity,
Installed in a dark place at a temperature of 60 ° C. and an amplitude of 0.
After applying vibration of 1 mm for 24 hours, AM1.5 (10
The change in photoelectric conversion efficiency under irradiation of 0 mW / cm ² (photoelectric conversion efficiency after durability test / initial photoelectric conversion efficiency) was determined. As a result of the measurement, for the (SC Ex 1) solar cell,
The durability characteristics of (SC ratio 1-1) to (SC ratio 1-7) are as follows.

(SC ratio 1-1) 0.89 times (SC ratio 1-2) 0.81 times (SC ratio 1-3) 0.72 times (SC ratio 1-4) 0.80 times (SC ratio 1-5) 0.72 times (SC ratio 1-6) 0.73 times (SC ratio 1-7) 0.83 times Next, stainless steel substrate and barium borosilicate glass (Corning Corp. 7059) substrate Except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate are set to the values shown in Table 2,
Under the same manufacturing conditions as the i-type layer of Example 1, an i-type layer was formed on the substrate to a thickness of 1 μm to prepare a sample for measuring physical properties. These samples will be referred to as (SP1-1) to (SP1-7). The bandgap (Eg) and the composition of the produced sample for measuring physical properties were analyzed to find the relationship between the bandgap and the composition ratio of Si (silicon) atoms and C (carbon) atoms. To measure the bandgap, the glass substrate on which the i-type layer was made was placed on a spectrophotometer (type 330 manufactured by Hitachi, Ltd.), and the wavelength dependence of the absorption coefficient of the i-type layer was measured. The band gap of the i-type layer was determined by the method described in p109 of Makoto Konagai, co-authored by Shokoido Co., Ltd.

For composition analysis, a stainless steel substrate having an i-type layer was prepared by using an Auger electron spectroscopy analyzer (JAM manufactured by JEOL Ltd.).
It was installed in P-3) and the composition ratio of Si atoms and C atoms was measured. The band gap and the result of composition analysis are shown in Table 2 and FIG. Next, the composition analysis in the layer thickness direction of Si atoms and C atoms in the i-type layers of the manufactured solar cells (SC Ex 1) and (SC ratio 1-1) to (SC ratio 1-7) was carried out by the above composition analysis. The same method was used.

Next, a sample of a Si layer having a layer thickness of 1 μm was prepared, and the band gap was determined by the above method.
It was 1.75 (eV). This sample (SP1-
8). (SP1-1) to (SP1-
7), the change in the band gap in the layer thickness direction of the i-type layer and the Si layer was determined from the relationship between the composition ratio of Si atoms and C atoms and the band gap determined in (SP1-8). The result is shown in FIG. As can be seen from FIG. 8, (SC Ex 1), (SC Ex
In the solar cells of ratio 1-2) to (SC ratio 1-7), the position of the minimum value of the band gap is p / p than that of the center position of the i-type layer.
It was found that the solar cell of (SC ratio 1-1) is biased toward the i interface, and the position of the minimum value of the band gap is biased toward the Si / i interface from the center position of the i-type layer.

As described above, (SC Ex 1), (SC Ratio 1-1) to
The change in the bandgap with respect to the layer thickness direction of (SC ratio 1-7) is caused by the raw material gas containing Si (SiH ₄ gas in this case) and the raw material gas containing C (in this case, inflow into the deposition chamber). It was found that it depends on the flow rate ratio of CH ₄ gas). (Comparative Example 1-8) Several solar cells were produced under the same conditions as in Example 1 except that the μW power and the RF power introduced when forming the i-type layer were variously changed. FIG. 9 shows the relationship between the μW power and the deposition rate. The deposition rate does not depend on the RF power, and is constant when the μW power is 0.32 W / cm ³ or more. With this power, SiH ₄ gas and CH ₄ gas, which are the source gases, are used. Is 1
It was found to have been decomposed by 00%. AM1.5 (1
When the initial photoelectric conversion efficiency of the solar cell when irradiated with light of 00 mW / cm ² ) was measured, the results shown in FIG. 10 were obtained. The curve in this figure is an envelope for showing the ratio of the initial photoelectric conversion efficiency of each solar cell when the initial photoelectric conversion efficiency of Example 1 is 1. As you can see from the figure,
μW power is less than μW power (0.32 W / cm ³ ) that decomposes SiH ₄ gas and CH ₄ gas by 100%, and R
It was found that the initial photoelectric conversion efficiency was significantly improved when the F power was higher than the μW power.

(Comparative Example 1-9) An i-type layer was formed in Example 1.
At this time, the flow rate of the gas introduced into the deposition chamber 401 is set to SiH. _Four
Gas 50 sccm, CH_FourChange to 10 sccm gas,
H₂Without introducing gas, various μW power and RF power
Instead, several solar cells were produced. Other conditions are Example 1
Same as. Relationship between deposition rate and μW power, RF power
As a result of examination, the deposition rate was found to be RF electric current as in Comparative Example 1-8.
Independent of force, μW power is 0.18W / cm³Above
At this constant power of μW, the source gas SiH_Fourgas
And CH_FourIt turns out that the gas is 100% decomposed
It was. Initial light of solar cell when irradiated with AM1.5 light
When the electric conversion efficiency was measured, it showed the same tendency as in FIG.
It was a result. That is, μW power is SiH_FourGas
And CH_FourΜW power to decompose gas 100% (0.18
W / cm³) Or less and RF power is greater than μW power
It can be seen that the initial photoelectric conversion efficiency has improved significantly when
won.

(Comparative Example 1-10) In Example 1, the i-type layer was formed.
When forming, the flow rate of the gas introduced into the deposition chamber 401 is set to SiH.
_FourGas 200 sccm, CH_FourGas 50sccm, H₂
The gas was changed to 500 sccm and the substrate temperature was changed to 300.
Change the heater setting so that the temperature becomes ℃
By changing the RF power variously and making several solar cells
It was The other conditions were the same as in Example 1.

When the relationship between the deposition rate and the μW power and the RF power was examined, the deposition rate did not depend on the RF power as in Comparative Example 1-8, and the μW power was constant at 0.65 W / cm ³ or more. With this power, the raw material gas, SiH ₄ gas and C
It was found that the H ₄ gas was 100% decomposed. A
When the initial photoelectric conversion efficiency of the solar cell when irradiated with M1.5 light was measured, the result showed the same tendency as in FIG. 10. That is, μW power is 100% of that of SiH ₄ gas.
It was found that the initial photoelectric conversion efficiency was significantly improved when the power to be decomposed was μW power (0.65 W / cm ³ ) or less and the RF power was higher than the μW power.

(Comparative Example 1-11) When the i-type layer was formed in Example 1, the pressure in the deposition chamber was changed from 3 mTorr to 200 m.
Several solar cells were manufactured under the same conditions as in Example 1 except that the conditions were changed to Torr. The initial photoelectric conversion efficiency of the solar cell when irradiated with AM1.5 light was as shown in FIG. 11, and the pressure was 50 mTorr.
It was found that the initial photoelectric conversion efficiency was significantly reduced at r or higher.

(Comparative Example 1-12) When forming the Si layer in Example 1, the deposition rate was variously changed by changing the SiH ₄ gas flow rate and the RF power, and other conditions were the same as Example 1.
Several solar cells were prepared in the same manner as in. AM1.5
The initial photoelectric conversion efficiency of the solar cell when irradiated with light was measured, and it was found that the initial photoelectric conversion efficiency was significantly reduced when the deposition rate of the Si layer was 2 nm / sec or more.

(Comparative Example 1-13) Several solar cells were produced under the same conditions as in Example 1 except that the layer thickness was variously changed when the Si layer was formed in Example 1. When the initial photoelectric conversion efficiency of the solar cell when irradiated with AM1.5 light was measured, it was found that the initial photoelectric conversion efficiency was significantly reduced when the layer thickness was 30 nm or more.

As mentioned above, (Comparative Example 1-1) to (Comparative Example 1-1)
As seen in 3), the solar cell of this example (SC Ex 1)
However, conventional solar cells (SC ratio 1-1) to (SC ratio 1-
It has been demonstrated that it has even better properties than 7). (Example 2) Band gap (Eg) in Example 1
Several solar cells were manufactured by changing the position of the local minimum value in the layer thickness direction, the size of the local minimum value, and the pattern, and the initial photoelectric conversion efficiency and durability characteristics thereof were examined in the same manner as in Example 1. At this time, the SiH ₄ gas flow rate of the i-type layer and CH ₄
Except for the change pattern of the gas flow rate, it was the same as in Example 1.
FIG. 12 shows a band diagram in the layer thickness direction of the solar cell when the change patterns of the SiH ₄ gas flow rate and the CH ₄ gas flow rate are changed. (SC Ex 2-1) to (SC Ex 2-5) are obtained by changing the position of the minimum value of the band gap with respect to the layer thickness direction, and according to (SC Ex 2-1) to (SC Ex 2-5), p
It is changed from the / i interface to the i / Si interface. (SC Ex 2-6) and (SC Ex 2-7) are obtained by changing the minimum value of the band gap of (SC Ex 2-1). (SC Ex 2-8) to (SC Ex 2-10) are different patterns of bands. Table 3 shows the results of examining the initial photoelectric conversion efficiency and durability characteristics of these manufactured solar cells (the values in the table are based on SC actual (2-1)). As can be seen from these results, the band gap of the i-type layer changes smoothly in the layer thickness direction regardless of the size of the minimum value of the band gap and the change pattern, and the position of the minimum value of the band gap is located in the i-type layer. P / i from the center position of
It was found that the solar cell of the present invention, which is offset toward the interface, is superior.

Example 3 A solar cell of FIG. 1-a containing a valence electron control agent in the Si layer was produced. (Example 3-1) When forming a Si layer, SiH ₄ gas,
Except for flowing PH ₃ / H ₂ gas in 2sccm deposition chamber in addition to the H ₂ gas were the same as in Example 1. The manufactured solar cell (SC Ex 3-1) has a better initial photoelectric conversion efficiency and durability than the conventional solar cells (SC Ratio 1-1) to (SC Ratio 1-7), similar to (SC Ex 1). It was found to have characteristics.

(Example 3-2) When forming a Si layer, S
₂ sc of PH ₃ / H ₂ gas in addition to iH ₄ gas and H ₂ gas
cm, B ₂ H ₆ / H ₂ gas was made to be the same as in Example 1 except that 0.5 sccm gas was introduced into the deposition chamber. Similar to (SC Ex 1), the manufactured solar cell (SC Ex 3-2) had better initial photoelectric conversion efficiency and durability than conventional solar cells (SC Ratio 1-1) to (SC Ratio 1-7). It was found to have characteristics.

Example 4 Using the p-type polycrystalline silicon substrate, the solar cell of FIG. 1-b was produced. First on the board
The n-type layer, p-type layer, i-type layer, Si layer, and second n-type layer were sequentially formed. Table 4 shows the forming conditions. When forming the i-type layer, the SiH ₄ gas flow rate and the CH ₄ gas flow rate are changed as shown in the pattern of FIG. 6 so that the minimum value of the band gap comes from the i / p interface, and the deposition rate of the Si layer is 0.15
nm / sec. The substrate and layers other than the semiconductor layer were manufactured under the same conditions and methods as in Example 1.

The produced solar cell (SC Ex 4) was similar to (SC Ex 1) in the conventional solar cells (SC ratio 1-1) to (SC Ex).
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the ratio 1-7). (Example 5) A solar cell having a maximum bandgap value of the i-type layer near the p / i interface and a thickness of that region of 20 nm was manufactured. FIG. 13-a shows the flow rate change pattern of the i-type layer.

It was manufactured using the same conditions and method as in Example 1 except that the flow rate change pattern of the i-type layer was changed. Next, the composition analysis of the solar cell was performed in the same manner as in Example 1, and the change in the band gap of the i-type layer in the layer thickness direction was examined based on FIG. 7. The results shown in FIG. 13-b were obtained. Became. Like the (SC Ex 1), the produced vertical (SC Ex 5) has better initial photoelectric conversion efficiency and durability than the conventional solar cells (SC Ratio 1-1) to (SC Ratio 1-7). I found out.

(Comparative Example 5) There was a region having the maximum bandgap near the p / i interface of the i-type layer, and several solar cells having various thicknesses were manufactured.
Except for the thickness of the region, the same conditions and methods as in Example 5 were used. When the initial photoelectric conversion efficiency and durability of the manufactured solar cell were measured, the thickness of the region was 1 nm or more,
When the thickness is 30 nm or less, the initial photoelectric conversion efficiency and durability which are better than those of the solar cell of Example 1 (SC Ex 1) were obtained.

Example 6 There is a maximum bandgap of the i-type layer near the i / Si interface, and the thickness of that region is 15
A solar cell having a size of nm was manufactured. FIG. 13-c shows the flow rate change pattern of the i-type layer. It was manufactured using the same conditions and method as in Example 1 except that the flow rate change pattern of the i-type layer was changed. Next, the composition analysis of the solar cell was performed in the same manner as in Example 1, and the change in the band gap in the layer thickness direction of the i-type layer was examined based on FIG. 7. The results shown in FIG. 13-d were obtained. Became. The manufactured solar cell (SC Ex 6) is the same as (SC Ex 1) in the conventional solar cells (SC ratio 1-1) to (SC).
It was found that it has better initial photoelectric conversion efficiency and durability than the ratio 17).

(Comparative Example 6) There was a region having the maximum bandgap in the vicinity of the i / Si interface of the i-type layer, and several solar cells having various thicknesses were manufactured.
It was manufactured using the same conditions and the same method as in Example 6 except for the thickness of the region. When the initial photoelectric conversion efficiency and durability of the manufactured solar cell were measured, the thickness of the region was 1 nm or more,
When the thickness was 30 nm or less, the initial photoelectric conversion efficiency and durability were better than those of the solar cell of Example 1 (SC Ex 1).

Example 7 When the first p-type layer was formed by the gas diffusion method and the i-type layer was formed, C ₂ H ₂ gas was used and μ
Solar cells with different W power were produced. First, O ₂ /
BBr _{3 obtained} by diluting a He gas cylinder with hydrogen to 1% (purity 99.999%, hereinafter referred to as “BBr ₃ / H ₂ gas”)
The cylinder was replaced with a cylinder, and the CH ₄ gas cylinder was replaced with C ₂ H ₂ gas (purity 99.99%). When forming the first p-type layer, the substrate temperature was set to 850 ° C., BBr ₃ / H ₂ gas was introduced into the deposition chamber at 500 sccm, and the internal pressure was set to 10 Torr.
Then, B was diffused into the n-type substrate. When the junction depth reaches 300 nm, the introduction of BBr ₃ / H ₂ gas is stopped and H
₂ gas was kept flowing for 5 minutes. Further, when forming the i-type layer, C ₂ H ₂ gas is introduced instead of CH ₄ gas, and
It was changed according to the flow pattern such as -a. Further, the μW power was changed as shown in FIG. 14-b. Except for the first p-type layer and the i-type layer, the same conditions, the same method, and the same procedure as in Example 1 were used. The produced solar cell (SC Ex 7) is (SC
Like the actual 1), the conventional solar cells (SC ratio 1-1) to (S
It was found that the initial photoelectric conversion efficiency and durability were better than those of C ratio 1-7).

Example 8 A solar cell having an i-type layer containing oxygen atoms was produced. When forming the i-type layer, 10 sccc of O ₂ / He gas was used in addition to the gas flowing in Example 1.
m, the same conditions, the same method and the same procedure as in Example 1 were used except that the same was introduced into the deposition chamber 401. The produced solar cell (SC Ex 8) has a better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC ratio 1-1) to (SC ratio 1-7), similar to (SC Ex 1). Found to have.

Further, the content of oxygen atoms in the i-type layer is determined by SI
When examined by MS, it was found to contain almost uniformly 2 × 10 ¹⁹
It was found to be (pieces / cm ² ). (Example 9) A silicon solar cell in which a nitrogen atom was contained in the i-type layer was produced. Example 1 in forming the i-type layer
The same conditions, the same method, and the same procedure as in Example 1 were used, except that NH ₃ / H ₂ gas of 5 sccm was introduced into the deposition chamber 401 in addition to the gas that was flowed in. The prepared solar cell (SC Ex 9) is similar to the conventional solar cell (SC Ex 1) with SC Ex 1
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of -1) to (SC ratio 1-7). Also, when the content of nitrogen atoms in the i-type layer was examined by SIMS, it was found that the i-type layer contained almost uniformly 3 × 10 ¹⁷ (pieces / cm ² ).
It turned out that

Example 10 A solar cell having an i-type layer containing oxygen atoms and nitrogen atoms was produced. When the i-type layer is formed, the same conditions as in Example 1 except that O ₂ / He gas is 5 sccm, NH ₂ / H ₂ gas is 5 sccm, and is introduced into the deposition chamber 401 in addition to the gas flowing in Example 1. , Same method, same procedure. Fabricated solar cell (SC Ex 1
0) is a conventional solar cell (SC ratio 1
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of -1) to (SC ratio 1-7). In addition, the contents of oxygen atoms and nitrogen atoms in the i-type layer are measured by SIMS.
It was found that they were contained almost uniformly,
It was found to be 10 ¹⁹ (pieces / cm ² ), 3 × 10 ¹⁷ (pieces / cm ² ).

Example 11 A solar cell was produced in which the hydrogen content of the i-type layer was changed in accordance with the silicon content. The O ₂ / He gas cylinder was replaced with SiF ₄ gas (purity 99.
(999%) When replacing the cylinder and forming the i-type layer, as shown in FIG.
According to the flow pattern of 5-a, SiH ₄ gas, CH ₄
The flow rates of the gas and SiF ₄ gas were changed. The band gap change in the layer thickness direction of this solar cell (SC Ex 11) was obtained by the same method as in Example 1. Figure 15-b
Shown in.

Further, the secondary ion mass spectrometer was used to analyze the content of hydrogen atoms and silicon atoms in the layer thickness direction. As a result, as shown in FIG. 15-c, it was found that the hydrogen atom content has a layer thickness direction distribution corresponding to the silicon atom content. This solar cell (SC Ex 1
When the initial photoelectric conversion efficiency and durability characteristics of 1) were obtained, similar to the solar cell of Example 1, a conventional solar cell (SC ratio 1-
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of 1) to (SC ratio 1-7).

(Embodiment 12) When a semiconductor layer of the solar cell of FIG. 1 is formed by the manufacturing apparatus using the microwave plasma CVD method shown in FIG. 4, a silicon atom-containing gas (Si
A solar cell (SC Ex 12) was produced by the same method and the same procedure as in Example 1 except that the H ₄ gas) and the carbon atom-containing gas (CH ₄ gas) were mixed at a distance of 1 m from the deposition chamber. It was found that the manufactured solar cell (SC Ex 12) had better initial photoelectric conversion efficiency and durability characteristics than (SC Ex 1).

(Example 13) When forming the i-type layer, RF
Applying a positive DC bias to electrode 410, RF power, D
A solar cell in which the C bias and the μW power were changed as shown in FIG. 16 was produced. Prepared solar cell (SC Ex 13)
Is the same as (SC Ex 1), the conventional solar cell (SC ratio 1-
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of 1) to (SC ratio 1-7).

(Embodiment 14) Using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, FIG.
A triple solar cell was manufactured. The solar cell of FIG. 17 is obtained by adding a set of nip structure to the solar cell of FIG. 1, and includes the first p-type layer, n-type layer, i-type layer, and second
17 are the first p-type layers in FIG.
It corresponds to the second n-type layer, the second i-type layer, and the third p-type layer.

As the substrate, an n-type polycrystalline silicon substrate manufactured by the casting method was used. 50 × 50m
One side of the m ² substrate was immersed in NaOH (diluted to 1% with H ₂ O) at a temperature of 100 ° C. for 5 minutes and washed with pure water.
When the surface immersed in NaOH was observed with a scanning electron microscope (SEM), irregularities having a pyramid structure were formed on the surface, and the substrate was textured (Textu).
red). Next, ultrasonically clean with acetone and isopropanol, and then with pure water.
It was dried with warm air.

Hydrogen plasma treatment was performed by the same procedure and method as in Example 1 to form a first p-type layer on the textured surface of the substrate, and further, a first n-type layer and a first i-type layer were formed. layer,
A second p-type layer, a second n-type layer, a Si layer, a second i-type layer,
A third p-type layer was sequentially formed. When forming the second i-type layer, the SiH ₄ gas flow rate and the CH ₄ gas flow rate were changed according to the flow rate change pattern as shown in FIG. 5, and the Si layer deposition rate was set to 0.15 nm / sec.

Then, as in Example 1, ITO (In ₂ O) having a layer thickness of 70 nm was formed as a transparent electrode on the second p-type layer.
₃ + SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method. Next, as in Example 1, a collector electrode made of silver (Ag) and having a layer thickness of 5 μm was vacuum-deposited on the transparent electrode by a usual vacuum deposition method. Next, as in Example 1, a back electrode made of an Ag—Ti alloy and having a layer thickness of 3 μm was vacuum-deposited on the back surface of the substrate by a normal vacuum deposition method.

As described above, the production of the triple type solar cell using the microwave plasma CVD method is completed. This solar cell will be referred to as (SC Ex 14), and the manufacturing conditions of each semiconductor layer are shown in Table 5. (Comparative Example 14-1) A method similar to that in Example 14 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were changed in accordance with the flow rate change pattern of FIG. 6 when the second i-type layer of FIG. 17 was formed. A triple solar cell was manufactured by the same procedure. This solar cell will be called (SC ratio 14-1).

(Comparative Example 14-2) When the second i-type layer shown in FIG. 17 was formed, a triplet was prepared in the same manner as in Example 14 except that the μW power was 0.5 W / cm ^3. Type solar cell was produced. This solar cell (SC ratio 14-2)
I will call it. (Comparative Example 14-3) A triple solar cell is manufactured by the same method and procedure as in Example 14, except that the RF power is set to 0.15 W / cm ³ when the second i-type layer in FIG. 17 is formed. Was produced. This solar cell will be called (SC ratio 14-3).

[0221] (Comparative Example 14-4) when forming the second i-type layer in FIG. 17, except that the μW power 0.5 W / cm ^3, the RF power to 0.55 W / cm ³ Example 14 A triple type solar cell was manufactured by the same method and the same procedure. This solar cell will be called (SC ratio 14-4).

(Comparative Example 14-5) When the second i-type layer shown in FIG. 17 is formed, the pressure in the deposition chamber 401 is set to 0.08 Torr.
A triple type solar cell was manufactured by the same method and procedure as in Example 14 except that the above was used. This solar cell is called (SC ratio 14-5). (Comparative Example 14-6) A triple solar cell was produced by the same method and procedure as in Example 14, except that the deposition rate was set to 3 nm / sec when the Si layer in FIG. 17 was formed. This solar cell is called (SC ratio 14-6).

(Comparative Example 14-7) A triple-type solar cell was prepared by the same method and procedure as in Example 14, except that the layer thickness was 40 nm when the Si layer shown in FIG. 17 was formed.
This solar cell is called (SC ratio 14-7).
When the initial photoelectric conversion efficiency and durability characteristics of these produced triple solar cells were measured by the same method as in Example 1, (SC Ex. 14) shows that the conventional triple solar cells (SC
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the ratios 14-1) to (SC ratio 14-7).

Example 15 Using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, the solar cell of Example 1 was prepared, modularized, and applied to a power generation system. 65 solar cells (SC Ex 1) of 50 × 50 mm ² were prepared under the same conditions, the same method, and the same procedure as in Example 1. EVA on a 5.0 mm thick aluminum plate
An adhesive sheet made of (ethylene vinyl acetate) was placed, a nylon sheet was placed on the sheet, and the solar cells produced were arranged on the sheet, and serialized and parallelized. An EVA adhesive sheet was placed thereon, and a fluororesin sheet was further placed thereon, followed by vacuum lamination to form a module. The initial photoelectric conversion efficiency of the manufactured module was measured by the same method as in Example 1. Connect the module to the circuit showing the power generation system in Figure 18,
An external light that lights at night was used as the load. The whole system was operated by the storage battery and the power of the module, and the module was installed at the angle that could collect the most sunlight. The photoelectric conversion efficiency after one year was measured, and the photodegradation rate (photoelectric conversion efficiency after one year / initial photoelectric conversion efficiency) was obtained. This module will be called (MJ Ex 15).

(Comparative Example 15-1) Conventional solar cell (SC
Ratio 1-X) (X: 1 to 7) under the same conditions as in Comparative Examples 1 to X,
Sixty-five pieces were produced by the same method and the same procedure, and were modularized in the same manner as in Example 15. This module (MJ ratio 15-
X). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after one year passed were measured under the same conditions, the same method, and the same procedure as in Example 15, and the photodegradation rate was obtained.

As a result, the photodegradation rate of (MJ ratio 15-X) was as follows with respect to (MJ ex. 15). Module light deterioration rate ratio ───────────────────────── MJ actual 15 1.00 MJ ratio 15-1 0.86 MJ ratio 15-2 0.67 MJ ratio 15-3 0.86 MJ ratio 15-4 0.70 MJ ratio 15-5 0.82 MJ ratio 15-6 0.70 MJ ratio 15-7 0.83 It has been found that the solar cell module has better photodegradation characteristics than the conventional solar cell module.

(Example 16) Using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, p / i
The solar cell of FIG. 19 having the second Si layer at the interface was produced. As in Example 1, a 50 × 50 mm ² n-type polycrystalline silicon substrate manufactured by the casting method was immersed in an aqueous solution of HF and HNO ₃ (diluted to 10% with H ₂ O) for several seconds, and then pure water was used. Washed. Next, it was ultrasonically washed with acetone and isopropanol, further washed with pure water, and dried with warm air.

Hydrogen plasma treatment was applied in the same procedure and method as in Example 1 to form a first p-type layer on the substrate,
Further, the first n-type layer, the first Si layer, the i-type layer, and the second S layer.
The i layer and the second p-type layer were sequentially formed. When forming the i-type layer, Si is formed according to the flow rate change pattern as shown in FIG.
By changing the H ₄ gas flow rate and the CH ₄ gas flow rate, the first Si
Layer, second Si layer deposition rate is 0.15 nm / sec,
The layer thickness was 10 nm.

Next, on the second p-type layer, ITO (In ₂
O ₃ + SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method.
Next, as in Example 1, a collector electrode made of silver (Ag) and having a layer thickness of 5 μm was vacuum-deposited on the transparent electrode by a usual vacuum deposition method. Next, as in Example 1, Ag-Ti was formed on the back surface of the substrate.
A back electrode made of an alloy and having a layer thickness of 3 μm was vacuum-deposited by a usual vacuum deposition method.

This solar cell will be referred to as (SC Ex 16), and the manufacturing conditions of each semiconductor layer are shown in Table 6. When the initial photoelectric conversion efficiency and durability characteristics of the manufactured solar cell were measured by the same method as in Example 1, (SC Ex 16) was the same as that of (SC Ex 1) in the conventional solar cell (SC ratio 1-1). ~ (SC
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the ratio 1-7).

As described above, it was proved that the effect of the photovoltaic element of the present invention was exhibited regardless of the element structure, element material, and element manufacturing conditions. (Example 17) In this example, a photovoltaic device was prepared in which the i-type layer contained B and P atoms. First, the solar cell of FIG. 1-a was manufactured using an n-type polycrystalline silicon substrate manufactured by the casting method.

A 50 × 50 m ² substrate having a thickness of 500 μm was immersed in an aqueous solution of HF and HNO ₃ (diluted to 10% with H ₂ O) for several seconds and washed with pure water. Next, it was ultrasonically cleaned with acetone and perisopropanol, further washed with pure water, and dried with warm air. Next, a semiconductor layer was formed on the substrate by the manufacturing apparatus using the glow discharge decomposition method including the source gas supply device 2000 and the deposition device 400 shown in FIG. The manufacturing procedure will be described below.

In the gas cylinders 2041 to 2047 in the figure, the same source gas as in Example 1 is sealed. After the preparation for film formation was completed in the same manner as in Example 1, the substrate was subjected to hydrogen plasma treatment, and subsequently, the first p-layer was formed on the substrate 404.
A mold layer, an n-type layer, a Si layer, an i-type layer, and a second p-type layer were formed.

First, to perform the hydrogen plasma treatment, the valve 2003 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the H ₂ gas flow rate to 500 sccm. The pressure inside the deposition chamber is adjusted to 2.0 Torr by adjusting the conductance valve while watching the vacuum gauge 402, and the heater 405 is set so that the temperature of the substrate 404 becomes 550 ° C. When the substrate temperature becomes stable, the shutter 415 is set. , The microwave (μW) power source is set to 0.20 W / cm ³ , μW power is introduced, glow discharge is generated, the shutter 415 is opened, and the substrate is subjected to hydrogen plasma treatment. Started. After 10 minutes, the shutter was closed, the μW power supply was turned off, the glow discharge was stopped, and the hydrogen plasma treatment was completed. 5 minutes, deposition chamber 401
After continuously flowing H ₂ gas into the inside, the valve 2003 was closed and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, in order to form the first p-type layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller is set so that the H ₂ gas flow rate becomes 50 sccm. Adjusted in 2013. Adjusting the conductance valve while watching the vacuum gauge 402 so that the pressure in the deposition chamber becomes 2.0 Torr, and setting the heater 405 so that the temperature of the substrate 404 becomes 350 ° C., the substrate temperature is stable. Valve 200
1, 2005 gradually open, SiH ₄ gas, B ₂ H ₆
/ H ₂ gas was caused to flow into the deposition chamber 401. At this time, S
iH ₄ gas flow rate is 5 sccm, H ₂ gas flow rate is 100 s
It was adjusted with each mass flow controller so that ccm and B ₂ H ₆ / H ₂ gas became 500 sccm. The opening of the conductance valve 407 was adjusted while observing the vacuum gauge 402 so that the pressure in the deposition chamber 401 was 2.0 Torr. Make sure the shutter 415 is closed, set the RF power supply to 0.20 W / cm ³ , and
Shutter 41 is generated by introducing electric power to cause glow discharge.
5 was opened and the formation of the first p-type layer on the substrate was started. After the first p-type layer having a layer thickness of 100 nm was prepared, the shutter was closed, the RF power was turned off, the glow discharge was stopped, and the first
The formation of the p-type layer was completed. The valves 2001 and 2005 are closed, and SiH ₄ gas, B ₂ H ₆ /
Stopping the flow of H ₂ gas for 5 minutes, H ₂ into the deposition chamber 401
After continuing to flow the gas, the valve 2003 was closed and the inside of the deposition chamber 401 and the gas pipe were evacuated.

To form the n-type layer, the auxiliary valve 40
8, gradually open the valve 2003, H₂Gas to gas
It is introduced into the deposition chamber 401 through the inlet pipe 411, and H₂gas
Mass flow control so that the flow rate is 50 sccm
Ra 2013 is set and the pressure in the deposition chamber is 1.0 Tor.
Adjust the conductance valve to r
Heater 405 so that the temperature of 04 becomes 350 ° C.
It was set. When the substrate temperature is stable,
Open 2001 and 2004 gradually to SiH_FourGas, P
H₃/ H₂Gas was flowed into the deposition chamber 401. this
Sometimes SiH_FourGas flow rate is 2 sccm, H₂Gas flow rate is 1
00sccm, PH₃/ H₂Gas flow rate is 200 sccm
Adjust with each mass flow controller so that
It was The pressure in the deposition chamber 401 will be 1.0 Torr.
Thus, the opening of the conductance valve 407 was adjusted. R
The power of F power source is 0.01W / cm₃Set to RF electrode
Introduce RF power to 410 to cause glow discharge and
Open the shutter and start making the n-type layer on the first p-type layer
The n-type layer with a layer thickness of 30 nm was produced, and the shutter was released.
Closed, RF power turned off, glow discharge stopped, n-type
Finished forming layers. Close the valves 2001 and 2004
SiH into the deposition chamber 401_FourGas, PH₃/ H ₂Moth
Stop the flow of gas into the deposition chamber 401 for 5 minutes.₂Gas
After continuing the flow, the outflow valve 2003 is closed and the deposition chamber 4
The inside of 01 and the inside of the gas pipe were evacuated.

To form the Si layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401 through the introduction pipe 411, and the mass flow controller 2013 is set so that the H ₂ gas flow rate is 50 sccm. Then, the pressure inside the deposition chamber was adjusted to 1.5 Torr by a conductance valve, and the heater 405 was set so that the temperature of the substrate 404 became 270 ° C. When the substrate temperature became stable, the valve 2001 was gradually opened to allow SiH ₄ gas to flow into the deposition chamber 401. At this time, the SiH ₄ gas flow rate is ₂ sccm and the H ₂ gas flow rate is 1 sc
It was adjusted with each mass flow controller so as to be 00 sccm. The pressure in the deposition chamber 401 is 1.5 To
The opening of the conductance valve 407 was adjusted so as to be rr. The power of the RF power source was set to 0.01 W / cm ³ , RF power was introduced to the RF electrode 410 to cause glow discharge, the shutter was opened, the production of the Si layer on the n-type layer was started, and the deposition rate was 0. 0.15 nm / sec, layer thickness 10 nm
After the Si layer was produced, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the Si layer was completed. The valve 2001 is closed, and Si in the deposition chamber 401
The flow rate of H ₄ gas was stopped and H _{2 was} introduced into the deposition chamber 401 for 5 minutes.
After continuing to flow the gas, the outflow valve 2003 was closed and the inside of the deposition chamber 401 and the gas pipe were evacuated.

Next, to prepare the i-type layer, the valve 20 was used.
Open 03 gradually, H₂Introduce gas into deposition chamber 401
And H₂The mass flow should be 300sccm.
Adjusted with the low controller 2013. Deposition chamber pressure
With a conductance valve so that it becomes 0.01 Torr
Adjust and heat the substrate 404 to 350 ° C
Set the heater 405 and make sure the substrate temperature is stable.
Furthermore, valves 2001, 2002, 2004, 2005
Gradually open the SiH_FourGas, CH_FourGas, PH₃/
H₂Gas, B₂H₆/ H₂Let the gas flow into the deposition chamber 401
It was At this time, SiH_FourGas flow rate is 100 sccm, CH
_FourFlow rate is 30 sccm, H₂Gas flow rate is 300scc
m, PH₃/ H₂Gas flow rate 2 sccm, B₂H₆/ H₂gas
Each mass flow controller should have a flow rate of 5 sccm.
I adjusted it with a ruler. The pressure in the deposition chamber 401 is 0.01T
Opening of conductance valve 407 so as to be orr
Was adjusted. Next, the power of the RF power source 403 is 0.40 W /
cm³And was applied to the RF electrode 403. afterwards,
The power of the μW power source (not shown) is 0.20 W / cm³Set to
Introduce μW power into deposition 401 through dielectric window 413
Then, a glow discharge is generated, the shutter is opened, and the Si layer
The fabrication of the i-type layer on top was started. Mass flow controller
Using a computer connected to the
SiH according to the quantity change pattern_FourGas, CH_FourGas flow
By changing the amount, an i-type layer with a layer thickness of 300 nm was produced.
Filter, close the shutter, turn off the μW power supply, and glow discharge
Stop, turn off the RF power supply 403, and finish the production of the i-type layer
It was Valves 2001, 2002, 2004, 2005
Close the SiH into the deposition chamber 401_FourGas, CH_FourMoth
Su, PH₃/ H₂Gas, B₂H₆/ H₂Stop the flow of gas,
5 minutes into deposition chamber 401₂ After continuing to flow the gas,
The valve 2003 is closed, and the deposition chamber 401 and the gas pipe are closed.
Was evacuated.

Next, in order to form the second p-type layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller is set so that the H ₂ gas flow rate becomes 50 sccm. Adjusted in 2013. The pressure in the deposition chamber was adjusted to 2.0 Torr by a conductance valve, the heater 405 was set so that the temperature of the substrate 404 was 200 ° C., and the temperature of the substrate was stabilized. 2005 is gradually opened, SiH ₄ gas, CH ₄ gas, B ₂ H ₆ / H
_Two gases were allowed to flow into the deposition chamber 401. At this time, SiH
₄ gas flow rate is 1 sccm, CH ₄ gas flow rate is 0.5 sc
cm, H ₂ gas flow rate is 100 sccm, B ₂ H ₆ / H ₂
Each mass flow controller adjusted the gas flow rate to 100 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 2.0 Torr. RF power supply 0.20 W / cm
Setting to ³ , RF power was introduced to cause glow discharge, the shutter 415 was opened, and formation of the second p-type layer on the i-type layer was started. When the second p-type layer having a layer thickness of 10 nm was produced, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the second p-type layer was completed. Valve 2
001, 2002, 2005 are closed to stop the inflow of SiH ₄ gas, CH ₄ gas, and B ₂ H ₆ / H ₂ gas into the deposition chamber 401, and continue to flow H ₂ gas into the deposition chamber 401 for 5 minutes. After that, the valve 2003 was closed, the deposition chamber 401 and the gas pipe were evacuated, the auxiliary valve 408 was closed, the leak valve 409 was opened, and the deposition chamber 401 was leaked.

Next, a transparent electrode was formed on the second p-type layer.
The thickness of the ITO (In₂O ₂+ SnO₂)
Vacuum deposition was performed by a normal vacuum deposition method. Then silver on the transparent electrode
(Ag) layer thickness 5μm current collector electrode by normal vacuum evaporation
It was vacuum-deposited by the method. Next, if the Ag-Ti alloy is
The backside electrode with a layer thickness of 3 μm consisting of
It was vapor-deposited.

This completes the production of this solar cell. This solar cell will be referred to as (SC Ex 17), and Table 7 shows the manufacturing conditions of the first p-type layer, the n-type layer, the Si layer, the i-type layer, and the second p-type layer. (Comparative Example 17-1) The same conditions as in Example 17 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were adjusted by the respective mass flow controllers according to the flow rate pattern shown in FIG. 6 when forming the i-type layer. A solar cell was manufactured by the same procedure. This solar cell is called (SC ratio 17-1).

(Comparative Example 17-2) A solar cell was produced on a substrate by the same method and procedure as in Example 17, except that the PH ₃ / H ₂ gas was not passed when forming the i-type layer. This solar cell will be called (SC ratio 17-2). (Comparative Example 17-3) When forming an i-type layer, B ₂ H ₆ / H
_A solar cell was produced on the substrate by the same method and procedure as in Example 17, except that ₂ gas was not passed. This solar cell (SC
The ratio 17-3) will be called.

(Comparative Example 17-4) A solar cell was produced under the same conditions and in the same procedure as in Example 17, except that when the i-type layer was formed, the μW power was changed to 0.5 W / cm ³ . This solar cell will be called (SC ratio 17-4). (Comparative Example 17-5) A solar cell was produced under the same conditions and procedures as in Example 17, except that the RF power was set to 0.15 W / cm ³ when forming the i-type layer. This solar cell is called (SC ratio 17-5).

(Comparative Example 17-6) In forming the i-type layer, μW power was 0.5 W / cm ³ , and RF power was 0.55.
A solar cell was produced under the same conditions and the same procedure as in Example 17, except that W / cm ³ was used. This solar cell (SC ratio 1
7-6). (Comparative Example 17-7) A solar cell was produced under the same conditions and procedures as in Example 17, except that the pressure inside the deposition chamber was set to 0.08 Torr when forming the i-type layer. This solar cell will be called (SC ratio 17-7).

(Comparative Example 17-8) Example 1 was repeated except that the deposition rate was set to 3 nm / sec when the Si layer was formed.
A solar cell was produced under the same conditions and the same procedure as in No. 7. This solar cell is called (SC ratio 17-8). (Comparative Example 17-9) When the Si layer is formed, the layer thickness is set to 40.
A solar cell was produced under the same conditions and the same procedure as in Example 17, except that the thickness was changed to nm. This solar cell (SC ratio 17-
9).

Measurement of initial light conversion efficiency (photovoltaic power / incident light power) and durability characteristics of the manufactured solar cells (SC Ex 17) and (SC ratio 17-1) to (SC ratio 17-9) was carried out in Examples. It carried out similarly to 1. As a result of the measurement, (SC Ex 1
For the solar cell of 7), (SC ratio 17-1) to (SC
The initial photoelectric conversion efficiency of the ratio 17-9) was as follows.

(SC ratio 17-1) 0.82 times (SC ratio 17-2) 0.81 times (SC ratio 17-3) 0.80 times (SC ratio 17-4) 0.65 times (SC ratio 17-5) 0.81 times (SC ratio 17-6) 0.63 times (SC ratio 17-7) 0.68 times (SC ratio 17-8) 0.70 times (SC ratio 17-9) 83 times The durability characteristics were measured in the same manner as in Example 1. As a result of the measurement, for the solar cell of (SC Ex 17), (SC ratio 17
The durability characteristics of -1) to (SC ratio 17-9) are as follows.

(SC ratio 17-1) 0.82 times (SC ratio 17-2) 0.80 times (SC ratio 17-3) 0.80 times (SC ratio 17-4) 0.67 times (SC ratio 17-5) 0.83 times (SC ratio 17-6) 0.65 times (SC ratio 17-7) 0.76 times (SC ratio 17-8) 0.73 times (SC ratio 17-9) 85 times Next, when the relationship between the bandgap of the i-type layer and the C / Si composition was examined in the same manner as in Example 1, the same result as in FIG. 7 was obtained.

The manufactured solar cell (SC Ex. 17),
The composition analysis of Si atoms and C atoms in the i-type layer of (SC ratio 17-1) to (SC ratio 17-9) in the layer thickness direction is performed by the same method as the above composition analysis, to analyze Si atoms and carbon atoms. When the bandgap of the i-type layer in the layer thickness direction was obtained from the composition ratio, the same tendency as in FIG. Then, the position of the minimum value of the band gap is p from the position of the center of the i-type layer.
In the solar cell of (SC ratio 17-1), the position of the minimum value of the bandgap is found to be biased toward the Si / i interface from the center position of the i-type layer. .

Above, (SC actual 17), (SC ratio 17-
The band gap changes in the layer thickness direction of 1) to (SC ratio 17-9) are caused by the source gas containing Si (SiH ₄ gas in this case) and the source gas containing C (this In some cases, it was confirmed to depend on the flow rate ratio of CH ₄ gas). Next (SC Ex 17), (SC ratio 17-
1) to (SC ratio 17-9) P atom and B in the i-type layer
The composition analysis of the atoms in the layer thickness direction was performed with a secondary ion mass spectrometer (IMS-3F manufactured by CAMECA). As a result of the measurement, P atoms and B atoms were uniformly distributed in the layer thickness direction, and the composition ratio was as follows.

P / (Si + C) B / (Si + C) (SC Ex 17) to 3 ppm to 10 ppm (SC ratio 17-1) to 3 ppm to 10 ppm (SC ratio 17-2) N.P. D. 10 ppm (SC ratio 17-3) to 3 ppm N.V. D. (SC ratio 17-4) ~ 4ppm ~ 18ppm (SC ratio 17-5) ~ 3ppm ~ 10ppm (SC ratio 17-6) ~ 4ppm ~ 15ppm (SC ratio 17-7) ~ 3ppm ~ 10ppm (SC ratio 17-8) ) -3 ppm-10 ppm (SC ratio 17-9) -3 ppm-10 ppm N.C. D. Below detection limit (Comparative Example 17-10) μ introduced when forming an i-type layer
W power and RF power are variously changed, and other conditions are practical examples.
Several solar cells were produced in the same manner as 17. μW power
The force and the deposition rate have the same relationship as in FIG. 9, and the deposition rate is R
Independent of F power, μW power is 0.32 W / cm³that's all
Is constant, and this power is used as the source gas SiH_FourWith gas
CH_FourIt was found that the gas was 100% decomposed.
AM1.5 (100mW / cm ²) When illuminating
When the initial photoelectric conversion efficiency of the solar cell was measured, FIG.
The result is similar to the above. That is, μW power is S
iH_FourGas and CH_FourΜW electric that decomposes gas 100%
Power (0.32W / cm³) Or less and RF power is μW
When the power is larger than the power, the initial photoelectric conversion efficiency is significantly improved.
I found out.

(Comparative Example 17-11) When the i-type layer is formed in Example 17, the flow rate of the gas introduced into the deposition chamber 401 is S.
iH ₄ gas was changed to 50 sccm, CH ₄ gas was changed to 10 sccm, H ₂ gas was not introduced, and μW electric power and RF electric power were variously changed to manufacture some solar cells. The other conditions were the same as in Example 17. When the relationship between the deposition rate, the μW power, and the RF power was examined, the deposition rate did not depend on the RF power as in Comparative Example 17-10, and the μW power was 0.18 W / c.
It was found to be constant above m ³ , and it was found that the SiH ₄ gas and CH ₄ gas, which are the raw material gases, were decomposed 100% at this μW power. When the initial photoelectric conversion efficiency of the solar cell when irradiated with AM1.5 light was measured, the result showed the same tendency as in FIG. That is, μW power is S
μW that decomposes 100% of iH ₄ gas and CH ₄ gas
Power (0.18 W / cm ³ ) or less and RF power μ
It was found that the initial photoelectric conversion efficiency was significantly improved when the power was higher than W power.

(Comparative Example 17-12) When the i-type layer is formed in Example 17, the flow rate of the gas introduced into the deposition chamber 401 is S.
iH ₄ gas 200 sccm, CH ₄ gas 50 sccm,
H ₂ gas was changed to 500 sccm, and the substrate temperature was 3
Change the setting of the heater so that it becomes 00 ° C
Several solar cells were produced by changing the electric power and the RF power variously. The other conditions were the same as in Example 17.

When the relationship between the deposition rate and the μW power and RF power was examined, the deposition rate was R as in Comparative Example 17-10.
It was found that the μW power was constant at 0.65 W / cm ³ or more without depending on the F power, and the SiH ₄ gas and CH ₄ gas as the raw material gas were completely decomposed by this power. When the initial photoelectric conversion efficiency of the solar cell when irradiated with AM1.5 light was measured, the result showed the same tendency as in FIG. That, .mu.W power the SiH ₄ gas 1
It was found that the initial photoelectric conversion efficiency was significantly improved when the power was less than or equal to μW power (0.65 W / cm ³ ) for decomposition by 00% and the RF power was higher than the power of μW.

(Comparative Example 17-13) When the i-type layer was formed in Example 17, the pressure inside the deposition chamber was changed from 3 mTorr to 20.
Various changes were made up to 0 mTorr, and other conditions were in Example 17.
Several solar cells were prepared in the same manner as in. AM1.5
By measuring the initial photoelectric conversion efficiency of the solar cell when irradiated with light, the results shown in Fig. 11 were obtained, and the pressure was 50 m.
It was found that the initial photoelectric conversion efficiency was significantly reduced above Torr.

(Comparative Example 17-14) When the Si layer was formed in Example 17, the deposition rate was variously changed by changing the SiH ₄ gas flow rate and the RF power, and other conditions were the same as in Example 17. , Some solar cells were produced. AM
The initial photoelectric conversion efficiency of the solar cell when irradiated with 1.5 light was measured to show that the deposition rate of the Si layer was 2 nm / sec.
From the above, it was found that the initial photoelectric conversion efficiency was significantly reduced.

(Comparative Example 17-15) Several solar cells were produced under the same conditions as in Example 17 except that the layer thickness was variously changed when the Si layer was formed in Example 17. AM1.
When the initial photoelectric conversion efficiency of the solar cell when irradiated with 5 lights was measured, it was found that the initial photoelectric conversion efficiency was significantly reduced when the layer thickness was 30 nm or more.

As mentioned above, (Comparative Example 17-1) to (Comparative Example 17)
-15), the solar cell of the present invention (SC Ex 1
It has been proved that 7) has further superior characteristics to the conventional solar cells (SC ratio 17-1) to (SC ratio 17-9). (Example 18) The band gap (E
Several solar cells were manufactured by changing the position of the minimum value of g) in the layer thickness direction, the size of the minimum value, and the pattern,
The initial photoelectric conversion efficiency and durability characteristics were examined in the same manner as in Example 17. At this time, the solar cell having the band gap shown in FIG. 12 was produced in the same manner as in Example 17 except for the change patterns of the SiH ₄ gas flow rate and the CH ₄ gas flow rate of the i-type layer.

Table 8 shows the results of examining the initial photoelectric conversion efficiency and durability characteristics of these solar cells prepared (the values in the table are based on SC Ex (18-1)). As can be seen from these results, the band gap of the i-type layer changes smoothly in the layer thickness direction regardless of the size of the minimum value of the band gap and the change pattern, and the position of the minimum value of the band gap is located in the i-type layer. It was found that the solar cell of the present invention, which is deviated in the p / i interface direction from the center position, is superior.

(Example 19) In Example 17, a solar cell was prepared in which the concentration and kind of the valence electron controlling agent of the i-type layer were changed, and the initial photoelectric conversion characteristics and durability were the same as those in Example 1. I looked it up. At this time, the same procedure as in Example 17 was performed except that the concentration and type of the valence electron controlling agent in the i-type layer were changed.

(Example 19-1) The flow rate of the valence electron control agent gas (B ₂ H ₆ / H ₂ gas), which serves as an acceptor for the i-type layer, was increased to ⅕, and the total H ₂ flow rate was changed to that in Example 17. When a solar cell (SC Ex 19-1) that is the same as
Similar to (SC Ex 17), (SC Ex 19-1) has better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC Ratio 17-1) to (SC Ratio 17-9). I understood.

Example 19-2 The valence electron control agent gas (B ₂ H ₆ / H ₂ gas) flow rate serving as an acceptor for the i-type layer was quintupled, and the total H ₂ flow rate was the same as in Example 17. When the solar cell (SC Ex 19-2) was manufactured,
C Ex 19-2), like (SC Ex 17), may have better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC ratio 17-1) to (SC ratio 17-9). Do you get it.

(Example 19-3) The flow rate of the valence electron control agent gas (PH ₃ / H ₂ gas) serving as the donor of the i-type layer was ⅕, and the total H ₂ flow rate was the same as in Example 17. When the solar cell (SC Ex 19-3) was produced, (SC Ex 19-3) was similar to (SC Ex 17), but the conventional solar cells (SC Ratio 17-1) to (SC Ex 17-9) were used. It has been found that it has better initial photoelectric conversion efficiency and durability characteristics than

(Example 19-4) The flow rate of the valence electron control agent gas (PH ₃ / H ₂ gas) serving as the donor of the i-type layer was increased by 5 times, and the total H ₂ flow rate was the same as in Example 17. When a solar cell (SC Ex 19-3) was produced, (SC Ex 1
9-4) is a conventional solar cell (S
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of C ratio 17-1) to (SC ratio 17-9).

Example 19-5 As a valence electron control agent gas serving as an acceptor for the i-type layer, trimethylaluminum (Al (CH ₃ ) ₃ , TM was used instead of B ₂ H ₆ / H ₂ gas.
A solar cell using A) is manufactured. At this time, the TMA (purity 99.99%) sealed in the liquid cylinder was gasified by bubbling with hydrogen gas and introduced into the deposition chamber 401. 19-5) was produced. At this time, TMA / H ₂
The gas flow rate was 10 sccm. The produced solar cell (SC Ex 19-5) has a better initial photoelectric conversion efficiency and durability than the conventional solar cells (SC Ratio 17-1) to (SC Ratio 17-9), similar to (SC Ex 17). It was found to have characteristics.

Example 19-6 A solar cell using hydrogen sulfide (H ₂ S) instead of PH ₃ / H ₂ gas as a valence electron control agent gas serving as a donor of an i-type layer was produced. H ₂ S gas obtained by diluting the NH ₃ / H ₂ gas cylinder of Example 17 with hydrogen to 100 ppm (purity 99.999%, hereinafter referred to as “H ₂ S /
(Abbreviated as H ₂ ]) and replaced with a cylinder, and a solar cell (SC Ex 19-6) was produced by the same method and procedure as in Example 17.

At this time, the flow rate of the H ₂ S / H ₂ gas is 1 sccc.
m. The prepared solar cell (SC Ex 19-6) is (S
Similar to C Ex. 17), conventional solar cell (SC ratio 17-1)
(SC ratio 17-9), the initial photoelectric conversion efficiency and durability were better. Example 20 A solar cell of FIG. 1-b was produced using a p-type polycrystalline silicon substrate. Plasma treatment is applied to the substrate, and then the first n-type layer, p-type layer, i-type layer, S
The i layer and the second n-type layer were sequentially formed. Table 9 shows the forming conditions. When forming the i-type layer, SiH ₄ gas flow rate and CH ₄
The gas flow rate is changed as shown in the pattern of FIG. 6 so that the minimum value of the band gap comes from the i / p interface, and Si
The layer deposition rate was 0.15 nm / sec. The layers other than the substrate and the semiconductor layer were manufactured under the same conditions and the same method as in Example 17.

The manufactured solar cell (SC Ex 20) was
Similar to the actual 17), conventional solar cells (SC ratio 17-1) ~
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of (SC ratio 17-9). (Example 21) A solar cell having a maximum bandgap of the i-type layer near the p / i interface and a thickness of that region of 20 nm was used for the flow rate variation pattern of the i-type layer shown in FIG. 13-a. It was made using.

It was manufactured using the same conditions and the same method as in Example 17 except that the flow rate change pattern of the i-type layer was changed. Next, the composition analysis of the solar cell was performed in the same manner as in Example 17, and the change in the band gap in the layer thickness direction of the i-type layer was examined based on FIG. 7. The results shown in FIG. 13-b were obtained. Became. The prepared vertical (SC ex. 21) is similar to (SC ex. 17) in the conventional solar cells (SC ratio 17-1) to (SC ex. 17).
It was found that the initial photoelectric conversion efficiency and durability were better than those of -9).

(Comparative Example 21) There was a region having the maximum bandgap near the p / i interface of the i-type layer, and several solar cells having various thicknesses were manufactured. Except for the thickness of the region, the same conditions and methods as in Example 21 were used. When the initial photoelectric conversion efficiency and durability of the manufactured solar cell were measured, the region thickness was 1 nm.
Above 30 nm, the solar cell of Example 17 (SC
Even better initial photoelectric conversion efficiency and durability than Example 17) were obtained.

(Embodiment 22) There is a maximum bandgap of the i-type layer near the i / Si interface, and the thickness of the region is 1
A 5 nm solar cell was made using the i-type layer flow rate variation pattern shown in FIG. 13-c. It was manufactured using the same conditions and the same method as in Example 17, except that the flow rate change pattern of the i-type layer was changed. Next, the composition analysis of the solar cell was carried out in Example 17.
When the change in the band gap in the layer thickness direction of the i-type layer was examined based on FIG. 7 by the same method as in FIG. 7, the result was as shown in FIG. 13-d. The prepared solar cell (SC Ex 22) is similar to (SC Ex 17) in the conventional solar cell (SC ratio 17-
It was found that the initial photoelectric conversion efficiency and durability were better than those of 1) to (SC ratio 17-9).

(Comparative Example 22) There was a region having the maximum bandgap near the i / Si interface of the i-type layer, and several solar cells having various thicknesses were manufactured. Except for the thickness of the region, the same conditions and methods as in Example 22 were used. When the initial photoelectric conversion efficiency and durability of the manufactured solar cell were measured, the region thickness was 1 nm.
As described above, when the thickness is 30 nm or less, the initial photoelectric conversion efficiency and durability better than those of the solar cell of Example 17 (SC Ex 17) were obtained.

Example 23 A solar cell in which a valence electron control agent is distributed in the i-type layer was produced. PH _{3 in} FIG.
/ H ₂ of a gas and B ₂ H ₆ / H ₂ gas flow rate change pattern. At the time of production, the same conditions, the same method and procedure as in Example 17 were used except that the flow rates of PH ₃ / H ₂ gas and B ₂ H ₆ / H ₂ gas were changed.

The produced solar cell (SC Ex. 23) has (SC
Similar to the actual 17), conventional solar cells (SC ratio 17-1) ~
It was found that the initial photoelectric conversion efficiency and durability were better than those of (SC ratio 17-9). Moreover, when the changes in the layer thickness direction of P atoms and B atoms contained in the i-type layer were examined by using a secondary ion mass spectrometer (SIMS), as shown in FIG. It was found that the content of P and B atoms was minimum at the position.

Example 24 A solar cell having an i-type layer containing oxygen atoms was produced. When forming the i-type layer, 10 sc of O ₂ / He gas was used in addition to the gas flowing in Example 17.
cm, the same conditions, the same method, and the same procedure as in Example 17 were used except that the gas was introduced into the deposition chamber 401. The manufactured solar cell (SC Ex. 24) has a better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC Comp. 17-1) to (SC Comp. 17-9), like (SC Ex. 17). Found to have.

Further, the content of oxygen atoms in the i-type layer is determined by the SI
When examined by MS, it was found to contain almost uniformly 2 × 10 ¹⁹
It was found to be (pieces / cm ² ). (Example 25) A silicon solar cell in which a nitrogen atom was contained in the i-type layer was produced. When forming the i-type layer, NH ₃ / H ₂ gas is added in an amount of 5 sccc in addition to the gas flowing in Example 17.
m, the same conditions, the same method and the same procedure as in Example 17 were used except that the same was introduced into the deposition chamber 401. The produced solar cell (SC Ex. 25), like (SC Ex. 17), has better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC ratio 17-1) to (SC ratio 17-9). Found to have. In addition, the content of nitrogen atoms in the i-type layer can be adjusted to SI
When examined by MS, it was found that the content was almost uniform and 3 × 10 ¹⁷
It was found to be (pieces / cm ² ).

(Example 26) Oxygen atoms and nitrogen were added to the i-type layer.
A solar cell containing elementary atoms was manufactured. i-type layer
When forming, in addition to the gas flowing in Example 17, O₂/ He
5 sccm gas, NH₂/ H₂Gas 5sccm, stack
The same conditions as in Example 17 except that the same was introduced into the loading chamber 401,
The same method, same procedure was used. Fabricated solar cell (SC
Similar to (SC Ex 17), Ex 26) is a conventional solar cell (S
Even better than C ratio 17-1) to (SC ratio 17-9)
Have excellent initial photoelectric conversion efficiency and durability characteristics
It was. In addition, the contents of oxygen atoms and nitrogen atoms in the i-type layer
When examined by SIMS, it was found that the content was almost uniform.
1 x 10¹⁹(Pieces / cm²) 3 x 10¹⁷(Pieces / cm
²) Was found.

(Example 27) A solar cell was produced in which the hydrogen content of the i-type layer was changed corresponding to the silicon content. The O ₂ / He gas cylinder was replaced with SiF ₄ gas (purity 99.
(999%) When replacing the cylinder and forming the i-type layer, as shown in FIG.
According to the flow pattern of 5-a, SiH ₄ gas, CH ₄
The flow rates of the gas and SiF ₄ gas were changed. The change in the band gap in the layer thickness direction of this solar cell (SC Ex 27) was obtained by the same method as in Example 17, and FIG.
The result is similar to.

Further, the content of hydrogen atoms and silicon atoms was analyzed in the layer thickness direction using a secondary ion mass spectrometer. The results show the same tendency as in FIG. 15-c, and it was found that the content of hydrogen atoms has a distribution in the layer thickness direction corresponding to the content of silicon atoms. This solar cell (SC
When the initial photoelectric conversion efficiency and durability characteristics of Ex. 27) were obtained, similar to the solar cell of Example 17, the conventional solar cell (S
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of C ratio 17-1) to (SC ratio 17-9).

Example 28 A silicon atom-containing gas (Si
Example 17 except that H ₄ gas) and carbon atom-containing gas (CH ₄ gas) were mixed at a distance of 1 m from the deposition chamber.
A solar cell (SC Ex 28) was produced by the same method and the same procedure. The prepared solar cell (SC Ex 28) is (SC Ex 1
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of 7).

(Example 29) When the first p-type layer was formed by the gas diffusion method to form the i-type layer, C ₂ H ₂ gas was used instead of CH ₄ gas, and positive DC was applied to the RF electrode. A solar cell was manufactured by applying a bias and changing the RF power, DC bias, and μW power. First, BBr ₃ (BBr ₃ / H ₂ gas) prepared by diluting an O ₂ / He gas cylinder with hydrogen to 10%.
The cylinder was replaced with a cylinder, and the CH ₄ gas cylinder was replaced with C ₂ H ₂ gas.

When forming the first p-type layer, the substrate temperature is 90.
0 ° C., BBr ₃ / H ₂ gas flow rate 500 sccm, internal pressure 3
Under the condition of 0 Torr, B was diffused into the n-type substrate. When the junction depth reached 300 nm, the introduction of BBr ₃ / H ₂ gas was stopped. The H ₂ gas was kept flowing for 5 minutes. I
When forming the mold layer, C ₂ H ₂ gas was introduced instead of CH ₄ gas, and the flow rate pattern was changed as shown in FIG. 14-a. Further, as shown in FIG. 16, RF power, DC bias, and μW power were changed. Except for the first p-type layer and the i-type layer, the same conditions, the same method, and the same procedure as in Example 17 were used. The produced solar cell (SC Ex 29) is (SC Ex 17)
It was found that similarly to the conventional solar cells (SC ratio 17-1) to (SC ratio 17-9), the initial photoelectric conversion efficiency and durability were better.

(Embodiment 30) Using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, FIG.
A triple solar cell was manufactured. The substrate used in Example 17
An n-type polycrystalline silicon substrate manufactured by the casting method was used in the same manner as in.

One side of a 50 × 50 mm ² substrate is heated at a temperature of 10
It was immersed in a 1% NaOH aqueous solution at 0 ° C. for 5 minutes and washed with pure water. Scanning electron microscope (SE
As a result of observation with (M), unevenness having a pyramid structure is formed on the surface, and the substrate is textured (Te
xtured). Next, it was ultrasonically washed with acetone and isopropanol, further washed with pure water, and dried with warm air.

Using the same procedure and method as in Example 17, water was added.
The first plasma treatment is applied to the first on the textured surface of the substrate.
Forming a p-type layer, and further forming a first n-type layer and a first i-type layer
Layer, second p-type layer, second n-type layer, Si layer, second i-type
Layer and a third p-type layer were sequentially formed. Form second i-type layer
In doing so, according to the flow rate change pattern as shown in FIG.
_FourGas flow rate, CH_FourDeposition of Si layer by changing gas flow rate
The speed was 0.15 nm / sec.

Next, as in Example 17, on the third p-type layer, as a transparent electrode, ITO (In ₂ O) having a layer thickness of 70 nm was formed.
₃ + SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method. Next, in the same manner as in Example 17, a current collecting electrode made of silver (Ag) and having a layer thickness of 5 μm was vacuum-deposited on the transparent electrode by an ordinary vacuum deposition method. Then, as in Example 17, Ag-T was formed on the back surface of the substrate.
A back electrode made of an i alloy and having a layer thickness of 3 μm was vacuum-deposited by an ordinary vacuum deposition method.

As described above, the production of the triple type solar cell using the microwave plasma CVD method is completed. This solar cell will be called (SC Ex 30), and the manufacturing conditions of each semiconductor layer are shown in Table 10. (Comparative Example 30-1) A method similar to that in Example 30 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were changed in accordance with the flow rate change pattern of FIG. 6 when forming the second i-type layer of FIG. A triple solar cell was manufactured by the same procedure. This solar cell will be called (SC ratio 30-1).

(Comparative Example 30-2) A solar cell was formed on the substrate by the same method and procedure as in Example 30, except that PH ₃ / H ₂ gas was not flowed when the second i-type layer shown in FIG. 17 was formed. A battery was made. This solar cell will be referred to as (SC ratio 30-2). (Comparative Example 30-3) A solar cell was formed on a substrate by the same method and procedure as in Example 30, except that B ₂ H ₆ / H ₂ gas was not flowed when the second i-type layer in FIG. 17 was formed. Was produced. This solar cell will be called (SC ratio 30-3).

(Comparative Example 30-4) A triplet was formed in the same manner as in Example 30 except that the power of μW was set to 0.5 W / cm ³ when the second i-type layer shown in FIG. 17 was formed. Type solar cell was produced. This solar cell (SC ratio 30-4)
I will call it. (Comparative Example 30-5) A triple solar cell was manufactured in the same manner as in Example 30 except that the RF power was set to 0.15 W / cm ³ when the second i-type layer shown in FIG. 17 was formed. Was produced. This solar cell is called (SC ratio 30-5).

[0290] (Comparative Example 30-6) when forming the second i-type layer in FIG. 17, except that the μW power 0.5 W / cm ^3, the RF power to 0.55 W / cm ³ Example 30 A triple type solar cell was manufactured by the same method and the same procedure. This solar cell is called (SC ratio 30-6).

(Comparative Example 30-7) When forming the second i-type layer in FIG. 17, the pressure in the deposition chamber 401 was set to 0.08 Torr.
A triple type solar cell was produced by the same method and the same procedure as in Example 30 except that This solar cell is called (SC ratio 30-7). (Comparative Example 30-8) A triple solar cell was produced by the same method and procedure as in Example 30, except that the deposition rate was 3 nm / sec when the Si layer in FIG. 17 was formed. This solar cell is called (SC ratio 30-8).

(Comparative Example 30-9) A triple solar cell was prepared by the same method and procedure as in Example 30, except that the thickness of the Si layer shown in FIG. 17 was 40 nm.
This solar cell is called (SC ratio 30-9).
When the initial photoelectric conversion efficiency and durability characteristics of these produced triple solar cells were measured by the same method as in Example 17, (SC Ex 30) showed that the conventional triple solar cells (SC
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the ratios 30-1) to (SC ratio 30-9).

(Example 31) A solar cell of Example 17 was manufactured using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, modularized, and applied to a power generation system. Six solar cells (SC Ex 17) of 50 × 50 mm ² were prepared under the same conditions, the same method, and the same procedure as in Example 17.
Five pieces were produced. E on a 5.0 mm thick aluminum plate
An adhesive sheet made of VA (ethylene vinyl acetate) was placed on the sheet, a nylon sheet was placed on the sheet, and the solar cells produced on the sheet were arranged, and serialized and parallelized. An EVA adhesive sheet was placed thereon, and a fluororesin sheet was further placed thereon, followed by vacuum lamination to form a module. The initial photoelectric conversion efficiency of the manufactured module was measured in the same manner as in Example 17.
The module was connected to the circuit showing the power generation system in FIG. 18, and the night light was used as the load. The whole system was operated by the storage battery and the power of the module, and the module was installed at the angle that could collect the most sunlight. 1
The photoelectric conversion efficiency after the lapse of a year was measured, and the photodegradation rate (photoelectric conversion efficiency after 1 year / initial photoelectric conversion efficiency) was obtained. This module will be called (MJ real 31).

(Comparative Example 31-1) Conventional solar cell (SC
65 ratios 17-X) (X: 1 to 9) were manufactured under the same conditions, the same method, and the same procedure as Comparative Example 17-X, and were modularized in the same manner as in Example 31. This module (MJ ratio 3
1-X). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 1 year were measured under the same conditions, the same method, and the same procedure as in Example 31, and the photodegradation rate was obtained.

As a result, the photodegradation rate of (MJ ratio 31-X) was as follows with respect to (MJ ex 31). Module light deterioration rate ratio ───────────────────────── MJ actual 31 1.00 MJ ratio 31-1 0.80 MJ ratio 31-2 0.80 MJ ratio 31-3 0.78 MJ ratio 31-4 0.76 MJ ratio 31-5 0.80 MJ ratio 31-6 0.72 MJ ratio 31-7 0.68 MJ ratio 31-8 0. 70 MJ ratio 31-9 0.82 From the above results, it was found that the solar cell module of the present invention has more excellent photodegradation characteristics than the conventional solar cell module.

(Example 32) Microwave plasm of the present invention
P / i using the manufacturing apparatus of FIG.
A solar cell of FIG. 19 having a second Si layer at the interface was prepared.
It was Manufactured by the casting method as in Example 17.
50 x 50 mm made ²N-type polycrystalline silicon substrate
HF and HNO₃(H₂Aqueous solution diluted to 10% with O)
It was dipped in water for several seconds and washed with pure water. Then acetone and isop
Ultrasonic cleaning with ropanol, further cleaning with pure water, warm air
Dried.

Hydrogen plasma treatment was applied in the same procedure and method as in Example 17 to form a first p-type layer on the substrate, and further, an n-type layer, a first Si layer, an i-type layer, and a 2 Si
Layer and a second p-type layer were sequentially formed. When forming the i-type layer, the SiH ₄ gas flow rate and the CH ₄ gas flow rate are changed according to the flow rate change pattern as shown in FIG. 5, and the deposition rate of the first Si layer and the second Si layer is 0.15 nm / sec. The layer thickness was 10 nm.

Then, on the second p-type layer, ITO (In) having a layer thickness of 70 nm was formed as a transparent electrode in the same manner as in Example 17.
₂ O ₃ + SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method. Next, as in Example 17, silver (Ag) was formed on the transparent electrode.
A current collecting electrode having a layer thickness of 5 μm was vacuum-deposited by an ordinary vacuum deposition method. Next, in the same manner as in Example 17, A was applied to the back surface of the substrate.
A back electrode made of a g-Ti alloy and having a layer thickness of 3 μm was vacuum-deposited by an ordinary vacuum deposition method.

This solar cell is called (SC Ex 32), and the manufacturing conditions of each semiconductor layer are shown in Table 11. When the initial photoelectric conversion efficiency and the durability characteristics of the manufactured solar cell were measured by the same method as in Example 17, (SC Ex 32) was
Similar to the actual 17), conventional solar cells (SC ratio 17-1) ~
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of (SC ratio 17-9).

(Example 33) A solar cell having a laminated structure of a second p-type layer having the structure shown in Fig. 1-a was prepared by using an n-type polycrystalline silicon substrate prepared by the casting method. HF for 50 × 50m ² and 500μm thick substrate
And HNO ₃ (diluted to 10% with H ₂ O) aqueous solution for several seconds and washed with pure water. Next, it was ultrasonically cleaned with acetone and perisopropanol, further washed with pure water, and dried with warm air.

Next, the source gas supply device 200 shown in FIG.
0 and a deposition apparatus 400 were used to manufacture a semiconductor layer on the substrate by a manufacturing apparatus using a glow discharge decomposition method. The manufacturing procedure will be described below. In the gas cylinders 2041 to 2047 in the figure, the same raw material gas as in Example 1 is sealed.

After the preparation for film formation was completed in the same manner as in Example 1, the substrate was subjected to hydrogen plasma treatment, and then the substrate 40 was processed.
4 on which a first p-type layer, an n-type layer, a Si layer, an i-type layer, and a second
P-type layer was formed. First, to perform the hydrogen plasma treatment, the valve 2003 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the H ₂ gas flow rate to 500 sccm. Adjusting the conductance valve while observing the vacuum gauge 402 so that the pressure in the deposition chamber becomes 2.0 Torr, and heating the heater 4 so that the temperature of the substrate 404 becomes 550 ° C.
05 is set, and it is confirmed that the shutter 415 is closed when the substrate temperature becomes stable.
W) The power supply was set to 0.20 W / cm ³ , and μW power was introduced to cause glow discharge, the shutter 415 was opened, and hydrogen plasma treatment of the substrate was started. After 10 minutes, the shutter was closed, the μW power supply was turned off, the glow discharge was stopped, and the hydrogen plasma treatment was completed. After continuously flowing H ₂ gas into the deposition chamber 401 for 5 minutes, the valve 20
03 was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, in order to form the first p-type layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller is set so that the H ₂ gas flow rate becomes 50 sccm. Adjusted in 2013. Adjusting the conductance valve while watching the vacuum gauge 402 so that the pressure in the deposition chamber becomes 2.0 Torr, and setting the heater 405 so that the temperature of the substrate 404 becomes 350 ° C., the substrate temperature is stable. Valve 200
1, 2005 gradually open, SiH ₄ gas, B ₂ H ₆
/ H ₂ gas was caused to flow into the deposition chamber 401. At this time, S
iH ₄ gas flow rate is 5 sccm, H ₂ gas flow rate is 100 s
It was adjusted with each mass flow controller so that ccm and B ₂ H ₆ / H ₂ gas became 500 sccm. The opening of the conductance valve 407 was adjusted while observing the vacuum gauge 402 so that the pressure in the deposition chamber 401 was 2.0 Torr. Make sure the shutter 415 is closed, set the RF power supply to 0.20 W / cm ³ , and
Shutter 41 is generated by introducing electric power to cause glow discharge.
5 was opened and the formation of the first p-type layer on the substrate was started. After the first p-type layer having a layer thickness of 100 nm was prepared, the shutter was closed, the RF power was turned off, the glow discharge was stopped, and the first
The formation of the p-type layer was completed. The valves 2001 and 2005 are closed, and SiH ₄ gas, B ₂ H ₆ /
Stopping the flow of H ₂ gas for 5 minutes, H ₂ into the deposition chamber 401
After continuing to flow the gas, the valve 2003 was closed and the inside of the deposition chamber 401 and the gas pipe were evacuated.

To form the n-type layer, the auxiliary valve 40
8, gradually open the valve 2003, H₂Gas to gas
It is introduced into the deposition chamber 401 through the inlet pipe 411, and H₂gas
Mass flow control so that the flow rate is 50 sccm
Ra 2013 is set and the pressure in the deposition chamber is 1.0 Tor.
Adjust the conductance valve to r
Heater 405 so that the temperature of 04 becomes 350 ° C.
It was set. When the substrate temperature is stable,
Open 2001 and 2004 gradually to SiH_FourGas, P
H₃/ H₂Gas was flowed into the deposition chamber 401. this
Sometimes SiH_FourGas flow rate is 2 sccm, H₂Gas flow rate is 1
00sccm, PH₃/ H₂Gas flow rate is 200 sccm
Adjust with each mass flow controller so that
It was The pressure in the deposition chamber 401 will be 1.0 Torr.
Thus, the opening of the conductance valve 407 was adjusted. R
The power of F power source is 0.01W / cm³ Set to RF electrode
Introduce RF power to 410 to cause glow discharge and
Open the shutter and start making the n-type layer on the first p-type layer
The n-type layer with a layer thickness of 30 nm was produced, and the shutter was released.
Closed, RF power turned off, glow discharge stopped, n-type
Finished forming layers. Close the valves 2001 and 2004
SiH into the deposition chamber 401_FourGas, PH₃/ H ₂Moth
Stop the flow of gas into the deposition chamber 401 for 5 minutes.₂Gas
After continuing the flow, the outflow valve 2003 is closed and the deposition chamber 4
The inside of 01 and the inside of the gas pipe were evacuated.

To form the Si layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401 through the introduction pipe 411, and the mass flow controller 2013 is set so that the H ₂ gas flow rate becomes 50 sccm. Then, the pressure inside the deposition chamber was adjusted to 1.5 Torr by a conductance valve, and the heater 405 was set so that the temperature of the substrate 404 became 270 ° C. When the substrate temperature became stable, the valve 2001 was gradually opened to allow SiH ₄ gas to flow into the deposition chamber 401. At this time, the SiH ₄ gas flow rate is ₂ sccm and the H ₂ gas flow rate is 1 sc
It was adjusted with each mass flow controller so as to be 00 sccm. The pressure in the deposition chamber 401 is 1.5 To
The opening of the conductance valve 407 was adjusted so as to be rr. The power of the RF power source was set to 0.01 W / cm ³ , RF power was introduced to the RF electrode 410 to cause glow discharge, the shutter was opened, the production of the Si layer on the n-type layer was started, and the deposition rate was 0. 0.15 nm / sec, layer thickness 10 nm
After the Si layer was produced, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the Si layer was completed. The valve 2001 is closed, and Si in the deposition chamber 401
The flow rate of H ₄ gas was stopped and H _{2 was} introduced into the deposition chamber 401 for 5 minutes.
After continuing to flow the gas, the outflow valve 2003 was closed and the inside of the deposition chamber 401 and the gas pipe were evacuated.

Next, to prepare the i-type layer, the valve 20 was used.
Open 03 gradually, H₂Introduce gas into deposition chamber 401
And H₂The mass flow should be 300sccm.
Adjusted with the low controller 2013. Deposition chamber pressure
With a conductance valve so that it becomes 0.01 Torr
Adjust and heat the substrate 404 to 350 ° C
Set the heater 405 and make sure the substrate temperature is stable.
Further, the valves 2001 and 2002 are gradually opened to set the Si
H_FourGas, CH_FourGas was flowed into the deposition chamber 401.
At this time, SiH_FourGas flow rate is 100 sccm, CH_FourBut
Flow rate 30 sccm, H₂Gas flow rate is 300sccm
Adjust with each mass flow controller so that
It was The pressure in the deposition chamber 401 will be 0.01 Torr.
Thus, the opening of the conductance valve 407 was adjusted. Next
The power of the RF power supply 403 is 0.40 W / cm³Set to
Then, it was applied to the RF electrode 403. After that, μW not shown
The power of the power supply is 0.20 W / cm³Set the dielectric window 41 to
ΜW power is introduced into the deposition 401 through
Electricity is generated, the shutter is opened, and the i-type layer on the Si layer
Production was started. Connect to mass flow controller
Flow rate change pattern shown in FIG.
According to SiH_FourGas, CH_FourChange the flow rate of gas
When an i-type layer having a layer thickness of 300 nm was produced,
And turn off the μW power to stop glow discharge,
The F power supply 403 was turned off, and the production of the i-type layer was completed. Valve 2
001 and 2002 are closed, and SiH enters the deposition chamber 401.
_FourGas, CH _FourStop gas inflow, deposit chamber 40 for 5 minutes
1 into H₂Close the valve 2003 after continuing to flow the gas.
Then, the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, in order to form the second p-type layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller is set so that the H ₂ gas flow rate becomes 300 sccm. Adjusted in 2013. The pressure inside the deposition chamber is adjusted to 0.02 Torr by a conductance valve, the heater 405 is set so that the temperature of the substrate 404 becomes 200 ° C., and the temperature of the substrate is stabilized. 2005
Gradually open, SiH ₄ gas, CH ₄ gas, H ₂ , B
₂ H ₆ / H ₂ gas was caused to flow into the deposition chamber 401. At this time, SiH ₄ gas flow rate is 10 sccm, CH ₄ gas flow rate is 5 sccm, H ₂ gas flow rate is 300 sccm, and B ₂ H
Each mass flow controller was adjusted so that the ₆ / H ₂ gas flow rate was 10 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 0.02 Torr. Set the power of the μW power supply to
It is set to 30 W / cm ³ , and μW electric power is introduced into the deposition chamber 401 through the dielectric window 413 to cause glow discharge, the shutter 415 is opened, and the light-doped layer (A layer) is formed on the i-type layer. Started. When the layer A having a layer thickness of 3 nm was prepared, the shutter was closed, the μW power source was turned off, and the glow discharge was stopped. Valves 2001, 2002, 2005
Is closed to stop the inflow of SiH ₄ gas, CH ₄ gas and B ₂ H ₆ / H ₂ gas into the deposition chamber 401, and H ₂ gas is continuously flowed into the deposition chamber 401 for 5 minutes, and then the valve 2003
Was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, the valve 2005 was gradually opened, B ₂ H ₆ / H ₂ gas was introduced into the deposition chamber 401, and the mass flow controllers were adjusted so that the flow rate was 1000 sccm. The pressure in the deposition chamber 401 is 0.0
The opening of the conductance valve 407 was adjusted to be 2 Torr, the power of the μW power source was set to 0.20 W / cm ³ , and the μW was introduced into the deposition chamber 401 through the dielectric window 413.
Shutter 41 is generated by introducing electric power to cause glow discharge.
5 was opened, and the formation of boron (B layer) on the A layer was started.
After 6 seconds, the shutter was closed, the μW power supply was turned off, and the glow discharge was stopped. The valve 2005 is closed to stop the inflow of B ₂ H ₆ / H ₂ gas into the deposition chamber 401, and 5
After continuously flowing H ₂ gas into the deposition chamber 401 for a minute, the valve 2003 was closed and the inside of the deposition chamber 401 and the gas pipe were evacuated.

Next, the same methods, conditions and procedures as those described above
To form layer A on layer B, and then stack layers B and A,
The formation of the second p-type layer having a layer thickness of about 10 nm was completed. next,
On the second p-type layer, a transparent electrode having a layer thickness of 70 nm I
TO (In₂O ₂+ NO₂) Is vacuumed by the usual vacuum deposition method.
It was vapor-deposited. Next, a layer thickness 5 of silver (Ag) was formed on the transparent electrode.
The μm collector electrode was vacuum-deposited by a usual vacuum deposition method.

Next, a back electrode made of Ag—Ti alloy and having a layer thickness of 3 μm was vacuum-deposited on the back surface of the substrate by a usual vacuum deposition method. This completes the production of this solar cell. This solar cell will be referred to as (SC Ex 33), and the manufacturing conditions for the first p-type layer, n-type layer, Si layer, i-type layer, and second p-type layer are shown in Table 12.
Shown in.

Comparative Example 33-1 Example 33 was repeated except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were adjusted by the respective mass flow controllers according to the flow rate pattern shown in FIG. 6 when forming the i-type layer. A solar cell was manufactured under the same conditions and the same procedure as described above. This solar cell (SC ratio 33-
I will call it 1).

(Comparative Example 33-2) A solar cell was produced under the same conditions and the same procedure as in Example 33, except that the μW power was set to 0.5 W / cm ³ when the i-type layer was formed. This solar cell will be referred to as (SC ratio 33-2). (Comparative Example 33-3) A solar cell was produced under the same conditions and the same procedure as in Example 33, except that the RF power was set to 0.15 W / cm ³ when the i-type layer was formed. This solar cell will be called (SC ratio 33-3).

(Comparative Example 33-4) When forming the i-type layer, μW power was 0.5 W / cm ³ , and RF power was 0.55.
A solar cell was produced under the same conditions and the same procedure as in Example 33 except that W / cm ³ was used. This solar cell (SC ratio 3
3-4). (Comparative Example 33-5) A solar cell was manufactured under the same conditions and in the same procedure as in Example 33, except that the pressure inside the deposition chamber was set to 0.08 Torr when forming the i-type layer. This solar cell is called (SC ratio 33-5).

(Comparative Example 33-6) Example 3 was repeated except that the deposition rate was set to 3 nm / sec when the Si layer was formed.
A solar cell was manufactured under the same conditions and the same procedure as in 3. This solar cell is called (SC ratio 33-6). (Comparative Example 33-7) When forming a Si layer, the layer thickness is set to 40.
A solar cell was produced under the same conditions and the same procedure as in Example 33 except that the thickness was changed to nm. This solar cell (SC ratio 33-
7).

The initial light conversion efficiency (photovoltaic power / incident light power) and durability characteristics of the manufactured solar cells (SC Ex 33) and (SC ratio 33-1) to (SC ratio 33-7) were measured. . As a result of the measurement, for the solar cell of (SC Ex 33), the initial photoelectric conversion efficiencies of (SC ratio 33-1) to (SC ratio 33-7) were as follows.

(SC ratio 33-1) 0.78 times (SC ratio 33-2) 0.63 times (SC ratio 33-3) 0.80 times (SC ratio 33-4) 0.65 times (SC ratio 33-5) 0.77 times (SC ratio 33-6) 0.82 times (SC ratio 33-7) 0.86 times When the durability characteristics were measured, it was compared with the (SC Ex 33) solar cell. , (SC ratio 33-1) to (SC ratio 33-
The durability characteristics of 7) are as follows.

(SC ratio 33-1) 0.79 times (SC ratio 33-2) 0.71 times (SC ratio 33-3) 0.78 times (SC ratio 33-4) 0.70 times (SC ratio 33-5) 0.72 times (SC ratio 33-6) 0.83 times (SC ratio 33-7) 0.89 times Next, from the relationship between the composition ratio of Si atoms and C atoms and the band gap, the i-type layer And the change in the band gap of the Si layer in the layer thickness direction was determined to be (SC actual 33), (SC ratio 33-
In the solar cells of 2) to (SC ratio 33-7), the position of the minimum value of the band gap is offset from the central position of the i-type layer toward the p / i interface, and the solar cell of (SC ratio 33-1) is In the battery, it was found that the position of the minimum value of the band gap is offset in the i / Si interface direction from the position of the center of the i-type layer.

Above, (SC actual 33), (SC ratio 33-
1) to (SC ratio 33-7) changes in the band gap in the layer thickness direction are caused by the source gas containing Si (SiH ₄ gas in this case) and the source gas containing C (this In some cases, it was found to depend on the flow rate ratio of CH ₄ gas). Next, a second p-type layer having a laminated structure was formed on the polycrystalline silicon substrate, and its TEM (transmission electron microscope) image was observed. A second p-type layer was formed on the substrate by the same method and procedure as in Example 33 except that the B layer was deposited for 12 seconds. Cut the prepared sample in the cross-sectional direction,
As a result of observing the laminated state of the A layer and the B layer in the second p-type layer, as shown in FIG. 21, the B layer having a layer thickness of about 1 nm and the A layer having a layer thickness of about 3 nm are alternately laminated. I found out.

(Comparative Example 33-8) Several solar cells were produced under the same conditions as in Example 33 except that the μW power and RF power introduced when forming the i-type layer were variously changed. The relationship between the μW power and the deposition rate shows the same tendency as in FIG. 9, the deposition rate does not depend on the RF power, and the μW power is 0.3.
It was found that at 2 W / cm ³ or more, it was constant, and SiH ₄ gas and CH ₄ gas that were the raw material gases were decomposed by 100% by this electric power. When the initial photoelectric conversion efficiency of the solar cell when irradiated with AM1.5 (100 mW / cm ² ) light was measured, the result was as shown in FIG. 10. That is, μ
W power is less than μW power (0.32 W / cm ³ ) for 100% decomposition of SiH ₄ gas and CH ₄ gas, and RF
It has been found that the initial photoelectric conversion efficiency is significantly improved when the power is larger than the μW power.

(Comparative Example 33-9) When the i-type layer was formed in Example 33, the flow rate of the gas introduced into the deposition chamber 401 was set to Si.
Several solar cells were produced by changing the H ₄ gas to 50 sccm and the CH ₄ gas to 10 sccm, introducing no H ₂ gas, and varying the μW power and the RF power variously. The other conditions were the same as in Example 33. When the relationship between the deposition rate, the μW power, and the RF power was examined, the deposition rate did not depend on the RF power as in Comparative Example 33-8, and the μW power was 0.18 W / cm ^3.
The above is constant, and at this μW power, the source gas Si
It was found that 100% of H ₄ gas and CH ₄ gas were decomposed. When the initial photoelectric conversion efficiency of the solar cell when irradiated with AM1.5 light was measured, the result showed the same tendency as in FIG. That is, μW power is SiH
₄ gas and CH ₄ gas of 100% decomposed μW power (0.18W / cm ³⁾ or less, and the initial photoelectric conversion efficiency when RF power is greater than the μW power was found to be greatly improved.

(Comparative Example 33-10) When the i-type layer was formed in Example 33, the flow rate of the gas introduced into the deposition chamber 401 was changed to S
iH ₄ gas 200 sccm, CH ₄ gas 50 sccm,
H ₂ gas was changed to 500 sccm, and the substrate temperature was 3
Change the setting of the heater so that it becomes 00 ° C
Several solar cells were produced by changing the electric power and the RF power variously. The other conditions were the same as in Example 33.

When the relationship between the deposition rate and the μW power and RF power was examined, the deposition rate was found to be RF as in Comparative Example 33-8.
It was found that the μW power was constant at 0.65 W / cm ³ or more and did not depend on the power, and the SiH ₄ gas and CH ₄ gas as the raw material gas were decomposed 100% by this power.
When the initial photoelectric conversion efficiency of the solar cell when irradiated with AM1.5 light was measured, the result showed the same tendency as in FIG. That, .mu.W power the SiH ₄ gas 100
It was found that the initial photoelectric conversion efficiency was significantly improved when the μW power (0.65 W / cm ³ ) at which the RF power was decomposed and when the RF power was higher than the μW power.

(Comparative Example 33-11) When the i-type layer was formed in Example 33, the pressure inside the deposition chamber was changed from 3 mTorr to 20.
Various changes were made up to 0 mTorr, and other conditions were in Example 33.
Several solar cells were prepared in the same manner as in. AM1.5
By measuring the initial photoelectric conversion efficiency of the solar cell when irradiated with light, the results shown in Fig. 11 were obtained, and the pressure was 50 m.
It was found that the initial photoelectric conversion efficiency was significantly reduced above Torr.

(Comparative Example 33-12) When the Si layer was formed in Example 33, the deposition rate was variously changed by changing the SiH ₄ gas flow rate and the RF power, and other conditions were the same as in Example 33. , Some solar cells were produced. AM
The initial photoelectric conversion efficiency of the solar cell when irradiated with 1.5 light was measured to show that the deposition rate of the Si layer was 2 nm / sec.
From the above, it was found that the initial photoelectric conversion efficiency was significantly reduced.

(Comparative Example 33-13) Several solar cells were produced under the same conditions as in Example 33 except that the layer thickness was variously changed when the Si layer was formed in Example 33. AM1.
When the initial photoelectric conversion efficiency of the solar cell when irradiated with 5 lights was measured, it was found that the initial photoelectric conversion efficiency was significantly reduced when the layer thickness was 30 nm or more.

As mentioned above, (Comparative Example 33-1) to (Comparative Example 33)
-13), the solar cell of the present invention (SC Ex 3
It was demonstrated that 3) has the characteristics further superior to the conventional solar cells (SC ratio 33-1) to (SC ratio 33-7). (Example 34) The band gap (E
Several solar cells were manufactured by changing the position of the minimum value of g) in the layer thickness direction, the size of the minimum value, and the pattern,
The initial photoelectric conversion efficiency and durability characteristics were examined in the same manner as in Example 33. At this time, the solar cell having the band gap shown in FIG. 12 was produced in the same manner as in Example 33 except for the change patterns of the SiH ₄ gas flow rate and the CH ₄ gas flow rate of the i-type layer.

Table 13 shows the results of examining the initial photoelectric conversion efficiency and durability characteristics of these manufactured solar cells (the values in the table are based on SC Ex (34-1)). As can be seen from these results, the minimum value of the band gap,
The band gap of the i-type layer changes smoothly in the layer thickness direction regardless of the change pattern, and the position of the minimum value of the band gap deviates from the center position of the i-type layer toward the p / i interface. It turns out that solar cells are better.

Example 35 A solar cell in which the B layer was formed by the mercury-sensitized CVD method was produced. Φ10 in the deposition chamber of FIG.
A quartz glass window having a thickness of 0 mm and a thickness of 10 mm and a low-pressure mercury lamp were attached, and the light of the low-pressure mercury lamp was made incident on the deposition chamber through the quartz glass window. In addition, a shutter (window shutter) that covers the quartz glass window was installed inside the deposition chamber so that deposits would not adhere to the window. Further, a liquid cylinder 2048 having valves at its inlet and outlet was filled with mercury (purity 99.999%). Install the cylinder between the valve 2005 and the mass flow controllers 2015, by bubbling with B ₂ H ₆ / H ₂ gas, and to be able to introduce the mercury vaporized with B ₂ H ₆ / H ₂ gas into the deposition chamber.

When forming the B layer, the flow rate of the B ₂ H ₆ / H ₂ gas was set to 1000 sccm, the pressure was set to 1.0 Torr, the shutter 415 was opened in advance, the low pressure mercury lamp was turned on, and the window shutter was opened for 60 seconds. 1 is performed under the same conditions, method and procedure as in Example 33 except that the layer B is opened and the layer B is formed on the layer A.
The solar cell of was produced. Fabricated solar cell (SC Ex 3
It was found that, like (SC Ex. 33), 5) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC ratio 33-1) to (SC ratio 33-7).

Example 36 A solar cell of FIG. 1-b was produced using a p-type polycrystalline silicon substrate. A first n-type layer, a p-type layer, an i-type layer, a Si layer, and a second n-type layer were sequentially formed on the substrate. Table 14 shows the forming conditions. When forming the i-type layer, the SiH ₄ gas flow rate and the CH ₄ gas flow rate are changed as shown in the pattern of FIG. 0.
It was set to 15 nm / sec. Layers other than the substrate and the semiconductor layer were manufactured under the same conditions and the same method as those in Example 33.

The produced solar cell (SC Ex 36) was (SC
Similar to the actual 33), conventional solar cells (SC ratio 33-1) ~
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of (SC ratio 33-7). (Example 37) A solar cell having a maximum bandgap of the i-type layer near the p / i interface and a thickness of that region of 20 nm was measured using a flow rate variation pattern of the i-type layer shown in FIG. 13-a. It was made by using.

It was manufactured using the same conditions and method as in Example 33 except that the flow rate change pattern of the i-type layer was changed. Next, the composition analysis of the solar cell was performed in the same manner as in Example 1, and the change in the band gap in the layer thickness direction of the i-type layer was examined from the relationship between the band gap and the composition. It became a result. The (SC Ex 37) produced is (SC
Similar to the actual 33), conventional solar cells (SC ratio 33-1) ~
It was found that the initial photoelectric conversion efficiency and durability were better than those of (SC ratio 33-7).

(Comparative Example 37) There was a region having the maximum bandgap near the p / i interface of the i-type layer, and several solar cells having various thicknesses were manufactured. Except for the thickness of the region, the same conditions and methods as in Example 37 were used. When the initial photoelectric conversion efficiency and durability of the manufactured solar cell were measured, the region thickness was 1 nm.
Above 30 nm, the solar cell of Example 33 (SC
The initial photoelectric conversion efficiency and durability were better than those of Ex. 33).

(Example 38) There is a maximum bandgap of the i-type layer near the i / Si interface, and the thickness of the region is 1
A solar cell having a thickness of 5 nm was produced using the flow rate change pattern of the i-type layer shown in FIG. 13-c. It was manufactured using the same conditions and the same method as in Example 33 except that the flow rate change pattern of the i-type layer was changed. Next, the composition analysis of the solar cell was performed in Example 33.
When the change in the bandgap of the i-type layer in the layer thickness direction was examined by the same method as described above, the same result as in FIG. 13-d was obtained. The prepared solar cell (SC Ex 38) is (SC Ex 3
Similar to 3), the conventional solar cells (SC ratio 33-1) to (S
It was found that the initial photoelectric conversion efficiency and durability were better than those of C ratio 17).

(Comparative Example 38) There was a region having the maximum bandgap in the vicinity of the i / Si interface of the i-type layer, and several solar cells having various thicknesses were manufactured. It was manufactured using the same conditions and the same method as in Example 38 except for the thickness of the region. When the initial photoelectric conversion efficiency and durability of the manufactured solar cell were measured, the region thickness was 1 nm.
As described above, when the thickness is 30 nm or less, the initial photoelectric conversion efficiency and durability which are better than those of the solar cell of Example 33 (SC Ex 33) were obtained.

Example 39 In forming the second p-type layer, triethylboron ((abbreviated as B (C ₂ H ₅ ) ₃ , TEB) was used instead of B ₂ H ₆ / H ₂ gas. The solar cell used was manufactured, and liquid TEB (purity 9
(9.99%) was filled in a liquid cylinder 2048 having a valve at the inlet and the outlet. By attaching the cylinder to the source gas supply device and bubbling with H ₂ gas, it was possible to introduce vaporized TEB together with H ₂ gas into the deposition chamber.

When forming the A layer, TEB / H₂Gas 1
0 sccm, as in Example 33, except for flowing into the deposition chamber
A layer is formed on the i-type layer under the same conditions and procedures, and H is applied for 5 minutes.
₂Gas was introduced into the deposition chamber and then evacuated. Layer B
TEB / H when forming₂1000 sccm gas,
The same conditions and conditions as in Example 33 except for flowing into the deposition chamber
B layer is formed on the i-type layer in this order, and H is applied for 5 minutes. ₂Gas deposition
After flowing into the chamber, the chamber was evacuated.

Next, an A layer is formed on the B layer, and H _{2 is applied for} 5 minutes.
Gas was introduced into the deposition chamber and then evacuated. Then A
A layer B was formed on the layer, and H ₂ gas was introduced into the deposition chamber for 5 minutes, and then the layer was evacuated. Next, an A layer was formed on the B layer, and H ₂ gas was introduced into the deposition chamber for 5 minutes, and then vacuum exhaust was performed.

Except for the second p-type layer, the same conditions, methods and procedures as in Example 33 were used. The manufactured (SC ex. 39) is similar to the (SC ex. 33) in the conventional solar cell (SC ratio 33-
It was found that the initial photoelectric conversion efficiency and durability were better than those of 1) to (SC ratio 33-7). (Example 40) A solar cell having an i-type layer containing oxygen atoms was produced. When forming the i-type layer, the same conditions, the same method, and the same procedure as in Example 33 were used, except that O ₂ / He gas of 10 sccm was introduced into the deposition chamber 401 in addition to the gas flowing in Example 33. . Fabricated solar cell (SC Ex 4
It was found that 0) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC ratio 33-1) to (SC ratio 33-7), like (SC Ex 33).

Further, the content of oxygen atoms in the i-type layer is determined by SI
When examined by MS, it was found to contain almost uniformly 2 × 10 ¹⁹
It was found to be (pieces / cm ² ). (Example 41) A silicon solar cell in which a nitrogen atom was contained in the i-type layer was produced. When forming the i-type layer, NH ₃ / H ₂ gas is added at 5 sccc in addition to the gas flowing in Example 33.
m, the same conditions, the same methods, and the same procedures as in Example 33 were used, except that they were introduced into the deposition chamber 401. The produced solar cell (SC Ex 41) has a better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC Ratio 33-1) to (SC Ratio 33-7), similarly to (SC Ex 33). Found to have. In addition, the content of nitrogen atoms in the i-type layer can be adjusted to SI
When examined by MS, it was found that the content was almost uniform and 3 × 10 ¹⁷
It was found to be (pieces / cm ² ).

(Example 42) Oxygen atoms and nitrogen were added to the i-type layer.
A solar cell containing elementary atoms was manufactured. i-type layer
When forming, in addition to the gas flowing in Example 33, O₂/ He
5 sccm gas, NH₂/ H₂Gas 5sccm, stack
The same conditions as in Example 33, except that they were introduced into the loading chamber 401,
The same method, same procedure was used. Fabricated solar cell (SC
Ex 42) is similar to (SC Ex 33), the conventional solar cell (S
Even better than C ratio 33-1) to (SC ratio 33-7)
Have excellent initial photoelectric conversion efficiency and durability characteristics
It was. In addition, the contents of oxygen atoms and nitrogen atoms in the i-type layer
When examined by SIMS, it was found that the content was almost uniform.
1 x 10¹⁹(Pieces / cm²) 3 x 10¹⁷(Pieces / cm
²) Was found.

(Example 43) A solar cell was produced in which the hydrogen content of the i-type layer was changed corresponding to the silicon content. The O ₂ / He gas cylinder was replaced with SiF ₄ gas (purity 99.
(999%) When replacing the cylinder and forming the i-type layer, as shown in FIG.
According to the flow pattern of 5-a, SiH ₄ gas, CH ₄
The flow rates of the gas and SiF ₄ gas were changed. When the change in the band gap in the layer thickness direction of this solar cell (SC Ex 43) was obtained by the same method as in Example 33, FIG.
The result was similar to that of b.

Further, the secondary ion mass spectrometer was used to analyze the contents of hydrogen atoms and silicon atoms in the layer thickness direction. The same results as in FIG. 15-c were obtained, and it was found that the hydrogen atom content has a layer thickness direction distribution corresponding to the silicon atom content. This solar cell (SC Ex 43)
When the initial photoelectric conversion efficiency and durability characteristics of No. 3 were determined, similar to the solar cell of Example 33, the conventional solar cell (SC ratio 33-
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of 1) to (SC ratio 33-7).

(Example 44) When a semiconductor layer of the solar cell of FIG. 1 was formed by the manufacturing apparatus using the microwave plasma CVD method shown in FIG. 4, a silicon atom-containing gas (Si
Example 33 except that the H ₄ gas) and the carbon atom-containing gas (CH ₄ gas) were mixed at a distance of 1 m from the deposition chamber.
A solar cell (SC Ex 44) was produced by the same method and the same procedure. The produced solar cell (SC Ex. 44) is (SC Ex. 3
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of 3).

(Example 45) When a first p-type layer was formed by a gas diffusion method to form an i-type layer, C ₂ H ₂ gas was used instead of CH ₄ gas, and a positive electrode was used for the RF electrode. A solar cell was manufactured by applying a DC bias and changing the RF power, DC bias, and μW power. First, O ₂ / He BBr ₃ to the gas cylinder and diluted to 10% with hydrogen was replaced with (BBr ₃ / H ₂ gas) cylinder, a further CH ₄ gas cylinder C ₂ H
₂ gas was exchanged. When forming the first p-type layer, the substrate temperature is 900 ° C., the BBr ₃ / H ₂ gas flow rate is 500 sccm,
B was diffused under the diffusion condition of the internal pressure of 30 Torr. When the junction depth reached 300 nm, the introduction of BBr ₃ / H ₂ gas was stopped. On the other hand, when forming the i-type layer, C ₂ H ₂ gas was introduced instead of CH ₄ gas, and the flow rate pattern was changed as shown in FIG. 14-a. Further, as shown in FIG. 16, RF power, DC bias, and μW power were changed.
Except for the first p-type layer and the i-type layer, the same conditions, the same method, and the same procedure as in Example 33 were used.

The produced solar cell (SC Ex. 45) was (SC
Similar to the actual 33), conventional solar cells (SC ratio 33-1) ~
It was found that the initial photoelectric conversion efficiency and durability were better than those of (SC ratio 33-7). (Example 46) The triple type solar cell of FIG. 17 was manufactured using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention.

As the substrate, an n-type polycrystalline silicon substrate manufactured by the casting method was used. 50 × 50m
One side of the m ² substrate was immersed in a 1% NaOH aqueous solution at a temperature of 100 ° C. for 5 minutes and washed with pure water. As a result of observing the surface immersed in NaOH with a scanning electron microscope (SEM), it was found that unevenness having a pyramid structure was formed on the surface and the substrate was textured. Next, it was ultrasonically washed with acetone and isopropanol, further washed with pure water, and dried with warm air.

Using the same procedure and method as in Example 33, water was added.
The first plasma treatment is applied to the first on the textured surface of the substrate.
Forming a p-type layer, and further forming a first n-type layer and a first i-type layer
Layer, second p-type layer, second n-type layer, Si layer, second i-type
Layer and a third p-type layer were sequentially formed. Form second i-type layer
In doing so, according to the flow rate change pattern as shown in FIG.
_FourGas flow rate, CH_FourDeposition of Si layer by changing gas flow rate
The speed was 0.15 nm / sec. The third p-type layer is actually
A laminated structure was formed as in the case of Example 33.

Next, as in Example 33, ITO (In ₂ O) having a layer thickness of 70 nm was formed as a transparent electrode on the third p-type layer.
₃ + SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method. Next, as in Example 33, a collector electrode made of silver (Ag) and having a layer thickness of 5 μm was vacuum-deposited on the transparent electrode by a usual vacuum vapor deposition method. Next, as in Example 33, Ag-T was formed on the back surface of the substrate.
A back electrode made of an i alloy and having a layer thickness of 3 μm was vacuum-deposited by an ordinary vacuum deposition method.

Thus, the production of the triple type solar cell using the microwave plasma CVD method is completed. This solar cell will be called (SC Ex 46), and the manufacturing conditions of each semiconductor layer are shown in Table 15. (Comparative Example 46-1) A method similar to that of Example 46 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were changed in accordance with the flow rate change pattern of FIG. 6 when the second i-type layer of FIG. 17 was formed. A triple solar cell was manufactured by the same procedure. This solar cell will be called (SC ratio 46-1).

(Comparative Example 46-2) When the second i-type layer shown in FIG. 17 was formed, a triplet was formed in the same manner as in Example 46 except that the μW power was set to 0.5 W / cm ^3. Type solar cell was produced. This solar cell (SC ratio 46-2)
I will call it. (Comparative Example 46-3) A triple solar cell was manufactured in the same manner as in Example 46 except that the RF power was set to 0.15 W / cm ³ when the second i-type layer shown in FIG. 17 was formed. Was produced. This solar cell will be called (SC ratio 46-3).

[0352] (Comparative Example 46-4) when forming the second i-type layer in FIG. 17, except that the μW power 0.5 W / cm ^3, the RF power to 0.55 W / cm ³ Example 46 A triple type solar cell was manufactured by the same method and the same procedure. This solar cell will be called (SC ratio 46-4).

(Comparative Example 46-5) When the second i-type layer shown in FIG. 17 was formed, the pressure in the deposition chamber 401 was set to 0.08 Torr.
A triple type solar cell was manufactured by the same method and the same procedure as in Example 46 except that the above was used. This solar cell will be referred to as (SC ratio 46-5). (Comparative Example 46-6) A triple solar cell was produced by the same method and procedure as in Example 46 except that the deposition rate was set to 3 nm / sec when the Si layer in FIG. 17 was formed. This solar cell is called (SC ratio 46-6).

(Comparative Example 46-7) A triple-type solar cell was produced by the same method and procedure as in Example 46, except that the layer thickness was 40 nm when the Si layer shown in FIG. 17 was formed.
This solar cell is called (SC ratio 46-7).
When the initial photoelectric conversion efficiency and durability characteristics of these produced triple solar cells were measured by the same method as in Example 33, (SC Ex 46) showed that the conventional triple solar cells (SC
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the ratios 46-1) to (SC ratio 46-7).

Example 47 A solar cell of Example 33 was produced using the production apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, made into a module, and applied to a power generation system. A solar cell of 50 × 50 nm ² (SC Ex 33) was prepared under the same conditions, the same method and the same procedure as in Example 33.
Five pieces were produced. E on a 5.0 mm thick aluminum plate
An adhesive sheet made of VA (ethylene vinyl acetate) was placed on the sheet, a nylon sheet was placed on the sheet, and the solar cells produced on the sheet were arranged, and serialized and parallelized. An EVA adhesive sheet was placed thereon, and a fluororesin sheet was further placed thereon, followed by vacuum lamination to form a module. The initial photoelectric conversion efficiency of the manufactured module was measured by the same method as in Example 33.
The module was connected to the circuit showing the power generation system in FIG. 18, and the night light was used as the load. The whole system was operated by the storage battery and the power of the module, and the module was installed at the angle that could collect the most sunlight. 1
The photoelectric conversion efficiency after the lapse of a year was measured, and the photodegradation rate (photoelectric conversion efficiency after 1 year / initial photoelectric conversion efficiency) was obtained. This module will be called (MJ real 47).

(Comparative Example 47-1) Conventional solar cell (SC
Sixty-three ratios 33-X) (X: 1 to 7) were produced under the same conditions, the same method, and the same procedure as Comparative Example 33-X, and were modularized in the same manner as in Example 47. This module (MJ ratio 4
7-X). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after one year were measured under the same conditions, the same method, and the same procedure as in Example 47, and the photodegradation rate was obtained.

As a result, the photodegradation rate of (MJ ratio 47-X) was as follows with respect to (MJ ex. 47). Module light deterioration ratio ───────────────────────── MJ actual 47 1.00 MJ ratio 47-1 0.76 MJ ratio 47-2 0.72 MJ ratio 47-3 0.86 MJ ratio 47-4 0.70 MJ ratio 47-5 0.82 MJ ratio 47-6 0.70 MJ ratio 47-7 0.83 It has been found that the solar cell module has better photodegradation characteristics than the conventional solar cell module.

(Example 48) Microwave plasm of the present invention
P / i using the manufacturing apparatus of FIG.
A solar cell of FIG. 19 having a second Si layer at the interface was prepared.
It was Manufactured by the casting method as in Example 33.
50 x 50 mm made ²N-type polycrystalline silicon substrate
HF and HNO₃(H₂Aqueous solution diluted to 10% with O)
It was dipped in water for several seconds and washed with pure water. Then acetone and isop
Ultrasonic cleaning with ropanol, further cleaning with pure water, warm air
Dried.

Hydrogen plasma treatment was performed in the same procedure and method as in Example 33 to form a first p-type layer on the substrate, and further, a first n-type layer, a first Si layer, and an i-type layer were formed. Layer, second
The Si layer and the second p-type layer were sequentially formed. When forming the i-type layer, the SiH ₄ gas flow rate and the CH ₄ gas flow rate are changed according to the flow rate change pattern as shown in FIG. 13-a, and the deposition rate of the first Si layer and the second Si layer is 0.15 nm. / Se
c, the layer thickness was 10 nm. The second p-type layer had a laminated structure as in Example 33.

Then, ITO (In) having a layer thickness of 70 nm was formed as a transparent electrode on the second p-type layer in the same manner as in Example 33.
₂ O ₃ + SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method. Then, silver (Ag) was formed on the transparent electrode in the same manner as in Example 33.
A current collecting electrode having a layer thickness of 5 μm was vacuum-deposited by an ordinary vacuum deposition method. Then, in the same manner as in Example 33, A was formed on the back surface of the substrate.
A back electrode made of a g-Ti alloy and having a layer thickness of 3 μm was vacuum-deposited by an ordinary vacuum deposition method.

This solar cell is called (SC Ex 48), and the manufacturing conditions of each semiconductor layer are shown in Table 16. The initial photoelectric conversion efficiency and the durability characteristics of the manufactured solar cell were measured by the same method as in Example 33.
Similar to the actual 33), conventional solar cells (SC ratio 33-1) ~
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of (SC ratio 33-7).

(Example 49) In this example, B was added to the i-type layer.
And a P atom were contained, and a photovoltaic element having a laminated structure of the second p-type layer was produced. First, the solar cell of FIG. 1-a was manufactured using an n-type polycrystalline silicon substrate manufactured by the casting method.

A 50 × 50 m ² substrate having a thickness of 500 μm was dipped in an aqueous solution of HF and HNO ₃ (diluted to 10% with H ₂ O) for several seconds and washed with pure water. Next, it was ultrasonically cleaned with acetone and perisopropanol, further washed with pure water, and dried with warm air. Next, a semiconductor layer was formed on the substrate by the manufacturing apparatus using the glow discharge decomposition method including the source gas supply device 2000 and the deposition device 400 shown in FIG. The manufacturing procedure will be described below.

The gas cylinders 2041 to 2047 in the figure are sealed with the same source gas as in the first embodiment. After the preparation for film formation was completed in the same manner as in Example 1, the substrate was subjected to hydrogen plasma treatment, and subsequently, the first p-layer was formed on the substrate 404.
A mold layer, an n-type layer, a Si layer, an i-type layer, and a second p-type layer were formed.

First, to perform the hydrogen plasma treatment, the valve 2003 was gradually opened, H ₂ gas was introduced into the deposition chamber 401, and the mass flow controller 2013 adjusted the H ₂ gas flow rate to 500 sccm. The pressure inside the deposition chamber is adjusted to 2.0 Torr by adjusting the conductance valve while watching the vacuum gauge 402, and the heater 405 is set so that the temperature of the substrate 404 becomes 550 ° C. When the substrate temperature becomes stable, the shutter 415 is set. , The microwave (μW) power source is set to 0.20 W / cm ³ , μW power is introduced, glow discharge is generated, the shutter 415 is opened, and the substrate is subjected to hydrogen plasma treatment. Started. After 10 minutes, the shutter was closed, the μW power supply was turned off, the glow discharge was stopped, and the hydrogen plasma treatment was completed. 5 minutes, deposition chamber 401
After continuously flowing H ₂ gas into the inside, the valve 2003 was closed and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, to form the first p-type layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller is set so that the H ₂ gas flow rate is 50 sccm. Adjusted in 2013. Adjusting the conductance valve while watching the vacuum gauge 402 so that the pressure in the deposition chamber becomes 2.0 Torr, and setting the heater 405 so that the temperature of the substrate 404 becomes 350 ° C., the substrate temperature is stable. Valve 200
1, 2005 gradually open, SiH ₄ gas, B ₂ H ₆
/ H ₂ gas was caused to flow into the deposition chamber 401. At this time, S
iH ₄ gas flow rate is 5 sccm, H ₂ gas flow rate is 100 s
It was adjusted with each mass flow controller so that ccm and B ₂ H ₆ / H ₂ gas became 500 sccm. The opening of the conductance valve 407 was adjusted while observing the vacuum gauge 402 so that the pressure in the deposition chamber 401 was 2.0 Torr. Make sure the shutter 415 is closed, set the RF power supply to 0.20 W / cm ³ , and
Shutter 41 is generated by introducing electric power to cause glow discharge.
5 was opened and the formation of the first p-type layer on the substrate was started. After the first p-type layer having a layer thickness of 100 nm was prepared, the shutter was closed, the RF power was turned off, the glow discharge was stopped, and the first
The formation of the p-type layer was completed. The valves 2001 and 2005 are closed, and SiH ₄ gas, B ₂ H ₆ /
Stopping the flow of H ₂ gas for 5 minutes, H ₂ into the deposition chamber 401
After continuing to flow the gas, the valve 2003 was closed and the inside of the deposition chamber 401 and the gas pipe were evacuated.

To form the n-type layer, the auxiliary valve 40
8, gradually open the valve 2003, H₂Gas to gas
It is introduced into the deposition chamber 401 through the inlet pipe 411, and H₂gas
Mass flow control so that the flow rate is 50 sccm
Ra 2013 is set and the pressure in the deposition chamber is 1.0 Tor.
Adjust the conductance valve to r
Heater 405 so that the temperature of 04 becomes 350 ° C.
It was set. When the substrate temperature is stable,
Open 2001 and 2004 gradually to SiH_FourGas, P
H₃/ H₂Gas was flowed into the deposition chamber 401. this
Sometimes SiH_FourGas flow rate is 2 sccm, H₂Gas flow rate is 1
00sccm, PH₃/ H₂Gas flow rate is 200 sccm
Adjust with each mass flow controller so that
It was The pressure in the deposition chamber 401 will be 1.0 Torr.
Thus, the opening of the conductance valve 407 was adjusted. R
The power of F power source is 0.01W / cm₃Set to RF electrode
Introduce RF power to 410 to cause glow discharge and
Open the shutter and start making the n-type layer on the first p-type layer
The n-type layer with a layer thickness of 30 nm was produced, and the shutter was released.
Closed, RF power turned off, glow discharge stopped, n-type
Finished forming layers. Close the valves 2001 and 2004
SiH into the deposition chamber 401_FourGas, PH₃/ H ₂Moth
Stop the flow of gas into the deposition chamber 401 for 5 minutes.₂Gas
After continuing the flow, the outflow valve 2003 is closed and the deposition chamber 4
The inside of 01 and the inside of the gas pipe were evacuated.

To form the Si layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401 through the introduction pipe 411, and the mass flow controller 2013 is set so that the H ₂ gas flow rate is 50 sccm. Then, the pressure inside the deposition chamber was adjusted to 1.5 Torr by a conductance valve, and the heater 405 was set so that the temperature of the substrate 404 became 270 ° C. When the substrate temperature became stable, the valve 2001 was gradually opened to allow SiH ₄ gas to flow into the deposition chamber 401. At this time, the SiH ₄ gas flow rate is ₂ sccm and the H ₂ gas flow rate is 1 sc
It was adjusted with each mass flow controller so as to be 00 sccm. The pressure in the deposition chamber 401 is 1.5 To
The opening of the conductance valve 407 was adjusted so as to be rr. The power of the RF power source was set to 0.01 W / cm ³ , RF power was introduced to the RF electrode 410 to cause glow discharge, the shutter was opened, the production of the Si layer on the n-type layer was started, and the deposition rate was 0. 0.15 nm / sec, layer thickness 10 nm
After the Si layer was produced, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the Si layer was completed. The valve 2001 is closed, and Si in the deposition chamber 401
The flow rate of H ₄ gas was stopped and H _{2 was} introduced into the deposition chamber 401 for 5 minutes.
After continuing to flow the gas, the outflow valve 2003 was closed and the inside of the deposition chamber 401 and the gas pipe were evacuated.

Next, to prepare the i-type layer, the valve 20 was used.
Open 03 gradually, H₂Introduce gas into deposition chamber 401
And H₂The mass flow should be 300sccm.
Adjusted with the low controller 2013. Deposition chamber pressure
With a conductance valve so that it becomes 0.01 Torr
Adjust and heat the substrate 404 to 350 ° C
Set the heater 405 and make sure the substrate temperature is stable.
Furthermore, valves 2001, 2002, 2004, 2005
Gradually open the SiH_FourGas, CH_FourGas, PH₃/
H₂Gas, B₂H₆/ H₂Let the gas flow into the deposition chamber 401
It was At this time, SiH_FourGas flow rate is 100 sccm, CH
_FourGas flow rate 30 sccm, H₂Gas flow rate is 300scc
m, PH₃/ H₂Gas flow rate 2 sccm, B₂H₆/ H₂gas
Each mass flow controller should have a flow rate of 5 sccm.
I adjusted it with a ruler. The pressure in the deposition chamber 401 is 0.01T
Opening of conductance valve 407 so as to be orr
Was adjusted. Next, the power of the RF power source 403 is 0.40 W /
cm³And was applied to the RF electrode 403. afterwards,
The power of the μW power source (not shown) is 0.20 W / cm³Set to
Introduce μW power into deposition 401 through dielectric window 413
Then, a glow discharge is generated, the shutter is opened, and the Si layer
The fabrication of the i-type layer on top was started. Mass flow controller
Using a computer connected to the
SiH according to the quantity change pattern_FourGas, CH_FourGas flow
By changing the amount, an i-type layer with a layer thickness of 300 nm was produced.
Filter, close the shutter, turn off the μW power supply, and glow discharge
Stop, turn off the RF power supply 403, and finish the production of the i-type layer
It was Valves 2001, 2002, 2004, 2005
Close the SiH into the deposition chamber 401_FourGas, CH_FourMoth
Su, PH₃/ H₂Gas, B₂H₆/ H₂Stop the flow of gas,
5 minutes into deposition chamber 401₂ After continuing to flow the gas,
The valve 2003 is closed, and the deposition chamber 401 and the gas pipe are closed.
Was evacuated.

Next, to form the second p-type layer, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller is set so that the H ₂ gas flow rate becomes 300 sccm. Adjusted in 2013. The pressure inside the deposition chamber is adjusted to 0.02 Torr by a conductance valve, the heater 405 is set so that the temperature of the substrate 404 becomes 200 ° C., and the temperature of the substrate is stabilized. 2005
Gradually open, SiH ₄ gas, CH ₄ gas, H ₂ , B
₂ H ₆ / H ₂ gas was caused to flow into the deposition chamber 401. At this time, SiH ₄ gas flow rate is 10 sccm, CH ₄ gas flow rate is 5 sccm, H ₂ gas flow rate is 300 sccm, and B ₂ H
Each mass flow controller was adjusted so that the ₆ / H ₂ gas flow rate was 10 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 0.02 Torr. Set the power of the μW power supply to
It is set to 30 W / cm ³ , and μW electric power is introduced into the deposition chamber 401 through the dielectric window 413 to cause glow discharge, the shutter 415 is opened, and the light-doped layer (A layer) is formed on the i-type layer. Started. When the layer A having a layer thickness of 3 nm was prepared, the shutter was closed, the μW power source was turned off, and the glow discharge was stopped. Valves 2001, 2002, 2005
Is closed to stop the inflow of SiH ₄ gas, CH ₄ gas and B ₂ H ₆ / H ₂ gas into the deposition chamber 401, and H ₂ gas is continuously flowed into the deposition chamber 401 for 5 minutes, and then the valve 2003
Was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

Next, the valve 2005 was gradually opened, B ₂ H ₆ / H ₂ gas was introduced into the deposition chamber 401, and the mass flow controllers were adjusted so that the flow rate was 1000 sccm. The pressure in the deposition chamber 401 is 0.0
The opening of the conductance valve 407 was adjusted to be 2 Torr, the power of the μW power source was set to 0.20 W / cm ³ , and the μW was introduced into the deposition chamber 401 through the dielectric window 413.
Shutter 41 is generated by introducing electric power to cause glow discharge.
5 was opened, and the formation of boron (B layer) on the A layer was started.
After 6 seconds, the shutter was closed, the μW power supply was turned off, and the glow discharge was stopped. The valve 2005 is closed to stop the inflow of B ₂ H ₆ / H ₂ gas into the deposition chamber 401, and 5
After continuously flowing H ₂ gas into the deposition chamber 401 for a minute, the valve 2003 was closed and the inside of the deposition chamber 401 and the gas pipe were evacuated.

Next, the layer A is formed on the layer B by the same method, condition and procedure as those described above, and the layers B and A are further laminated,
The formation of the second p-type layer having a layer thickness of about 10 nm was completed. After continuing to flow H ₂ gas into the deposition chamber 401, the valve 2003
Was closed, the inside of the deposition chamber 401 and the gas pipe were evacuated, the auxiliary valve 408 was closed, the leak valve 409 was opened, and the deposition chamber 401 was leaked.

Next, a transparent electrode was formed on the second p-type layer.
The thickness of the ITO (In₂O ₂+ NO₂) Through
It was vacuum-deposited by a usual vacuum deposition method. Then silver on the transparent electrode
(Ag) layer thickness 5μm current collector electrode by normal vacuum evaporation
It was vacuum-deposited by the method. Next, if the Ag-Ti alloy is
The backside electrode with a layer thickness of 3 μm consisting of
It was vapor-deposited.

This completes the fabrication of this solar cell. This solar cell will be referred to as (SC Ex 49), and Table 17 shows the manufacturing conditions for the first p-type layer, n-type layer, Si layer, i-type layer, and second p-type layer. (Comparative Example 49-1) The same conditions as in Example 49 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were adjusted by the respective mass flow controllers according to the flow rate pattern shown in FIG. 6 when forming the i-type layer. A solar cell was manufactured by the same procedure. This solar cell will be called (SC ratio 49-1).

(Comparative Example 49-2) A solar cell was produced on a substrate by the same method and procedure as in Example 49 except that the PH ₃ / H ₂ gas was not passed when forming the i-type layer. This solar cell is called (SC ratio 49-2). (Comparative Example 49-3) When forming the i-type layer, B ₂ H ₆ / H
_A solar cell was produced on the substrate by the same method and procedure as in Example 49 except that ₂ gas was not passed. This solar cell (SC
Ratio 49-3).

(Comparative Example 49-4) A solar cell was produced under the same conditions and in the same procedure as in Example 49, except that the μW power was changed to 0.5 W / cm ³ when the i-type layer was formed. This solar cell will be called (SC ratio 49-4). (Comparative Example 49-5) A solar cell was manufactured under the same conditions and in the same procedure as in Example 49, except that the RF power was set to 0.15 W / cm ³ when the i-type layer was formed. This solar cell is called (SC ratio 49-5).

(Comparative Example 49-6) In forming an i-type layer, μW power was 0.5 W / cm ³ , and RF power was 0.55.
A solar cell was produced under the same conditions and the same procedure as in Example 49 except that W / cm ³ was used. This solar cell (SC ratio 4
9-6). (Comparative Example 49-7) A solar cell was manufactured under the same conditions and in the same procedure as in Example 49, except that the pressure inside the deposition chamber was set to 0.08 Torr when the i-type layer was formed. This solar cell is called (SC ratio 49-7).

(Comparative Example 49-8) Example 4 was repeated except that the deposition rate was set to 3 nm / sec when the Si layer was formed.
A solar cell was manufactured under the same conditions and the same procedure as in No. 9. This solar cell is called (SC ratio 49-8). (Comparative Example 49-9) When forming a Si layer, the layer thickness is set to 40.
A solar cell was produced under the same conditions and the same procedure as in Example 49 except that the thickness was changed to nm. This solar cell (SC ratio 49-
9).

Measurement of initial light conversion efficiency (photovoltaic power / incident light power) and durability characteristics of the manufactured solar cells (SC Ex 49) and (SC ratio 49-1) to (SC ratio 49-9) was carried out in Examples. It carried out similarly to 1. As a result of the measurement, (SC Ex 4
For the solar cell of 9), (SC ratio 49-1) to (SC ratio)
The initial photoelectric conversion efficiency of the ratio 49-9) was as follows.

(SC ratio 49-1) 0.75 times (SC ratio 49-2) 0.74 times (SC ratio 49-3) 0.73 times (SC ratio 49-4) 0.66 times (SC ratio 49-5) 0.82 times (SC ratio 49-6) 0.61 times (SC ratio 49-7) 0.69 times (SC ratio 49-8) 0.70 times (SC ratio 49-9) 82 times The durability characteristics were measured in the same manner as in Example 1. As a result of the measurement, the (SC ratio 49
The durability characteristics of (-1) to (SC ratio 49-9) are as follows.

(SC ratio 49-1) 0.73 times (SC ratio 49-2) 0.72 times (SC ratio 49-3) 0.71 times (SC ratio 49-4) 0.64 times (SC ratio 49-5) 0.80 times (SC ratio 49-6) 0.61 times (SC ratio 49-7) 0.71 times (SC ratio 49-8) 0.70 times (SC ratio 49-9) 0. 82 times Next, when the relationship between the bandgap of the i-type layer and the C / Si composition was examined in the same manner as in Example 1, the same result as in FIG. 7 was obtained.

Also, the manufactured solar cell (SC Ex 49),
The composition analysis of Si atoms and C atoms in the i-type layer of (SC ratio 49-1) to (SC ratio 49-9) in the layer thickness direction is performed by the same method as the above composition analysis, and the Si atoms and the carbon atoms are analyzed. When the bandgap of the i-type layer in the layer thickness direction was obtained from the composition ratio, the same tendency as in FIG. 8 was obtained, and the solar cells of (SC Ex 49), (SC Ratio 49-2) to (SC Ratio 49-9) were obtained. Then, the position of the minimum value of the band gap is p from the position of the center of the i-type layer.
In the solar cell of (SC ratio 49-1), the position of the minimum value of the bandgap was found to be offset in the i / Si interface direction from the center position of the i-type layer. .

As described above, (SC actual 49), (SC ratio 49-
1) to (SC ratio 49-9) changes in the band gap in the layer thickness direction are caused by the source gas containing Si (SiH ₄ gas in this case) and the source gas containing C (this In some cases, it was found to depend on the flow rate ratio of CH ₄ gas). Next (SC Ex 49), (SC ratio 49-1)
To (SC ratio 49-9), the composition analysis of P atoms and B atoms in the layer thickness direction in the i-type layer was performed using a secondary ion mass spectrometer (CA).
It was carried out by IMS-3F manufactured by MECA). As a result of the measurement, it was confirmed that P atoms and B atoms were uniformly distributed in the layer thickness direction.

In the same manner as in Example 33, polycrystalline
Forming a second p-type layer having a laminated structure on a con substrate
Then, the TEM (transmission electron microscope) image was observed. First
The p-type layer 2 is a B layer having a layer thickness of about 1 nm and an A layer having a layer thickness of about 3 nm.
It was confirmed that the layers were alternately stacked. (Comparative Example 49-10) μ introduced when forming an i-type layer
W power and RF power are variously changed, and other conditions are practical examples.
Several solar cells were produced in the same manner as 49. μW power
The force and the deposition rate have the same relationship as in FIG. 9, and the deposition rate is R
Independent of F power, μW power is 0.32 W / cm³that's all
Is constant, and this power is used as the source gas SiH_FourWith gas
CH_FourIt was found that the gas was 100% decomposed.
AM1.5 (100mW / cm ²) When illuminating
When the initial photoelectric conversion efficiency of the solar cell was measured, FIG.
The result is similar to the above. That is, μW power is S
iH_FourGas and CH_FourΜW electric that decomposes gas 100%
Power (0.32W / cm³) Or less and RF power is μW
When the power is larger than the power, the initial photoelectric conversion efficiency is significantly improved.
I found out.

(Comparative Example 49-11) When the i-type layer was formed in Example 49, the flow rate of the gas introduced into the deposition chamber 401 was changed to S
iH ₄ gas was changed to 50 sccm, CH ₄ gas was changed to 10 sccm, H ₂ gas was not introduced, and μW electric power and RF electric power were variously changed to manufacture some solar cells. Other conditions were the same as in Example 49. When the relationship between the deposition rate, the μW power, and the RF power was examined, the deposition rate did not depend on the RF power as in Comparative Example 49-10, and the μW power was 0.18 W / c.
It was found to be constant above m ³ , and it was found that the SiH ₄ gas and CH ₄ gas, which are the raw material gases, were decomposed 100% at this μW power. When the initial photoelectric conversion efficiency of the solar cell when irradiated with AM1.5 light was measured, the result showed the same tendency as in FIG. That is, μW power is S
μW that decomposes 100% of iH ₄ gas and CH ₄ gas
Power (0.18 W / cm ³ ) or less and RF power μ
It was found that the initial photoelectric conversion efficiency was significantly improved when the power was higher than W power.

(Comparative Example 49-12) When the i-type layer was formed in Example 49, the flow rate of the gas introduced into the deposition chamber 401 was changed to S
iH ₄ gas 200 sccm, CH ₄ gas 50 sccm,
H ₂ gas was changed to 500 sccm, and the substrate temperature was 3
Change the setting of the heater so that it becomes 00 ° C
Several solar cells were produced by changing the electric power and the RF power variously. Other conditions were the same as in Example 49.

When the relationship between the deposition rate and the μW power and RF power was examined, the deposition rate was R as in Comparative Example 49-10.
It was found that the μW power was constant at 0.65 W / cm ³ or more without depending on the F power, and the SiH ₄ gas and CH ₄ gas as the raw material gas were completely decomposed by this power. When the initial photoelectric conversion efficiency of the solar cell when irradiated with AM1.5 light was measured, the result showed the same tendency as in FIG. That, .mu.W power the SiH ₄ gas 1
It was found that the initial photoelectric conversion efficiency was significantly improved when the power was less than or equal to μW power (0.65 W / cm ³ ) for decomposition by 00% and the RF power was higher than the power of μW.

(Comparative Example 49-13) When the i-type layer was formed in Example 49, the pressure in the deposition chamber was changed from 3 mTorr to 20.
Various conditions up to 0 mTorr, other conditions are the same as in Example 49.
Several solar cells were prepared in the same manner as in. AM1.5
By measuring the initial photoelectric conversion efficiency of the solar cell when irradiated with light, the results shown in Fig. 11 were obtained, and the pressure was 50 m.
It was found that the initial photoelectric conversion efficiency was significantly reduced above Torr.

(Comparative Example 49-14) When the Si layer was formed in Example 49, the deposition rate was variously changed by changing the SiH ₄ gas flow rate and the RF power, and the other conditions were the same as in Example 49. , Some solar cells were produced. AM
The initial photoelectric conversion efficiency of the solar cell when irradiated with 1.5 light was measured to show that the deposition rate of the Si layer was 2 nm / sec.
From the above, it was found that the initial photoelectric conversion efficiency was significantly reduced.

(Comparative Example 49-15) Several solar cells were produced under the same conditions as in Example 49 except that the layer thickness was variously changed when the Si layer was formed in Example 49. AM1.
When the initial photoelectric conversion efficiency of the solar cell when irradiated with 5 lights was measured, it was found that the initial photoelectric conversion efficiency was significantly reduced when the layer thickness was 30 nm or more.

As mentioned above, (Comparative Example 49-1) to (Comparative Example 49)
-15), the solar cell of the present invention (SC Ex 4
It was demonstrated that 9) has further excellent characteristics than the conventional solar cells (SC ratio 49-1) to (SC ratio 49-9). (Example 50) The bandgap (E
Several solar cells were manufactured by changing the position of the minimum value of g) in the layer thickness direction, the size of the minimum value, and the pattern,
The initial photoelectric conversion efficiency and durability characteristics were examined in the same manner as in Example 49. At this time, the solar cell having the band gap shown in FIG. 12 was produced in the same manner as in Example 49 except for the change patterns of the SiH ₄ gas flow rate and the CH ₄ gas flow rate of the i-type layer.

Table 18 shows the results of examining the initial photoelectric conversion efficiency and durability characteristics of these manufactured solar cells (the values in the table are based on SC ex (50-1)). As can be seen from these results, the minimum value of the band gap,
The band gap of the i-type layer changes smoothly in the layer thickness direction regardless of the change pattern, and the position of the minimum value of the band gap deviates from the center position of the i-type layer toward the p / i interface. It turns out that solar cells are better.

(Example 51) A solar cell in which the concentration and type of the valence electron controlling agent in the i-type layer were changed to those in Example 49 was prepared, and the initial photoelectric conversion characteristics and durability thereof were the same as in Example 1. I looked it up. At this time, the same procedure as in Example 49 was performed except that the concentration and type of the valence electron controlling agent in the i-type layer were changed.

(Example 51-1) The flow rate of the valence electron control agent gas (B ₂ H ₆ / H ₂ gas), which serves as an acceptor for the i-type layer, was ⅕, and the total H ₂ flow rate was changed to that in Example 49. When a solar cell (SC Ex 51-1) that is the same as
(SC Ex 51-1) has better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC Ratio 49-1) to (SC Ratio 49-9), similar to (SC Ex 49). I understood.

(Example 51-2) The flow rate of the gas (B ₂ H ₆ / H ₂ gas) of the valence electron control agent serving as the acceptor of the i-type layer was increased to 5 times, and the total H ₂ flow rate was the same as in Example 49. When the solar cell (SC Ex 51-2) was manufactured,
Similar to (SC Ex 49), C Ex 51-2) may have better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC Ratio 49-1) to (SC Ratio 49-9). Do you get it.

(Example 51-3) The flow rate of the valence electron control agent gas (PH ₃ / H ₂ gas) serving as the donor of the i-type layer was ⅕, and the total H ₂ flow rate was the same as in Example 49. When the solar cell (SC ex. 51-3) was manufactured, the (SC ex. 51-3) was similar to the (SC ex. 49) in the conventional solar cells (SC ratio 49-1) to (SC ex. 49-9). It has been found that it has better initial photoelectric conversion efficiency and durability characteristics than

(Example 51-4) The flow rate of the valence electron control agent gas (PH ₃ / H ₂ gas) serving as the donor of the i-type layer was increased five times, and the total H ₂ flow rate was the same as in Example 49. When a solar cell (SC Ex 51-3) was produced, (SC Ex 5
1-4) is the same as (SC Ex 49), the conventional solar cell (S
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the C ratio 49-1) to (SC ratio 49-9).

Example 51-5 Trimethylaluminum (Al (CH ₃ ) ₃ , TM instead of the B ₂ H ₆ / H ₂ gas was used as the valence electron control gas serving as the acceptor of the i-type layer.
A solar cell using A) was produced. At this time, TMA (purity 99.99%) hermetically sealed in a liquid cylinder was bubbled with hydrogen gas to be gasified, and introduced into the deposition chamber 401 by the same method and procedure as in Example 49. 5
1-5) was produced.

At this time, the flow rate of TMA / H ₂ gas is 10 s.
It was set to ccm. The prepared solar cell (SC Ex 51-5) is similar to the conventional solar cell (SC Ex 49-SC) in the same manner as (SC Ex 49).
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of 1) to (SC ratio 49-9). (Example 51-6) PH as the gas in the i-type layer serving as a donor of the valence control agent ₃ / H ₂ hydrogen sulfide in place of the gas (H ₂
A solar cell using S) was produced. NH _{3 of} Example 49
/ H ₂ S diluted with hydrogen gas to 100 ppm with H ₂ S
A gas (H ₂ S / H ₂ ) cylinder was replaced, and a solar cell (SC Ex 51-6) was produced by the same method and procedure as in Example 49.

At this time, the flow rate of the H ₂ S / H ₂ gas is 1 sccc.
m. The produced solar cell (SC Ex 51-6) is (S
Conventional solar cell (SC ratio 49-1) similar to C Ex 49)
(SC ratio 49-9), the initial photoelectric conversion efficiency and durability characteristics were better. (Example 52) A solar cell of FIG. 1-b was produced using a p-type polycrystalline silicon substrate. Plasma treatment is applied to the substrate, and then the first n-type layer, p-type layer, i-type layer, S
The i layer and the second n-type layer were sequentially formed. Table 19 shows the forming conditions. When forming the i-type layer, SiH ₄ gas flow rate and CH
₄ Change the gas flow rate as shown in the pattern in Fig. 6, and set i / p
The minimum value of the band gap was set to come from the interface.
The second n-type layer had a laminated structure as in Example 49, and the Si layer deposition rate was 0.15 nm / sec. The substrate and the layers other than the semiconductor layer are under the same conditions as in Example 49,
Made using the same method.

The manufactured solar cell (SC Ex 52) is (SC
Similar to the actual 49), conventional solar cells (SC ratio 49-1) ~
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of (SC ratio 49-9). (Example 53) A solar cell having a maximum bandgap of the i-type layer near the p / i interface and a thickness of that region of 20 nm was measured by a flow rate change pattern of the i-type layer shown in FIG. 13-a. It was made using.

It was manufactured using the same conditions and the same method as in Example 49 except that the flow rate change pattern of the i-type layer was changed. Next, the composition of the solar cell was analyzed in the same manner as in Example 49, and the change in the band gap of the i-type layer in the layer thickness direction was examined. The results were similar to those shown in FIG. 13-b. The produced solar cell (SC Ex. 53) has a better initial photoelectric conversion efficiency and durability than the conventional solar cells (SC Ex. 49-1) to (SC Ex. 49-9), like (SC Ex. 49). Found to have.

(Comparative Example 53) There was a region having the maximum bandgap near the p / i interface of the i-type layer, and several solar cells having various thicknesses were manufactured. It was manufactured using the same conditions and the same method as in Example 53 except for the thickness of the region. When the initial photoelectric conversion efficiency and durability of the manufactured solar cell were measured, the region thickness was 1 nm.
Above 30 nm, the solar cell of Example 49 (SC
Even better initial photoelectric conversion efficiency and durability than Example 49) were obtained.

(Example 54) There is a maximum bandgap of the i-type layer near the i / Si interface, and the thickness of the region is 1
A solar cell having a thickness of 5 nm was produced using the flow rate change pattern of the i-type layer shown in FIG. 13-c. It was manufactured using the same conditions and the same method as in Example 49 except that the flow rate change pattern of the i-type layer was changed. Next, the composition analysis of the solar cell was carried out in Example 4.
When the change in the band gap of the i-type layer in the layer thickness direction was examined by the same method as in Example 9, the same result as in FIG. 13-d was obtained. The prepared solar cell (SC Ex 54) is (SC Ex 4
As in 9), the conventional solar cells (SC ratio 49-1) to (S
It was found that the initial photoelectric conversion efficiency and durability were better than those of C ratio 49-9).

(Comparative Example 54) There was a region having the maximum bandgap near the i / Si interface of the i-type layer, and several solar cells having various thicknesses were manufactured. It was manufactured using the same conditions and the same method as in Example 54 except for the thickness of the region. When the initial photoelectric conversion efficiency and durability of the manufactured solar cell were measured, the region thickness was 1 nm.
As described above, when the thickness is 30 nm or less, the initial photoelectric conversion efficiency and durability which are better than those of the solar cell of Example 49 (SC Ex 49) were obtained.

(Example 55) A solar cell in which a valence electron control agent is distributed in an i-type layer is used as PH ₃ / H ₂ shown in FIG. 20-a.
Gas and B ₂ H ₆ / H ₂ gas flow patterns were used for the production. At the time of manufacture, the same conditions, the same method, and the same procedure as in Example 49 were used except that the flow rates of PH ₃ / H ₂ gas and B ₂ H ₆ / H ₂ gas were changed. Fabricated solar cell (SC Ex 23)
Is the same as the (SC Ex 49) conventional solar cell (SC ratio 49
It was found that the initial photoelectric conversion efficiency and durability were better than those of -1) to (SC ratio 49-9). In addition, when the changes in the layer thickness direction of P atoms and B atoms contained in the i-type layer were examined by using a secondary ion mass spectrometer (SIMS), the same results as in FIG. It was found that the contents of P and B atoms were minimum at the minimum position.

(Example 56) A solar cell having an i-type layer containing oxygen atoms was produced. When forming the i-type layer, 10 sc of O ₂ / He gas was used in addition to the gas flowing in Example 49.
cm, the same conditions, the same method, and the same procedure as in Example 49 were used except that the gas was introduced into the deposition chamber 401. The manufactured solar cell (SC Ex 56) has a better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC Comp Ex 49-1) to (SC Comp Ex 49-9), similarly to (SC Ex 49). Found to have.

Also, the content of oxygen atoms in the i-type layer was determined to be SI
When examined by MS, it was found to contain almost uniformly 2 × 10 ¹⁹
It was found to be (pieces / cm ² ). (Example 57) A silicon solar cell in which a nitrogen atom is contained in the i-type layer was produced. When the i-type layer is formed, NH ₃ / H ₂ gas is added at 5 sccc in addition to the gas flowing in Example 49.
m, the same conditions, the same method and the same procedure as in Example 49 were used except that the same was introduced into the deposition chamber 401. The produced solar cell (SC Ex 57) has a better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cells (SC Ratio 49-1) to (SC Ratio 49-9), similar to (SC Ex 49). Found to have. In addition, the content of nitrogen atoms in the i-type layer can be adjusted to SI
When examined by MS, it was found that the content was almost uniform and 3 × 10 ¹⁷
It was found to be (pieces / cm ² ).

Example 58 Oxygen atoms and nitrogen are added to the i-type layer.
A solar cell containing elementary atoms was manufactured. i-type layer
When forming, in addition to the gas flowing in Example 49, O₂/ He
5 sccm gas, NH₂/ H₂Gas 5sccm, stack
The same conditions as in Example 49, except that they were introduced into the loading chamber 401,
The same method, same procedure was used. Fabricated solar cell (SC
Similar to (SC Ex 49), Ex 58 is the conventional solar cell (S
Even better than C ratio 49-1) to (SC ratio 49-9)
Have excellent initial photoelectric conversion efficiency and durability characteristics
It was. In addition, the contents of oxygen atoms and nitrogen atoms in the i-type layer
When examined by SIMS, it was found that the content was almost uniform.
1 x 10¹⁹(Pieces / cm²) 3 x 10¹⁷(Pieces / cm
²) Was found.

(Example 59) A solar cell was produced in which the hydrogen content of the i-type layer was changed corresponding to the silicon content. The O ₂ / He gas cylinder was replaced with SiF ₄ gas (purity 99.
(999%) When replacing the cylinder and forming the i-type layer, as shown in FIG.
According to the flow pattern of 5-a, SiH ₄ gas, CH ₄
The flow rates of the gas and SiF ₄ gas were changed. The change in bandgap in the layer thickness direction of this solar cell (SC Ex 59) was obtained by the same method as in Example 49, and FIG.
Similar results were obtained.

Further, the content of hydrogen atoms and silicon atoms was analyzed in the layer thickness direction using a secondary ion mass spectrometer. It was found that the content of hydrogen atoms has a distribution in the layer thickness direction corresponding to the content of silicon atoms. When the initial photoelectric conversion efficiency and durability characteristics of this solar cell (SC Ex 59) were determined, it was found from the conventional solar cells (SC ratio 49-1) to (SC ratio 49-9) as with the solar cell of Example 49. It has been found that also has a better initial photoelectric conversion efficiency and durability characteristics.

(Example 60) When a semiconductor layer of the solar cell of FIG. 1 is formed by the manufacturing apparatus using the microwave plasma CVD method shown in FIG.
Example 49 except that the H ₄ gas) and the carbon atom-containing gas (CH ₄ gas) were mixed at a distance of 1 m from the deposition chamber.
A solar cell (SC Ex 60) was produced by the same method and the same procedure. The produced solar cell (SC Ex 60) is (SC Ex 4
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of 9).

(Example 61) When the first p-type layer was formed by the gas diffusion method to form the i-type layer, C ₂ H ₂ gas was used instead of CH ₄ gas, and positive DC was applied to the RF electrode. A solar cell was manufactured by applying a bias and changing the RF power, DC bias, and μW power. First, BBr ₃ (BBr ₃ / H ₂ gas) prepared by diluting an O ₂ / He gas cylinder with hydrogen to 10%.
The cylinder was replaced with a cylinder, and the CH ₄ gas cylinder was replaced with C ₂ H ₂ gas.

When forming the first p-type layer, the substrate temperature is 90.
0 ° C., BBr ₃ / H ₂ gas flow rate 500 sccm, internal pressure 3
Under the condition of 0 Torr, B was diffused into the n-type substrate. When the junction depth reached 300 nm, the introduction of BBr ₃ / H ₂ gas was stopped. The H ₂ gas was kept flowing for 5 minutes. I
When forming the mold layer, C ₂ H ₂ gas was introduced instead of CH ₄ gas, and the flow rate pattern was changed as shown in FIG. 14-a. Further, as shown in FIG. 16, RF power, DC bias, and μW power were changed. Except for the first p-type layer and the i-type layer, the same conditions, the same method, and the same procedure as in Example 49 were used. The manufactured solar cell (SC Ex 61) is (SC Ex 49)
It was found that similarly to the conventional solar cells (SC ratio 49-1) to (SC ratio 49-9), the initial photoelectric conversion efficiency and durability were better.

(Example 62) Using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, FIG.
A triple solar cell was manufactured. The substrate is Example 49.
An n-type polycrystalline silicon substrate manufactured by the casting method was used in the same manner as in.

One side of a 50 × 50 mm ² substrate was heated at a temperature of 10
It was immersed in a 1% NaOH aqueous solution at 0 ° C. for 5 minutes and washed with pure water. Scanning electron microscope (SE
As a result of observation with (M), unevenness having a pyramid structure is formed on the surface, and the substrate is textured (Te
xtured). Next, it was ultrasonically washed with acetone and isopropanol, further washed with pure water, and dried with warm air.

Using the same procedure and method as in Example 49, water was added.
The first plasma treatment is applied to the first on the textured surface of the substrate.
Forming a p-type layer, and further forming a first n-type layer and a first i-type layer
Layer, second p-type layer, second n-type layer, Si layer, second i-type
Layer and a third p-type layer were sequentially formed. Form second i-type layer
In doing so, according to the flow rate change pattern as shown in FIG.
_FourGas flow rate, CH_FourDeposition of Si layer by changing gas flow rate
The speed was 0.15 nm / sec. Furthermore, the third p-type
The layers had a laminated structure as in Example 49.

Then, as in Example 49, ITO (In ₂ O) having a layer thickness of 70 nm was formed as a transparent electrode on the third p-type layer.
₃ + SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method. Next, in the same manner as in Example 49, a collector electrode made of silver (Ag) and having a layer thickness of 5 μm was vacuum-deposited on the transparent electrode by an ordinary vacuum deposition method. Next, as in Example 49, Ag-T was formed on the back surface of the substrate.
A back electrode made of an i alloy and having a layer thickness of 3 μm was vacuum-deposited by an ordinary vacuum deposition method.

As described above, the production of the triple type solar cell using the microwave plasma CVD method is completed. This solar cell will be referred to as (SC Ex 62), and the manufacturing conditions of each semiconductor layer are shown in Table 20. (Comparative Example 62-1) A method similar to that in Example 62 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were changed in accordance with the flow rate change pattern of FIG. 6 when the second i-type layer of FIG. 17 was formed. A triple solar cell was manufactured by the same procedure. This solar cell will be called (SC ratio 62-1).

(Comparative Example 62-2) A solar cell was formed on the substrate by the same method and procedure as in Example 62 except that the PH ₃ / H ₂ gas was not flowed when the second i-type layer shown in FIG. 17 was formed. A battery was made. This solar cell will be called (SC ratio 62-2). (Comparative Example 62-3) A solar cell on a substrate was formed by the same method and procedure as in Example 62 except that B ₂ H ₆ / H ₂ gas was not flowed when the second i-type layer in FIG. 17 was formed. Was produced. This solar cell will be called (SC ratio 62-3).

(Comparative Example 62-4) When the second i-type layer shown in FIG. 17 was formed, a triplet was formed in the same manner as in Example 62 except that the μW power was set to 0.5 W / cm ^3. Type solar cell was produced. This solar cell (SC ratio 62-4)
I will call it. (Comparative Example 62-5) A triple solar cell was manufactured in the same manner as in Example 62, except that the RF power was set to 0.15 W / cm ³ when the second i-type layer shown in FIG. 17 was formed. Was produced. This solar cell is called (SC ratio 62-5).

[0422] (Comparative Example 62-6) when forming the second i-type layer in FIG. 17, except that the μW power 0.5 W / cm ^3, the RF power to 0.55 W / cm ³ Example 62 A triple type solar cell was manufactured by the same method and the same procedure. This solar cell is called (SC ratio 62-6).

(Comparative Example 62-7) When the second i-type layer in FIG. 17 was formed, the pressure in the deposition chamber 401 was set to 0.08 Torr.
A triple type solar cell was prepared by the same method and procedure as in Example 62 except that This solar cell is called (SC ratio 62-7). (Comparative Example 62-8) A triple-type solar cell was produced by the same method and procedure as in Example 62, except that the deposition rate was 3 nm / sec when the Si layer in FIG. 17 was formed. This solar cell is called (SC ratio 62-8).

(Comparative Example 62-9) A triple-type solar cell was produced by the same method and procedure as in Example 62, except that the Si layer in FIG. 17 was formed to have a layer thickness of 40 nm.
This solar cell is called (SC ratio 62-9).
The initial photoelectric conversion efficiency and durability characteristics of these produced triple solar cells were measured by the same method as in Example 49. (SC Ex 62) shows that the conventional triple solar cells (SC
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the ratios 62-1) to (SC ratio 62-9).

Example 63 A solar cell of Example 49 was produced using the production apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, made into a module, and applied to a power generation system. Using the same conditions, the same method, and the same procedure as in Example 49, 6 × 50 × 50 mm ² solar cells (SC Ex 49) were used.
Five pieces were produced. E on a 5.0 mm thick aluminum plate
An adhesive sheet made of VA (ethylene vinyl acetate) was placed on the sheet, a nylon sheet was placed on the sheet, and the solar cells produced on the sheet were arranged, and serialized and parallelized. An EVA adhesive sheet was placed thereon, and a fluororesin sheet was further placed thereon, followed by vacuum lamination to form a module. The initial photoelectric conversion efficiency of the manufactured module was measured in the same manner as in Example 49.
The module was connected to the circuit showing the power generation system in FIG. 18, and the night light was used as the load. The whole system was operated by the storage battery and the power of the module, and the module was installed at the angle that could collect the most sunlight. 1
The photoelectric conversion efficiency after the lapse of a year was measured, and the photodegradation rate (photoelectric conversion efficiency after 1 year / initial photoelectric conversion efficiency) was obtained. This module will be called (MJ Ex 63).

(Comparative Example 63-1) Conventional solar cell (SC
Sixty-five ratios 49-X) (X: 1 to 9) were prepared under the same conditions, the same method, and the same procedure as Comparative Example 49-X, and were modularized in the same manner as in Example 63. This module (MJ ratio 6
3-X). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after one year were measured under the same conditions, the same method, and the same procedure as in Example 63, and the photodegradation rate was obtained.

As a result, the photodegradation rate of (MJ ratio 63-X) was as follows with respect to (MJ ex. 63). Module light deterioration rate ratio ───────────────────────── MJ actual 63 1.00 MJ ratio 63-1 0.72 MJ ratio 63-2 0.71 MJ ratio 63-3 0.70 MJ ratio 63-4 0.68 MJ ratio 63-5 0.75 MJ ratio 63-6 0.65 MJ ratio 63-7 0.72 MJ ratio 63-8 0. 70 MJ ratio 63-9 0.82 From the above results, it was found that the solar cell module of the present invention has more excellent photodegradation characteristics than the conventional solar cell module.

(Example 64) Microwave plasm of the present invention
P / i using the manufacturing apparatus of FIG.
A solar cell of FIG. 19 having a second Si layer at the interface was prepared.
It was Made by the casting method as in Example 49.
50 x 50 mm made ²N-type polycrystalline silicon substrate
HF and HNO₃(H₂Aqueous solution diluted to 10% with O)
It was dipped in water for several seconds and washed with pure water. Then acetone and isop
Ultrasonic cleaning with ropanol, further cleaning with pure water, warm air
Dried.

Hydrogen plasma treatment was performed in the same procedure and method as in Example 49 to form a first p-type layer on the substrate, and further, a first n-type layer, a first Si layer and an i-type layer were formed. Layer, second
The Si layer and the second p-type layer were sequentially formed. When forming the i-type layer, SiH is formed according to the flow rate change pattern as shown in FIG.
₄ gas flow rate, changing the CH ₄ gas flow rate, the first Si
Layer, second Si layer deposition rate is 0.15 nm / sec,
The layer thickness was 10 nm. In addition, the second p-type layer is the same as in Example 4.
The laminated structure was the same as in No. 9.

Then, on the second p-type layer, ITO (In) having a layer thickness of 70 nm was formed as a transparent electrode in the same manner as in Example 49.
₂ O ₃ + SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method. Then, silver (Ag) was formed on the transparent electrode in the same manner as in Example 49.
A current collecting electrode having a layer thickness of 5 μm was vacuum-deposited by an ordinary vacuum deposition method. Then, in the same manner as in Example 49, A was formed on the back surface of the substrate.
A back electrode made of a g-Ti alloy and having a layer thickness of 3 μm was vacuum-deposited by an ordinary vacuum deposition method.

This solar cell will be called (SC Ex 64), and the manufacturing conditions of each semiconductor layer are shown in Table 21. The initial photoelectric conversion efficiency and the durability characteristics of the manufactured solar cell were measured by the same method as in Example 49.
Similar to the actual 49), conventional solar cells (SC ratio 49-1) ~
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of (SC ratio 49-9).

As described above, it has been proved that the effect of the photovoltaic element of the present invention is exhibited regardless of the element structure, element material and element manufacturing conditions.

[0433]

[Table 1]

[0434]

[Table 2]

[0435]

[Table 3]

[0436]

[Table 4]

[0437]

[Table 5]

[0438]

[Table 6]

[0439]

[Table 7]

[0440]

[Table 8]

[0441]

[Table 9]

[0442]

[Table 10]

[0443]

[Table 11]

[0444]

[Table 12]

[0445]

[Table 13]

[0446]

[Table 14]

[0447]

[Table 15]

[0448]

[Table 16]

[0449]

[Table 17]

[0450]

[Table 18]

[0451]

[Table 19]

[0452]

[Table 20]

[0453]

[Table 21]

[0454]

As described above, the photovoltaic device of the present invention prevents recombination of photoexcited carriers, improves the open-circuit voltage and the carrier range of holes, and improves the sensitivity of short-wavelength light and long-wavelength light. It is possible to provide a photovoltaic cell having improved photoelectric conversion efficiency. Further, the photovoltaic device of the present invention can suppress a decrease in photoelectric conversion efficiency that occurs when light is irradiated for a long time. In addition, the photovoltaic device of the present invention is less likely to lower the photoelectric conversion efficiency when annealed under vibration for a long time.

Furthermore, the power supply system using the photovoltaic element of the present invention exhibits an excellent electricity supply capability even when the irradiation light is weak.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a layer structure of a photovoltaic element of the present invention.

FIG. 2 is a diagram showing a band gap of the photovoltaic device of the present invention.

FIG. 3 is a diagram showing a band gap of the photovoltaic device of the present invention.

FIG. 4 is a conceptual diagram showing an example of an apparatus for manufacturing a photovoltaic element of the present invention.

FIG. 5 is a graph showing SiH ₄ and CH ₄ gas flow rate patterns.

FIG. 6 is a graph showing SiH ₄ and CH ₄ gas flow patterns.

FIG. 7 is a graph showing the relationship between the composition ratio of Si atoms and C atoms and the band gap.

FIG. 8 is a graph showing changes in bandgap in the layer thickness direction.

FIG. 9 is a graph showing the relationship between μW power and deposition rate.

FIG. 10 is a graph showing the dependence of the initial photoelectric conversion efficiency on μW power and RF power.

FIG. 11 is a graph showing pressure dependence of initial photoelectric conversion efficiency.

FIG. 12 is a view showing a change in band gap in the layer thickness direction.

FIG. 13 is a graph showing changes in the flow pattern and band gap in the layer thickness direction.

FIG. 14 is a graph showing a C ₂ H ₂ flow rate pattern and a μW electric power change pattern.

FIG. 15 is a graph showing a band gap and hydrogen content of an i-type layer in which hydrogen atoms are distributed, and a gas flow rate pattern at the time of forming the i-type layer.

FIG. 16 is a graph showing change patterns of DC bias, RF power, and μW power.

FIG. 17 is a conceptual diagram showing the layer structure of a triple solar cell.

FIG. 18 is a block diagram showing a power generation system of the present invention.

FIG. 19 is a conceptual diagram showing a photovoltaic device having a second Si layer at the p / i interface.

FIG. 20 shows B ₂ H ₆ / H ₂ and PH ₃ / H ₂ when forming an i-type layer.
The graph which shows the flow rate pattern of gas, and the distribution of B and P atom content in the i-type layer in the layer thickness direction.

FIG. 21 is a diagram showing a TEM of a p-layer having a laminated structure.

[Explanation of symbols]

101 back surface electrode 102 n-type silicon substrate 103 first p-type layer 104 n-type layer 105 Si layer 106 i-type layer 107 second p-type layer 108 transparent electrode 109 current collecting electrode 121 back surface electrode 122 p-type silicon substrate 123 1 n-type layer 124 p-type layer 125 i-type layer 126 Si layer 127 second n-type layer 128 transparent electrode 129 current collecting electrode 211,221 i-type layer 212,222 Si layer 311, 321, 331, 341, 351 , 361, 3
71 Regions where band gap changes 312, 322, 332, 333, 342, 343, 3
52, 362, 372, 373 Constant band gap region 334, 344, 354, 364, 374 Si layer 401 Deposition chamber 402 Vacuum gauge 403 RF power source 404 Substrate 405 Heater 407 Conductance valve 408 Auxiliary valve 409 Leak valve 410 RF electrode 411 Gas introduction pipe 412 Microwave waveguide 413 Dielectric window 415 Shutter 2000 Raw material gas supply device 2001-2007, 2021-2027 Valve 2011-2017 Mass flow controller 2031-2037 Pressure regulator 2041-2047 Raw material gas cylinder.

Claims (17)

[Claims] 1. A first p-type layer made of microcrystalline silicon, polycrystalline silicon or single crystal silicon, and a non-single crystalline semiconductor material on an n-type substrate made of polycrystalline silicon or single crystal silicon. To a photovoltaic element in which an n-type layer made of a non-single-crystal silicon material, an i-type layer made of a non-single-crystal semiconductor material, and a second p-type layer made of a non-single-crystal semiconductor material are sequentially stacked. In the above, the i-type layer contains silicon atoms and carbon atoms, the band gap of the i-type layer changes smoothly in the layer thickness direction, and the minimum value of the band gap is from the central position of the layer thickness to the second Photovoltaic device characterized by being biased toward the p-type layer of 2. The photovoltaic element according to claim 1, further comprising a Si layer made of a non-single-crystal silicon material between the i-type layer and the second p-type layer. 3. A main constituent element of at least one layer of the second p-type layer, the n-type layer, and the l-th p-type layer is selected from silicon, carbon, oxygen, and nitrogen. A layer (A layer) containing at least one element and containing a group III element, a group V element, or a group VI element of the periodic table as a valence electron control agent, and a group III element or the group V of the periodic table 2. A laminated structure with a layer (B layer) containing a Group Group element or a Group VI element as a main constituent element.
Alternatively, the photovoltaic element according to item 2. 4. A first n-type layer made of microcrystalline silicon, polycrystalline silicon or single crystal silicon, and a non-single crystalline semiconductor material on a p-type substrate made of polycrystalline silicon or single crystal silicon. To a photovoltaic element in which a p-type layer made of a non-single-crystal semiconductor material, an i-type layer made of a non-single-crystal silicon material, a second n-type layer made of a non-single-crystal semiconductor material are sequentially stacked. The i-type layer contains silicon atoms and carbon atoms, the band gap of the i-type layer changes smoothly in the layer thickness direction, and the minimum value of the band gap is the p-type from the central position of the layer thickness. Photovoltaic device characterized by being biased in the direction of the layers. 5. The photovoltaic element according to claim 4, further comprising a Si layer made of a non-single-crystal silicon material between the i-type layer and the p-type layer. 6. At least one layer of the second n-type layer, the p-type layer, and the first n-type layer has a main constituent element selected from silicon, carbon, oxygen, and nitrogen. A layer (A layer) containing at least one element and containing a group III element, a group V element, or a group VI element of the periodic table as a valence electron control agent, and a group III element or the group V of the periodic table 5. A layered structure with a layer (B layer) containing a Group Group element or a Group VI element as a main constituent element.
Alternatively, the photovoltaic element according to item 5. 7. A region having a maximum bandgap of the i-type layer is present on at least one of both ends in the layer thickness direction of the i-type layer, and the region having the maximum bandgap is 1 to 1.
It is 30 nm, The photovoltaic element of any one of Claims 1-6 characterized by the above-mentioned. 8. The photovoltaic element according to claim 1, wherein the i-type layer contains both a valence electron control agent which serves as a donor and a valence electron control agent which serves as an acceptor. Power element. 9. The valence electron control agent serving as a donor is a Group V element or a VI group element of the periodic table, and the valence electron control agent serving as an acceptor is a Group III element of the periodic table. The photovoltaic element according to claim 8, which is characterized in that. 10. The valence electron control agent is distributed in the layer thickness direction inside the i-type layer.
Photovoltaic device according to. 11. The photovoltaic element according to claim 1, wherein the i-type layer contains oxygen atoms and / or nitrogen atoms. 12. The content of hydrogen atoms contained in the i-type layer changes in accordance with the content of silicon atoms, according to claim 1. Photovoltaic device. 13. The i-type layer causes a microwave energy lower than a microwave energy required for 100% decomposition of a raw material gas for depositing a deposited film to act on the raw material gas at a vacuum degree of an internal pressure of 50 mTorr or less, At the same time, RF energy higher than the microwave energy is applied to the source gas to form the source gas.
The photovoltaic element according to any one of 1 to 12. 14. The photovoltaic element according to claim 1, wherein the Si layer contains a Group V element and / or a Group VI element of the periodic table. 15. The Si layer contains a Group III element of the periodic table and a Group V element and / or a Group VI element of the periodic table together. The photovoltaic element according to any one of items. 16. The Si layer is formed by an RF plasma CVD method, and has a deposition rate of 2 nm / sec or less and a layer thickness of 30 nm or less.
The photovoltaic element according to any one of 5 above. 17. The photovoltaic element according to claim 1, and the photovoltaic element to a storage battery and / or an external load by monitoring the voltage and / or current of the photovoltaic element. A power generation system comprising a control system for controlling power supply from an element and a storage battery for storing power from the photovoltaic element and / or supplying power to an external load.