JPH06204514A - Photovoltaic element and generation system - Google Patents

Abstract

PURPOSE:To provide a photovoltaic element in which recombination of photovol taic carrier is prevented and an open voltage and carrier range of holes are improved and its generator system. CONSTITUTION:A photovoltaic element comprises a first p-type layer 103 formed of fine crystalline silicon, polycrystalline silicon or single crystal silicon, an n-type layer 104 formed of nonsingle crystal semiconductor material, an i-type layer 105 formed of nonsingle crystal semiconductor material, an Si layer 106 formed of a nonsingle crystal silicon material, and a Second p-type layer 107 formed of nonsingle crystal semiconductor material sequentially laminated on an n-type substrate 102 formed of polycrystalline silicon or single crystal silicon, wherein the layer 105 contains silicon atoms and carbon atoms. A band gap of the layer 105 is smoothly varied in a layer thickness direction, and a minimum value of the gap is deviated toward the layer 107 from a central position of a layer thickness.

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) "Opti
mum deposition conditions for a- (Si, Ge): H using a
triode-configurated rf glow discharge system ", J.
A. Bragagnolo, P. Littlefield, A. Mastrovito and G. Stor
ti.Conf.Rec.19th IEEE Photovoltaic Specialists Con
ference-1987 pp.878, (2) “Efficiency improvement
in amorphous-SiGe: H solar cells and its applicatio
n to tandem type solar cells ", S.Yoshida, S.Yamanak
a, M.Konagai and K.Takahashi, Conf.Rec.19th IEEE Ph
otovoltaic Specialists Conference-1987 pp.1101,
(3) “Stability and terrestrial application of a
-Si tandem type solar cells "A.Hiroe, H.Yamagishi,
H.Nishio, M.Kondo and Y.Tawada, Conf.Rec.19th IEEE
Photovoltaic Specialists Conference-1987 pp.1111,
(4) “Preparation of high quality a-SiGe: H Films
and its applicationto the high efficiency triple-
junction amorphous solar cells "K. Sato, K. Kawabata,
S.Terazono, H.Sasaki, M.Deguchi, T.Itagaki, H.Morikaw
a, M.Aiga and K.Fujikawa, Conf.Rec.20th IEEE Photov
oltaic Specialists Conference-1988 pp.73, (5) USP
4,816,082 etc. have been reported.

A theoretical study on the characteristics of a photovoltaic element having a changed band gap is given in, for example, (6) "A.
novel design for amorphous silicon alloy solar cel
ls "S.Guha, J.Yang, A.Pawlikiewicz, T.Glatfelter, R.Ro
ss, and SROvshinsky, Conf.Rec.20th IEEE Photovolta
ic Specialists Conference-1988 pp.79, (7) “Numer
ial modeling of multijunction amorphous silicon ba
sed PIN solar cells "AHPawlikiewicz and S. Guh
a, Conf.Rec.20th IEEE Photovoltaic Specialists Conf
erence-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.

Further, p formed on a polycrystalline silicon substrate
A photovoltaic element in which an n-junction and a pin junction made of amorphous silicon are stacked has been reported. For example,
(8) “Amorphous Si / Polycrystalline Si Stacked So
lar Cell Having MoreThan 12% Conversion Efficienc
y "Koji.Okuda, Hiroaki.Okamoto and Yoshihiro.Hamaka
wa, Japanese Journal of Physics Vol.22 No.9 Sep. 1
983 pp.L605, (9) “Device Physics and Optimum De
sign of a-Si / poly Si Tandem SolarCells "H.Takakur
a, K.Miyagi, H.Okamato, Y.Hamakawa, Proceedings of 4t
h Intenatinal Photovoltaic Science and Engineering
Conference 1989 pp.403 etc.

Further, a photovoltaic device has been reported 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. For example, (10) "Characterization of δ-dope
d a-SiC p-Layer Prepared by Trimetylboron and Tri
ethylboron and its application to Solar Cells ", K.
Higuchi, K.Tabuchi, S.yamanaka, M.Konagai and K.Takah
ashi, Proceedings of 5th International Photovoltai
c Science and Engineering Conference 1990, pp529,
(11) "High Efficiency Amouphous Silicone Solar
Cells with Delta-Doped p-Layer ", Y. Kazama, K. Seki,
WYKim.S.Yamanaka, M.Konagai and K.Takahashi, Japa
nese Journal of Applied Physics Vol.28, No.7 July 1
989 pp.1160-1164, (12) ”High Efficiency Delta-D
oped Amouphous Silicone Solar Cells Prepared by ph
otochemical Vapor Deposition ", K. Higuchi, K. Tabuchi,
KSLim, M.Konagai and K.Takahashi, Japanese Journa
l of Applied Physics Vol.30, No.8 August 1991 pp.16
35-1640, (13) ”High Efficiency Amouphous Silico
ne Solar Cells with Delta-Doped p-Layer ", A. Shibat
a, Y.Kazama, K.Seki, WYKim.S.Yamanaka, M.Konagai and
K.Takahashi, Conf.Rec.20th IEEE Photovoltaic Specia
lists Conference-1988 pp.317.

[0007]

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, and the conversion efficiency is lowered when the photovoltaic element is irradiated with light.
In addition, there is a problem in that the photoelectric conversion efficiency decreases when annealed in the presence of vibration or the like.

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.

It is another object of the present invention 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 it is annealed under vibration for a long period of time.

A further object of the present invention is to provide a photovoltaic element 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 which achieves the above object.

[0015]

In order to solve the above problems and achieve the object of the present invention, the inventors of the present invention have made extensive studies and found that the photovoltaic element of the present invention is polycrystalline. On a n-type substrate made of silicon or single crystal silicon, a first p-type layer made of microcrystalline silicon, polycrystalline silicon or single crystal silicon, an n-type layer made of non-single crystal semiconductor material, I made of crystalline semiconductor material
In a photovoltaic device in which a p-type layer, a Si layer made of a non-single-crystal silicon-based material, and a second p-type layer made of a non-single-crystal semiconductor material are sequentially stacked, the i-type layer is a silicon atom and a carbon atom. And 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 second p-type layer. I am trying.

Alternatively, on a p-type substrate made of polycrystalline silicon or single crystal silicon, a first n-type layer made of microcrystalline silicon, polycrystalline silicon or single crystal silicon, and a non-single crystal semiconductor material are used. P-type layer, Si layer made of non-single-crystal silicon material, i-type layer made of non-single-crystal semiconductor material, second layer made of 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 element of the present invention, at least one of the interface between the i-type layer and the Si layer or the interface with the n-type layer (or the second n-type layer) is
The photovoltaic element has the maximum bandgap of the i-type layer and the region of the maximum bandgap is within 1 to 30 nm.

Another desirable mode 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 first 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.

As a desirable mode of the photovoltaic element of the present invention, the Si layer contains a group III element of the periodic table and a group V element and / or group VI element of the periodic table. It is an electromotive force element.

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, a desirable mode of the photovoltaic element of the present invention is a photovoltaic element in which the hydrogen content contained in the i-type layer changes in accordance with the content of silicon atoms. .

Furthermore, a desirable form of the photovoltaic element of the present invention is that the i-type layer has a vacuum degree of 50 mTorr or less, and has a microwave energy lower than the microwave energy required to decompose 100% of the source gas for depositing the deposited film. A photovoltaic element formed by applying microwave energy to the source gas and simultaneously applying RF energy higher than the microwave energy to the source gas, wherein the Si layer has a deposition rate of 2 nm / sec or less. Is a photovoltaic element formed by the RF plasma CVD method and having a layer thickness of 30 nm or less.

A system using the photovoltaic element of the present invention is the above 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. A control system for controlling the supply of power from the device, and storage and / or storage of the power from the photovoltaic device
Alternatively, it is characterized by being configured with a storage battery that supplies electric power to an external load.

[0026]

The operation and structure of the present invention will be described in detail below with reference to the drawings.

1A and 1B are schematic explanatory views of the photovoltaic element of the present invention.

In FIG. 1-a, the photovoltaic device of the present invention comprises a back electrode 101, an n-type silicon substrate 102, and a first p-type.
Mold layer 103, n-type layer 104, i layer 105, Si layer 10
6, the second p-type layer 107, the transparent electrode 108, the collector electrode 109, and the like. The interface between the n-type silicon substrate and the first p-type layer is referred to as “p / substrate interface”, the first p-type interface.
The interface between the type layer and the n-type layer is “n / p interface”, the interface between the n-type layer and i layer is “i / n interface”, and the interface between the i layer and Si layer is “Si /
The “i interface” and the interface between the Si layer and the second p-type layer will be referred to as the “p / Si interface”.

Similarly, referring to FIG. 1-b, the photovoltaic device of the present invention includes a back electrode 121, a p-type silicon substrate 122,
First n-type layer 123, p-type layer 124, Si layer 125, i
The layer 126, the second n-type layer 127, the transparent electrode 128, the collector electrode 129, and the like. In addition, the interface between the p-type silicon substrate and the first n-type layer is the “n / substrate interface”, the interface between the first n-type layer and the p-type layer is the “p / n interface”, and the p-type layer and the Si layer are The interface is the “Si / p interface”, the interface between the Si layer and the i layer is the “i / Si interface”, and the interface between the i layer and the second n-type layer is “n”.
/ I interface ”.

In the present invention, since the position of the minimum band gap value of the i-type layer is offset to the second p-type layer (p-type layer) side, the Si / i interface (i / Si interface) of the i-type layer is In the vicinity, the electric field in the conduction band is large, so that 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,
Since the electric field in the valence band increases toward the i / n interface (n / i interface), recombination of electrons and holes photoexcited near the i / n interface (n / i interface) is reduced. It is possible to improve the photoelectric conversion efficiency, and further, it is possible to suppress a decrease in the photoelectric conversion efficiency (photodegradation) due to irradiation of the photovoltaic element with light for a long time.

Further, the carrier range of electrons and holes can be lengthened by adding both a valence electron control agent serving as a donor and a valence electron control agent serving as an acceptor into the i-type layer. In particular, by containing a relatively large amount of a valence electron control agent at a large band gap, the carrier range of electrons and holes can be effectively lengthened. As a result, the high electric field in the vicinity of the Si / i interface (i / Si interface) and the high electric field in the vicinity of the i / n interface (n / i interface) can be more effectively utilized and photoexcited in the i-type layer. The efficiency of collecting electrons and holes can be significantly improved. In addition, near the Si / i interface (i / Si interface) and i / n
Defect levels (so-called D) near the interface (n / i interface)
^- , D ⁺ ) 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. Particularly in the vicinity of the interface, by containing a valence electron control agent in a larger amount than in the i-type layer,
The internal stress such as strain due to the abrupt change of the constituent elements peculiar to the interface can be reduced, so that 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.
And in the case of the present invention, both the valence electron control agent used as a donor and the valence electron control agent used as an acceptor are contained in the i-type 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.

Even when the intensity of light applied to the photovoltaic element is low, 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 optical storage element is weak.

In addition, the photovoltaic element of the present invention is such that the photoelectric conversion efficiency does not easily 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. Especially Si / i
Near the interface (i / Si interface) or p / Si interface (S
In the Si layer near the (i / p interface), the valence electron control agent is contained in a larger amount than in the central region of the Si layer,
That the constituent elements peculiar to the interface are rapidly changing,
Alternatively, the defect level near the interface can be reduced by reducing the internal stress caused by stopping the plasma. This can improve the open circuit voltage and fill factor of the photovoltaic element.

Furthermore, 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, since the underlying layer of the n (p) type layer formed of the non-single crystal material formed on the pn junction is made of microcrystalline silicon, polycrystalline silicon or single crystal silicon semiconductor material, Because it can be easily microcrystallized,
The open circuit voltage can be improved.

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

In the photovoltaic element of the present invention, the Si layer is deposited by RF plasma CVD at a deposition rate of 2 nm /
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 Si / i interface (i / Si
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, it is considered that the surface level of the i-type layer immediately after the completion of the deposition is not sufficiently relaxed and therefore the surface level is extremely large.

RF plasma C is formed on the surface of such an i-type layer.
By forming a deposited film having a low deposition rate by the VD method, the surface state of the i-type layer can be reduced by annealing due to the diffusion of hydrogen atoms which occurs at the same time when the deposited film is formed by RF plasma CVD, and the photovoltaic power is reduced. The open circuit voltage and fill factor of the device can be improved. This is remarkable when the i-type layer is formed by the microwave plasma CVD method.

The Si layer contains a valence electron control agent (group III element of the periodic table) which serves as an acceptor, whereby the structure between the second p-type layer (p-type layer) and the i-type layer is formed. Since the internal stress such as strain due to the abrupt change of the element can be reduced, defects in the Si layer near the p / Si interface (Si / p interface) or the Si / i interface (i / Si interface) The level 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 both 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.

Even when the intensity of light applied to the photovoltaic element is low, 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 is such that the photoelectric conversion efficiency does not easily decrease even when it is annealed under vibration for a long time. Although the detailed mechanism of this is unknown, the Si / i interface (i
(/ Si interface), the local flexibility is increased by adding both the valence electron control agent serving as a donor and the valence electron control agent serving as an acceptor, and the photovoltaic element of the photovoltaic device can be annealed even during long-term vibration annealing. It is considered that the decrease in 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 position of the minimum band gap of
It is located near the i interface (i / Si interface) and the maximum position of the band gap is the Si / i interface (i / Si interface)
It is configured so as to be in contact with the / n interface (n / i interface). Like FIG. 2A, FIG. 2B has the Si layer 222 formed by the RF plasma CVD method, and the i-type layer 221 has a minimum bandgap position from the center position from the Si / i interface. It is located near the (i / Si interface), and the maximum value of the band gap is in contact with the Si / i interface (i / Si interface). The open circuit voltage can be particularly increased by adopting the bandgap configuration as shown in FIG. 2-2.

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

In FIG. 3-1, 313 is a Si layer, and Si /
The i-type layer near the i interface (i / Si interface) has a region 312 with a constant band gap, and the band gap is from the i / n interface (n / i interface) side to the Si / i interface (i / S).
This is an example having a region 311 that decreases toward the (i 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, when the layer thickness of the region 312 where the band gap is constant is thicker than 30 nm, photoexcited holes are easily accumulated near the interface between the region 312 where the band gap is constant and the region 311 where the band gap is changed. , The collection efficiency of photoexcited carriers is reduced. That is, the short circuit photocurrent is reduced.

FIG. 3-2 shows the Si / i interface (i / S) of the i-type layer.
A region 32 having a constant band gap in the i-type layer near the (i interface)
Area 32 in which 2 is provided and the band gap is changed
This is an example in which the band gap at the i / n interface (n / i interface) of 1 is equal to the band gap of the region 322.

FIG. 3-3 shows the Si / i interface (i / Si interface).
Regions 332 and 333 having a constant band gap are provided in the vicinity of the i-type layer near the i / n interface (n / 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.

FIGS. 3-4 to 3-7 show the vicinity of the Si / i interface (i / Si interface) or / and the i / n interface (n /
(i interface) has a region with a constant band gap in the i-type layer, and has a Si / i interface (i / Si interface) and / or i
It is an example of the photovoltaic device of the present invention which has a region where the bandgap changes abruptly in the / n interface (n / i interface) direction.

FIG. 3-4 shows the Si / i interface (i / Si interface).
The i-type layer in the vicinity and in the vicinity of the i / n interface (n / i interface) have regions 342 and 343 with a constant band gap, and a region 341 in which the band gap is changed. The minimum position is offset to the Si / i interface side, and the band gap of the region 341 and the region 34
In this example, the band gaps of 2,343 are continuous. 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, when the regions 342 and 343 having a constant band gap are thinner than 5 nm and the band gap of the i-type layer is abruptly changed, the dark current when a reverse bias is applied to the photovoltaic element is reduced. Therefore, the open circuit voltage of the photovoltaic element 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. If the region where the band gap is constant is thin at 5 nm or less and the layer thickness of the region where the band gap changes rapidly is 10 nm or less, the region where the band gap is constant and the region where the band gap changes are continuous. The photoelectric conversion efficiency of the photovoltaic element is higher when the layers are connected together, while the layer thickness in the region where the bandgap is constant is thicker than 5 nm and the layer thickness in the region where the bandgap changes rapidly. In the case of 10 to 30 nm, the conversion efficiency of the photovoltaic element improves when the region where the band gap is constant and the region where the band gap changes are connected discontinuously.

FIG. 3-6 shows an example in which a region where the band gap is constant and a region where the band gap changes are connected in two stages. Further, the position where the band gap is extremely small is from the center position of the i-type layer to the Si / i interface (i / Si interface)
This is an example that is closer to you. Carriers photoexcited in the region 361 where the bandgap is changed by connecting to a constant region 362 with a wide bandgap through a stage where the bandgap is gradually widened and a stage where the bandgap is widened rapidly. Can be collected efficiently. Further, in FIG. 3-6, the i / n interface (n
/ I interface), i / n interface (n / i interface)
It has a region in which the band gap changes sharply toward.

FIG. 3-7 shows that the i-type layer near the Si / i interface (i / Si interface) and the i / n interface (n / i interface) has a region having a constant band gap and that Si / Region 37 with a constant band gap near the i interface (i / Si interface)
2 is connected from the bandgap changing region 371 through a two-step bandgap change, and is connected to the i / n interface (n / i
In this example, a region 373 having a constant band gap at the 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 the state where the constituent elements are similar to each other, 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 bandgap value of the i-type layer containing silicon atoms and carbon atoms is variously selected depending on the spectrum of irradiation light, but is 1.7 to 2.0 eV. Is desirable.

Further, in the photovoltaic element 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 element. It is preferable that the slope of the tail state at the minimum value of the band gap 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 40.
3, substrate 404, heater 405, conductance valve 407, auxiliary valve 408, leak valve 40
9, RF electrode 410, gas introduction pipe 411, microwave waveguide 412, dielectric window 413, shutter 415, source gas supply device 2000, mass flow controller 20.
11-2017, valves 2001-2007, 2021
˜2027, pressure regulators 2031 to 2037, raw material gas cylinders 2041 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.

The source gas is decomposed by causing microwave energy lower than the microwave energy (abbreviated as "MPw") required for 100% decomposition of the source gas to decompose the source gas, and RF energy higher than MPw is obtained. It is considered that an active species suitable for forming a deposited film can be selected by acting on the source gas at the same time as microwave energy. Further, when the internal pressure in the deposition chamber when decomposing the source gas is 50 mTorr or less, it is considered that the gas phase reaction can be suppressed as much as possible because the mean free path of active species suitable for forming a good quality deposited film is sufficiently long. . When the internal pressure in the deposition chamber is 50 mTorr or less, R
It is considered that the F energy has almost no influence 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 the RF
By introducing energy at the same time as microwave energy, the potential difference between the plasma and the substrate (+ on the plasma side and − on the substrate side) can be increased. 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 voltage of + polarity to the DC voltage applied to the RF electrode where the content of hydrogen atoms is desired to be increased. 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 of 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 atom but containing a silicon atom (for example, SiH ₄ , Si ₂ H ₂ , Si ₃
H ₂ , SiD ₄ , SiHD ₅ , SiH ₂ D ₂ , SiH ₃ D, S
iD ₃ H, 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. Regarding the detailed mechanism,
Although it is 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 will increase, and radicals containing halogen atoms will increase. It is considered that the halogen atom and the hydrogen atom existing in the i-type layer cause a substitution reaction, and the hydrogen content in the i-type layer decreases.

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,
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, the substrate 404 for forming a deposited film is attached in the deposition chamber 401 shown in FIG. 4, and the inside of the deposition chamber is sufficiently evacuated to 10 ⁻⁴ Torr or less. For this exhaust, turbo molecular pump,
Alternatively, an oil diffusion pump is suitable. In the case of an oil diffusion pump, the deposition chamber 40 should prevent
When the internal pressure of 1 drops below 10 ^-4 Torr, H ₂ , He,
It is preferable to introduce a gas such as Ar, Ne, Kr, Xe into the deposition chamber. After exhausting the inside of the deposition chamber sufficiently, H ₂ , H
Gases such as e, Ar, Ne, 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 flown. As the pressure in the deposition chamber,
The optimum range is 0.5 to 50 mTorr. When the internal pressure in the deposition chamber becomes stable, the heater 405 is turned on to heat the substrate to 100 to 500 ° C. When the substrate temperature stabilizes at a predetermined temperature, H ₂ , He, Ar, Ne, K
A gas such as r or Xe is stopped, and a predetermined amount of a raw material gas for forming a deposited film is introduced into a deposition chamber from a gas cylinder via a mass flow controller.

The supply amount of the raw material 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 the preferable range of the RF energy is. 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 the RF energy is supplied, 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 deposited film forming method as described above, the following compounds are suitable as the compounds to be cited as the source gas for depositing silicon.

Specifically, gasification containing silicon atoms
SiH as the compound to be obtained_Four, Si₂H₆, SiX_Four(X:
Halogen atom), SiXH₂, SiX₂H₂, SiX₃H,
Si ₂X₆, Si₂H₃, SiD_Four, SiHD₃, SiH
₂D₃, SiH₂D, SiFD₂, SiX₂D₂, SiD
₃H, Si₂D₃H₃Etc. (collectively abbreviated as “compound (Si)”
Note)).

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 is a halogen atom), C _n X _2n (n is an integer), C ₂ H ₂ , C ₆ H ₅ , C
O ₂ , CO, etc. (collectively referred to as “compound (C)”)
Is mentioned.

In the present invention, 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 is a group III atom, a group V atom or a group VI atom of the periodic table. A genus atom is 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 12, B 6 H 14 , etc. borohydride, B
Examples thereof include boron halides such as F ₃ , BCl ₃ and BBr ₃ . In addition to this, AlCl ₃ , Al (CH ₃ )
₃ , GaCl ₃ , InCl ₃ , TlCl _{3 and the} like can also be mentioned.

In the present invention, the starting 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, PF_Five,
PCl₃, PCl_Five, PBr₃, PBr_Five, Pl₃Etc. halo
Phosphorus genide, P₂O_Five, POCl₃Oxygen compounds such as
Be done. In addition, AsH₃, AsF₃, AsCl₃, AsB
r₃, AsF_Five, SbH₃, SbF₃, SbF_Five, SbC
l₃, SbCl_Five, BiCl_Five, BiBr₃And so on
You can

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 , T
_{eH 2, TeF 6, (CH} 5) 2 Te, include (C ₂ H _{3) 2} Te, and the like.

A preferable amount of the group III atom, the group V atom, or the group VI atom introduced into the i-type layer made of a non-single crystal semiconductor material is 1000 ppm or less. 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.

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. Particularly, the most suitable gas for diluting the gasifiable compound is H ₂ , D ₂ , He or A.
r is mentioned.

As the nitrogen-containing gas introduced for containing nitrogen in the i-type layer of the non-single crystal semiconductor layer, N ₂ and N are used.
H ₃ , ND ₃ , NO, NO ₂ , and N ₂ O (generally abbreviated as “compound (N)”) can be mentioned.

O ₂ and C are used as the oxygen-containing gas introduced to contain oxygen in the i-type layer of the non-single-crystal semiconductor layer.
O, CO ₂ , NO, NO ₂ , N ₂ O, CH ₃ CH ₂ OH, C
H ₃ OH and the like (generally abbreviated as “compound (O)”) can be mentioned.

In the photovoltaic element of the present invention, the second p-type layer, the n-type layer, the first p-type layer, or the second n-type layer, the p-type layer, and the first n-type layer are included. At least one of the layers preferably has a laminated structure. The laminated structure in the photovoltaic element of the present invention has a main constituent element of silicon and carbon, oxygen, and at least one element selected from nitrogen,
Group III element or V of the periodic table as a valence electron control material
It is composed of a layer containing a group element or a group VI element (A layer) 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 (layer B).

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 more than the conventional one, 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 element 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 or / and oxygen or / and nitrogen, the generated strain and stress are relaxed inside the A layer, and therefore, it is suitable for long-term annealing such as vibration. On the other hand, it is considered that the decrease in photoelectric conversion efficiency can be suppressed.

Furthermore, the photovoltaic element 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. Although dangling bonds are generated inside the A layer when irradiated with light for a long time, 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 layer A 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.

As the amorphous material, for example, a-Si:
H, a-Si: HX, a-SiC: H, a-SiC: H
X, a-SiO: H, a-SiO: HX, a-SiN:
H, a-SiN: HX, a-SiON: H, a-SiO
N: HX, a-SiOCN: H, a-SiOCN: H
X, (X: halogen atom) and the like can be mentioned.

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.

Examples of the polycrystalline material include 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.

When the n (p) type layer and the second p (n) type layer have a laminated structure, as the A layer, a microcrystalline material, a polycrystalline material, or a single crystal having a small absorption coefficient for short wavelength light is used. Materials are preferably used.

In order to form a p-type A layer, a p-type valence electron control agent (group III atom B, A of the periodic table) is added to the above materials.
1, Ga, In, Tl) to form an n-type A layer, an n-type valence electron control agent (group V atom P, As, Sb, Bi or / and the periodic law) is used. Group VI atoms S, Se, Te) are added.

The amount of the group III atom added to the p-type A layer, or the group V atom of the periodic table added to the n-type A layer,
The optimum amount of the Group VI atom added is 10 to 10,000 ppm.

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 compensate for dangling bonds in the A layer. It works and improves the doping efficiency. 0 hydrogen or halogen atoms added to layer A
An optimum amount is 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. In this way, by increasing the content of hydrogen atoms or halogen atoms near the interface, the defect level near the interface and the stress in the layer are reduced,
Furthermore, mechanical strain can be relaxed and the photovoltaic power and photocurrent of the photovoltaic device of the present invention can be increased.
The layer thickness of the layer A is preferably 5 to 30Å.

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 the layer A is formed by these methods, the following gasifiable compounds and mixed gases of the compounds 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 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 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.

Compounds (V) mentioned above can be effectively used as a starting material for introducing a group V atom, and PH ₃ and PF ₃ are 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.

Compounds (VI) mentioned 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 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 are used.
The method is preferred. 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 ²The optimum deposition rate is 0.1 to 1Å / sec.
It is mentioned as a matter.

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.

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 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 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.
~ 30mTorr, microwave power 0.005-1
W / cm ³ , microwave frequency is 0.5 to 10 GHz
Is mentioned as a preferable range.

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.

In particular, when depositing an A layer made of a microcrystal, a polycrystal, or a single crystal material, hydrogen gas is added in an amount of 2-1.
It is preferable to dilute the source gas by a factor of 00 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 to 60.
0 ° C., internal pressure 0.1 to 10 Torr, deposition rate 0.0
The optimum condition is 1 to 1Å / sec, and 1 to 100% of mercury is introduced while introducing the gasifiable compound.
About ppm may be introduced.

Examples of the compound (Si) include Si ₂ H ₆ ,
Higher order silanes such as Si ₂ H _N X _6-N (X: halogen atom) are 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.

In particular, when depositing an A layer made of a microcrystal, a polycrystal, or a single crystal material, hydrogen gas is added in an amount of 2-1.
It is preferable to introduce the raw material gas by diluting it by 00 times.

The main constituent atoms of the B layer, when laminated with the p-type A layer, are 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 30Å.

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.

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 B (CH ₃ ) ₃ are particularly suitable.

Compounds (V) described above 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 used.
The method is preferred. 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 2Å / sec.

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.

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 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 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.

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.

When the layer B is deposited by the photo CVD method, a low pressure mercury lamp is used as a light source and the substrate temperature is 100 to 60.
0 ° C, internal pressure 0.1 to 10 Torr, deposition rate 0.0
1-2 Å / sec is mentioned as the optimum condition, and the compound which can be gasified is introduced and mercury is added in an amount of 1-100.
About ppm may be introduced.

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 with the A layer and ends with the A layer. For example, the laminated structure of ABA, ABABA, ABABABA, etc. (AB) _n A, Or A ₁ B ₁ A ₂ , A ₁ B ₁ A
A laminated form of (A _n B _n ) A _{n + 1} such as ₂ B ₂ A ₃ may be mentioned.
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, AB, A
Examples include a laminated form of (AB) _n such as BAB and ABABAB, or a laminated form of (A _n B _n ) such as A ₁ B ₁ , A ₁ B ₁ A ₂ B _{2, and the} like.

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 a polycrystal silicon layer on a support made of an insulating material or a conductive material. It may be a stack of single crystal silicon 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 an electrically insulating support, a film or sheet of synthetic resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, or the like, glass, ceramics, etc. , Paper, etc. 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 + SnO
₂ ) to provide conductivity by providing a thin film of etc., or synthetic resin film such as polyester film, NiCr, Al, Ag, Pb, Zn, Ni,
Au, Cr, Mo, Ir, Nb, Ta, V, Tl, Pt
A metal thin film such as 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 a plasma CVD method, a thermal CVD method, an optical CVD method, and the like. 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 improve the collection efficiency of the 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) 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-).

As the microcrystalline material, for example, μc-S
i: H, μc-SiC: H, μc-Si: HX, μc-
SiC: HX, μc-SiGe: H, μc-SiO:
H, μc-SiGeC: H, μc-SiN: H, μc-
SiON: HX, μc-SiOCN: HX, etc. (X: halogen atom) can be mentioned.

Polycrystalline materials include, for example, 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 of the periodic table) is used.
s, Sb, Bi and / or Group VI atom of the periodic table
S, Se, Te) is added in high concentration.

Addition amount of Group III atom to the first p-type layer, or V to V of the periodic table to the first n-type layer
The optimum amount of the group I atom added is 0.1 to 10 at%.

Also, 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 2000Å 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 source gas is a gasifiable compound containing a silicon atom, a gasifiable compound containing a carbon atom, and the like. And the like.

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.

Gasifiable containing germanium atoms
As a compound, GeH_Four, Ge₂H ₆, GeH_NX
_4-N(X: halogen) and other compounds (collectively referred to as “compound
(Ge) ").

As the nitrogen-containing gas, the above-mentioned compound (N) can be mentioned.

As the oxygen-containing gas, the above-mentioned compound (O) can be mentioned.

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 preferably diluted with a gas such as H ₂ , He or Ar to a desired concentration before use.

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. Dilute to a desired concentration with a gas such as H ₂ , He or Ar before use.

Compounds (VI) mentioned 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 used.
Dilute to a desired concentration with a gas such as H ₂ , He or Ar 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 capacitive coupling type 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 ² , and the deposition rate is 0.1 to 30 Å / sec.

The compounds capable of being gasified 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. The suitable range of the RF frequency is 1 MHz 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 atoms of the periodic table are added. Diffuse near the substrate 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, Alternatively, the Group VI atoms are diffused near the surface of the substrate. Examples of the diffusion gas include the compound (V) and the compound (VI) described above, 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, the group III atoms of the periodic table are accelerated under a high electric field and are irradiated on the surface of the n-type substrate, and the group III atoms are irradiated inside the substrate. Inject. For example, when implanting boron, 1-1
It is preferable to perform 0 × 10 ¹⁵ (pieces / cm ² ) of ¹¹ B ⁺ with an acceleration voltage of about 5 to 50 keV.

When the first n-type layer is formed by the ion implantation method, the group V atom or the group VI atom of the periodic table is accelerated under a high electric field to irradiate the surface of the n-type substrate, Group V atoms or group VI atoms are implanted inside the substrate. For example, when phosphorus is injected, 0.5 to 10 × 10 ¹⁵ (pieces / cm ² ) ³¹ P ⁺ may be used at an acceleration voltage of about ¹ to 10 keV.

N (p) type layer (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 configured will be 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.

As the amorphous material, for example, a-Si:
H, a-Si: HX, a-SiC: H, a-SiC: H
X, a-SiGe: H, a-SiGeC: HX, a-S
iO: H, a-SiN: H, a-SiON: HX, a-
SiOCN: HX etc. are mentioned.

Microcrystalline materials include 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.

As the polycrystalline material, for example, poly-S is used.
i: H, poly-Si: HX, poly-SiC:
H, poly-SiC: HX, poly-SiGe:
H, poly-Si, poly-SiC, poly-S
iGe etc. are mentioned.

To make the conductivity type p-type, a p-type valence electron controlling 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 (atoms P, As, Sb, Bi of Group V of the Periodic Table, atoms S, Se and Te of Group VI of the Periodic Table) are added as described above. It is added to the material at a high concentration.

In particular, the second p (n) -type layer contains a microcrystalline material with little light absorption or a non-single crystalline material with a wide band gap, such as 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 I of the p-type layer and the second p-type layer
The added amount of the group II atom and the added amount of the group V atom and the group VI of the periodic table to the n-type layer and the second n-type layer are 0.1 to 0.1%.
The optimum amount is 50 at%.

The hydrogen atoms (H, D) or halogen atoms contained in the n (p) type layer and the second p (n) type layer serve to compensate dangling bonds and improve the doping efficiency. The optimum amount is 0.1 to 40 at%. Particularly when the n (p) type layer and the second p (n) type layer are made of a microcrystalline material or a polycrystalline material, the optimum amount of hydrogen atom or halogen atom is 0.1 to 10 at%.
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 electrical 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.
1000Å is preferred, 30-300Å is optimal,
The layer thickness of the second p (n) type layer is preferably 10 to 500Å, and most preferably 30 to 200Å.

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.

When the n (p) type layer and the second p (n) type layer are formed by the plasma CVD method, the source gas is a gasifiable compound containing silicon atoms or a gasified compound containing carbon atoms. Examples thereof include the compound to be obtained, and a mixed gas of the compound.

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 above-mentioned compound (Ge).

As the nitrogen-containing gas, the above-mentioned compound (N) can be mentioned.

As the oxygen-containing gas, the above-mentioned compound (O) can be mentioned.

Compounds (II) mentioned above can be 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 a starting material for introducing a Group V atom. Particularly, PH ₃ and PF ₅ are suitable.

Compounds (VI) described above can be effectively used as starting materials for introducing a Group VI atom.

The deposition methods preferably used as the plasma CVD method are the RF plasma CVD method and the microwave plasma CVD method. 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 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 to 30Å / sec.
It is mentioned as a matter.

The frequency of RF is 1 MHz to 100 M
Hz is a suitable range, and particularly a frequency near 13.56 MHz is optimum.

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-S
iO: H, μc-SiN: H, μc-SiON: HX,
μc-SiOCN: HX, poly-Si: H, pol
y-Si: HX, poly-SiC: H, poly-S
iC: HX, poly-Si, poly-SiC: H,
a-SiC: H, a-SiC: HX, a-SiO: H,
a-SiN: H, a-SiON: HX, a-SiOC
When depositing a microcrystalline layer such as N: HX having little light absorption, a polycrystalline layer, or an amorphous layer having a wide bandgap, the source gas is diluted 2 to 100 times with hydrogen gas, and the RF power is relatively high. It is preferable to introduce high power.

When depositing by the microwave plasma CVD method, the microwave plasma CVD apparatus is preferably a method in which the microwave is introduced into the deposition chamber through the dielectric window by the 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-S
iO: H, μc-SiN: H, μc-SiON: HX,
μc-SiOCN: HX, poly-Si: H, pol
y-Si: HX, poly-SiC: H, poly-S
iC: HX, poly-Si, poly-SiC: H,
a-SiC: H, a-SiC: HX, a-SiO: H,
a-SiN: H, a-SiON: HX, a-SiOC
N: When depositing a microcrystalline layer such as 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 (105, 126) 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.

As the i-type layer of the photovoltaic element of the present invention,
The bandgap containing silicon atoms and carbon atoms changes smoothly in the layer thickness direction of the i-type layer, and the position of the minimum value of the bandgap is at the Si / i interface (i
/ Si interface). 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 serves to compensate the interface states of the Si / i interface (i / Si interface) and i / n interface (n / i interface), and improves the photovoltaic power, photocurrent and photoresponsiveness of the photovoltaic device. It has the effect of The hydrogen atom and / or halogen atom contained in the i-type layer is 1 to 30a.
The optimum content is t%.

Particularly, the Si / i interface (i / Si interface), i
/ N interface (n / i interface) has a large content of hydrogen atoms and / or halogen atoms distributed as a preferable distribution form, and the hydrogen atom and / or halogen atom content near the interface is included. 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 in contrast to the increase and 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 in the range of 1 to 10 at%, and is 0.3 of the maximum region of the content of hydrogen atoms and / or halogen atoms.
The preferable range is ˜0.8 times.

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 where the band gap is narrow, and hydrogen atom or / and 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 very small amount of oxygen and / or nitrogen of 100 ppm or less to the i-type layer containing silicon atoms and carbon atoms, the photovoltaic element has good durability against annealing due to long-term vibration. 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.

The layer thickness of the i-type layer largely depends on the structure of the photovoltaic element (eg, single cell, tandem cell, triple cell) and the bandgap of the i-type layer, but is 0.05.
The optimum layer thickness is up to 1.0 μm.

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 should be designed so as to widen from the bulk toward the Si / i interface (i / Si interface) and / or toward the i / n interface (n / i interface). Is preferred. By designing in this way, it is possible to increase the photovoltaic power and photocurrent of the photovoltaic element, and it is possible to control the decrease in photoelectric conversion efficiency (photodegradation) when light is irradiated for a long time. it can.

Si layer (106, 125) In the photovoltaic device 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.

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.

The hydrogen atom (H, D) or the halogen atom (X) contained in the Si layer serves to compensate the unbonded hands of the Si layer, and determines the product of the carrier mobility and the lifetime of the Si layer. To improve. Further, it functions to compensate the interface order of the p / Si interface (Si / p interface) and the Si / i interface (i / Si interface), and the photovoltaic power, photocurrent, and photoresponsiveness of the photovoltaic device. It has the effect of improving.
The optimum content of hydrogen atoms and / or halogen atoms contained in the Si layer is 1 to 30 at%.

In particular, in the Si layer near the p / Si interface (Si / p interface) and near the Si / i interface (i / 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, oxygen and / or nitrogen is added to the Si layer in an amount of 1
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 p from the Si / i interface (i / Si interface).
A distribution that decreases toward the / Si interface (Si / p interface) is preferable.

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.

The layer thickness of the Si layer is a necessary 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 a photo CVD method can also be used. When depositing the Si layer using the RF plasma CVD method, the capacitive coupling type RF plasma CVD 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
0.1-10 Torr, RF power 0.005-
The optimum condition is 0.1 W / cm ² .

The RF frequency is 1 MHz to 100 M
Hz is a suitable range, and particularly a frequency near 13.56 MHz is optimum.

Specific examples of the raw material gas include the compounds (Si) described above as the gasifiable compounds containing silicon atoms.

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.

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 a Group III element of the periodic table, and the substance introduced to make the conductivity type slightly n-type is the periodic table. Examples include Group V atoms or / 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. 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 ₆ are suitable.

Compounds (VI) described above can be effectively used as starting materials for introducing a Group VI atom.

Further, the compound capable of being gasified is replaced with H ₂ or H ₂ .
It may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or 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.

Specific examples of the raw material gas include the compounds (Si) described above as the gasifiable compounds containing silicon atoms. In this case, when a low-pressure mercury lamp is used as a light source, a high-order silane such as Si ₂ H ₆ ,
Si ₂ H _n X _6-n (X: halogen) and the like are suitable.

Examples of the gasifiable compound containing a germanium atom include the above-mentioned compound (Ge). 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.

As the oxygen-containing gas, the above-mentioned compound (O) can be mentioned.

The substance introduced to make the conductivity type slightly p-type includes an atom of a group III element in the periodic table, and the substance introduced to make the conductivity type slightly n-type is the periodic rule. Table Group V atoms and / or Group VI atoms are included.

Compounds (II) mentioned above can be 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 a starting material for introducing a Group V atom. Particularly, PH ₃ and PF ₅ are suitable.

Compounds (VI) described above can be effectively used as starting materials for introducing a Group VI atom.

The compound capable of being gasified 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.

The Si layer of the present invention has a small tail state on the valence band side, and the slope of the tail state is 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 full width at half maximum of the peak at 2000 cm ⁻¹ representing a state where 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.

Indium is used in the sputtering device.
When depositing a transparent electrode made of oxide on a substrate,
Get is metallic indium (In) or indium oxide
(In ₂O₃) Etc. are used.

When a transparent electrode made of indium-tin oxide is further deposited on the substrate, the target is metallic tin, metallic indium or an alloy of metallic tin and metallic indium,
Targets such as tin oxide, indium oxide, and indium-tin oxide are appropriately combined and used.

In the case of 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 above-mentioned inert gas or the like, the pressure in the discharge space is 0.1 to 50 mTorr in order to perform the sputtering effectively.
Is mentioned as a preferable range.

In addition, as a power source for the sputtering method, a DC power source or an RF power source is suitable. 10-1000W as electric power at the time of sputtering
Is a suitable range.

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 the 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.

A suitable substrate temperature range for depositing the transparent electrode is 25 ° C. to 600 ° C.

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 ) is introduced into the deposition chamber in the range of 5 × 10 ^-5 Torr to 9 × 10 ^-4 Torr. It is necessary to introduce.

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 above-mentioned degree of vacuum to generate plasma, and vapor deposition may be performed through the plasma.

A preferable range of the deposition rate of the transparent electrode under the above conditions is 0.01 to 10 nm / sec.
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) As the backside electrodes, Ni, Au, Ti, Pd, Ag and A are used.
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.

In the case of forming by the plating method, Ni, Al, or Cr is suitable, and by performing the sintering treatment at 300 ° C. to 800 ° C. after the plating treatment, a better ohmic contact can be obtained. ,
The interface level existing at the interface with the substrate can be reduced. Finally, in order to reduce the series resistance of the electrode, C
You may plate u.

In the case of forming by a printing method, an Ag paste is printed on the n-type silicon substrate and an Al paste is printed on the p-type silicon substrate by a screen printing machine, and thereafter, sintering is performed to obtain a good result. Get contacts.

Suitable layer thicknesses of these metals are 10 nm to 5000 nm. In order to make the surface of the back electrode uneven (textured), the temperature of the substrate at the time of deposition is 200 ° C. in the case of the vacuum evaporation method.
As described above, in the case of the plating method or the printing method, the substrate temperature may be set to 200 ° C. or higher after the back surface electrode deposition, and the thermal annealing may be performed.

Collecting Electrode (109, 129) The material and forming method of the collecting electrode are basically the same as those for 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 material 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, which usually has a small specific resistance, is 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 the 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. Examples of the storage battery include a nickel cadmium battery, a rechargeable silver oxide battery, a lead storage battery and a flywheel energy storage unit.

The voltage control circuit is almost equal to the output of the solar cell until the battery is fully charged, but when the battery is fully charged, the charging current is stopped by the charging control IC.

The solar cell system utilizing such a 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 device 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.

[0279]

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, using an n-type polycrystalline silicon substrate manufactured by the casting method, as shown in FIG.
The solar cell of a was produced.

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 isopropanol, 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.

Gas cylinders 2041 to 2047 in the figure are sealed with a raw material gas for producing the photovoltaic element of the present invention, and 2041 is SiH ₄ gas (purity 99.
999%) cylinder, 2042 is CH ₄ gas (purity 99.
Cylinder 2043 is H ₂ gas (purity 99.
9999%) cylinder, 2044 is H ₂ gas 100pp
PH ₃ gas diluted to m (purity 99.99%, hereinafter abbreviated as "PH ₃ / H _2") bomb, 2045 B ₂ H ₆ gas (purity 99 diluted to 100ppm with H ₂ gas.
99%, hereinafter abbreviated as "B ₂ H ₆ / H ₂ ") cylinder, 2
046 is NH ₃ gas diluted to 1% with H ₂ gas (purity 9
9.9999%, hereinafter abbreviated as “NH ₃ / H ₂ ”) cylinder, 2047 is O ₂ gas diluted to 1% with He gas (purity 99.9999%, hereinafter abbreviated as “O ₂ / He”) It's a cylinder. In advance, gas cylinders 2041 to 204
When attaching 7, each gas is supplied to the valves 2021 to 2021.
Introduced into the gas pipe up to 2027, pressure regulator 203
Each gas pressure was adjusted to ² kg / cm ² by 1 to 2037.

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, an i-type layer, a Si 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. 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. 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 350 ° C. When the substrate temperature becomes stable, the valve is further adjusted. 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, Si
H ₄ gas flow rate is 5 sccm, H ₂ gas flow rate is 100 sccc
m and B ₂ H ₆ / H ₂ gas was adjusted to 500 sccm by each mass flow controller. Deposition chamber 40
The pressure in 1 is set to 2.0 Torr by a vacuum gauge 40
While watching 2, the opening of the conductance valve 407 was adjusted. Confirm that the shutter 415 is closed, set the RF power supply to 0.20 W / cm ³ , introduce RF power, cause glow discharge, open the shutter 415, and open the first p-type on the substrate. The formation of layers started. Layer thickness 1
When the first p-type layer of 00 nm was formed, the shutter was closed, the RF power was turned off, the glow discharge was stopped, and the first p-type layer was formed.
The formation of the mold layer is completed. The valves 2001 and 2005 are closed to stop the inflow of SiH ₄ gas and B ₂ H ₆ / H ₂ gas into the deposition chamber 401, and after the H ₂ gas is continuously flowed into the deposition chamber 401 for 5 minutes, the valve 2003 Was closed, and the inside of the deposition chamber 401 and the inside of the gas pipe were evacuated.

To form the n-type layer, the auxiliary valve 40
8. The valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401 through the gas introduction pipe 411, the mass flow controller 2013 is set so that the H ₂ gas flow rate is 50 sccm, and the pressure in the deposition chamber is set to 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 became stable, the valves 2001 and 2004 were gradually opened to SiH ₄ gas, P
The H ₃ / H ₂ gas was caused to flow into the deposition chamber 401. At this time,
SiH ₄ gas flow rate is ₂ sccm, H ₂ gas flow rate is 100 s
Each mass flow controller adjusted the flow rate of ccm and PH ₃ / H ₂ gas to be 200 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 1.0 Torr. The power of the RF power source is set to 0.01 W / cm ³ , RF power is introduced to the RF electrode 410 to cause glow discharge, the shutter is opened, and the production of the n-type layer on the first p-type layer is started. Then, when the n-type layer having a layer thickness of 30 nm was produced, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the n-type layer was completed. The valves 2001 and 2004 are closed to stop the inflow of SiH ₄ gas and PH ₃ / H ₂ gas into the deposition chamber 401, and after the H ₂ gas is continuously flowed into the deposition chamber 401 for 5 minutes, the outflow valve 2003 is turned on. The inside of the deposition chamber 401 and the inside of the gas pipe were evacuated to a vacuum.

Next, the valve 20 is used to form the i-type layer.
03 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 300 sccm. The conductance valve is adjusted so that the pressure in the deposition chamber is 0.01 Torr, the heater 405 is set so that the temperature of the substrate 404 is 350 ° C., and when the substrate temperature is stable, the valves 2001 and 2002 are gradually opened. , Si
H ₄ gas and CH ₄ gas were caused to flow into the deposition chamber 401. At this time, the mass flow controllers were adjusted so that the SiH ₄ gas flow rate was 100 sccm, the CH ₄ gas flow rate was 30 sccm, and the H ₂ gas flow rate was 300 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 0.01 Torr. Next RF
The power of the power supply 403 is set to 0.40 W / cm ³ and RF
It was applied to the electrode 403. After that, the power of a μW power source (not shown) is set to 0.20 W / cm ³ , and μW power is introduced into the deposition 401 through the dielectric window 413 to cause glow discharge, open the shutter, and open the i-type on the n-type layer. The production of the mold layer was started. Using a computer connected to a mass flow controller, the flow rate of SiH ₄ gas and CH ₄ gas was changed according to the flow rate change pattern shown in FIG.
When the 0 nm i-type layer was produced, the shutter was closed and the μW power supply was turned off to stop the glow discharge.
3 was cut and the production of the i-type layer was completed. Valves 2001, 2
002 is closed, and SiH ₄ gas, C
The inflow of H ₄ gas was stopped, and H ₂ gas was continuously flowed into the deposition chamber 401 for 5 minutes, then the valve 2003 was closed and the deposition chamber 4 was closed.
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 conductance valve was adjusted so that the pressure in the deposition chamber was 1.5 Torr, and the heater 405 was set so that the temperature of the substrate 404 was 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 10 sccm.
It was adjusted with each mass flow controller so as to be 0 sccm. The pressure in the deposition chamber 401 is 1.5 Tor
The opening of the conductance valve 407 was adjusted to be r. 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 i-type layer was started, and the deposition rate was 0. 0.15 nm / sec, layer thickness 10 nm
When the Si layer was prepared, the shutter was closed, the RF power 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 gas was allowed to continue flowing into the deposition chamber 401 for 5 minutes, then the outflow valve 2003 was closed and the deposition chamber 401 and the gas pipe were 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 50 sccm. Adjusted in 2013. The conductance valve is adjusted so that the pressure in the deposition chamber is 2.0 Torr, the heater 405 is set so that the temperature of the substrate 404 is 200 ° C., and when the substrate temperature is stable, valves 2001, 2002 and 2005 are further added. The chamber was gradually opened, and SiH ₄ gas, CH ₄ gas, and B ₂ H ₆ / H ₂ gas were caused to flow into the deposition chamber 401. At this time, the SiH ₄ gas flow rate is 1 sccm, and the CH ₄ gas flow rate is 0.5 sccc.
m, the flow rate of H ₂ gas was 100 sccm, and the flow rate of B ₂ H ₆ / H ₂ gas was 100 sccm. The pressure in the deposition chamber 401 is 2.
The opening of the conductance valve 407 was adjusted so as to be 0 Torr. The RF power supply was set to 0.20 W / cm ³ , RF power was introduced to cause glow discharge, the shutter 415 was opened, and formation of the second p-type layer on the Si 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. Valves 2001, 2
002 and 2005 are closed, and SiH in the deposition chamber 401 is closed.
Stop the inflow of ₄ gas, CH ₄ gas, B ₂ H ₆ / H ₂ gas, and 5
After continuously flowing H ₂ gas into the deposition chamber 401 for a minute, the valve 2003 is closed, the deposition chamber 401 and the gas pipe are evacuated, the auxiliary valve 408 is closed, the leak valve 409 is opened, and the deposition chamber 401 is opened. Leaked.

Next, ITO (In ₂ O ₂ + SnO ₂ ) having a layer thickness of 70 nm was vacuum-deposited on the second p-type layer as a transparent electrode by a usual vacuum vapor deposition method.

Next, a 5 μm-thick current collecting electrode made of silver (Ag) was vacuum-deposited on the transparent electrode 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 fabrication 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 i-type layer, the Si layer, and the second p-type layer.

Comparative Example 1 When forming the i-type layer, Si was used.
A solar cell was manufactured under the same conditions and the same procedure as in Example 1 except that the H 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. This solar cell will be called (SC ratio 1).

Example 1-1 A solar cell was produced under the same conditions and procedure as in Example 1, except that the μW power was 0.5 W / cm ³ when forming the i-type layer. This solar cell will be called (SC Ex 1-1).

Example 1-2 When forming an i-type layer,
Example 1 except that the RF power was 0.15 W / cm ^3.
A solar cell was manufactured under the same conditions and the same procedure as described above. This solar cell will be referred to as (SC Ex 1-2).

Example 1-3 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 Ex 1-3)
I will call it.

Example 1-4 When forming the i-type layer,
A solar cell was produced under the same conditions and the same procedure as in Example 1, except that the pressure inside the deposition chamber was set to 0.08 Torr. This solar cell will be called (SC Ex 1-4).

Example 1-5 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 called (SC Ex 1-5).

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 layer thickness was 40 nm. This solar cell will be called (SC Ex 1-6).

The prepared solar cells (SC Ex 1) and (S
C ratio 1), (SC Ex 1-1) to (SC Ex 1-6) were measured for initial light conversion efficiency (photovoltaic power / incident optical power) and durability characteristics.

The initial photoelectric conversion efficiency can be measured by placing the manufactured solar cell under AM-1.5 (100 mW / cm ² ) light irradiation and measuring the V-1 characteristic. As a result of the measurement, for the (SC Ex 1) solar cell,
The initial photoelectric conversion efficiencies of (SC ratio 1) and (SC Ex 1-1) to (SC Ex 1-6) are as follows.

(SC ratio 1) 0.43 times (SC ex 1-1) 0.63 times (SC ex 1-2) 0.80 times (SC ex 1-3) 0.65 times (SC ex 1-) 4) 0.69 times (SC Ex 1-5) 0.74 times (SC Ex 1-6) 0.80 times The durability characteristics were measured by measuring the manufactured 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, AM-1.5 (1
The change (photoelectric conversion efficiency after durability test / initial photoelectric conversion efficiency) in photoelectric conversion efficiency under irradiation of 00 mW / cm ² ) was determined. As a result of the measurement, for the solar cell of (SC Ex 1), (SC ratio 1), (SC Ex 1-1) to (SC Ex 1-
The durability characteristics of 6) are as follows.

(SC ratio 1) 0.72 times (SC ex 1-1) 0.92 times (SC ex 1-2) 0.95 times (SC ex 1-3) 0.97 times (SC ex 1-) 4) 0.86 times (SC Ex 1-5) 0.87 times (SC Ex 1-6) 0.92 times Next, a stainless steel substrate and a barium borosilicate glass (Corning Corp. 7059) substrate were used. , SiH ₄ gas flow rate and CH ₄ gas flow rate are the values shown in Table 2, except that
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.

Composition analysis was carried out by using an Auger electron spectroscopic 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 manufactured solar cell (SC Ex 1),
(SC ratio 1), (SC Ex 1-1) to (SC Ex 1-6) were subjected to composition analysis in the layer thickness direction of Si atoms and C atoms in the i-type layers by the same method as the composition analysis. .

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), (SP
A 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 1-8). The result is shown in FIG. As can be seen from FIG. 8, (SC Ex 1), (SC Ex 1-1) to
In the solar cell of (SC Ex 1-6), the position of the minimum value of the band gap is offset in the p / i interface direction from the center position of the i-type layer, and in the solar cell of (SC ratio 1), the band gap is The position of the minimum value of is Si / from the position of the center of the i-type layer
It was found that there was a deviation in the i interface direction.

Above, (SC actual 1), (SC ratio 1), (S
The change of the band gap in the layer thickness direction of C Ex 1-1) to (SC Ex 1-6) includes the source gas containing Si (SiH ₄ gas in this case) and C which are introduced into the deposition chamber. It was found that it depends on the flow rate ratio of the source gas (CH ₄ gas in this case).

(Example 1-7) Several solar cells were manufactured under the same conditions as in Example 1 except that the μW power and 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 which are source gases
It was found that the gas was 100% decomposed. AM-
When the initial photoelectric conversion efficiency of the solar cell when irradiated with 1.5 (100 mW / cm ² ) light was measured, the result shown in FIG. 10 was 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 can be seen from the figure, the power of μW is less than that of SiH ₄ gas and CH ₄ gas.
In 100% decomposed μW power (0.32W / 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.

(Example 1-8) 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 Example 1-7.
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 stage of solar cell when irradiated with AM-1.5 light
When the photoelectric conversion efficiency was measured, the same tendency as in FIG. 10 was observed.
The results are shown below. That is, μW power is SiH_Fourgas
And CH_FourΜW power (0.1%) to decompose gas 100%
8 W / cm³) Or less and RF power is greater than μW power
At the threshold, the initial photoelectric conversion efficiency has improved significantly.
Do you get it.

(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 200 sccm, CH_FourGas 50sccm, H₂gas
Change to 500sccm, and the substrate temperature to 300 ℃
Change the setting of the heater so that μW power and R
Several solar cells were produced by changing the F power in various ways. other
The conditions were the same as in Example 1.

When the relationship between the deposition rate and the μW power and RF power was examined, the deposition rate did not depend on the RF power as in Example 1-7, 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 M-1.5 light was measured, the result showed the same tendency as in FIG. 10. 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.

(Example 1-10) When forming the i-type layer in Example 1, the pressure inside 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. When the initial photoelectric conversion efficiency of the solar cell when irradiated with AM-1.5 light was measured, the results shown in FIG. 11 were obtained, and the pressure was 50 mTo.
It was found that the initial photoelectric conversion efficiency was significantly reduced above rr.

(Example 1-11) 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. AM-1.
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 deposition rate of the Si layer was 2 nm / sec or more.

(Example 1-12) When forming the Si layer in Example 1, several solar cells were manufactured under the same conditions as in Example 1 except that the layer thickness was variously changed. When the initial photoelectric conversion efficiency of the solar cell when irradiated with AM-1.5 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 can be seen from the above, it was demonstrated that the solar cell of this example (SC Ex 1) had further superior characteristics to the conventional solar cell (SC ratio 1).

Example 2 Several solar cells were prepared by changing the position of the minimum value of the band gap (Eg) in the layer thickness direction, the size of the minimum value, and the pattern in Example 1, and the initial photoelectric conversion thereof was performed. Example 1 for efficiency and durability characteristics
It investigated in the same way as. At this time, the same procedure as in Example 1 was performed except for the change patterns of the SiH ₄ gas flow rate and the CH ₄ gas flow rate of the i-type layer. 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-
In 5), the position of the minimum value of the band gap in the layer thickness direction is changed. (SC Ex 2-1) to (SC Ex 2-5)
According to the above, the p / i interface is changed to the i / Si interface. (SC Ex 2-6), (SC Ex 2-7)
Indicates that the minimum value of the band gap of (SC Ex 2-1) is changed. (SC Ex 2-8) to (SC Ex 2-1)
0) is the band pattern changed. 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, i does not depend on the size of the minimum value of the band gap and the change pattern.
The band gap of the mold layer changes smoothly in the layer thickness direction,
It was found that the solar cell of the present invention in which the position of the minimum value of the band gap is offset in the p / i interface direction from the position of the center of the i-type layer is superior.

Example 3 A solar cell having a Si layer containing a valence electron control agent was prepared.

Example 3-1 When forming a Si layer, B
Same as Example 1 except that ₂ H ₆ / H ₂ gas was introduced into the deposition chamber at 1 sccm. Fabricated solar cell (SC Ex 3-
It was found that 1) had a better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 1) as in (SC Ex 1).

Example 3-2 When forming a Si layer, B
₂ H ₆ / H ₂ gas 10 sccm, PH ₃ / H ₂ gas 1 s
ccm, the same as in Example 1 except that it was made to flow into the deposition chamber.

The produced solar cell (SC Ex 3-2) was manufactured by (S
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the conventional solar cell (SC ratio 1) as in C Ex 1).

Example 4 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, a Si layer, an i-type layer, and a second n-type layer were sequentially formed on the hydrogen plasma-treated substrate. 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 / Si interface, and the deposition rate of the Si layer is It was set to 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.

It was found that the manufactured solar cell (SC Ex 4) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 1) as in (SC Ex 1).

Example 5 There is a maximum bandgap of the i-type layer near the Si / i interface, and the thickness of that region is 20.
A solar cell having a size of 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 the same 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. It was found that the produced vertical (SC Ex 5) had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 1), similar to (SC Ex 1).

(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 in the vicinity of the i / n interface, and the thickness of the region is 15n.
A solar cell of m was produced. 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 produced solar cell (SC Ex 6) is (SC Ex 1)
It was found that the initial photoelectric conversion efficiency and durability were better than those of the conventional solar cell (SC ratio 1), as in the above.

(Comparative Example 6) There was a region having the maximum bandgap near the i / n 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 region thickness was 1 nm or more and 3
When the thickness is 0 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 7 A solar cell in which μW power was changed when forming an i-type layer was produced. Example 1 except that the μW power was changed as shown in FIG. 14 when forming the i-type layer.
The same manufacturing conditions, methods, and procedures were used. It was found that the fabricated solar cell (SC Ex 7) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 1), similar to (SC Ex 1).

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. It was found that the fabricated solar cell (SC Ex 8) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 1), similar to (SC Ex 1).

Further, the content of oxygen atoms in the i-type layer can be adjusted to 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 is contained in the i-type layer was produced. When forming the i-type layer, NH ₃ / H ₂ gas is added for 5 s in addition to the gas flowing in Example 1.
ccm, the same conditions, the same method, and the same procedure as in Example 1 were used except that they were introduced into the deposition chamber 401. It was found that the fabricated solar cell (SC Ex 9) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 1), similar to (SC Ex 1). In addition, when the content of nitrogen atoms in the i-type layer was examined by SIMS, it was found that the content was substantially uniform and 3 × 10 ¹⁷ (pieces / cm ² ).

Example 10 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 1, O₂/ He moth
5 sccm, NH₂/ H₂5 sccm gas, deposition chamber
Same conditions and same conditions as in Example 1 except that it is introduced in 401
Method, same procedure was used. Fabricated solar cell (SC Ex 1
0) is the same as (SC Ex 1), the conventional solar cell (SC ratio
Initial photoelectric conversion efficiency and durability characteristics better than 1)
It turned out to have sex. In addition, oxygen atoms in the i-type layer
When the contents of nitrogen and nitrogen atoms were investigated by SIMS,
1 x 10 each ¹⁹(Pieces / cm²),
3 x 10¹⁷(Pieces / cm²) Was found.

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 99.9).
99%) When replacing the cylinder and forming the i-type layer, as shown in FIG.
The flow rates of SiH ₄ gas, CH ₄ gas, and SiF ₄ gas were changed according to the flow pattern of −a. 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. It is shown in Figure 15-b.

Further, the secondary ion mass spectrometer was used to analyze the contents 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 the durability characteristic of 1) were obtained, the conventional solar cell (SC ratio 1) was obtained as with the solar cell of Example 1.
It has been found that it has better initial photoelectric conversion efficiency and durability characteristics than the above.

(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 the first p-type layer was formed by the gas diffusion method and the i-type layer was formed, a positive DC bias was applied to the RF electrode to apply RF power, DC bias and μW power. The changed solar cell was produced. First, BBr ₃ (purity 99.9) obtained by diluting an O ₂ / He gas cylinder with hydrogen to 1% was used.
99%, hereinafter referred to as "BBr ₃ / H ₂ gas").

When forming the first p-type layer, the substrate temperature is set to 8
The temperature was set to 00 ° C., BBr ₃ / H ₂ gas was introduced into the deposition chamber at 500 sccm, and B was diffused into the n-type substrate at an internal pressure of 10 Torr. At the junction depth of 300 nm, BBr ₃
The introduction of / H ₂ gas was stopped, and H ₂ gas was kept flowing for 5 minutes.
When further forming the i-type layer, as shown in FIG. 16, RF power,
DC bias and μW power were varied. 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. It was found that the manufactured solar cell (SC Ex 13) had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC Ratio 1), similar to (SC Ex 1).

(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 shown in FIG. 17 is obtained by adding a set of nip structure to the solar cell shown in FIG. 1, and includes the first p-type layer, the n-type layer, the i-type layer, and the second p-type layer in the present invention. The type layers are the first p-type layer, the second n-type layer, and the second i-type layer in FIG. 17, respectively.
The mold layer corresponds to the third p-type layer.

As the substrate, an n-type polycrystalline silicon substrate manufactured by the casting method was used.

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), irregularities having a pyramid structure are formed on the surface, and the substrate is textured (Text
ured). Next, it was ultrasonically washed with acetone and isopropanol, further washed with pure water, and dried with warm air.

Hydrogen plasma treatment was performed in 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,
Second p-type layer, second n-type layer, second i-type layer, Si 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.

Next, as in Example 1, ITO (In ₂ O ₃₎ having a layer thickness of 70 nm was formed as a transparent electrode on the second p-type layer.
+ SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method.

Next, as in Example 1, 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 1, Ag was applied to the back surface of the substrate.
A back electrode made of —Ti 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 referred to as (SC Ex 14), and the manufacturing conditions of each semiconductor layer are shown in Table 5.

(Comparative Example 14) When forming the second i-type layer of FIG. 17, SiH ₄ was formed according to the flow rate change pattern of FIG.
Example 1 except that the gas flow rate and CH ₄ gas flow rate were changed
A triple type solar cell was produced by the same method and procedure as in No. 4. This solar cell will be called (SC ratio 14).

The initial photoelectric conversion efficiency and durability characteristics of these produced triple type solar cells were measured by the same method as in Example 1. As a result, (SC Ex 14) was obtained from the conventional triple type solar cell (SC ratio 14). It has been found that also has a better initial photoelectric conversion efficiency and durability characteristics.

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 manufactured, modularized, and applied to a power generation system.

65 solar cells of 50 × 50 mm ² (SC Ex 1) were produced 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) A conventional solar cell (SC ratio 1) was used under the same conditions, the same method and the same procedure as those of Comparative Example 1 65.
Individually produced and modularized in the same manner as in Example 15. This module is called (MJ ratio 15). 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) was as follows with respect to (MJ actual 15).

Module photodegradation ratio ───────────────────────── MJ actual 15 1.00 MJ ratio 15 0.88 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 16) In this example, B was added to the i-type layer.
A photovoltaic element containing and P atoms was produced.

First, the solar cell of FIG. 1-a was manufactured using the n-type polycrystalline silicon substrate manufactured by the casting method.

A substrate of 50 × 50 m ² and 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 isopropanol, 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 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 then the substrate 40 was processed.
4 on which a first p-type layer, an n-type layer, an i-type layer, a Si 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. 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,
Gradually open BU 2003, H₂Gas deposition chamber 401 chamber
Introduced to H₂Make sure that the gas flow rate is 50 sccm.
It was adjusted with the sflow controller 2013. Deposition chamber
Check the vacuum gauge 402 so that the pressure in the
While adjusting the conductance valve,
Set the heater 405 so that the temperature is 350 ° C
Then, when the substrate temperature becomes stable, the valve 200
1, 2005 gradually open, SiH_FourGas, B₂H ₆/
H₂Gas was flowed into the deposition chamber 401. At this time, Si
H_FourGas flow rate is 5 sccm, H₂Gas flow rate is 100scc
m, B₂H₆/ H₂Gas so that it becomes 500 sccm
Adjusted with various mass flow controllers. Deposition chamber 40
The pressure in 1 is set to 2.0 Torr by a vacuum gauge 40
Adjust the opening of conductance valve 407 while watching 2.
did. Make sure the shutter 415 is closed
And RF power 0.20 W / cm³Set to RF power
Is introduced, a glow discharge is generated, and the shutter 415 is opened.
It was opened and the formation of the first p-type layer on the substrate was started. Layer thickness 1
Shutter when the first p-type layer of 00 nm is formed
Closed, the RF power is turned off, the glow discharge is stopped, and the first p
The formation of the mold layer is completed. Close the valves 2001 and 2005
SiH into the deposition chamber 401_FourGas, B₂H₆/ H₂gas
Flow of hydrogen is stopped, and H flows into the deposition chamber 401 for 5 minutes.₂Flowing gas
Then, the valve 2003 is closed and the inside of the deposition chamber 401 is closed.
And the gas pipe was evacuated.

To form the n-type layer, the auxiliary valve 40
8. The valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401 through the gas introduction pipe 411, the mass flow controller 2013 is set so that the H ₂ gas flow rate is 50 sccm, and the pressure in the deposition chamber is set to 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 became stable, the valves 2001 and 2004 were gradually opened to SiH ₄ gas, P
The H ₃ / H ₂ gas was caused to flow into the deposition chamber 401. At this time,
SiH ₄ gas flow rate is ₂ sccm, H ₂ gas flow rate is 100 s
Each mass flow controller adjusted the flow rate of ccm and PH ₃ / H ₂ gas to be 200 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 1.0 Torr. The power of the RF power source is set to 0.01 W / cm ₃ , RF power is introduced to the RF electrode 410 to cause glow discharge, the shutter is opened, and the production of the n-type layer on the first p-type layer is started. Then, when the n-type layer having a layer thickness of 30 nm was produced, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the n-type layer was completed. The valves 2001 and 2004 are closed to stop the inflow of SiH ₄ gas and PH ₃ / H ₂ gas into the deposition chamber 401, and after the H ₂ gas is continuously flowed into the deposition chamber 401 for 5 minutes, the outflow valve 2003 is turned on. The inside of the deposition chamber 401 and the inside of the gas pipe were evacuated to a vacuum.

Next, to prepare the i-type layer, the valve 20 was used.
03 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 300 sccm. The conductance valve is adjusted so that the pressure in the deposition chamber is 0.01 Torr, and the heater 405 is set so that the temperature of the substrate 404 is 350 ° C. When the substrate temperature is stable, valves 2001, 2002, 2004, 2005 are further added.
Gradually open, SiH ₄ gas, CH ₄ gas, PH ₃ / H ₂
Gas, B ₂ H ₆ / H ₂ gas, was caused to flow into the deposition chamber 401. At this time, the SiH ₄ gas flow rate is 100 sccm, CH ₄
Gas flow rate 30 sccm, H ₂ gas flow rate 300 sccc
m, PH ₃ / H ₂ gas flow rate was ₂ sccm, and B ₂ H ₆ / H ₂ gas flow rate was 5 sccm. The pressure in the deposition chamber 401 is 0.01T
The opening of the conductance valve 407 was adjusted to be orr. Next, the power of the RF power source 403 is 0.40 W /
It was set to cm ³ and applied to the RF electrode 403. afterwards,
The power of a μW power source (not shown) is set to 0.20 W / cm ³ , and μW power is introduced into the deposition 401 through the dielectric window 413 to cause glow discharge, open the shutter, and open the i-type layer on the n-type layer. The production of was started. Using the computer connected to the mass flow controller, the flow rate of SiH ₄ gas and CH ₄ gas was changed according to the flow rate change pattern shown in FIG. 5, and when the i-type layer with a layer thickness of 300 nm was produced, the shutter was closed and the μW power supply Then, the glow discharge was stopped, the RF power source 403 was turned off, and the production of the i-type layer was completed.
The valves 2001, 2002, 2004, and 2005 are closed, and SiH ₄ gas, CH ₄ gas, and PH into the deposition chamber 401 are closed.
Stop the inflow of ₃ / H ₂ gas and B ₂ H ₆ / H ₂ gas for 5 minutes,
After continuously flowing H ₂ gas into the deposition chamber 401, the valve 2
003 was closed, and the inside of the deposition chamber 401 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 conductance valve was adjusted so that the pressure in the deposition chamber was 1.5 Torr, and the heater 405 was set so that the temperature of the substrate 404 was 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 10 sccm.
It was adjusted with each mass flow controller so as to be 0 sccm. The pressure in the deposition chamber 401 is 1.5 Tor
The opening of the conductance valve 407 was adjusted to be r. 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 i-type layer was started, and the deposition rate was 0. 0.15 nm / sec, layer thickness 10 nm
When the Si layer was prepared, the shutter was closed, the RF power 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 gas was allowed to continue flowing into the deposition chamber 401 for 5 minutes, then the outflow valve 2003 was closed and the deposition chamber 401 and 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 conductance valve is adjusted so that the pressure in the deposition chamber is 2.0 Torr, the heater 405 is set so that the temperature of the substrate 404 is 200 ° C., and when the substrate temperature is stable, valves 2001, 2002 and 2005 are further added. The chamber was gradually opened, and SiH ₄ gas, CH gas, and B ₂ H ₆ / H ₂ gas were caused to flow into the deposition chamber 401. At this time, the SiH ₄ gas flow rate is 1 sccm, the CH ₄ gas flow rate is 0.5 sccm,
The mass flow controllers were adjusted so that the H ₂ gas flow rate was 100 sccm and the B ₂ H ₆ / H ₂ gas flow rate was 100 sccm. The pressure in the deposition chamber 401 is 2.0T
The opening of the conductance valve 407 was adjusted to be orr. Set the RF power supply to 0.20 W / cm ³ ,
RF power was introduced to cause glow discharge, the shutter 415 was opened, and formation of the second p-type layer on the Si 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 was turned off, the glow discharge was stopped,
The formation of the second p-type layer is completed. Valves 2001, 200
2, 2005 is closed, the inflow of SiH ₄ gas, CH ₄ gas, and B ₂ H ₆ / H ₂ gas into the deposition chamber 401 is stopped, and H ₂ gas is continuously flowed into the deposition chamber 401 for 5 minutes. The valve 2003 is closed, the deposition chamber 401 and the gas pipe are evacuated, the auxiliary valve 408 is closed, and the leak valve 4 is closed.
09 was opened, and the deposition chamber 401 was leaked.

Next, ITO (In ₂ O ₂ + SnO ₂ ) having a layer thickness of 70 nm was vacuum-deposited on the second p-type layer as a transparent electrode by a usual vacuum vapor deposition method.

Next, a 5 μm-thick current collecting electrode made of silver (Ag) was vacuum-deposited on the transparent electrode by a usual vacuum evaporation 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 fabrication of this solar cell. This solar cell will be referred to as (SC Ex 16), and Table 6 shows the manufacturing conditions of the first p-type layer, the n-type layer, the i-type layer, the Si layer, and the second p-type layer.

(Comparative Example 16) When forming an i-type layer, S
A solar cell was produced under the same conditions and the same procedure as in Example 16, except that the iH 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. This solar cell will be called (SC ratio 16).

Example 16-1 A solar cell was produced on a substrate by the same method and procedure as in Example 16 except that PH ₃ / H ₂ gas was not passed when forming the i-type layer. This solar cell will be called (SC Ex 16-1).

(Example 16-2) A solar cell was produced on a substrate by the same method and procedure as in Example 16 except that B ₂ H ₆ / H ₂ gas was not passed when forming the i-type layer. . This solar cell will be called (SC Ex 16-2).

The produced solar cells (SC Ex 16) and (SC Ratio 16), (SC Ex 16-1) to (SC Ex 16-)
The measurement of the initial light conversion efficiency (photovoltaic power / incident light power) and durability characteristics in 2) was performed in the same manner as in Example 1.

As a result of the measurement, for the solar cell of (SC Ex 16), (SC ratio 16), (SC Ex 16-1) to (SC Ex 16)
The initial photoelectric conversion efficiency of actual 16-2) was as follows.

(SC ratio 16) 0.62 times (SC Ex 16-1) 0.95 times (SC Ex 16-2) 0.94 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 actual 16), (SC ratio 1
6) and (SC Ex 16-1) to (SC Ex 16-2) have the following durability characteristics.

(SC ratio 16) 0.65 times (SC Ex 16-1) 0.94 times (SC Ex 16-2) 0.93 times Next, in the same manner as in Example 1, the band gap of the i-type layer was obtained. When the relationship between C and Si composition was investigated, the same result as in FIG. 7 was obtained.

Next, (SC actual 16), (SC ratio 16),
Composition analysis in the layer thickness direction of P atoms and B atoms in the i-type layers of (SC Ex 16-1) and (SC Ex 16-2) 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 16) -3 ppm-10 ppm (SC ratio 16) -3 ppm-10 ppm (SC Ex 16-1) N.P. D. -10 ppm (SC Ex 16-2) -3 ppm N.C. D. N. D. Below detection limit

As can be seen from the above, it was demonstrated that the solar cell of the present invention (SC Ex 16) has further superior characteristics to the conventional solar cell (SC ratio 16).

Example 17 Some solar cells were manufactured by changing the position of the minimum value of the band gap (Eg) in the layer thickness direction, the size of the minimum value, and the pattern in Example 16, and the initial photoelectric conversion thereof was performed. The efficiency and durability characteristics were examined by the same method as in Example 16. At this time, the SiH of the i-type layer
₄ gas flow rate and CH ₄ except gas flow rate change pattern Example 16 and same west, to produce a solar cell having a band gap shown in FIG. 12.

Table 7 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 17-1)). 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 offset from the central position in the direction of Si / i interface, is superior.

(Example 18) A solar cell in which the concentration and kind of the valence electron controlling agent in the i-type layer were changed to that in Example 16 was prepared, 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 16 was performed except that the concentration and type of the valence electron control agent in the i-type layer were changed.

(Example 18-1) The flow rate of the valence electron control agent gas (B ₂ H ₆ / H ₂ gas) serving as the acceptor of the i-type layer was made 1/5 times, and the total H ₂ flow rate was changed to that in Example 16. When a solar cell (SC Ex 18-1) that is the same as
It was found that (SC Ex 18-1) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 16), similar to (SC Ex 16).

(Example 18-2) The gas (B ₂ H ₆ / H ₂ gas) flow rate of the valence electron control agent serving as the acceptor of the i-type layer was increased by 5 times, and the total H ₂ flow rate was the same as in Example 16. When the solar cell (SC Ex 18-2) was manufactured, (S
Similar to (SC Ex. 16), C Ex. 18-2) was found to have better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 16).

(Example 18-3) 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 16. When the solar cell (SC Ex 18-3) was manufactured, the initial photoelectric conversion efficiency of (SC Ex 18-3) was even better than that of the conventional solar cell (SC ratio 16), similar to (SC Ex 16). And has been found to have durable properties.

(Example 18-4) 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 that of Example 16. When a solar cell (SC Ex 18-3) was produced, (SC Ex 1
8-4) 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 16).

(Example 18-5) Trimethylaluminum (Al (CH ₃ ) ₃ , TM was used as a valence electron control agent gas serving as an acceptor for the i-type layer instead of B ₂ H ₆ / H ₂ gas.
A solar cell using A) is manufactured. At this time, TMA (purity 99.99%) 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 16 (solar cell (SC)). 18-5) was produced. At this time, TMA / H ₂
The gas flow rate was 10 sccm. It was found that the manufactured solar cell (SC Ex 18-5) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC Ex 16), similar to (SC Ex 16).

Example 18-6 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 16 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 18-6) was produced by the same method and procedure as in Example 16.

At this time, the flow rate of the H ₂ S / H ₂ gas is 1 sccc.
m. The manufactured solar cell (SC Ex 18-6) is (S
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the conventional solar cell (SC ratio 16) as in C Ex 16).

Example 19 A solar cell of FIG. 1-b was produced using a p-type polycrystalline silicon substrate. The substrate was subjected to plasma treatment, and subsequently, a first n-type layer, a p-type layer, a Si layer, an i-type layer, and a second n-type layer were sequentially formed on the substrate. Table 8 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 / Si interface, and the deposition rate of the Si layer is 0.15 nm / sec
I chose The substrate and layers other than the semiconductor layer were manufactured under the same conditions and the same method as in Example 16.

The manufactured solar cell (SC Ex. 19) was (SC
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the conventional solar cell (SC ratio 16) as in the case of the actual 16).

(Embodiment 20) There is a maximum bandgap of the i-type layer near the Si / i interface, and the thickness of the region is 2
A solar cell having a thickness of 0 nm was produced using the flow rate change pattern of the i-type layer shown in FIG. 13-a.

It was manufactured using the same conditions and the same method as in Example 16 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 16, 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. It was found that the produced vertical (SC Ex 20) had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 16) like (SC Ex 16).

(Comparative Example 20) There was a region having the maximum bandgap near the Si / 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 20 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 16 (SC
Even better initial photoelectric conversion efficiency and durability than Example 16) were obtained.

(Example 21) There was a maximum bandgap of the i-type layer near the i / n interface, and the thickness of that region was 15
A solar cell having a thickness of nm was manufactured 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 16 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 16, and the change in the band gap of the i-type layer in the layer thickness direction was examined. The result was as shown in FIG. 13-d. The produced solar cell (SC Ex 21) is (SC Ex 16)
It was found that the initial photoelectric conversion efficiency and durability were even better than those of the conventional solar cell (SC ratio 16), as in the above.

(Comparative Example 21) There was a region having the maximum bandgap near the i / n 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 the durability of the produced solar cell were measured, the solar cell of Example 16 (SC Ex 1) was obtained when the region thickness was 1 nm or more and 30 nm or less.
Even better initial photoelectric conversion efficiency and durability than 6) were obtained.

Example 22 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 manufacture, the same conditions, the same method, and the same procedure as in Example 16 were used except that the flow rates of PH ₃ / H ₂ gas and B ₂ H ₆ / H ₂ gas were changed.

The manufactured solar cell (SC Ex 22) is (SC
Similar to the actual 16), it was found that the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 16). Further, P atom and B contained in the i-type layer
A secondary ion mass spectrometer (SI
19B, it was found that the contents of P and B atoms were minimum at the position where the band gap was minimum.

(Example 23) 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 16.
cm, the same conditions, the same method, and the same procedure as in Example 16 were used except that the gas was introduced into the deposition chamber 401. It was found that the manufactured solar cell (SC Ex. 23) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC Ex. 16), similarly to (SC Ex. 16).

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 24) A silicon solar cell in which a nitrogen atom was contained in the i-type layer was produced. When forming the i-type layer, Example ₃ was repeated except that NH ₃ / H ₂ gas of 5 sccm was introduced into the deposition chamber 401 in addition to the gas flowing in Example 16.
The same conditions, the same method, and the same procedure as those in No. 6 were used. It was found that the manufactured solar cell (SC Ex. 24) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC Ex. 16) as in (SC Ex. 16). 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 25 A solar cell having an i-type layer containing oxygen atoms and nitrogen atoms was produced. When forming the i-type layer, in addition to the gas flowing in Example 16, O ₂ / He
The same conditions, the same method, and the same procedure as in Example 16 were used except that gas was introduced at 5 sccm and NH ₂ / H ₂ gas was introduced at 5 sccm into the deposition chamber 401. The prepared solar cell (SC Ex 25) is the same as the conventional solar cell (SC Ex 16).
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the ratio 16). Moreover, when the contents of oxygen atoms and nitrogen atoms in the i-type layer were examined by SIMS, they were found to be contained almost uniformly, and each was 1 × 10 ¹⁹ (pieces / c
m ² ), 3 × 10 ¹⁷ (pieces / cm ² ).

(Example 26) 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 99.9).
99%) When replacing the cylinder and forming the i-type layer, as shown in FIG.
The flow rates of SiH ₄ gas, CH ₄ gas, and SiF ₄ gas were changed according to the flow pattern of −a. When the change in the band gap in the layer thickness direction of this solar cell (SC Ex 26) was obtained by the same method as in Example 16, the same result as in FIG. 15-b was obtained.

Further, the secondary ion mass spectrometer was used to analyze the content of hydrogen atoms and silicon atoms in the layer thickness direction. 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 Example 26) were obtained, similar to the solar cell of Example 16, the conventional solar cell (S
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of C ratio 16).

Example 27 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
A solar cell (SC Ex 27) was produced by the same method and the same procedure as in Example 16 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. The produced solar cell (SC Ex 27) is (SC Ex 16)
It has been found that it has better initial photoelectric conversion efficiency and durability characteristics than the above.

(Example 28) 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, and R
A positive DC bias was applied to the F electrode to produce a solar cell in which RF power, DC bias and μW power were changed. First, the O ₂ / He gas cylinder was diluted with hydrogen to 10% B
Replace with a Br ₃ (BBr ₃ / H ₂ gas) cylinder, and then add C
The H 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 30
The introduction of BBr ₃ / H ₂ gas was stopped when the junction depth reached 300 nm under the Torr diffusion conditions. The H ₂ gas was kept flowing for 5 minutes.

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. 20-a. Furthermore, as shown in Fig. 20-b, R
F 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 16 were used. Fabricated solar cell (SC Ex 2
It was found that 8) had a better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 16), similar to (SC Ex 16).

(Example 29) Using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, FIG.
A triple solar cell was manufactured.

As the substrate, an n-type polycrystalline silicon substrate manufactured by the casting method as in Example 16 was used.

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), irregularities having a pyramid structure are formed on the surface, and the substrate is textured (Text
ured). 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 16, 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, second i-type layer, Si
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_FourThe deposition rate of Si layer is changed by changing the gas flow rate.
The degree was 0.15 nm / sec.

Next, as in Example 16, ITO (In ₂ O ₃₎ having a layer thickness of 70 nm was formed as a transparent electrode on the third p-type layer.
+ SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method.

Next, as in Example 16, a current collecting 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.

Then, in the same manner as in Example 16, 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.

Thus, the production of a triple solar cell using the microwave plasma CVD method is completed.

This solar cell is referred to as (SC Ex 29), and the manufacturing conditions of each semiconductor layer are shown in Table 9.

(Comparative Example 29) When forming the second i-type layer of FIG. 17, SiH ₄ was formed in accordance with the flow rate change pattern of FIG.
Example 2 except that the gas flow rate and CH ₄ gas flow rate were changed
A triple type solar cell was produced by the same method and the same procedure as in No. 9. This solar cell is called (SC ratio 29).

The initial photoelectric conversion efficiency and durability of these produced triple solar cells were measured by the same method as in Example 16. (SC Ex. 29) shows that the conventional triple solar cell (SC ratio 29) It has been found that also has a better initial photoelectric conversion efficiency and durability characteristics.

Example 30 A solar cell of Example 16 was produced using the production apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, modularized, and applied to a power generation system.

A solar cell (SC Ex 16) of 50 × 50 mm ² was formed under the same conditions, the same method and the same procedure as in Example 16 by 65.
Individually made. EV on a 5.0 mm thick aluminum plate
An adhesive sheet made of A (ethylene vinyl acetate) was placed, a nylon sheet was placed on the adhesive sheet, and the solar cells produced were further arranged on the sheet to perform serialization and parallelization. Put EVA adhesive sheet on it, put fluororesin sheet on it, vacuum laminate,
Modularized. The initial photoelectric conversion efficiency of the manufactured module was measured in the same manner as in Example 16. 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. 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 real 30).

(Comparative Example 30) Conventional solar cell (SC ratio 1
6) under the same conditions, methods and procedures as Comparative Example 16
Five pieces were produced and modularized in the same manner as in Example 30. This module is called (MJ ratio 30). 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 30, and the photodegradation rate was obtained.

As a result, the photodegradation rate of (MJ ratio 30) was as follows with respect to (MJ actual 30).

Ratio of module light deterioration rate ───────────────────────── MJ actual 30 1.00 MJ ratio 30 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 31) Using an n-type polycrystalline silicon substrate manufactured by the casting method, as shown in FIG.
A solar cell having a laminated structure of the second p-type layer having the structure shown in was produced.

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 isopropanol, 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.

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 then the substrate 40 was formed.
4 on which a first p-type layer, an n-type layer, an i-type layer, a Si layer, and a second
P-type layer was formed.

First, in order 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,
Gradually open BU 2003, H₂Gas deposition chamber 401 chamber
Introduced to H₂Make sure that the gas flow rate is 50 sccm.
It was adjusted with the sflow controller 2013. Deposition chamber
Check the vacuum gauge 402 so that the pressure in the
While adjusting the conductance valve,
Set the heater 405 so that the temperature is 350 ° C
Then, when the substrate temperature becomes stable, the valve 200
1, 2005 gradually open, SiH_FourGas, B₂H ₆/
H₂Gas was flowed into the deposition chamber 401. At this time, Si
H_FourGas flow rate is 5 sccm, H₂Gas flow rate is 100scc
m, B₂H₆/ H₂Gas so that it becomes 500 sccm
Adjusted with various mass flow controllers. Deposition chamber 40
The pressure in 1 is set to 2.0 Torr by a vacuum gauge 40
Adjust the opening of conductance valve 407 while watching 2.
did. Make sure the shutter 415 is closed
And RF power 0.20 W / cm³Set to RF power
Is introduced, a glow discharge is generated, and the shutter 415 is opened.
It was opened and the formation of the first p-type layer on the substrate was started. Layer thickness 1
Shutter when the first p-type layer of 00 nm is formed
Closed, the RF power is turned off, the glow discharge is stopped, and the first p
The formation of the mold layer is completed. Close the valves 2001 and 2005
SiH into the deposition chamber 401_FourGas, B₂H₆/ H₂gas
Flow of hydrogen is stopped, and H flows into the deposition chamber 401 for 5 minutes.₂Flowing gas
Then, the valve 2003 is closed and the inside of the deposition chamber 401 is closed.
And the gas pipe was evacuated.

To form the n-type layer, the auxiliary valve 40
8. The valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401 through the gas introduction pipe 411, the mass flow controller 2013 is set so that the H ₂ gas flow rate is 50 sccm, and the pressure in the deposition chamber is set to 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 became stable, the valves 2001 and 2004 were gradually opened to SiH ₄ gas, P
The H ₃ / H ₂ gas was caused to flow into the deposition chamber 401. At this time,
SiH ₄ gas flow rate is ₂ sccm, H ₂ gas flow rate is 100 s
Each mass flow controller adjusted the flow rate of ccm and PH ₃ / H ₂ gas to be 200 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 1.0 Torr. The power of the RF power source is set to 0.01 W / cm ³ , RF power is introduced to the RF electrode 410 to cause glow discharge, the shutter is opened, and the production of the n-type layer on the first p-type layer is started. Then, when the n-type layer having a layer thickness of 30 nm was produced, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the n-type layer was completed. The valves 2001 and 2004 are closed to stop the inflow of SiH ₄ gas and PH ₃ / H ₂ gas into the deposition chamber 401, and after the H ₂ gas is continuously flowed into the deposition chamber 401 for 5 minutes, the outflow valve 2003 is turned on. The inside of the deposition chamber 401 and the inside of the gas pipe were evacuated to a vacuum.

Next, the valve 20 was used to form the i-type layer.
03 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 300 sccm. The conductance valve is adjusted so that the pressure in the deposition chamber is 0.01 Torr, the heater 405 is set so that the temperature of the substrate 404 is 350 ° C., and when the substrate temperature is stable, the valves 2001 and 2002 are gradually opened. , Si
H ₄ gas and CH ₄ gas were caused to flow into the deposition chamber 401. At this time, the mass flow controllers were adjusted so that the SiH ₄ gas flow rate was 100 sccm, the CH ₄ gas flow rate was 30 sccm, and the H ₂ gas flow rate was 300 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 0.01 Torr. Next RF
The power of the power supply 403 is set to 0.40 W / cm ³ and RF
It was applied to the electrode 403. After that, the power of a μW power source (not shown) is set to 0.20 W / cm ³ , and μW power is introduced into the deposition 401 through the dielectric window 413 to cause glow discharge, open the shutter, and open the i-type on the n-type layer. The production of the mold layer was started. Using a computer connected to a mass flow controller, the flow rate of SiH ₄ gas and CH ₄ gas was changed according to the flow rate change pattern shown in FIG.
When the 0 nm i-type layer was produced, the shutter was closed and the μW power supply was turned off to stop the glow discharge.
3 was cut and the production of the i-type layer was completed. Valves 2001, 2
002 is closed, and SiH ₄ gas, C
The inflow of H ₄ gas was stopped, and H ₂ gas was continuously flowed into the deposition chamber 401 for 5 minutes, then the valve 2003 was closed and the deposition chamber 4 was closed.
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 conductance valve was adjusted so that the pressure in the deposition chamber was 1.5 Torr, and the heater 405 was set so that the temperature of the substrate 404 was 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 10 sccm.
It was adjusted with each mass flow controller so as to be 0 sccm. The pressure in the deposition chamber 401 is 1.5 Tor
The opening of the conductance valve 407 was adjusted to be r. 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 i-type layer was started, and the deposition rate was 0. 0.15 nm / sec, layer thickness 10 nm
When the Si layer was prepared, the shutter was closed, the RF power 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 gas was allowed to continue flowing into the deposition chamber 401 for 5 minutes, then the outflow valve 2003 was closed and the deposition chamber 401 and the gas pipe were evacuated.

Next, to form the second p-type layer,
Gradually open BU 2003, H₂Gas in the deposition chamber 401
Introduced to H₂So that the gas flow rate is 300 sccm
It was adjusted by the mass flow controller 2013. Deposition chamber
Conductance so that the internal pressure is 0.02 Torr
Adjust the temperature with the valve to bring the temperature of the substrate 404 to 200 ° C.
Set the heater 405 so that the substrate temperature stabilizes.
By the way, further valves 2001, 2002, 2005
Gradually open the SiH_FourGas, CH_FourGas, H ₂, B₂H
₆/ H₂Gas was flowed into the deposition chamber 401. At this time, S
iH_FourGas flow rate is 10 sccm, CH_FourGas flow rate is 5sc
cm, H₂Gas flow rate is 300 sccm, B₂H₆/ H₂gas
Each mass flow controller should have a flow rate of 10 sccm.
Adjusted with a troller. The pressure in the deposition chamber 401 is 0.
Conductance valve 407 to be 02 Torr
Adjusted the opening. The power of the μW power supply is 0.30 W / cm
³To the inside of the deposition chamber 401 through the dielectric window 413.
Introduces μW electric power to cause glow discharge and shutter
415 is opened to form a lightly doped layer (A layer) on the Si layer.
Has begun to grow. When the A layer with a layer thickness of 3 nm was prepared,
Close the shutter, turn off the μW power, and stop glow discharge.
It was Close valves 2001, 2002 and 2005 to
SiH into the loading chamber 401_FourGas, CH_FourGas, B₂H₆/ H
₂Stop the flow of gas and put H into the deposition chamber 401 for 5 minutes.₂gas
And then the valve 2003 is closed and the deposition chamber 40
The inside of 1 and the inside of the gas pipe were evacuated.

Next, the valve 2005 is gradually opened to allow the B ₂ H ₆ / H ₂ gas to flow into the deposition chamber 401 at a flow rate of 1
It was adjusted with each mass flow controller so as to be 000 sccm. The pressure in the deposition chamber 401 is 0.02
The opening of the conductance valve 407 was adjusted to Torr, the power of the μW power source was set to 0.20 W / cm ³ , and the μW power was introduced into the deposition chamber 401 through the dielectric window 413 to cause glow discharge. , Shutter 415
Then, the formation of an atomic layer 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 B ₂ H ₆ / H ₂ gas from flowing into the deposition chamber 401, and the H ₂ gas is continuously flowed into the deposition chamber 401 for 5 minutes. Then, the valve 2003 is closed and the deposition chamber 401 is closed. The inside 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 layer B and the layer A are further laminated,
The formation of the second p-type layer having a layer thickness of about 10 nm was completed.

Next, ITO (In ₂ O ₂ + nO ₂ ) having a layer thickness of 70 nm was vacuum-deposited on the second p-type layer as a transparent electrode by a usual vacuum vapor deposition method.

Next, a current collecting electrode of silver (Ag) having a layer thickness of 5 μm was vacuum-deposited on the transparent electrode by an ordinary vacuum deposition method.

Next, a back electrode made of Ag—Ti and having a layer thickness of 3 μm was vacuum-deposited on the back surface of the substrate by a usual vacuum deposition method.

Thus, the production of this solar cell was completed. This solar cell will be referred to as (SC Ex 31), and Table 10 shows the manufacturing conditions of the first p-type layer, the n-type layer, the i-type layer, the Si layer, and the second p-type layer.

(Comparative Example 31) When forming an i-type layer, S
A solar cell was produced under the same conditions and the same procedure as in Example 31, except that the iH 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. This solar cell will be called (SC ratio 31).

The initial light conversion efficiency (photovoltaic power / incident light power) and durability characteristics of the manufactured solar cells (SC Ex 31) and (SC ratio 31) were measured. As a result of measurement, (S
For the C real 31) solar cell, the initial photoelectric conversion efficiency of (SC ratio 31) was as follows. (SC ratio 31) 0.80 times

When the durability characteristics were measured, the durability characteristics (SC ratio 31) of the solar cell (SC Ex 31) were as follows. (SC ratio 31) 0.81 times

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 31, except that the deposition time of the B layer was 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.

As can be seen from the above, it was demonstrated that the solar cell of the present invention (SC Ex 31) has further superior characteristics to the conventional solar cell (SC ratio 31).

(Example 32) In Example 31, several solar cells were manufactured by changing the position of the minimum value of the band gap (Eg) in the layer thickness direction, the size of the minimum value, and the pattern, and the initial photoelectric conversion thereof was performed. The efficiency and durability characteristics were examined by the same method as in Example 31. At this time, the SiH of the i-type layer
₄ gas flow rate and CH ₄ except gas flow rate change pattern Example 31 and same west, to produce a solar cell having a band gap shown in FIG. 12.

Table 11 shows the results of examining the initial photoelectric conversion efficiency and durability of these solar cells produced (the values in the table are based on (SC Ex 32-1)). 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 central position of the i-type layer toward the Si / i interface. It turns out that solar cells are better.

Example 33 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 to enter 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%). A cylinder was attached between the valve 2005 and the mass flow controller 2015, and bubbling with B ₂ H ₆ / H ₂ gas was performed so that vaporized mercury could be introduced into the deposition chamber together with the B ₂ H ₆ / H ₂ gas.

When forming the B layer, the flow rate of the B ₂ H ₆ / H ₂ gas was 1000 sccm, the pressure was 1.0 Torr, the shutter 415 was opened beforehand, 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 31, except that the layer B is opened and the layer B is formed on the layer A.
The solar cell of was produced.

The manufactured solar cell (SC Ex 33) is (SC
It was found that similar to the actual case 31), it has a better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 31).

Example 34 A solar cell shown in FIG. 1-b was produced using a p-type polycrystalline silicon substrate. A first n-type layer, a p-type layer, a Si layer, an i-type layer, and a second n-type layer were sequentially formed on the substrate. Table 12 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 / Si interface, and the deposition rate of the Si layer is 0.
It was set to 15 nm / sec. The substrate and layers other than the semiconductor layer were manufactured under the same conditions and the same method as in Example 31.

The manufactured solar cell (SC Ex. 34) was (SC
It was found that similar to the actual case 31), it has a better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 31).

(Example 35) There is a maximum bandgap of the i-type layer near the Si / i interface, and the thickness of the region is 2
A solar cell having a thickness of 0 nm was produced using the flow rate change pattern of the i-type layer shown in FIG. 13-a.

It was manufactured using the same conditions and method as in Example 31, 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 35) produced is (SC
It was found that, similarly to the actual 31), it has a better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 31).

(Comparative Example 35) There were regions having the maximum bandgap in the vicinity of the Si / 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 35 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 31 (SC
The initial photoelectric conversion efficiency and durability were better than those of Ex. 31).

(Example 36) There is a maximum bandgap of the i-type layer near the i / n interface, and the thickness of the region is 15
A solar cell having a thickness of 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 31 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 31, 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 in FIG. 13-d. The manufactured solar cell (SC Ex 36) is (SC Ex 31)
It was found that, similarly to the above, the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 31).

(Comparative Example 36) A region having a maximum band gap value was present in the vicinity of the i / n 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 36 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 or more.
Below 30 nm, the solar cell of Example 31 (SC Ex 31)
Even better initial photoelectric conversion efficiency and durability were obtained.

(Example 37) In forming the second p-type layer, triethylboron (B (C ₂ H ₅ ) ₃ , abbreviated as TEB) was used instead of B ₂ H ₆ / H ₂ gas. The solar cell was prepared.

Liquid TEB (purity 99.9 at room temperature and normal thickness)
Liquid cylinder 20 with valve at inlet and outlet
Stuffed to 48. Attach the cylinder to the raw material gas supply device H
By bubbling with ₂ gas, TEB vaporized together with H ₂ gas can be introduced into the deposition chamber.

When forming the layer A, TEB / H ₂ gas was added to 1
A layer A is formed on the i-type layer under the same conditions and procedures as in Example 31, except that the flow rate is 0 sccm and the flow rate is set to H for 5 minutes.
_Two gases were introduced into the deposition chamber and then evacuated.

When forming layer B, TEB / H₂Gas 1
Example 3 with the exception of flowing into the deposition chamber at 000 sccm
Form the B layer on the i-type layer under the same conditions and procedure as in 1 and then 5 minutes
Between H ₂Gas was introduced into the deposition chamber and then evacuated.

Next, the layer A is formed on the layer B, and H _{2 is used for} 5 minutes.
Gas was introduced into the deposition chamber and then evacuated.

Next, a layer B is formed on the layer A, and H _{2 is used for} 5 minutes.
Gas was introduced into the deposition chamber and then 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.

Except for the second p-type layer, the same conditions, methods and procedures as in Example 31 were used.

The produced (SC Ex. 37) is (SC Ex. 31)
It was found that, similarly to the above, the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 31).

Example 38 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 31.
cm, the same conditions, the same method, and the same procedure as in Example 31 were used except that the gas was introduced into the deposition chamber 401. It was found that the manufactured solar cell (SC Ex. 38) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC Ratio 31), similar to (SC Ex. 31).

Also, 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 39) A silicon solar cell having a nitrogen atom in the i-type layer was produced. In forming the i-type layer, NH ₃ / H ₂ gas of 5 sccm was introduced into the deposition chamber 401 in addition to the gas flowing in Example 31, and Example ₃ was repeated.
The same conditions, the same method, and the same procedure as in 1 were used. It was found that the manufactured solar cell (SC Ex. 39) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC Ex. 31), similar to (SC Ex. 31). 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 40 A solar cell having an i-type layer containing oxygen atoms and nitrogen atoms was produced. When forming the i-type layer, in addition to the gas flowing in Example 31, O ₂ / He
The same conditions, the same method, and the same procedure as in Example 31 were used, except that 5 sccm of gas and 5 sccm of NH ₃ / H ₂ gas were introduced into the deposition chamber 401. The manufactured solar cell (SC Ex 40) is the same as the conventional solar cell (SC Ex 31).
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the ratio 31). Moreover, when the contents of oxygen atoms and nitrogen atoms in the i-type layer were examined by SIMS, they were found to be contained almost uniformly, and each was 1 × 10 ¹⁹ (pieces / c
m ² ), 3 × 10 ¹⁷ (pieces / cm ² ).

(Example 41) A solar cell in which the hydrogen content of the i-type layer was changed corresponding to the silicon content was produced. The O ₂ / He gas cylinder was replaced with SiF ₄ gas (purity 99.9).
99%) When replacing the cylinder and forming the i-type layer, as shown in FIG.
The flow rates of SiH ₄ gas, CH ₄ gas, and SiF ₄ gas were changed according to the flow pattern of −a. When the change in the band gap in the layer thickness direction of this solar cell (SC Ex 41) was obtained by the same method as in Example 31, 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 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 41)
When the initial photoelectric conversion efficiency and durability characteristics of No. 1 were determined, similar to the solar cell of Example 31, the conventional solar cell (SC ratio 31)
It has been found that it has better initial photoelectric conversion efficiency and durability characteristics than the above.

(Example 42) 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.
A solar cell (SC Ex 42) was produced by the same method and procedure as in Example 31, 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. The manufactured solar cell (SC Ex 42) is (SC Ex 31)
It has been found that it has better initial photoelectric conversion efficiency and durability characteristics than the above.

(Example 43) 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, 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 90
0 ° C., BBr ₃ / H ₂ gas flow rate 500 sccm, internal pressure 30
B was diffused under the diffusion condition of Torr. Junction depth 30
When it reached 0 nm, the introduction of BBr ₃ / H ₂ gas was stopped. Meanwhile when forming the i-type layer, instead C ₂ of CH ₄ gas
H ₂ gas was introduced and changed according to the flow rate pattern as shown in FIG. Further, as shown in FIG. 20-b, the 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 31 were used.

The produced solar cell (SC Ex 43) is (SC
It was found that, similarly to the actual 31), it has a better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 31).

(Example 44) Using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, FIG.
A triple solar cell was manufactured.

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. Observation of the surface soaked in NaOH with a scanning electron microscope (SEM) revealed that irregularities having a pyramid structure were formed on the surface and that 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 31, 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, second i-type layer, Si
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_FourThe deposition rate of Si layer is changed by changing the gas flow rate.
The degree was 0.15 nm / sec. Third p-type layer implemented
A laminated structure was formed as in Example 31.

Then, similarly to Example 31, ITO (In ₂ O ₃₎ having a layer thickness of 70 nm was formed as a transparent electrode on the third p-type layer.
+ SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method.

Next, as in Example 31, a current collecting 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.

Then, in the same manner as in Example 31, 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.

As described above, the production of the triple type solar cell using the microwave plasma CVD method is completed.

This solar cell is called (SC Ex 44), and the manufacturing conditions of each semiconductor layer are shown in Table 13.

(Comparative Example 44) When forming the second i-type layer of FIG. 17, SiH ₄ was formed in accordance with the flow rate change pattern of FIG.
Example 4 except that the gas flow rate and the CH ₄ gas flow rate were changed.
A triple type solar cell was produced by the same method and procedure as in No. 4. This solar cell is called (SC ratio 44).

The initial photoelectric conversion efficiency and durability characteristics of these produced triple solar cells were measured by the same method as in Example 31. As a result, (SC Ex. 44) was obtained from the conventional triple solar cell (SC ratio 44). It has been found that also has a better initial photoelectric conversion efficiency and durability characteristics.

Example 45 A solar cell of Example 31 was produced using the production apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, modularized, and applied to a power generation system.

A 50 × 50 nm ² solar cell (SC Ex 31) was prepared under the same conditions, the same method, and the same procedure as in Example 31.
Individually made. EV on a 5.0 mm thick aluminum plate
An adhesive sheet made of A (ethylene vinyl acetate) was placed, a nylon sheet was placed on the adhesive sheet, and the solar cells produced were further arranged on the sheet to perform serialization and parallelization. Put EVA adhesive sheet on it, put fluororesin sheet on it, vacuum laminate,
Modularized. The initial photoelectric conversion efficiency of the manufactured module was measured in the same manner as in Example 31. 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. 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 real 45).

(Comparative Example 45) Conventional solar cell (SC ratio 3
6) under the same conditions, same method, and same procedure as in Comparative Example 31.
Five pieces were prepared and modularized in the same manner as in Example 45. This module is called (MJ ratio 45). 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 45, and the photodegradation rate was obtained.

As a result, the photodegradation rate of (MJ ratio 45) was as follows with respect to (MJ actual 45).

Ratio of module light deterioration rate ───────────────────────── MJ actual 45 1.00 MJ ratio 45 0.78 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 46) 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 isopropanol, 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 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 then the substrate 40 was processed.
4 on which a first p-type layer, an n-type layer, an i-type layer, a Si layer, and a second
P-type layer was formed.

First, in order to perform the hydrogen plasma treatment on the substrate, the valve 2003 is gradually opened, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller 2013 adjusts the H ₂ gas flow rate to 500 sccm. did. 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, to form the first p-type layer,
Gradually open BU 2003, H₂Gas deposition chamber 401 chamber
Introduced to H₂Make sure that the gas flow rate is 50 sccm.
It was adjusted with the sflow controller 2013. Deposition chamber
Check the vacuum gauge 402 so that the pressure in the
While adjusting the conductance valve,
Set the heater 405 so that the temperature is 350 ° C
Then, when the substrate temperature becomes stable, the valve 200
1, 2005 gradually open, SiH_FourGas, B₂H ₆/
H₂Gas was flowed into the deposition chamber 401. At this time, Si
H_FourGas flow rate is 5 sccm, H₂Gas flow rate is 100sc
cm, B₂H₆/ H₂So that the gas is 500 sccm
It adjusted with each mass flow controller. Deposition chamber 4
The pressure inside 01 is set to 2.0 Torr by vacuum gauge 4
While watching 02, adjust the opening of conductance valve 407.
Arranged Make sure the shutter 415 is closed
And RF power 0.20 W / cm³Set to RF power
Is introduced, a glow discharge is generated, and the shutter 415 is opened.
It was opened and the formation of the first p-type layer on the substrate was started. Layer thickness 1
Shutter when the first p-type layer of 00 nm is formed
Closed, the RF power is turned off, the glow discharge is stopped, and the first p
The formation of the mold layer is completed. Close the valves 2001 and 2005
SiH into the deposition chamber 401_FourGas, B₂H₆/ H₂gas
Flow of hydrogen is stopped, and H flows into the deposition chamber 401 for 5 minutes.₂Flowing gas
Then, the valve 2003 is closed and the inside of the deposition chamber 401 is closed.
And the gas pipe was evacuated.

To form the n-type layer, the auxiliary valve 40
8, gradually open the valve 2003, H Gas is introduced into the deposition chamber 401 through the gas introduction pipe 411, the mass flow controller 2013 is set so that the H ₂ gas flow rate is 50 sccm, and the pressure in the deposition chamber is 1.0 Torr.
Adjust the conductance valve to r
Heater 405 so that the temperature of 04 becomes 350 ° C.
It was set. When the substrate temperature became stable, the valves 2001 and 2004 were gradually opened to SiH ₄ gas, P
The H ₃ / H ₂ gas was caused to flow into the deposition chamber 401. At this time,
SiH ₄ gas flow rate is ₂ sccm, H ₂ gas flow rate is 100 s
Each mass flow controller adjusted the flow rate of ccm and PH ₃ / H ₂ gas to be 200 sccm. The opening of the conductance valve 407 was adjusted so that the pressure in the deposition chamber 401 was 1.0 Torr. The power of the RF power source is set to 0.01 W / cm ³ , RF power is introduced to the RF electrode 410 to cause glow discharge, the shutter is opened, and the production of the n-type layer on the first p-type layer is started. Then, when the n-type layer having a layer thickness of 30 nm was produced, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the n-type layer was completed. The valves 2001 and 2004 are closed to stop the inflow of SiH ₄ gas and PH ₃ / H ₂ gas into the deposition chamber 401, and after the H ₂ gas is continuously flowed into the deposition chamber 401 for 5 minutes, the outflow valve 2003 is turned on. The inside of the deposition chamber 401 and the inside of the gas pipe were evacuated to a vacuum.

Next, to prepare the i-type layer, the valve 20 was used.
03 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 300 sccm. The conductance valve is adjusted so that the pressure in the deposition chamber is 0.01 Torr, and the heater 405 is set so that the temperature of the substrate 404 is 350 ° C. When the substrate temperature is stable, valves 2001, 2002, 2004, 2005 are further added.
Gradually open, SiH ₄ gas, CH ₄ gas, PH ₃ / H ₂
Gas, B ₂ H ₆ / H ₂ gas, was caused to flow into the deposition chamber 401. At this time, the SiH ₄ gas flow rate is 100 sccm, CH ₄
Gas flow rate 30 sccm, H ₂ gas flow rate 300 sccc
m, PH ₃ / H ₂ gas flow rate was ₂ sccm, and B ₂ H ₆ / H ₂ gas flow rate was 5 sccm. The pressure in the deposition chamber 401 is 0.01T
The opening of the conductance valve 407 was adjusted to be orr. Next, the power of the RF power source 403 is 0.40 W /
It was set to cm ³ and applied to the RF electrode 403. afterwards,
The power of a μW power source (not shown) is set to 0.20 W / cm ³ , and μW power is introduced into the deposition 401 through the dielectric window 413 to cause glow discharge, open the shutter, and open the i-type layer on the n-type layer. The production of was started. Using the computer connected to the mass flow controller, the flow rate of SiH ₄ gas and CH ₄ gas was changed according to the flow rate change pattern shown in FIG. 5, and when the i-type layer with a layer thickness of 300 nm was produced, the shutter was closed and the μW power supply Then, the glow discharge was stopped, the RF power source 403 was turned off, and the production of the i-type layer was completed.
The valves 2001, 2002, 2004, and 2005 are closed, and SiH ₄ gas, CH ₄ gas, and PH into the deposition chamber 401 are closed.
Stop the inflow of ₃ / H ₂ gas and B ₂ H ₆ / H ₂ gas for 5 minutes,
After continuously flowing H ₂ gas into the deposition chamber 401, the valve 2
003 was closed, and the inside of the deposition chamber 401 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 conductance valve was adjusted so that the pressure in the deposition chamber was 1.5 Torr, and the heater 405 was set so that the temperature of the substrate 404 was 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 10 sccm.
It was adjusted with each mass flow controller so as to be 0 sccm. The pressure in the deposition chamber 401 is 1.5 Tor
The opening of the conductance valve 407 was adjusted to be r. 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 i-type layer was started, and the deposition rate was 0. 0.15 nm / sec, layer thickness 10 nm
When the Si layer was prepared, the shutter was closed, the RF power 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 gas was allowed to continue flowing into the deposition chamber 401 for 5 minutes, then the outflow valve 2003 was closed and the deposition chamber 401 and the gas pipe were evacuated.

Next, to form the second p-type layer,
Gradually open BU 2003, H₂Gas in the deposition chamber 401
Introduced to H₂So that the gas flow rate is 300 sccm
It was adjusted by the mass flow controller 2013. Deposition chamber
Conductance so that the internal pressure is 0.02 Torr
Adjust the temperature with the valve to bring the temperature of the substrate 404 to 200 ° C.
Set the heater 405 so that the substrate temperature stabilizes.
By the way, further valves 2001, 2002, 2005
Gradually open the SiH_FourGas, CH_FourGas, H ₂, B₂H
₆/ H₂Gas was flowed into the deposition chamber 401. At this time, S
iH_FourGas flow rate is 10 sccm, CH_FourGas flow rate is 5sc
cm, H₂Gas flow rate is 300 sccm, B₂H₆/ H₂gas
Each mass flow controller should have a flow rate of 10 sccm.
Adjusted with a troller. The pressure in the deposition chamber 401 is 0.
Conductance valve 407 to be 02 Torr
Adjusted the opening. The power of the μW power supply is 0.30 W / cm
³To the inside of the deposition chamber 401 through the dielectric window 413.
Introduces μW electric power to cause glow discharge and shutter
415 is opened to form a lightly doped layer (A layer) on the Si layer.
Has begun to grow. When the A layer with a layer thickness of 3 nm was prepared,
Close the shutter, turn off the μW power, and stop glow discharge.
It was Close valves 2001, 2002 and 2005 to
SiH into the loading chamber 401_FourGas, CH_FourGas, B₂H₆/ H
₂Stop the flow of gas and put H into the deposition chamber 401 for 5 minutes.₂gas
And then the valve 2003 is closed and the deposition chamber 40
The inside of 1 and the inside of the gas pipe were evacuated.

Next, the valve 2005 is gradually opened to allow the B ₂ H ₆ / H ₂ gas to flow into the deposition chamber 401 at a flow rate of 1
It was adjusted with each mass flow controller so as to be 000 sccm. The pressure in the deposition chamber 401 is 0.02
The opening of the conductance valve 407 was adjusted to Torr, the power of the μW power source was set to 0.20 W / cm ³ , and the μW power was introduced into the deposition chamber 401 through the dielectric window 413 to cause glow discharge. , Shutter 415
Then, the formation of boron (B layer) on the A layer was started. 6
After a lapse of 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 B ₂ H ₆ / H ₂ gas from flowing into the deposition chamber 401, and the H ₂ gas is continuously flowed into the deposition chamber 401 for 5 minutes, then the valve 2003 is closed and the deposition chamber 401 is closed. The inside 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 continuously flowing H ₂ gas into the deposition chamber 401, the valve 2003 is closed, the deposition chamber 401 and the gas pipe are evacuated, the auxiliary valve 408 is closed, the leak valve 409 is opened, and the deposition chamber is opened. 401 leaked.

Next, ITO (In ₂ O ₂ + nO ₂ ) having a layer thickness of 70 nm was vacuum-deposited on the second p-type layer as a transparent electrode by a usual vacuum vapor deposition method.

Next, a 5 μm-thick current collecting electrode made of silver (Ag) was vacuum-deposited on the transparent electrode by an ordinary 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.

[0515] This completes the production of this solar cell. This solar cell will be referred to as (SC Ex. 46), and Table 14 shows the manufacturing conditions of the first p-type layer, the n-type layer, the i-type layer, the Si layer, and the second p-type layer.

(Comparative Example 46) When the i-type layer was formed, S
A solar cell was produced under the same conditions and the same procedure as in Example 46, except that the iH 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. This solar cell is called (SC ratio 46).

(Example 46-1) A solar cell was produced on a substrate by the same method and procedure as in Example 46 except that PH ₃ / H ₂ gas was not passed when forming the i-type layer. This solar cell will be called (SC Ex 46-1).

(Example 46-2) A solar cell was produced on a substrate by the same method and procedure as in Example 46 except that B ₂ H ₆ / H ₂ gas was not passed when forming the i-type layer. . This solar cell will be referred to as (SC Ex 46-2).

The produced solar cells (SC Ex 46) and (SC Ex 46), (SC Ex 46-1), (SC Ex 46-)
The measurement of the initial light conversion efficiency (photovoltaic power / incident light power) and durability characteristics in 2) was performed in the same manner as in Example 1.

As a result of the measurement, for the solar cell of (SC Ex 46), (SC ratio 46), (SC Ex 46-1), (SC Ex 46-1),
The actual photoelectric conversion efficiency of actual 46-2) is as follows.

(SC ratio 46) 0.41 times (SC ex 46-1) 0.74 times (SC ex 46-2) 0.73 times The durability characteristics were measured in the same manner as in Example 1. As a result of the measurement, the (SC ex.
The durability characteristics of 6), (SC Ex 46-1), and (SC Ex 46-2) were as follows.

(SC ratio 46) 0.65 times (SC real 46-1) 0.94 times (SC real 46-2) 0.93 times Next (SC real 46), (SC ratio 46), (SC Fruit 46-
1), P atom and B in the i-type layer of (SC Ex 46-2)
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, it was confirmed that P atoms and B atoms were uniformly distributed in the layer thickness direction.

Further, a second p-type layer having a laminated structure was formed on the polycrystalline silicon substrate in the same manner as in Example 31, and the TEM (transmission electron microscope) image thereof was observed.

It was confirmed that the B layer having a layer thickness of about 1 nm and the A layer having a layer thickness of about 3 nm were alternately laminated as the second p-type layer.

As can be seen from the above, it was demonstrated that the solar cell of the present invention (SC Ex 46) has further superior characteristics to the conventional solar cell (SC ratio 46).

(Example 47) In Example 46, several solar cells were manufactured by changing the position of the minimum value of the band gap (Eg) in the layer thickness direction, the size of the minimum value, and the pattern, and the initial photoelectric conversion thereof was performed. The efficiency and durability characteristics were examined by the same method as in Example 46. At this time, SiH of the i-type layer
₄ gas flow rate and CH ₄ except gas flow rate change pattern Example 46 and same west, to produce a solar cell having a band gap shown in FIG. 12.

Table 15 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 47-1)). 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 central position of the i-type layer toward the Si / i interface. It turns out that solar cells are better.

(Example 48) A solar cell was prepared by changing the concentration and type of the valence electron controlling agent in the i-type layer in Example 46, and the initial photoelectric conversion characteristics and durability were the same as in Example 1. I looked it up. At this time, the same procedure as in Example 46 was performed except that the concentration and type of the valence electron controlling agent in the i-type layer were changed.

(Example 48-1) 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 ⅕, and the total H ₂ flow rate was the same as in Example 46. When the same solar cell (SC Ex 48-1) was manufactured,
It was found that (SC Ex 48-1) has better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 46), similar to (SC Ex 46).

(Example 48-2) 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 by 5 times, and the total H ₂ flow rate was the same as in Example 46. When a solar cell (SC Ex 48-2) was manufactured,
It was found that C Ex 48-2) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 46), similar to (SC Ex 46).

(Example 48-3) 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 46. When the solar cell (SC Ex 48-3) was manufactured, the initial photoelectric conversion efficiency of (SC Ex 48-3) was better than that of the conventional solar cell (SC ratio 46), similar to (SC Ex 46). And has been found to have durable properties.

(Example 48-4) 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 46. When a solar cell (SC Ex 48-3) was produced, (SC Ex 4
8-4) is a conventional solar cell (S
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the C ratio 46).

(Example 48-5) As a valence electron control agent gas serving as an acceptor for an 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) was produced. At this time, the TMA (purity 99.99%) sealed in the 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 46. Four
8-5) was produced.

At this time, the flow rate of TMA / H ₂ gas is 10 s.
It was set to ccm. The produced solar cell (SC Ex 48-5) is the same as the conventional solar cell (SC Ex 46), similar to (SC Ex 46).
It has been found that it has better initial photoelectric conversion efficiency and durability characteristics than the above.

Example 48-6 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. The NH ₃ / H ₂ gas cylinder of Example 46 was replaced with an H ₂ S gas (H ₂ S / H ₂ ) cylinder diluted to 100 ppm with hydrogen, and the solar cell (SC Ex 48 −
6) was produced.

At this time, the flow rate of the H ₂ S / H ₂ gas is 1 sccc.
m. The produced solar cell (SC Ex 48-6) is (S
It was found that, like C Ex. 46), it has a better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 46).

Example 49 A solar cell shown in FIG. 1-b was produced using a p-type polycrystalline silicon substrate. The substrate was subjected to plasma treatment, and subsequently, a first n-type layer, a p-type layer, a Si layer, an i-type layer, and a second n-type layer were sequentially formed on the substrate. Table 16 shows the forming conditions. When forming the i-type layer, SiH ₄
The gas flow rate and the CH ₄ gas flow rate were changed as shown in the pattern of FIG. 6 so that the minimum value of the band gap came to be closer to the i / Si interface. The second n-type layer has a laminated structure as in Example 46, and the deposition rate of the Si layer is 0.15 nm / s.
It was ec. The substrate and layers other than the semiconductor layer are the same as those in Example 4.
It was manufactured using the same conditions and the same method as in No. 6.

The manufactured solar cell (SC Ex 49) is (SC
It was found that similar to the actual cell 46), it has better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC ratio 46).

(Example 50) There is a maximum bandgap of the i-type layer near the Si / i interface, and the thickness of the region is 2
A solar cell having a thickness of 0 nm was produced using the flow rate change pattern of the i-type layer shown in FIG. 13-a.

It was manufactured using the same conditions and method as those of Example 46 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 46, and the change in the band gap in the layer thickness direction of the i-type layer was examined. The results were similar to those shown in FIG. 13-b. It was found that the manufactured solar cell (SC Ex 50) had a better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 46), similar to (SC Ex 46).

(Comparative Example 50) There was a region having the maximum bandgap near the Si / i interface of the i-type layer, and several solar cells having various thicknesses were manufactured. Except for the region thickness, the same conditions and methods as in Example 50 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 46 (SC
The initial photoelectric conversion efficiency and durability were better than those of Ex. 46).

(Example 51) There is a maximum bandgap of the i-type layer near the i / n interface, and the thickness of the region is 15
A solar cell having a thickness of nm was produced using the flow rate change pattern of the i-type layer shown in FIG. 13-c. It was produced using the same conditions and the same method as in Example 46 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 46.
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 manufactured solar cell (SC Ex 51) is (SC Ex 4
Similar to 6), it was found that the solar cell had better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 46).

(Comparative Example 51) There was a region having the maximum bandgap near the i / n 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 51 except for the thickness of the region. When the initial photoelectric conversion efficiency and durability of the produced solar cell were measured, the solar cell of Example 46 (SC Ex 4) was obtained when the region thickness was 1 nm or more and 30 nm or less.
Even better initial photoelectric conversion efficiency and durability than 6) were obtained.

(Example 52) PH ₃ / H ₂ shown in FIG. 19-a was applied to a solar cell in which a valence electron control agent is distributed in the i-type layer.
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 procedure as in Example 46 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 (SC Ex 46), the conventional solar cell (SC ratio 4
It was found that the initial photoelectric conversion efficiency and durability were better than those of 6). Moreover, when the change in the layer thickness direction of P atoms and B atoms contained in the i-type layer was examined by using a secondary ion mass spectrometer (SIMS), the same result as in FIG. P and B at the minimum position
It was found that the atomic content was the minimum.

(Example 53) 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 46.
cm, the same conditions, the same method, and the same procedure as in Example 46 were used except that the gas was introduced into the deposition chamber 401. It was found that the manufactured solar cell (SC Ex. 53) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC Ex. 46), similar to (SC Ex. 46).

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 54) A silicon solar cell in which a nitrogen atom was contained in the i-type layer was produced. In forming the i-type layer, in addition to the gas flowing in Example 46, 5 sccm of NH ₃ / H ₂ gas was introduced into the deposition chamber 401 in Example 4
The same conditions, the same method, and the same procedure as those in No. 6 were used. It was found that the manufactured solar cell (SC Ex. 54) had better initial photoelectric conversion efficiency and durability characteristics than the conventional solar cell (SC Compar. 46), similar to (SC Ex. 46). 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 55) A solar cell having an i-type layer containing oxygen atoms and nitrogen atoms was produced. When forming the i-type layer, in addition to the gas flowing in Example 46, O ₂ / He
The same conditions, the same method, and the same procedure as in Example 46 were used except that gas was introduced at 5 sccm and NH ₂ / H ₂ gas was introduced at 5 sccm into the deposition chamber 401. The produced solar cell (SC Ex 55) is the same as the conventional solar cell (SC Ex 46).
It was found that the initial photoelectric conversion efficiency and durability characteristics were better than those of the ratio 46). Moreover, when the contents of oxygen atoms and nitrogen atoms in the i-type layer were examined by SIMS, they were found to be contained almost uniformly, and each was 1 × 10 ¹⁹ (pieces / c
m ² ), 3 × 10 ¹⁷ (pieces / cm ² ).

(Example 56) A solar cell in which the hydrogen content of the i-type layer was changed corresponding to the silicon content was produced. The O ₂ / He gas cylinder was replaced with SiF ₄ gas (purity 99.9).
99%) When replacing the cylinder and forming the i-type layer, as shown in FIG.
The flow rates of SiH ₄ gas, CH ₄ gas, and SiF ₄ gas were changed according to the flow pattern of −a. When the change in the band gap in the layer thickness direction of this solar cell (SC Ex 56) was obtained by the same method as in Example 46, the same result as in FIG. 15-b was obtained.

Further, the secondary ion mass spectrometer was used to analyze the contents of hydrogen atoms and silicon atoms in the layer thickness direction. 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 56) were determined, similar to the solar cell of Example 46, the initial photoelectric conversion efficiency and durability were better than those of the conventional solar cell (SC ratio 46). It was found to have characteristics.

(Example 57) 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 57) was produced by the same method and the same procedure as in Example 46 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. The manufactured solar cell (SC Ex 57) is (SC Ex 46)
It has been found that it has better initial photoelectric conversion efficiency and durability characteristics than the above.

(Example 58) 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, the O ₂ / He gas cylinder was replaced with a BBr ₃ (BBr ₃ / H ₂ gas) cylinder diluted with hydrogen to 10%, and further 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 30
Under the condition of Torr, B was diffused into the n-type substrate. Stop the introduction of BBr ₃ / H ₂ gas at the junction depth of 300 nm. The H ₂ gas was kept flowing for 5 minutes.

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. 20-a. Furthermore, as shown in Fig. 20-b, R
F 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 46 were used. Fabricated solar cell (SC Ex 5
It was found that 8) had a better initial photoelectric conversion efficiency and durability than the conventional solar cell (SC ratio 46), similar to (SC Ex 46).

(Example 59) Using the manufacturing apparatus of FIG. 4 using the microwave plasma CVD method of the present invention, FIG.
A triple solar cell was manufactured.

As the substrate, an n-type polycrystalline silicon substrate manufactured by the casting method as in Example 46 was used.

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), irregularities having a pyramid structure are formed on the surface, and the substrate is textured (Text
ured). 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 46, 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, second i-type layer, Si
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_FourThe deposition rate of Si layer is changed by changing the gas flow rate.
The degree was 0.15 nm / sec. Furthermore, a third p-type layer
Has a laminated structure as in Example 46.

Next, as in Example 46, ITO (In ₂ O ₃₎ having a layer thickness of 70 nm was formed as a transparent electrode on the third p-type layer.
+ SnO ₂ ) was vacuum-deposited by a usual vacuum deposition method.

Next, as in Example 46, a current collecting 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.

Then, in the same manner as in Example 46, 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.

[0562] Through the above steps, the production of a triple solar cell using the microwave plasma CVD method is completed.

This solar cell is referred to as (SC Ex 59), and the manufacturing conditions of each semiconductor layer are shown in Table 17.

(Comparative Example 59) When forming the second i-type layer of FIG. 17, SiH ₄ was formed in accordance with the flow rate change pattern of FIG.
Example 5 except that the gas flow rate and CH ₄ gas flow rate were changed
A triple type solar cell was produced by the same method and the same procedure as in No. 9. This solar cell is called (SC ratio 59).

The initial photoelectric conversion efficiency and durability of these produced triple type solar cells were measured by the same method as in Example 46. (SC Ex 59) shows that the conventional triple type solar cell (SC ratio 59) It has been found that also has a better initial photoelectric conversion efficiency and durability characteristics.

Example 60 A solar cell of Example 46 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 mm ² (SC Ex 46) was prepared under the same conditions, the same method and the same procedure as in Example 46.
Individually made. EV on a 5.0 mm thick aluminum plate
An adhesive sheet made of A (ethylene vinyl acetate) was placed, a nylon sheet was placed on the adhesive sheet, and the solar cells produced were further arranged on the sheet to perform serialization and parallelization. Put EVA adhesive sheet on it, put fluororesin sheet on it, vacuum laminate,
Modularized. The initial photoelectric conversion efficiency of the manufactured module was measured in the same manner as in Example 46. 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. 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 real 60).

(Comparative Example 60) A conventional solar cell (SC ratio 4
6) under the same conditions, the same method and the same procedure as in Comparative Example 46.
Five pieces were produced and modularized in the same manner as in Example 60. This module will be referred to as (MJ ratio 60). 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 60, and the photodegradation rate was obtained.

As a result, the photodegradation rate for (MJ ratio 60) was as follows for (MJ actual 60).

[0570] Ratio of module light deterioration rate ───────────────────────── MJ actual 60 1.00 MJ ratio 60 0.74 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.

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.

[0572]

[Table 1]

[0573]

[Table 2]

[0574]

[Table 3]

[0575]

[Table 4]

[0576]

[Table 5]

[0577]

[Table 6]

[0578]

[Table 7]

[0579]

[Table 8]

[0580]

[Table 9]

[0581]

[Table 10]

[0582]

[Table 11]

[0583]

[Table 12]

[0584]

[Table 13]

[0585]

[Table 14]

[0586]

[Table 15]

[0587]

[Table 16]

[0588]

[Table 17]

[0589]

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 change pattern of μW power.

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 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. 20 is a graph showing a C ₂ H ₂ flow rate pattern and a change pattern of DC bias, RF power, and μW power.

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 i layer, 106 Si layer, 107 second p-type layer, 108 transparent electrode, 109 current collecting electrode, 121 back surface Electrode, 122 p-type silicon substrate, 123 first 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 band gap changing region, 312, 322, 332, 333, 342, 343, 3
52, 353, 362, 372, 373 band gap constant region, 313, 323, 334, 344, 354, 364, 3
74 Si layer, 401 deposition chamber, 402 vacuum gauge, 403 RF power supply, 404 substrate, 405 heating heater, 407 conductance valve, 408 auxiliary valve, 409 leak valve, 410 RF electrode, 411 gas introduction tube, 412 microwave waveguide section, 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 (16)

[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 semiconductor 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. Where 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 2. A photovoltaic element, which is biased in the direction of the p-type layer. 2. A region having a maximum bandgap of the i-type layer is present on at least one of the interface between the i-type layer and the Si layer or the interface between the i-type layer and the n-type layer. The bandgap maximum value region is 1 to 30 n
The photovoltaic element according to claim 1, wherein the photovoltaic element is m. 3. A main constituent element of at least one of the second p-type layer, the n-type layer, and the first 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 silicon material, an i-type layer made of a non-single-crystal semiconductor material, and a second n-type layer made of a non-single-crystal semiconductor material are sequentially stacked. Where 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 maximum bandgap of the i-type layer is present at at least one of the interface between the i-type layer and the Si layer or the interface between the i-type layer and the second n-type layer. There is a region, and the region of the band gap maximum value is 1 to 3
It is 0 nm, The photovoltaic element of Claim 4 characterized by the above-mentioned. 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. 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. 8. The valence electron control agent serving as the donor is a group V element and / or a group VI 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 7, wherein 9. The photovoltaic element according to claim 7, wherein the valence electron control agent is distributed in the layer thickness direction inside the i-type layer. 10. The photovoltaic element according to claim 1, wherein the i-type layer contains oxygen atoms and / or nitrogen atoms. 11. The content of hydrogen atoms contained in the i-type layer changes according to the content of silicon atoms, according to any one of claims 1 to 10. Photovoltaic device. 12. The i-type layer causes a microwave energy lower than a microwave energy required to decompose 100% 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 11. 13. The photovoltaic element according to claim 1, wherein the Si layer contains a Group III element of the periodic table. 14. The Si layer according to claim 1, wherein a group III element of the periodic table and a group V element and / or a group VI element of the periodic table are contained together. The photovoltaic element according to any one of items. 15. The Si layer has a deposition rate of 2 nm / s.
It is formed by an RF plasma CVD method with a thickness of ec or less and a layer thickness of 30 nm or less.
4. The photovoltaic element according to any one of 4 above. 16. 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.