JPH06204522A - Photovoltaic element and generation system - Google Patents

Abstract

PURPOSE:To improve a photoelectric conversion efficiency by forming a doping layer and an i-type layer of a pin type photovoltaic element formed of nonsingle crystalline silicon semiconductor material by a microwave plasma CVD method. CONSTITUTION:A photovoltaic element comprises a substrate 101, a microwave (MW) n-type layer 102 having an n-type conductivity, an i-type layer 104 containing one type of Ge, Sn and C and alkaline earth metal element and a MW p-type layer 106 to be formed by an MW PCVD method, a PF n-type layer 103 having an n-type conductivity, a PF p-type layer 105 having a p-type conductivity to be formed by a PFPCVD method, a transparent electrode 107 and a condensing electrode 108. Since the MWPCVD method is used when the MW doping layer and the i-type layer are formed, its depositing speed is fast to improve its throughput, and the element having excellent characteristics can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pin type photovoltaic element made of a non-single crystal silicon semiconductor material, and in particular, a light emitting layer having a doping layer and an i type layer formed by a microwave plasma CVD method (MWPCVD method). The present invention relates to an electromotive force element. The present invention also relates to a photovoltaic element in which a semiconductor layer made of a non-single crystal silicon semiconductor material (simply referred to as a semiconductor layer) contains an alkaline earth metal. It also relates to a photovoltaic element having a semiconductor layer containing fluorine. In addition, it relates to a power generation system using the photovoltaic element.

[0002]

2. Description of the Related Art In recent years, photovoltaic devices have been vigorously studied by using the MWPCVD method, which has a higher deposition rate and an excellent utilization efficiency of raw material gas. For example, as an example of forming the i-type layer by the MWPCVD method, 1. “A-Si Solar Cell by Microwave Plasma CVD Method”, Kazufumi Higashi, Takeshi Watanabe, Juichi Shimada, Proceedings of the 50th JSAP Academic Conference pp.566. Etc. In this photovoltaic element, the i-type layer is MWP
The i-type layer having a high quality and a high deposition rate is obtained by the CVD method.

As an example of forming the doping layer by the MWPCVD method, for example, 2. “High Efficiency Amorphous Solar Cell Employi
ng ECR-CVD Produced p-Type Microcrystalline SiC Fi
lm ", Y.Hattori, D.Kruangam, T.Toyama, H.Okamotoand Y.
Hamakawa, Proceedings of the International PVSEC-3
Tokyo Japan 1987 pp.171. 3. "HIGH-CONDUCTIVE WIDE BAND GAP P-TYPE a-SiC: H
PREPARED BY ECR CVDAND ITS APPLICATION TO HIGH EF
FICIENCY a-Si BASIS SOLAR CELLS ", Y.Hattori, D.Krua
ngam, K.Katou, Y.Nitta, H.Okamoto and Y.Hamakawa,
Proceedings of 19th IEEE Photovoltaic Specialists
Conference 1987 pp.689. And the like. In these photovoltaic devices, M is used in the p-type layer.
A good quality p-type layer is obtained by using the WPCVD method.

However, in these examples, the i-type layer and p
No MWPCVD method has been used to form both mold layers. Currently, i-type layer formed by MWPCVD method and MWP
It is considered that when a doping layer formed by the CVD method is stacked, many defect levels occur at the interface, and a photovoltaic element having good characteristics cannot be obtained.

Regarding the study of a non-single crystal silicon semiconductor layer containing an alkaline earth metal and a photovoltaic element using the same, only the following are known. 4. "Characteristic stabilizing effect of a-Si: H thin film by ion addition", Yuchi Harada, Nao Tagami, Jiji Nakazawa, Kuniomi Nakamura, Proceedings of Spring Conference of IEICE 1991. Here, it is stated that addition of calcium suppresses photodegradation. In this example, calcium is contained in the amorphous silicon by the ion implantation method, but since the content is very large at about 0.1%, the activation energy is considerably small at 0.36 eV,
It is not applicable to photovoltaic devices. Moreover, the degree of photodegradation is not suitable for a photovoltaic element.

Regarding a photovoltaic device having a pin structure made of a non-single-crystal silicon semiconductor material, the i-type layer contains silicon atoms, germanium atoms or carbon atoms, and the band gap is changed. Various proposals have been made. For example, 5. “Optimum deposition conditions for a- (si, Ge):
H using a triode-configurated rf glow discharge sy
stem ”, JABragagnolo, P.Littlefield, A.Mastrovit
o and G. Storti, Proceedings of 19th IEEE Photovolt
aic Specialists Conference 1987 pp.878. 6. “Efficiency improvement in amorphous-SiGe: H s
olar cells and itsapplication to tandem type solar
cells ”, S.yoshida, S.yamanaka, M.Konagai and KT
akahashi, Proceedings of 19th IEEE Photovoltaic Sp
ecialists Conference 1987 pp.1101. 7. “Preparation of high quality a-SiGe: H Films a
nd its application to the high efficiency triple-ju
nction amorphous solar cells ", K.Sato, K.kawabata,
S.Terazono, H.Sasaki, M.Deguchi, T.Itagaki, H.Mori
kawa, M.Aiga and K.Fujikawa, Proceedings of 20th IE
EE Photovoltaic SpecialistsConference 1988 pp.73. 8. USP 4,816,082 9. "A novel structure high conversion efficiency
p-SiC / graded p-SiC / i-Si / n-Si / metal substrate-type
amorphous silicon solar cell ", Koeng.Su.Lim, Makoto
Konagai and Kiyoshi Takahashi, Journal of Applied
Physics, vol 56 (2), 1984 pp538. 10. "a-SiC / a-Si / a-SiGe multi-banndgap stacked so
lar cekks with bandgapprofilling ", H. Sannomiya, S.
Moriuchi, Y. Inoue, K. Nomoto, A. Yokota, M. Itoh, Y. Na
kata, T. Tsuji, Technical Digest of the Internation
al PVSEC-5, Kyoto, Japan, 1990 pp387. 11. "Effect of a-Si: C: H graded p / i interface on
the performance andstability of a-Si: H pin solar
cells ", RR Arya, MSBennet, A.Catalano, K.Rajan,
Technical Digest of the International PVSEC-5, To
kyo, Japan, 1987 pp457. etc. have been reported.

Theoretical studies of the characteristics of photovoltaic devices with varying band gaps are described in, for example, 12. “A novel design for amorphous silicon all
oy solar cells ”, S.Guha, J. Yang, A. Pawlikiewicz,
T.Glatfelter, R.Ross, and SROvshinsky, Proceeding
s of 20th IEEE Photovoltaic Specialists Conference
1988 pp.79. 13. “Numerical modeling of multijunction, amorph
ous silicon based PIN solar cells ", AHPawlikew
icz and S. Guha, Proceedings of 20th IEEEPhotovolta
ic Specialists Conference 1988 pp.251 etc. have been reported.

In such a conventional photovoltaic element, p
/ I, i / n i-type layer having a changed band gap at the interface for the purpose of preventing recombination of photoexcited carriers near the interface, increasing open-circuit voltage, and improving the carrier range of holes Is formed. However, in these examples as well, although the reduction of photodegradation and the photoelectric conversion efficiency are mentioned, the relation with vibration degradation and the relation with layer peeling are not mentioned.

Further, investigations on a non-single crystal silicon semiconductor layer containing fluorine and a photovoltaic element using the same are also underway. For example, 14. "Practical application research of amorphous solar cells: Research on manufacturing of highly reliable amorphous solar cells", overview of research and development of sunshine plan. Solar energy 1. Light utilization technology VO
L.1985 pp.I.231-I.243 1986. “The Chemical and configurational basis of
high efficiencyamorphous photovoltaic cells ”, Ovs
hinsky.SR, Proceedings of 17th IEEE Photovoltaic S
pecialists Conference 1983 pp.1365. 16. “Preparation and properties of sputtered a-
Si: HF films ", Beyer.W, Chevallier.J, Reichelt.K, So
lar Energy Material vol.9, No2, pp.229-2451983. 17. Development of the scientific and technical
basis for integratedamorphous silicon modules. Re
serch on a-Si: F: H (B) alloys and module testing at I
ET-CIEMAT, Gutierrez MT, P Delgado L, Photovolt.
Power Gener., Pp.70-75 1988. 18. The effect of fluorine on the photovoltaic p
roperties of amorphous silicon. Konagai.M, Nishihat
aK, Takahashi.K, Komoro.K, Proceedings of15th IEE
E Photovoltaic Specialists Conference 1981 pp.906.

However, in the above-mentioned conventional method,
Although the photodegradation phenomenon and thermal stability are mentioned,
No mention is made of the relationship between the change of fluorine in the layer thickness direction and the photoelectric conversion efficiency, the relationship of hydrogen with the layer thickness direction, or the relationship with vibration deterioration. Further, in these examples, a good-quality doping layer is obtained, but a photovoltaic element having high photoelectric conversion efficiency has not been obtained yet.

In the conventional photovoltaic device, when the MWPCVD method is used for both the formation of the i-type layer and the formation of the doping layer, recombination and release of the photoexcited carriers near the p / i interface and the n / i interface. It is desired to improve the voltage and the carrier range of holes.

Further, the doping layer and the i-type layer are MWPCV
The photovoltaic element formed by the D method has a problem that the photoelectric conversion efficiency is lowered (photo-deteriorated) when the photovoltaic element is irradiated with light.

Further, a doping layer and an i-type layer are formed on the MWPC.
The photovoltaic element formed by the VD method has a problem that there is strain near the interface between the doping layer and the i-type layer and the photoelectric conversion efficiency decreases (vibration deterioration) when placed in an environment where there is vibration for a long period of time. .

Further, in the above photovoltaic element, the photodegradation and the vibration degradation were remarkable when it was placed in a high temperature environment for a long period of time.

Furthermore, in the above-mentioned photovoltaic element, photodegradation and vibration degradation were remarkable when it was placed in a high humidity environment for a long period of time.

Further, in the above photovoltaic element, the light deterioration and the vibration deterioration when a forward bias was applied were remarkable.

Further, the photovoltaic element containing a large amount of alkaline earth metal has a problem that the photoelectric conversion efficiency is extremely low.

Further, the non-single-crystal silicon-based semiconductor layer containing fluorine has a problem that the layer is easily peeled off as compared with a layer containing no fluorine.

[0019]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above problems. That is, it is an object of the present invention to provide a photovoltaic element having an improved photoelectric conversion efficiency in the conventional photovoltaic element having an improved deposition rate.

Another object of the present invention is to provide a photovoltaic element which suppresses optical deterioration and vibration deterioration.

A further object of the present invention is to suppress photodegradation and vibration degradation of the photovoltaic element when the photovoltaic element is placed in a high temperature environment.

A further object of the present invention is to suppress the photodegradation and vibration degradation of the photovoltaic element when the photovoltaic element is placed in a high humidity environment.

A further object of the present invention is to suppress optical deterioration and vibration deterioration when a forward bias is applied to the photovoltaic element.

A further object of the present invention is to provide a photovoltaic element in which the semiconductor layer does not peel off even when the photovoltaic element is placed in the above environment.

Still another object of the present invention is to provide a photovoltaic device having excellent productivity.

Still another object of the present invention is to provide a system using a photovoltaic element that achieves the above object.

[0027]

The present invention has been made in order to solve the conventional problems and achieve the above object, and as a result,
The photovoltaic element of the present invention has been found,
P containing a non-single-crystal silicon-based semiconductor material containing hydrogen
A photovoltaic layer containing at least one of germanium, tin, and carbon and an alkaline earth metal, wherein the i-type layer, the i-type layer, and the n-type layer are laminated on a substrate. The p-type layer and / or the n-type layer are a MW doping layer and an RF layer formed by a microwave plasma CVD method.
The RF doping layer is formed by a stacked structure with an RF doping layer formed by a plasma CVD method, the RF doping layer is disposed between the MW doping layer and the i-type layer, and germanium or tin contained in the i-type layer. Alternatively, the carbon content changes smoothly in the layer thickness direction, and the maximum value of the carbon content is located closer to the p-type layer than the central position of the i-type layer.

A desirable mode of the present invention is a photovoltaic element in which 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.

A desirable mode of the present invention is a photovoltaic device having an i-type layer (RF-i layer) formed by an RF plasma CVD method between the i-type layer and the RF doping layer.

A desirable mode of the present invention is the RF-
A photovoltaic element in which the i layer contains both a valence electron control agent which serves as a donor and a valence electron control agent which serves as an acceptor.

A desirable mode of the present invention is that the MW doping layer, the RF doping layer, the RF-i layer, and the i-type layer have the maximum hydrogen content in the vicinity of at least one of the two interfaces. It is a photovoltaic element.

A desirable mode of the present invention is that in the MW doping layer, the RF doping layer, the RF-i layer, and the i-type layer, the content of the valence electron control agent is maximum in the vicinity of at least one of the two interfaces. Is a photovoltaic element.

A preferred embodiment of the present invention is a photovoltaic device in which at least one of the i-type layer, the RF-i layer, the MW doping layer, and the RF doping layer contains oxygen and / or nitrogen atoms. is there.

A preferred embodiment of the present invention is the RF-
A photovoltaic element in which at least one of the i layer, the MW doping layer, and the RF doping layer contains fluorine, and further, the photovoltaic element has a minimum fluorine content in the vicinity of at least one interface. Is.

A preferred embodiment of the present invention is the RF-
At least one layer of the i layer, the MW doping layer, and the RF doping layer is to contain an alkaline earth metal. A desirable mode of the present invention is the i-type layer, RF-
That is, the content of the alkaline earth metal contained in the i layer, the MW doping layer, and the RF doping layer changes smoothly in the layer thickness direction, and becomes the minimum in the vicinity of at least one interface.

A desirable mode of the present invention is that the alkaline earth metal contains at least one element selected from beryllium, magnesium and calcium.

In the power generation system of the present invention, the photovoltaic element and the voltage and / or current of the photovoltaic element are monitored to supply power from the photovoltaic element to a storage battery and / or an external load. And a storage battery that stores electric power from the photovoltaic element and / or supplies electric power to an external load.

[0038]

Next, the present invention will be described with reference to the drawings.

FIG. 1-a is a schematic explanatory view showing an example of the photovoltaic element of the present invention. The photovoltaic device of FIG. 1-a is
Substrate 101, MWn-type layer 102 formed by MWPCVD method and having n-type conductivity, RFn-type layer 103 formed by RFPCVD method and having n-type conductivity, MWP
I-type layer 104 formed by the CVD method and containing hydrogen, alkaline earth metal, and germanium or / and tin or / and carbon, RF p-type layer 105 having the p-type conductivity type formed by the RFPCVD method, MWPCVD A MW p-type layer 106 having a p-type conductivity type formed by a method, a transparent electrode 107, a collector electrode 108, and the like.

FIG. 1-b is another example of a schematic explanatory view of the photovoltaic element of the present invention. In FIG. 1-b, the photovoltaic element is a substrate 111, an n-type layer 112 having an n-type conductivity,
i-type layer 114, RFp-type layer 115, MWp-type layer 116,
It is composed of a transparent electrode 117, a collector electrode 118 and the like.

FIG. 1-c is another example of a schematic explanatory view of the photovoltaic element of the present invention. In FIG. 1-c, the photovoltaic device includes a substrate 121, a MWn type layer 122, and an RFn type layer 12.
3, i-type layer 124, p-type layer 12 having p-type conductivity
5, a transparent electrode 127, a collector electrode 128, and the like.

Although the n-type layer and the p-type layer are formed by the RFPCVD method or the MWPCVD method in FIGS. 1-b to 1-c, the RFPCVD method is preferable.

Further, a pin as shown in FIGS. 1-a to 1-c
In addition to the photovoltaic device of the n-type structure, a photovoltaic device of the nip-type structure in which the stacking order of the n-type layer and the p-type layer is reversed may be used. Further, in a photovoltaic device having a pin-type structure as shown in FIGS. 1A to 1C, an i-type layer (R) formed by an RFPCVD method between a doping layer having a laminated structure and an i-type layer is used.
A photovoltaic device as shown in FIGS. 2-a to 2-c having an F-i layer) may be used.

Further, the doping layer having the laminated structure of the present invention is RFp type layer / MWp type layer / RFp type layer / i.
Layer, i-type layer / RFn-type layer / MWn-type layer / RFn-type layer, etc., may have a laminated structure composed of three or more layers of (RF / MW) _n / RF-type, or MWp Mold layer /
It may be a (MW / RF) _n type laminated structure such as RFp type layer / MWp type layer / RFp type layer / i type layer.

The photovoltaic element of the present invention is a pinpin.
It may be a stack of pin structures such as a structure or a pinpinpin structure.

The photovoltaic element of the present invention is a nipnip
It may be a stack of nip structures such as a structure or a nipnipnip structure.

In the photovoltaic device of the present invention, since the MWPCVD method is used when forming the doping layer and the i-type layer, the deposition rate is high, the throughput can be improved, and the utilization efficiency of the source gas is high. It is possible to improve the production efficiency and has excellent productivity.

Further, in the photovoltaic element of the present invention, since the doping layer is formed by the MWPCVD method, a doping layer having good characteristics as a photovoltaic element can be obtained.
That is, the doping layer is excellent as a doping layer because it has good light transmittance, high electric conductivity, and low activation energy, and is particularly effective as a doping layer on the light incident side. Further, since it is formed by the MWPCVD method, a good-quality microcrystalline silicon-based semiconductor material or a good-quality amorphous silicon-based semiconductor material with a wide band gap can be formed relatively easily, and the doping layer on the light incident side can be formed. Is effective as.

Further, in the photovoltaic element of the present invention, since the doping layer is formed by the MWPCVD method, it is possible to suppress the photodegradation of the photovoltaic element, especially the degradation of the open circuit voltage. Although the detailed mechanism is unknown, it is considered as follows. 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. MWPC
Doping layer formed by VD method (MW doping layer)
Is formed at a deposition rate of 2 nm / sec or more, the introduced valence electron control agent is not 100% activated,
Even if a dangling bond is generated, the inactive valence electron control agent terminates it, so that it is considered that the characteristics of the photovoltaic element, particularly the decrease in open circuit voltage, can be suppressed.

Since there is a doping layer (RF doping layer) formed by the RFPCVD method between the i-type layer formed by the MWPCVD method and the doping layer (MW doping layer) formed by the MWPCVD method, the interface is formed. The level can be reduced and the photoelectric conversion efficiency can be improved. Although the detailed mechanism is unknown, it is considered as follows.

The RF doping layer is formed with a low power so that the vapor phase reaction is unlikely to occur, and the deposition rate is 1 nm / sec or less. As a result, the packing density is increased, and when the layer is laminated with the i-type layer, the interface state of each layer is reduced. Especially the deposition rate of the i-type layer is 5 nm
In the case of / sec or more, immediately after the glow discharge is excited by the microwave or immediately after the glow discharge is stopped, the vicinity of the surface of the i-type layer is not sufficiently relaxed, and the surface level is increased.

By forming the i-type layer on the RF doping layer having a slow deposition rate, the initial film of the i-type layer immediately after the glow discharge is generated is affected by the underlying layer, the packing density is increased, and the dangling is increased. It is considered that the layer has few ring bonds and the surface level is reduced.

On the other hand, by forming an RF doping layer having a low deposition rate on the surface of the i-type layer, the surface level of the i-type layer is reduced by annealing due to the diffusion of hydrogen atoms which occurs at the same time when the RF doping layer is formed. It is thought that they can be made to do.

Further, by making the content of the valence electron control agent in the RF doping layer lower than the content of the valence electron control agent in the MW doping layer, the open circuit voltage and fill factor of the photovoltaic element can be improved. .

In addition, the photovoltaic element of the present invention is less susceptible to vibration deterioration. Although the detailed mechanism of this is not clear, MW-doped layers and i having very different constituent element ratios
By providing the RF doping layer between the type layers, the local flexibility is increased, the internal stress between the MW doping layer and the i-type layer can be relaxed, and the occurrence of defect levels due to the internal stress is prevented. Therefore, it is considered that the deterioration of the photoelectric conversion efficiency of the photovoltaic element can be suppressed even when it is left under vibration for a long time. This is particularly effective when the hydrogen content at both interfaces of the RF doping layer is high.

It is generally known that the band gap becomes smaller as the content of germanium and tin in the i-type layer made of the amorphous silicon semiconductor material increases, and the band gap becomes larger as the content of carbon increases. There is.

In the photovoltaic element of the present invention, the content of germanium and tin or carbon atoms in the i-type layer changes smoothly in the layer thickness direction. By doing so, the photoelectric conversion efficiency is improved.

That is, for example, as shown in FIG. 3-a, the content of germanium and tin is reduced on the p-type layer side and the n-type layer side of the i-type layer, and the germanium and / or tin content is maximized. As shown in FIG. 4A, the band gap of the i-type layer is maximum on the p-type layer side and the n-type layer side, and the minimum is the p-type layer inside the bulk. Be on the side. Alternatively, as shown in FIG. 14-a, the content of carbon atoms is increased on the p-type layer side and the n-type layer side of the i-type layer,
Moreover, the band gap of the i-type layer is maximized on the p-type layer side and the n-type layer side as shown in FIG. , The minimum is on the p-type layer side inside the bulk. Therefore i
On the p-type layer side of the p-type layer, electrons and holes are efficiently separated due to a large electric field in the conduction band, and recombination of electrons and holes near the interface between the p-type layer and the i-type layer is reduced. be able to. In addition, it is possible to prevent electrons from being diffused back into the p-type layer. Further, since the electric field in the valence band increases from the i-type layer toward the n-type layer, recombination of electrons and holes excited on the i-type layer side can be reduced.

Further, by reducing the content of germanium and / or tin in the vicinity of the interface between the doping layer and the i-type layer, the open circuit voltage and fill factor of the photovoltaic element can be improved.

Further, by containing a smaller amount of germanium and / or tin in the vicinity of the interface than in the interior, it is possible to reduce the internal stress due to the abrupt change of the constituent elements peculiar to the interface. As a result, it is possible to prevent the photoelectric conversion efficiency from decreasing even if it is left under vibration for a long period of time. Further, it is particularly effective when the heterojunction (Si / SiGe, SiC / SiGe, etc.) is formed between the i-type layer and the doping layer.

Generally, it is considered that many interface states and internal stress exist at the interface of the heterojunction. In the photovoltaic device of the present invention, by containing a small amount of germanium and / or tin near the interface of the heterojunction, flexibility near the hetero interface can be increased, internal stress can be relaxed, and the interface level can be reduced. .

Further, by containing a larger number of carbon atoms in the vicinity of the interface than in the interior, it is possible to reduce the internal stress caused by the abrupt change of the constituent elements peculiar to the interface. As a result, it is possible to prevent the photoelectric conversion efficiency from decreasing even if it is left under vibration for a long period of time. It is particularly effective when the junction with the doping layer is a homojunction.
Hereinafter, with reference to the drawings, an example of a desirable change pattern of the germanium or / and tin content of the i-type layer in the photovoltaic element of the present invention, which is considered from the change of the band gap in the layer thickness direction, will be described.

FIG. 3A shows an example in which the contents of germanium and tin are drastically changed on the p-type layer side as described above, and the maximum content is on the p-type layer side inside the bulk. In FIG. 14-a, as described above, the content of carbon atoms is rapidly changed on the p-type layer side, and the minimum value of the content is on the p-type layer side inside the bulk. In this case, the band gap is as shown in FIG. 4-a or FIG. 15-a, and when light is incident from the p-type layer side, the high electric field near the interface between the p-type layer and the i-type layer and the n-type layer are generated. The high electric field near the interface of the i-type layer can be used more effectively, and the collection efficiency of electrons and holes photoexcited in the i-type layer can be improved. Also ni
When light is incident from the n-type layer side in the p-type photovoltaic element, the change pattern may be reversed with respect to the layer thickness direction.
Further, it is particularly effective when the band gap of the i-type layer is small or when the number of carbon atoms contained in the i-type layer is relatively small.

FIG. 3-b or FIG. 14-b shows an example in which the p-type layer side is slowly changed to the n-type layer side, and the maximum contents are at the interfaces with the p-type layer and the n-type layer, respectively. is there. In this case, the band gap becomes as shown in FIG. 4-b or FIG. 15-b, and the electric field of the valence band can be increased over the entire region of the i-type layer, and the carrier range for holes can be particularly improved. It is possible to improve the fill factor. When light is incident from the n-type layer side in the nip-type photovoltaic element, the change pattern may be reversed with respect to the layer thickness direction. When the content of germanium and / or tin in the i-type layer is relatively high, or i
It is particularly effective when the content of carbon atoms in the mold layer is relatively low.

FIG. 3-c or FIG. 14-c is an example in which the contents of germanium and tin or carbon atoms are drastically changed on the p-type layer side and the n-type layer side of the i-type layer. In this case, the bandgap becomes as shown in FIG. 4-c or FIG. 15-c, and the electric field of the conduction band can be strengthened on the p-type layer side of the i-type layer, and in particular, electrons are inversely diffused to the p-type layer. Can be suppressed. Further, the electric field in the valence band can be strengthened on the i-type layer side and the n-type layer side, and in particular, back diffusion of holes into the n-type layer can be suppressed. Further, it is particularly effective for a photovoltaic device having an i-type layer having a relatively low germanium and / or tin content or a photovoltaic device having an i-type layer having a relatively high carbon atom content. That is, FIG.
When light is incident from the p-type layer side in FIG. 15c or FIG. 15-c, the i-type layer having a large band gap cannot sufficiently absorb the light, and photoexcited carriers near the interface between the i-type layer and the n-type layer are recombined Without being carried out, they are separated by the strong electric field in the vicinity of this interface, and the collection efficiency can be improved. Further, it is effective for a photovoltaic element having a light reflecting layer. That is, in a photovoltaic device having a light reflecting layer, since light is incident from both layers, collection efficiency can be similarly improved.

Furthermore, in the photovoltaic element of the present invention, the i-type layer contains an alkaline earth metal, and the alkaline earth metal content changes smoothly in the layer thickness direction. By doing so, it is possible to suppress optical deterioration and vibration deterioration when a forward bias voltage is applied to the photovoltaic element. The detailed mechanism is unknown, but it is considered as follows. I made of non-single-crystal silicon semiconductor material
When the mold layer contains an alkaline earth metal, the alkaline earth metal is i, such as silicon, germanium, tin or carbon.
Electrons are donated to the main constituent elements of the mold layer to be ionized. It is considered that the ionized alkaline earth metal is relatively easy to move inside the i-type layer, and the ionized alkaline earth metal is likely to collect in the weak electric field region generated by applying the forward bias. In addition, generally, when the internal electric field of the i-type layer is weak, photo-induced defects and vibration-induced defects are likely to occur, and there is a tendency that photo-degradation and vibration-deterioration become strong.
Therefore, in the present invention, by containing a relatively large alkaline earth metal content in the weak electric field region and as little as possible in the strong electric field region, ionized alkaline earth metals even when photo-induced defects and vibration deterioration occur. It is considered that the metal bonds to compensate. Further, it is desirable to reduce the content of the alkaline earth metal as much as possible in the high electric field region where the photo-induced defects and the vibration-induced defects are unlikely to occur. It is considered that such a compensation mechanism in the weak electric field region does not appear by containing other elements. It is also conceivable that atomic alkaline earth metals compensate for photo-induced defects and vibration-induced defects and become ionized.

The above effects are particularly strong when the doping layer has a laminated structure as in the present invention. Furthermore, the above effect is obtained when the content of germanium and tin or carbon atoms in the i-type layer is changed as in the present invention, and when the hydrogen content and the fluorine content are changed in the layer thickness direction as described below. When it is changed, or when both the valence electron control agent which becomes a donor and the valence electron control agent which becomes an acceptor are contained in the i-type layer, it becomes stronger.

Next, an example of a desirable change pattern of the alkaline earth metal content of the i-type layer in the photovoltaic element of the present invention will be described.

FIG. 3-a or FIG. 14-a shows an example in which the alkaline earth metal content is drastically changed on the p-type layer side and the minimum content is on the p-type layer side inside the bulk. In this case, the change pattern of germanium, tin, or carbon content in the layer thickness direction is preferably as shown in FIG. 3-a or FIG. 14-a. When light is incident from the n-type layer side in the nip-type photovoltaic element, the change pattern may be reversed with respect to the layer thickness direction. Further, it is particularly effective when the p / i interface is composed of a heterojunction.

FIG. 3B or FIG. 14B is an example in which the p-type layer side is slowly changed to the n-type layer side, and the minimum alkaline earth metal content is at the interface with the n-type layer. In this case, the change pattern of germanium, tin, or carbon content with respect to the layer thickness direction is preferably as shown in FIG. 3-b or FIG. 14-b. When light is incident from the n-type layer side in the nip-type photovoltaic element, the change pattern may be reversed with respect to the layer thickness direction.

In FIG. 3-c or FIG. 14-c, p of the i-type layer is
This is an example in which the alkaline earth metal content changes drastically on the mold layer side and the n-type layer side. In this case, the change pattern of the content of germanium, tin, or carbon with respect to the layer thickness direction is preferably that shown in FIG. 3-c or FIG. 14-c. p / i
It is particularly effective when the interface and the n / i interface are heterojunctions.

In the present invention, the content of the alkaline earth metal changes in the layer thickness direction, but the maximum value (Cmax) of the content in the minute region is 3 × 10 ¹⁸ cm ^-3 or less, and the minimum value (Cmax).
min) is preferably 3 × 10 ¹⁴ cm ⁻³ or more.

The effect of the i-type layer has been described above. However, the alkaline earth metal may be contained in the layer thickness direction, and the content thereof may be changed by changing the RF doping layer and the MW.
It is also applicable to the doping layer and the RF-i layer described later.

In the photovoltaic device of the present invention, the i-type layer, the MW doping layer, the RF doping layer, and the RF-i layer were made to contain fluorine, so that the photovoltaic device was placed in a high temperature environment for a long period of time. In this case, light deterioration and vibration deterioration can be suppressed. In addition, it is possible to suppress light deterioration and vibration deterioration when the photovoltaic element is placed in a high humidity environment for a long period of time. In addition, it is possible to suppress photodegradation and vibration degradation when the photovoltaic element is left in an environment of high temperature and high humidity for a long period of time.

Although the details of the mechanism are unknown, the electric energy of the fluorine atom is very large, and the binding energy between the fluorine atom and the silicon atom, the fluorine atom and the germanium atom, the fluorine atom and the tin atom, or the fluorine atom and the carbon atom. Is a big one. Therefore, it is considered that a semiconductor layer that is thermally and mechanically stable and chemically stable can be obtained.

Further, like hydrogen, fluorine can terminate dangling bonds in the semiconductor layer, so that the defect level can be reduced. Further, since the atomic radius is very small like hydrogen, even when contained in the semiconductor layer, structural strain is not induced.

In the present invention, the content of fluorine is reduced near the interface of the semiconductor layer. As will be described later, in the photovoltaic device of the present invention, a large amount of hydrogen is contained in the vicinity of the interface of the semiconductor layer to relax the structural strain. In order to keep the packing density of the semiconductor layer high, it is considered desirable to reduce the fluorine content in the vicinity of the interface where the hydrogen content is increased. By doing so, the level induced by the bond between hydrogen and fluorine in the semiconductor or by the reduction in the mutual distance can be reduced.

Further, by including fluorine in the doping layer, the doping efficiency can be improved, and further the light transmittance can be improved, so that the photovoltaic device can be improved. In addition, since the microcrystalline silicon semiconductor material can be obtained with relatively low power by including fluorine in the doping layer, the doping layer made of the microcrystalline silicon semiconductor material is formed without adversely affecting the base layer. It is possible to reduce the interface state. Therefore, the photovoltaic element can be improved.

In the photovoltaic device of the present invention, since the MW doping layer is formed by the MWPCVD method, a particularly good quality doping layer can be obtained.

In the photovoltaic element of the present invention, since the doping layer containing fluorine has a laminated structure, the effect of containing fluorine (suppression of photodegradation and vibration degradation under high temperature and high humidity environment) is obtained. ) Can be further exerted. Further, the semiconductor layer is not peeled off even when the photovoltaic element is placed in the above environment.

Next, an example of a desirable change pattern of the fluorine content of the i-type layer in the photovoltaic element of the present invention will be described.

FIG. 5A shows an example in which the fluorine content is drastically changed on the p-type layer side and the maximum content is on the p-type layer side inside the bulk. In this case, the change pattern of the hydrogen content in the layer thickness direction is preferably that shown in FIG. Also n
When light is incident from the n-type layer side in the ip type photovoltaic element, the change pattern may be reversed with respect to the layer thickness direction. Further, it is particularly effective when the p / i interface is composed of a heterojunction.

FIG. 5B shows an example in which the maximum value of the fluorine content is gradually changed from the p-type layer side to the n-type layer side, and the maximum value is at the interface with the p-type layer. In this case, the change pattern of the hydrogen content in the layer thickness direction is preferably that shown in FIG. When light is incident from the n-type layer side in the nip type photovoltaic element, the change pattern may be reversed with respect to the layer thickness direction.

FIG. 5C shows an example in which the fluorine content changes abruptly on the p-type layer side and the n-type layer side of the i-type layer. In this case, the change pattern of the hydrogen content in the layer thickness direction is preferably that shown in FIG. It is particularly effective when the p / i interface and the n / i interface are heterojunctions.

Although the effect of the i-type layer has been described above, changing the fluorine content in the layer thickness direction can be achieved by using the RF doping layer, the MW doping layer, and the RF-type layer described later.
It is also applicable to the i layer.

In the photovoltaic device of the present invention, the content of hydrogen atoms in the i-type layer changes smoothly in the layer thickness direction.

Further, by increasing the hydrogen content in the vicinity of the interface between the doping layer and the i-type layer, the defect level is compensated by hydrogen atoms, so that dark current due to hopping conduction through the defect level (during reverse bias). Can be reduced, and the open circuit voltage and fill factor of the photovoltaic device can be improved.

By containing more hydrogen atoms in the vicinity of the interface than in the interior, it is possible to reduce the internal stress caused by the abrupt change of the constituent elements peculiar to the interface. As a result, it is possible to prevent the photoelectric conversion efficiency from being lowered even when it is left under vibration for a long time. In addition, a heterojunction (Si / SiGe, Si
It is particularly effective when it is made of C / SiGe or Si / SiC. It is generally considered that many interfaces and internal stresses exist at the interface of the heterojunction. In the photovoltaic device of the present invention, by containing a large number of hydrogen atoms near the interface of the heterojunction, flexibility near the hetero interface can be increased, internal stress can be relaxed, and the interface level can be reduced.

The following example shown in FIG. 8 can be given as a variation pattern of the hydrogen content in the layer thickness direction.

FIG. 8A shows an example in which the hydrogen content is drastically changed on the p-type layer side and the minimum value of the hydrogen content is on the p-type layer side inside the bulk. When light is incident from the n-type layer side in the nip-type photovoltaic element, the change pattern may be reversed with respect to the layer thickness direction. Further, it is particularly effective when the p / i interface is a heterojunction.

FIG. 8B is an example in which the p-type layer side is slowly changed to the n-type layer side, and the minimum content is at the interface with the p-type layer. In particular, when light is incident from the p-type layer side, i
The packing density is increased on the p-type layer side of the mold layer, which has the effect of suppressing photodegradation.

When light is incident from the n-type layer side in the nip-type photovoltaic element, the change pattern may be reversed with respect to the layer thickness direction. Further, it is particularly effective when the n / i interface is a heterojunction.

FIG. 8C shows an example in which the hydrogen content changes abruptly on the p-type layer side and the n-type layer side of the i-type layer. Further, it is particularly effective when the p / i interface and the n / i interface are heterojunctions. Further, it is particularly effective when the photovoltaic element is placed in an environment where vibration is large. Such a hydrogen content distribution can be applied not only to the i-type layer but also to each semiconductor layer.

The effect of the i-type layer has been described above. Changing the hydrogen content in the layer thickness direction
RF doping layer, MW doping layer, RF-
It is also applicable to the i layer.

In the present invention, photodegradation can be suppressed by incorporating both a valence electron control agent that serves as a donor and a valence electron control agent that serves as an acceptor into the i-type layer.

Although the details of the mechanism are unknown, in the present invention, the valence electron control agent in the i-type layer is not 100% activated. As a result, even if the weak bond is broken and a dangling bond is generated by light irradiation, it is considered that these react with the unactivated valence electron control agent to compensate the dangling bond.

Further, it is considered that there are many weak bonds particularly near the interface of the i-type layer, and in the case of the present invention, a large number of valence electron control agents are distributed near the interface with the doping layer,
It is considered that the non-activated valence electron control agent compensates for dangling bonds produced by breaking weak bonds.

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

In addition, the photovoltaic device of the present invention is such that the photoelectric conversion efficiency is unlikely to decrease even if it is left under vibration for a long period of time. Generally, since the constituent elements are very different at the interface between the i-type layer and the doping layer, internal stress exists at the interface,
It is believed that vibrations form dangling bonds and reduce the photoelectric conversion efficiency. However, even if a dangling bond is generated by containing both the valence electron control agent serving as a donor and the valence electron control agent serving as an acceptor inside the i-type layer, the valence electron control agent is not activated. It is considered to react to compensate dangling bonds. Further, when the content of the valence electron control agent that serves as a donor and the content of the valence electron control agent that serves as an acceptor change smoothly in the layer thickness direction, and the content of the valence electron control agent increases near the interface , Especially effective. In addition, a heterojunction (Si / SiGe, SiC / Si) is formed between the i-type layer and the doping layer.
It is particularly effective when it is made of Ge, Si / SiC, or the like. It is generally considered that many interfaces and internal stresses exist at the interface of the heterojunction. In the photovoltaic device of the present invention, the interface state can be reduced by including a large amount of inactive valence electron control agent near the interface of the heterojunction.

The following examples shown in FIG. 9 can be given as patterns of changes in the content of the valence electron control agent in the layer thickness direction. In FIG. 9, (B content) indicates the content of the valence electron control agent serving as the acceptor, and P content indicates the content of the valence electron control agent serving as the donor. FIG. 9-a shows p of the i-type layer.
Example in which the content is maximized on the mold layer side and the n-type layer side, and is minimized on the p-type layer side inside the bulk of the i-type layer, and the content is steeply sloped on the p-type layer side Is. In particular, it is effective when light is incident from the p-type layer side. When light is incident from the n-type layer side, the pattern may be reversed with respect to the layer thickness direction. It is particularly effective for a photovoltaic device having an i-type layer having a small band gap.

FIG. 9-b shows an example in which the i-type layer has a maximum content on the p-type layer side and a minimum content on the n-type layer side, and has a sharp content gradient on the p-type layer side. Is. In particular, it is effective when light is incident from the p-type layer side. When light is incident from the n-type layer side, the pattern may be reversed with respect to the layer thickness direction. Further, it is particularly effective for a photovoltaic device having an i-type layer having a small band gap.

FIG. 9-c shows that the content is maximized on the p-type layer side and the n-type layer side of the i-type layer, and that there is a steep gradient of the content on the p-type layer side and the n-type layer side. It is an example. In particular, it is effective when light is incident from the p-type layer side. When light is incident from the n-type layer side, the pattern may be reversed with respect to the layer thickness direction. The change pattern as shown in FIG. 9C is particularly effective for a photovoltaic device having an i-type layer made of a material having a large band gap. That is, in FIG. 9-c, when light is incident from the p-type layer side, carriers are excited also on the n-type layer side, so it is desirable to increase the content of the valence electron control agent also in this region.

In the i-type layer, it is preferable that the valence electron control agent serving as a donor and the valence electron control agent serving as an acceptor are contained so as to compensate each other.

Such a distribution of the valence electron controlling agent can be applied to each semiconductor layer.

In the photovoltaic device of the present invention, the i-type layer may contain germanium (or / and tin atom) and carbon atom. At that time, the content of germanium and tin atoms changes in the layer thickness direction, and also changes corresponding to the content of carbon atoms.

As shown in FIG. 16-b, where the content of carbon atoms is high, the content of germanium and tin atoms is low, and where the content of carbon atoms is low,
The content of germanium and tin atoms is high. In this case, the bandgap is as shown in FIG. 16-c, which has a longer wavelength (8000 nm) than that of the photovoltaic element in which the i-type layer does not contain germanium or tin atoms.
The light of can be collected efficiently. Furthermore, the open-circuit voltage can be improved as compared with a photovoltaic device in which the i-type layer contains germanium or tin atoms and does not contain carbon atoms. The band gap of the i-type layer is shown in FIG.
Since it is such as -c, the photoexcited carriers are well separated near the interface between the i-type layer and the p-type layer and the n-type layer,
Back diffusion of electrons into the p-type layer can be prevented. Further, the i-type layer contains germanium or tin atoms as well as carbon atoms, and these atoms change in the layer thickness direction, whereby stress such as strain inside the i-type layer can be relaxed.

In the photovoltaic element of the present invention, the slope of the tail state of the valence band of the i-type layer is an important factor that influences the characteristics of the photovoltaic element, and the tail at the minimum bandgap. It is preferable that the slope from the state to the slope of the tail state at the maximum band gap is smoothly continuous.

In the photovoltaic device of the present invention, the i-type layer (RF-i layer) formed by the RFPCVD method is provided between the RF doping layer and the i-type layer to further improve the photoelectric conversion efficiency. It is possible. Further, by containing more valence electron control agent than the inside of the i-type layer,
It is possible to improve the open circuit voltage and fill factor of the photovoltaic element.

For example, in FIG. 2-a, R in FIG.
An RF-i layer is provided between the Fp type layer and the i type layer. Further, in FIG. 2-b, the RF-i layer is provided between the RF n-type layer and the i-type layer in FIG. 1-a. Further, in FIG. 2-c, between the RF n-type layer and the i-type layer of FIG. 1-a,
Also, an RF-i layer is provided between the RF p-type layer and the i-type layer.

It is preferable that the RF-i layer is formed with a low power in which vapor phase reaction does not easily occur, and the deposition rate is 1 nm / sec or less. As a result, the packing density of the RF-i layer is increased, and when the RF-i layer is laminated with the i-type layer, the interface level of the i-type layer and the interface level of the doping layer are reduced. is there. In particular, the deposition rate of the i-type layer is 5 nm /
In the case of depositing at a deposition rate of sec or more, immediately after the glow discharge is started or stopped by the microwave, the vicinity of the surface of the i-type layer is not sufficiently relaxed, so that the interface state becomes extremely large. ing.

By forming the i-type layer on the RF-i layer, the i-type layer immediately after the start of glow discharge by microwaves is affected by the base, and the packing density is increased, and the dangling bond is increased. It is considered that the layer has a small number of layers and the surface level is reduced.

By forming the RF-i layer on the surface of the i-type layer, the surface level of the i-type layer can be reduced by annealing due to the diffusion of hydrogen atoms which occurs simultaneously with the formation of the semiconductor layer by RFPCVD. It is considered to be a thing.

Photodegradation can be suppressed by incorporating both a valence electron control agent serving as a donor and a valence electron control agent serving as an acceptor inside the RF-i layer. Although the details of the mechanism are unknown, in the case of the present invention, R
Both the valence electron control agent that serves as a donor and the valence electron control agent that serves as an acceptor are contained inside the F-i layer.
Not activated by 0%. As a result, even if dangling bonds are generated by light irradiation, it is considered that they react with the unactivated valence electron control agent to compensate dangling bonds.

In addition, the photovoltaic element of the present invention is such that the photoelectric conversion efficiency is unlikely to drop even if it is left under vibration for a long period of time. Although the detailed mechanism is unknown, by containing a large number of hydrogen atoms in the vicinity of the interface where the constituent element ratios are very different, it is possible to relax the internal stress that is often present in the vicinity of the interface and prevent the occurrence of defect levels. It is thought to be possible. Further, the valence electron control agent serving as a donor and the valence electron control agent serving as an acceptor, which are contained in large amounts in the vicinity of the interface, are not 100% activated, and even if the bond is broken by vibration, the valence electron control agent is not activated This is to compensate unbonded hands.

In the present invention, tin (Sn) may be contained in the i-type layer and / or the RF-i layer, and the layer may be composed of amorphous silicon tin (a-SiSn).

When carbon atoms are contained, tin (Sn) is contained in the i-type layer, and the i-type layer is made of amorphous silicon.
It may be composed of carbon (a-SiSnC).

Sn atoms can be covalently bonded to silicon (Si) atoms to obtain an amorphous silicon semiconductor material having a small bandgap, and the content of Ge atoms in amorphous silicon-germanium (a-SiGe) is By comparison, the same band gap can be obtained with a smaller Sn content.
Therefore, it is considered that a-SiSn can form a semiconductor having a narrow band gap with less structural disorder than a-SiGe. Furthermore, although Sn atoms have a larger covalent radius than Ge atoms, they are considered to be able to reduce structural strain when alloyed with Si atoms because they have more metallic properties.

The band gap of a-SiSn suitable for the present invention is 1.30 to 1.65 eV, and the Sn content is preferably 0.1 to 30%. The hydrogen content is preferably 0.1 to 30%, and the proportion of hydrogen bonded to Sn is preferably 1 to 40%.

The structure of a-SiSn suitable for the present invention contains microvoids and is distributed so that the relationship between the radius of the microvoids and the number of microvoids becomes a fractal relationship. is there. The ratio of microvoids deposited is preferably 0.5 to 3%. Although the reason is still unclear due to the distribution of the microvoids in this way, photodegradation can be suppressed as compared with a-SiGe.

At least one of the i-type layer, the RF-i layer, the MW doping layer and the RF doping layer may contain oxygen and / or nitrogen atoms. A small amount (1%) of oxygen or / and nitrogen atoms in the i-type layer and RF-i layer
By virtue of being included in the following), vibration deterioration of the photovoltaic element can be suppressed. The detailed mechanism is unknown, but by adding a trace amount, i-type layer, R
It is considered that the internal stress of the F-i layer can be relaxed. Furthermore, by including it in the RF-i layer, it is possible to prevent back diffusion of electrons or holes and improve the photoelectric conversion efficiency of the photovoltaic element. Further, by containing a small amount (1% or less) in the MW doping layer and the RF doping layer, the stress inside the layer can be relaxed and vibration deterioration can be suppressed. Further, by containing a large amount (1% or more), the open circuit voltage of the photovoltaic element can be improved. Preferably, the content of oxygen and / or nitrogen atoms changes in the layer thickness direction. As a preferable change mode, the content is large near one interface. A preferable variation in the i-type layer corresponds to the Ge or / and Sn atom content.

Although the photovoltaic element having the pin structure has been described above, the photovoltaic element in which the pin structure such as the pinpin structure or the pinpinpin structure is laminated, or ni.
The present invention can also be applied to a photovoltaic device having a laminated nip structure such as a pnip structure or a nipnipnip structure.

In the case of such a stacked photovoltaic element, n
RFn type layer / MWn type layer / RFp so that the layers formed by the MWPCVD method at the p junction (pn junction) are not continuous.
Type layer / MWp type layer / RFp type layer or RFn type layer /
MWn type layer / RFn type layer / RFp type layer / MWp type layer / R
It is desirable to form a junction having a structure such as an Fp type layer.

FIG. 6 is a schematic explanatory view of a deposition apparatus suitable for forming a semiconductor layer made of a non-single crystal silicon semiconductor material of the photovoltaic element of the present invention. The deposition apparatus 400
Is a deposition chamber 401, a vacuum gauge 402, an RF power source 403, a substrate 404, a heater 405, a waveguide 406, a conductance valve 407, an auxiliary valve 408, a leak valve 40.
9, bias electrode 410, gas introduction tube 411, applicator 412, dielectric window 413, sputtering power source 414,
The shutter 415, the target 416, the target shutter 417, a microwave power source (not shown), a vacuum exhaust pump, a raw material gas supply device, and the like. The raw material gas supply device (not shown) is a raw material gas cylinder, a valve,
It consists of a mass flow controller.

The photovoltaic element of the present invention is produced, for example, as follows.

First, the substrate 404 is brought into close contact with the heater 405 installed in the deposition chamber 401 shown in FIG.
-Ventilate below ⁵ Torr. A turbo molecular pump or an oil diffusion pump is suitable for this exhaust.
After sufficiently exhausting the inside of the deposition chamber, a gas such as H ₂ , He, and Ar is 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 semiconductor layer is flown. Turn on the heater 405 and put the substrate at 100-500 ° C.
Heat to. When the temperature of the substrate stabilizes at a predetermined temperature, a predetermined amount of a raw material gas for semiconductor layer formation is introduced into the deposition chamber from a gas cylinder via a mass flow controller. The supply amount of the raw material gas for forming the semiconductor layer, which is introduced into the deposition chamber, is appropriately determined according to the volume of the deposition chamber and the desired deposition rate.

When the semiconductor layer is formed by the MWPCVD method, the pressure during the formation of the semiconductor layer is a very important factor, and the optimum pressure in the deposition chamber is 0.5 to 50 mTorr.
Is preferred.

The MW power introduced into the deposition chamber is an important factor. The MW power is appropriately determined depending on the flow rate of the source gas introduced into the deposition chamber, but a preferable range is 0.005 to 1 W / cm ³ . The preferable frequency range of MW power is 0.5 to
10 GHz is mentioned. A frequency near 2.45 GHz is particularly suitable. Further, in order to form a reproducible semiconductor layer and to maintain a stable glow discharge for several hours to several tens of hours, the frequency stability of the MW power is very important. It is preferable that the frequency variation is within ± 2%. Further, the ripple of the microwave is preferably within ± 2%. The MW power generated from such a microwave power source (not shown) is applied to the waveguide 4
06 transmission from the applicator 412 to the dielectric window 4
It is introduced into the deposition chamber via 13. In this state, the source gas is decomposed for a desired time to form a semiconductor layer having a desired layer thickness on the substrate. After that, the introduction of MW power is stopped, the deposition chamber is evacuated, and after being sufficiently barged with a gas such as H ₂ , He or Ar, the substrate is taken out from the deposition chamber. The dielectric window is made of a material that transmits microwaves well, such as alumina ceramics, quartz, or boron nitride.

As a method for incorporating an alkaline earth metal into the semiconductor layer, as shown in FIG. 6, a target electrode 418 having a sputtering target 416 adhered thereto is installed in the deposition chamber, and a target power source is used as the target electrode. 414 is connected. Then, when the i-type layer is formed, a DC voltage or RF power is applied to the target electrode to sputter a target composed of a compound of an alkaline earth metal, so that the i-type layer contains a desired alkaline earth metal. is there. When the target composed of the alkaline earth metal compound is conductive, D is added to the target electrode.
C voltage or RF power is applied, and if non-conductive, RF power is applied.

As another method for incorporating an alkaline earth metal into the semiconductor layer, a target can be obtained from inside the deposition chamber of FIG.
It is also possible to remove the target electrode, introduce a gas containing an alkaline earth metal element into the deposition chamber through the gas introduction pipe, and make the i-type layer contain the gas by the above MWPCVD method.

When forming the i-type layer of the photovoltaic element of the present invention, RF power may be introduced into the deposition chamber together with MW power. In this case, it is desirable that the MW power to be introduced is also small in MW power required for 100% decomposition of the source gas introduced into the deposition chamber, and the RF power to be introduced at the same time is preferably larger than the MW power. . A preferable range of RF power to be simultaneously introduced is 0.01
Is a ~2W / cm ^3. A preferable frequency range of the RF power is 1 to 100 MHz. Especially 13.
56 MHz is optimal. Also, the fluctuation of RF frequency is ±
It is preferable that the waveform is smooth within 2%. It is appropriately selected depending on the area ratio of the area of the RF electrode for supplying RF power to the area of ground, but especially when the area of the RF electrode for supplying RF power is smaller than the area of ground, it is for supplying RF power. It is better to ground the self-bias (DC component) on the power supply side. Alternatively, a DC voltage may be applied to the bias electrode. A preferable range of the DC voltage is about 30 to 300V. Further, RF power and DC voltage may be applied to the bias electrode at the same time.

Although the details of the deposition mechanism of the preferred method for depositing the i-type layer described above are unknown, it is considered as follows.

MW required for 100% decomposition of raw material gas
MW lower than electric power is applied to the raw material gas to generate MW.
It is considered that an active species suitable for forming a semiconductor layer can be selected by causing an RF power higher than the power to act on the raw material gas at the same time as the MW power. Furthermore, the pressure in the deposition chamber when decomposing the source gas is 50 mTorr
In the following conditions, it is considered that the gas phase reaction is suppressed as much as possible because the mean free path of the active species suitable for forming a good quality semiconductor layer is sufficiently long. Further, it is considered that when the pressure in the deposition chamber is 50 mTorr or less, the RF power has almost no effect on the decomposition of the source gas and controls the potential between the plasma and the substrate in the deposition chamber. That is M
In the case of the WPCVD method, the potential difference between the plasma and the substrate is small, but the potential difference between the plasma and the substrate (the plasma is + and the substrate side is −) can be increased by introducing the RF power at the same time as the MW power. . Since the plasma potential is positively high with respect to the substrate, M
It is considered that active species decomposed by W power are deposited on the substrate and at the same time + ions accelerated by the plasma potential collide with the substrate to promote the relaxation reaction on the substrate surface and obtain a good-quality semiconductor layer. And it is particularly effective when the deposition rate is 5 nm / sec or more. Further, 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 the usual RFPCVD method, a fluorine-containing source gas (for example, SiF ₄ gas, GeF ₄ gas, CF) is used.
₄ gas, etc.) has a decomposition energy of hydrogen-containing source gas (eg, SiH ₄ gas, GeH ₄ gas, CH ₄ gas, etc.)
About 10 of decomposition energy is required. Therefore, since a large amount of energy is applied to the glow discharge, the underlying semiconductor layer may be adversely affected.
According to the method, since the frequency of the applied electromagnetic wave is originally high, the raw material gas containing fluorine can be decomposed with low power, and it is effective as a means for forming a semiconductor layer containing fluorine. Furthermore, since the radical of the source gas containing fluorine has a relatively long life, the mean free path can be further lengthened in the MWPCVD method, so that the discharge space and the substrate surface can be easily separated without decreasing the deposition rate. can do. Furthermore, when a source gas containing fluorine is used in the MWPCVD method, the stability of discharge is improved, and glow discharge can be maintained for a long time of 20 hours or more.

As a method of changing the alkaline earth metal content contained in the semiconductor layer in the layer thickness direction, the RF power applied to the target electrode is increased to increase the alkaline earth metal content, and the alkaline earth metal content is increased. The RF power applied to the target electrode may be reduced where the metal content is desired to be reduced.

Further, in the case of applying DC power, it is sufficient to apply a large negative DC voltage applied to the target electrode in the case where it is desired to increase the content of alkaline earth metal. When it is desired to reduce the voltage, a negative DC voltage applied to the target electrode may be applied.

When the alkaline earth metal is contained by the MWPCVD method or the RFPCVD method, the flow rate of the gas containing the alkaline earth metal may be changed with time.

As a method of changing the content of germanium and / or tin contained in the semiconductor layer in the layer thickness direction, the flow rate of the source gas containing germanium and / or tin may be changed with time.

As another method for changing the germanium and / or tin contained in the semiconductor layer in the layer thickness direction,
It is sufficient to increase the MW electric power to be introduced where it is desired to increase the germanium and / or tin and to decrease the MW electric power to be introduced where it is desired to decrease the germanium and / or tin. Although the detailed mechanism is unknown, it is considered that the radical containing active germanium and / or tin is increased by increasing the MW power, and thus more germanium or / and tin is contained.

As a method of changing the valence electron control agent contained in the semiconductor layer in the layer thickness direction, the flow rate of the raw material gas for containing the valence electron control agent may be changed with time.

As a method for changing the hydrogen content contained in the semiconductor layer in the layer thickness direction, the MW power introduced when the hydrogen content is desired to be increased and the MW power introduced where the hydrogen content is desired to be decreased. It should be small. Although the detailed mechanism is still unknown,
It is considered that by increasing the MW power, the number of radicals containing active hydrogen atoms increases, and more hydrogen atoms are contained.

As another method for changing the hydrogen content contained in the semiconductor layer in the layer thickness direction, the RF power applied to the RF electrode is increased when the hydrogen content is desired to be increased,
The RF power applied to the RF electrode may be reduced where it is desired to reduce the hydrogen content. Although the detailed mechanism is still unknown, when the RF power applied to the RF electrode is increased, the plasma potential rises, and more hydrogen ions are accelerated toward the substrate, so that more hydrogen is added to the semiconductor layer. It is considered to contain atoms.

Further, in the case of applying DC power at the same time as RF power, it is sufficient to apply a large voltage of + polarity to the DC voltage applied to the RF electrode in order to increase the content of hydrogen atoms. When it is desired to reduce the amount, a DC voltage applied to the RF electrode may be applied with a small voltage with positive polarity. Regarding the detailed mechanism,
Although it is unknown, it is considered that when the DC power applied to the RF electrode is increased, the plasma potential rises and hydrogen ions are further accelerated toward the substrate, so that the semiconductor layer contains more hydrogen atoms. To be

Still another method for changing the hydrogen content contained in the semiconductor layer in the layer thickness direction is to provide a halogen lamp or a xenon lamp in the deposition chamber in the semiconductor layer forming method of the present invention. Flashing these lamps during semiconductor layer formation temporarily raises the substrate temperature. At that time, when the hydrogen content is desired to be reduced, the number of flushes per unit time is increased, the substrate temperature is temporarily raised, and where the hydrogen content is desired to be increased, the number of flushes per unit time is decreased. The substrate temperature may be temporarily lowered. It is considered that the desorption reaction of hydrogen from the surface of the semiconductor layer is activated by temporarily raising the substrate temperature.

As another method for changing the hydrogen content contained in the semiconductor layer in the layer thickness direction, a raw material gas containing fluorine and a raw material gas containing hydrogen are introduced at the time of forming the semiconductor layer system, and the respective raw materials are introduced. The gas flow rate may be changed with time. When it is desired to contain a large amount of hydrogen, a small amount of the raw material gas containing fluorine is allowed to flow, and where it is desired to contain a small amount of hydrogen, a large amount of the raw material gas containing fluorine is allowed to flow.

As a method of changing the fluorine content contained in the semiconductor layer in the layer thickness direction, the flow rate of the gas containing fluorine may be changed with time when the semiconductor layer is formed. Where a large amount of fluorine is desired, a large amount of fluorine-containing gas is allowed to flow, and where a small amount of fluorine is desired, a small amount of fluorine-containing gas may be allowed to flow.

As another method of changing the fluorine content in the layer thickness direction, the flow rate of the gas containing hydrogen may be changed with time when the semiconductor layer is formed. When a large amount of fluorine is desired to be contained, a small amount of hydrogen-containing gas is allowed to flow, and where a small amount of fluorine is desired to be included, a large amount of hydrogen-containing gas may be allowed to flow. It is considered that this is because the fluorine bonded to the surface of the semiconductor layer reacts with a radical containing hydrogen, the fluorine is extracted from the semiconductor layer, and the fluorine incorporated in the semiconductor layer is relatively reduced.

When the semiconductor layer is deposited by the RFPCVD method, the capacitive coupling type RFPCVD method is suitable. RFP
When the RF doping layer and the RF-i layer are formed by the CVD method, the substrate temperature in the deposition chamber is 100 to 500 ° C., the pressure is 0.1 to 10 Torr, and the RF power is 0.01 to 5.0 W.
/ Cm ² , and the deposition rate is 0.1 to ² nm / sec as optimum conditions. In order to maintain the RF glow discharge for a long time, it is desirable that the frequency fluctuation and the ripple of the RF power source are each 2% or less.

Further, US Pat. No. 4,400,409 discloses roll-to-roll (Roll to Ro).
A plasma CVD apparatus that continuously forms semiconductor layers, which employs the method of (ll), is disclosed. It is desirable that the semiconductor layer of the photovoltaic element of the present invention be continuously manufactured using such an apparatus. According to this apparatus, a plurality of deposition chambers are provided, a long and flexible substrate is arranged along a path through which the substrates sequentially pass through the deposition chamber, and the deposition chamber has a desired conductivity type. It is said that a photovoltaic element having a pin junction can be continuously manufactured by continuously transporting the substrate in the longitudinal direction while forming a semiconductor layer. In this specification, a gas gate is used in order to prevent a source gas for containing each valence electron control agent in a semiconductor layer from diffusing into another deposition chamber and mixing into another semiconductor layer. Has been. Specifically, the deposition chambers are separated from each other by a slit-shaped separation passage, and a scavenging gas such as Ar, H ₂ , or He is flown into each separation passage to prevent mutual diffusion of the source gases. ing.

The alkaline earth metals used in the present invention are beryllium, magnesium, calcium, strontium and barium, and preferably beryllium, magnesium and calcium having a small ionic radius are used.

In the above semiconductor layer forming method, when an alkaline earth metal is sputtered to be contained in the semiconductor layer, the following metals, compounds or mixtures thereof are suitable as the target material. When the alkaline earth metal is contained in the semiconductor layer by the MWPCVD method or the RFPCVD method, the following compounds are suitable as the source gas containing the alkaline earth metal.

For gasification, a compound that is liquid at room temperature can be obtained by encapsulating a compound in a liquid cylinder and bubbling with an inert gas such as He or Ar. It is obtained by heating the liquid cylinder, melting the compound, and bubbling with an inert gas such as He and Ar.

Compounds for containing beryllium in a semiconductor include Be (NO ₃ ) ₂ .3H ₂ O and Be.
_{(CH 3) 2, Be (} C 2 H 5) 2, Be (C 3 H 7)
₂ , Be (C ₄ H ₉ ) _{2 and the} like.

To include magnesium in the semiconductor
The compound of Mg (NO₃ ) ₂ ・ 6H₂ O, Mg
(CH₃ COO)₂ , MgSO_Four ・ 7H₂ O etc.
Be done. Compound for containing calcium in semiconductor
As a product, Ca (ClO₃)₂ ・ 2H₂ O, CaBr₂
 ・ 6H₂ O, CaI ・ 6H₂ O, Ca (NO₃ )₂・ 4
H₂ O etc. are mentioned.

Examples of the compound for containing strontium in the semiconductor include SrCl ₂ .6H ₂ O and the like.

Examples of the compound for containing barium in the semiconductor include Ba (OH) ₂ .8H ₂ O and the like.

In addition, the above MWPCVD method and RFPCVD
In the method of forming a semiconductor layer by the method, the following gas or a compound that can be gasified by bubbling is suitable as a source gas.

As a source gas for containing silicon atoms in a semiconductor, SiH ₄ (H includes deuterium D),
Examples include SiX ₄ (X: halogen atom), SiX _n H _4-n (n is an integer), Si ₂ X _n H _6-n , and the like. Collectively referred to as "source gas (Si)". Especially SiH ₄ , SiF
₄ , SiD ₄ , and Si ₂ H ₆ are suitable.

The source gas for containing fluorine atoms in the semiconductor includes F ₂ , SiF ₄ , Si ₂ F ₆ , and GeF.
₄ , CF ₄ , C ₂ F ₆ , C ₂ ClF ₅ , CCl ₂ F ₂ ,
ClF ₃ , C ₃ F ₈ , NF ₃ , PF ₅ , BF ₃ , SF ₄
Etc. Collectively referred to as "source gas (F)".
Particularly, SiF ₄ , GeF ₄ , CF ₄ , PF ₅ , and BF ₃ are suitable.

As the source gas for containing carbon atoms in the semiconductor, CH ₄ (H includes deuterium D), C _n H
_{2n +} 2 (n is an _{integer), C n H 2n, CX} 4 (X is a halogen _{atom), C n X 2n + 2} , C n X 2n, C 2 H 2, C 6 H 6 and the like. Collectively referred to as "source gas (C)". CH ₄ , CD ₄ , and C ₂ H ₂ are particularly suitable.

Examples of the source gas for containing a germanium atom in the semiconductor include GeH ₄ (H includes deuterium D), Ge _n H _{2n + 2} , GeX ₄ (X is a halogen atom) and the like. . Collectively referred to as "source gas (Ge)".
GeH ₄ and GeD ₄ are particularly suitable.

As a source gas for containing tin atoms in the semiconductor, SnH ₄ (H includes deuterium D), Sn
_n H _{2n + 2} , SnX ₄ (X is a halogen atom), SnR ₄
(R: alkyl group), SnX _n R _{4-n and the} like.
Collectively referred to as "source gas (Sn)". Especially SnH ₄ ,
SnD ₄ , Sn (CH ₃ ) ₄ are suitable.

Examples of the valence electron control agent introduced to make the conductivity type of the semiconductor layer p-type include Group III atoms (B, Al, Ga, In, Tl) of the periodic table. Examples of the valence electron control agent introduced to make it n-type include group V atoms (P, As, Sb, Bi) and group VI atoms (S, Se, Te) in the periodic table.

A group III atom of the periodic table is introduced into the semiconductor layer.
As a raw material gas to enter, B ₂ H₆ , B_Four H10,
B_Five H₉ , BF₃ , B (CH₃ )₃ , B (C₂ H_Five )
₃ , BCl₃ , AlCl₃ , Al (CH₃ )₃ , GaC
l₃ , InCl₃ , TlCl₃Can be mentioned
It Collectively referred to as "source gas (III)". Especially B₂ 
H ₆ , B (CH₃ )₃ , B (C₂ H_Five )₃ , Al (C
H₃ )₃ Is suitable.

PH ₃ , P ₂ H ₄ , and PH ₄ are used as the source gas for introducing the group V atom of the periodic table into the semiconductor layer.
I, PF ₃ , PF ₅ , PCl ₃ , PCl ₅ , PBr ₃ ,
PBr ₅ , PI ₃ , AsH ₃ , AsF ₃ , AsCl ₃ ,
AsBr ₃ , AsF ₅ , SbH ₃ , SbF ₃ , SbF
₅ , SbCl ₃ , SbCl ₅ , BiH ₃ , BiCl ₃ ,
BiBr _{3 and the} like can be mentioned. Collectively referred to as "source gas (V)". Particularly, PH ₃ and AsH ₃ are suitable.

Source gases for introducing Group VI atoms of the periodic table into the semiconductor layer include H ₂ S, SF ₄ , SF
₆ , CS ₂ , H ₂ Se, SeF ₆ , TeH ₂ , TeF
₆ , (CH ₃ ) ₂ Te, (C ₂ H ₅ ) ₂ Te, and the like. Collectively referred to as "source gas (VI)". Especially H ₂
S and H ₂ Se are suitable.

As a source gas for containing oxygen atoms in the semiconductor, O ₂ , CO ₂ , CO, NO, NO ₂ and N are used.
₂ O, H ₂ O, CH ₃ CH ₂ OH, CH ₃ OH and the like can be mentioned. Collectively referred to as "source gas (O)". Especially O
₂ , NO is suitable.

Raw material for containing nitrogen atom in semiconductor
As a charge gas, N₂ , NO, NO₂, N₂ O, NH₃ etc
Is mentioned. Collectively referred to as "source gas (N)". Special
To N ₂ , NH₃ Is suitable.

Further, these raw material gases were replaced with H ₂ , D ₂ , and H.
It may be appropriately diluted with a gas such as e or Ar and introduced into the deposition chamber.

The structure of the photovoltaic element of the present invention will be described in more detail below. Substrate The substrate may be made of a conductive material alone, or may be one having a conductive layer formed on a support made of an insulating material or a conductive material. As the conductive material, NiCr, stainless steel, Al, Cr, Mo, Au,
Examples include metals such as Nb, Ta, V, Ti, Pt, Pb, and Sn, or alloys thereof. In order to use these materials as a support, it is preferable that the material has a sheet shape or a roll shape in which a long sheet is wound around a cylindrical body.

As the insulating material, polyester, polyethylene, polycarbonate, cellulose acetate,
Examples thereof include synthetic resins such as polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene and polyamide, and glass, ceramics and paper. In order to use these materials as a support, it is preferable that the material has a sheet shape or a roll shape in which a long sheet is wound around a cylindrical body. In these insulating supports, a conductive layer is formed on at least one surface thereof, and the semiconductor layer of the present invention is formed on the surface on which the induction layer is formed.

For example, in the case of glass, NiC is formed on the surface.
r, Al, Ag, Cr, Mo, Ir, Nb, Ta, V,
Ti, Pt, Pb, In ₂ O ₃ , ITO (In ₂ O ₃ +
SnO ₂ ), ZnO, etc., or a conductive layer made of an alloy thereof is formed, and NiCr, Al, Ag, Pb, Z is formed on the surface of a synthetic resin sheet such as a polyester film.
n, Ni, Au, Cr, Mo, Ir, Nb, Ta, V,
A conductive layer made of a material such as Ti or Pt or an alloy thereof is formed, and NiCr, Al, Ag or C is used for stainless steel.
r, Mo, Ir, Nb, Ta, V, Ti, Pt, Pb,
In ₂ O ₃ , ITO (In ₂ O ₃ + SnO ₂ ), ZnO
A conductive layer made of a material such as the above or an alloy thereof is formed. As a forming method, a vacuum evaporation method, a sputtering method, a screen printing method, or the like is used. The surface shape of the support is preferably smooth or uneven with peak heights of 300 to 1000 nm at maximum.

The thickness of the substrate is appropriately determined so that a desired photovoltaic element can be formed. However, when flexibility as a photovoltaic element is required, the function as a support is sufficiently exerted. 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.

Preferred substrate forms in the photovoltaic element of the present invention include Ag, Al, Cu, A on the support.
This is to form a conductive layer (light reflection layer) made of a metal having a high reflectance in the near infrared from the control light such as 1Si. The light reflecting layer is suitably formed by a vacuum vapor deposition method, a sputtering method or the like. As a layer thickness of these metals as a light reflecting layer, a suitable layer thickness is 10 nm to 5000 nm. In order to texture the surface of the light reflection layer, the substrate temperature at the time of formation may be 200 ° C. or higher. As a more desirable substrate form in the photovoltaic element of the present invention,
ZnO, SnO ₂ , In ₂ O ₃ , ITO, on the light reflection layer,
TiO ₂ , CdO, Cd ₂ SnO ₄ , Bi ₂ O ₃ , Mo
This is to form a conductive layer (reflection-increasing layer) made of O ₃ , Nax WO _3, or the like. Suitable methods for depositing the reflection-increasing layer include vacuum vapor deposition, sputtering, CVD, spraying, spin-on, and dipping. As the layer thickness of the reflection increasing layer, the optimum layer thickness varies depending on the refractive index of the material of the reflection increasing layer, but a preferable range of the layer thickness is 50 nm to 10 μm. To further texture the reflection-increasing layer,
It is preferable to raise the substrate temperature to 200 ° C. or higher when forming the reflection enhancing layer. MW doping layer (MWp type layer, MWn type layer) This layer is an important layer that influences the characteristics of the photovoltaic device.

The MW doping layer is composed of an amorphous silicon semiconductor material, a microcrystalline silicon semiconductor material, or a polycrystalline silicon semiconductor material. Amorphous (a
Abbreviated as −) as a silicon-based semiconductor material is aS
i, a-SiC, a-SiGe, a-SiGeC, a-
SiO, a-SiN, a-SiON, a-SiCON, etc. are mentioned. Microcrystalline (abbreviated as μc−) silicon-based semiconductor materials include μc-Si, μc-SiC, μc-
SiGe, μc-SiO, μc-SiGeC, μc-S
iN, μc-SiON, μc-SiOCN and the like can be mentioned. Polycrystalline (abbreviated as poly-) silicon-based semiconductor materials include poly-Si, poly-SiC, and p.
Examples include oli-SiGe and the like.

Particularly, for the MW doping layer on the light incident side, a crystalline semiconductor material with little light absorption or an amorphous semiconductor layer with a wide band gap is suitable. Specifically, a-Si
C, a-SiO, a-SiN, a-SiON, a-Si
CON, μc-Si, μc-SiC, μc-SiO, μ
c-SiN, μc-SiON, μc-SiOCN, po
Ly-Si and poly-SiC are suitable.

The amount of the valence electron control agent introduced to make the conductivity type p-type or n-type is 1000 ppm to 10 ppm.
% Is mentioned as a preferable range, and it is desirable that the content is increased at at least one interface.

Further, the contained hydrogen (H, D) and fluorine serve to compensate dangling bonds and improve the doping efficiency. Hydrogen and fluorine content is 0.1-3
An optimum amount is 0 at%. Especially when the MW doping layer is crystalline, 0.01 to 10 at% can be mentioned as the optimum amount. Further, a preferable distribution form is one in which the hydrogen content on the interface side is large, and the hydrogen content in the vicinity of the interface is 1.1 to 3 times the content in the bulk as a preferable range. . In addition, a preferable distribution form is one in which the fluorine content is small on the interface side, and a preferable range is 0.3 to 0.9 times in the bulk.

The introduction amount of oxygen and nitrogen atoms is 0.1 ppm
20%, 0.1ppm to 1% when contained in a trace amount
Is a preferable range.

As electric characteristics, the activation energy is 0.
It is preferably 2 eV or less, and most preferably 0.1 eV or less. The specific resistance is preferably 100 Ωcm or less, and most preferably 1 Ωcm or less. Furthermore, the layer thickness is 1
50 nm is preferable and 3 to 30 nm is optimum.

In particular, when forming a crystalline semiconductor material having a small light absorption or an amorphous semiconductor layer having a wide band gap, the source gas is diluted 2 to 100 times with a gas such as H ₂ , D ₂ and He. However, it is preferable to introduce a relatively high MW power. RF doping layer (RFp type layer, RFn type layer) This layer is an important layer that influences the characteristics of the photovoltaic device.

The RF doping layer is composed of an amorphous silicon semiconductor material, a microcrystalline silicon semiconductor material, or a polycrystalline silicon semiconductor material. Amorphous silicon semiconductor materials include a-Si, a-SiC, a-
SiGe, a-SiGeC, a-SiO, a-SiN,
Examples include a-SiON and a-SiCON. As microcrystalline silicon-based semiconductor material, μc-Si, μc-Si
C, μc-SiGe, μc-SiO, μc-SiGe
C, μc-SiN, μc-SiON, μc-SiOC
N, etc. are mentioned. Polycrystalline silicon-based semiconductor materials include poly-Si, poly-SiC, and poly-Si.
SiGe, etc. are mentioned.

Particularly, for the RF doping layer on the light incident side, a crystalline semiconductor material with little light absorption or an amorphous semiconductor layer with a wide band gap is suitable. Specifically, a-Si
C, a-SiO, a-SiN, a-SiON, a-Si
CON, μc-Si, μc-SiC, μc-SiO, μ
c-SiN, μc-SiON, μc-SiOCN, po
Ly-Si and poly-SiC are suitable.

The amount of the valence electron control agent introduced to make the conductivity type p-type or n-type is preferably 800 ppm to 8%, and is preferably less than the amount introduced in the MW doping layer. . Further, it is desirable that the content is large at at least one interface.

Further, the contained hydrogen (H, D) and fluorine function to compensate dangling bonds and improve the doping efficiency. Hydrogen and fluorine content is 0.1-2
An optimum amount is 5 at%. Especially when the RF doping layer is crystalline, 0.01 to 10 at% is mentioned as the optimum amount. Further, a preferable distribution form is one in which the hydrogen content on the interface side is large, and the hydrogen content in the vicinity of the interface is 1.1 to 3 times the content in the bulk as a preferable range. . In addition, a preferable distribution form is one in which the fluorine content is small on the interface side, and a preferable range is 0.3 to 0.9 times in the bulk.

The amount of oxygen and nitrogen atoms introduced is 0.1 ppm to
20%, 0.1ppm to 1% when contained in a trace amount
Is a preferable range.

As electric characteristics, the activation energy is 0.
It is preferably 2 eV or less, and most preferably 0.1 eV or less. The specific resistance is preferably 100 Ωcm or less, and most preferably 1 Ωcm or less. Furthermore, the layer thickness is 1
50 nm is preferable and 5 to 20 nm is optimum.

In particular, when forming a crystalline semiconductor material with little light absorption or an amorphous semiconductor layer with a wide band gap, the source gas is diluted 2 to 100 times with a gas such as H ₂ , D ₂ and He. However, it is preferable to introduce a relatively high RF power. i-Type Layer In the photovoltaic device of the present invention, the i-type layer is the most important layer for generating and transporting photoexcited carriers.

As the i-type layer, a slightly p-type or slightly n-type layer can be used, which contains silicon atoms and germanium and / or tin, and / or carbon atoms, and is, for example, aS.
iGe, a-SiSn, a-SiSnGe, a-SiG
An amorphous semiconductor material such as eC, a-SiSnC, or a-SiSnGeC is used.

As the i-type layer of the photovoltaic element of the present invention,
It contains hydrogen atoms, and the content of germanium or / and tin or the content of carbon atoms changes smoothly in the layer thickness direction. The preferable range of the germanium and / or tin content is 1 to 50%, and the preferable range of the band gap is 1.3 to 1.7 (eV).
Is. The preferred range of carbon atom content is 1
.About.50%, and the preferable range of the band gap is 1.
8 to 2.2 (eV).

It is desirable that the i-type layer contains both a valence electron control agent serving as a donor and a valence electron control agent serving as an acceptor. More preferably, the content of the valence electron control agent changes smoothly in the layer thickness direction. It is desirable that the content is large on the p-type layer side and / or the n-type layer side.

Hydrogen (H, D) and fluorine contained in the i-type layer serve to compensate dangling bonds in the i-type layer and improve the product of carrier mobility and life in the i-type layer. It is a thing. Further, it has a function of compensating for the interface state of the interface, and has an effect of improving the photovoltaic power, the photocurrent and the photoresponsiveness of the photovoltaic device. The optimum content of hydrogen and fluorine in the i-type layer is 1 to 30 at%. In particular, the one in which the hydrogen content is large on the interface side is mentioned as a preferable distribution form, and the range of 1.1 to 3 times in the bulk is mentioned as a preferable range. A preferable distribution form is one in which the fluorine content is small on the interface side, and a preferable range is 0.3 to 0.9 times in the bulk.

The introduction amount of oxygen and nitrogen atoms is 0.1 ppm
1% is a suitable range.

The layer thickness of the i-type layer largely depends on the structure of the photovoltaic element (for example, single cell, tandem cell, triple cell) and band gap, but is 0.05 to 1.0 μm.
m is mentioned as the optimum layer thickness.

The i-type layer of the present invention has a deposition rate of 2.5 nm.
Even if it is increased above / sec, the tail state on the valence band side
It is a little, and the tilt of the tail state is 60 me.
V or less and not determined by electron spin resonance (ESR)
Bond density is 10¹⁷/ Cm ³ It is the following.

The MWPCVD method is used to form the i-type layer,
It is desirable to use RF in the MWPCVD method as described above.
Power is introduced at the same time, and more preferably RF power and DC power are introduced at the same time in the MWPCVD method as described above. RF-i layer In the photovoltaic device of the present invention, the RF-i layer is an important layer for transporting photoexcited carriers.

The RF-i layer is slightly p-type and slightly n-type.
A mold layer can also be used and is composed of an amorphous silicon semiconductor material or a microcrystalline silicon semiconductor material. Examples of the amorphous silicon-based semiconductor material include aS
i, a-SiC, a-SiO, a-SiN, a-SiG
e, a-SiGeC, a-SiSn, a-SiSnC, etc. are mentioned. Examples of the microcrystalline silicon-based semiconductor material include μc-Si, μc-SiC, μc-SiGe, and μc.
-SiSn, μc-SiO, μc-SiN, μc-Si
ON, μc-SiOCN and the like can be mentioned.

As shown in FIG. 2-a, the RF-i layer on the light incident side is a-Si, a-SiC, a-SiO, a-SiN.
The open circuit voltage of the photovoltaic element can be improved by using a semiconductor material such as.

R on the side opposite to the light incident side as shown in FIG.
As the F-i layer, a-Si, a-SiGe, a-SiS
By using a semiconductor material such as n, a-SiGeC, or a-SiSnC, the short-circuit current of the photovoltaic element can be improved.

Hydrogen (H, D) and fluorine contained in the RF-i layer serve to compensate dangling bonds in the RF-i layer, and are the product of carrier mobility and lifetime in the RF-i layer. Is to improve. It also has the effect of compensating for the interface state of the interface, and has the effect of improving the photovoltaic power, photocurrent, and photoresponsiveness of the photovoltaic device. The optimum content of hydrogen and fluorine in the RF-i layer is 1 to 30 at%. In particular, the one in which the hydrogen content is large on the interface side is mentioned as a preferable distribution form, and the range of 1.1 to 3 times the content in the bulk is mentioned as a preferable range. In addition, a preferable distribution form is one in which the fluorine content is low on the interface side, and a preferable range is 0.3 to 0.9 times the content in the bulk.

As another desirable form, a valence electron controlling agent (group V atom and / or group VI atom of the periodic table) serving as a donor and a valence electron controlling agent (group III atom of the periodic table) serving as an acceptor are used. Both are included. Further, it is preferable to contain a valence electron control agent as a donor and a valence electron control agent as an acceptor so as to compensate each other. 600 ppm or less is mentioned as a preferable range of the introduction amount of each of the group III atom, the group V atom, and the group VI atom of the periodic table introduced into the RF-i layer.

The amount of oxygen and nitrogen atoms introduced is 0.1 ppm to
20%, 0.1ppm to 1% when contained in a trace amount
Is a preferable range.

The optimum layer thickness of the RF-i layer is 0.5 to 30 nm or less, and the tail state on the valence band side is small, and the slope of the tail state is 5.
It is 5 meV or less, and the density of dangling bonds by electron spin resonance (ESR) is 10 ¹⁷ / cm ³ or less. Transparent electrode Indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ) and ITO (In ₂ O ₃ + SnO ₂ ) are suitable materials for the transparent electrode.

The sputtering method and the vacuum evaporation method are the most suitable deposition methods for depositing the transparent electrode. When depositing by a sputtering method, a target such as a metal target or an oxide target is appropriately combined and used.

When depositing by the sputtering method, the substrate temperature
The degree is an important factor, and 20 ° C to 600 ° C is preferable.
Listed as a range. Also, the gas for sputtering
Examples of the gas include inert gas such as Ar gas. Before again
Oxygen gas (O ₂ ) Is added as needed.
Is preferable. Especially targeting metal
Oxygen gas (O₂ ) Is mandatory.
Furthermore, the target is sputtered with the inert gas or the like.
When ringing, the pressure in the discharge space is effectively
0.1 to 50 mTorr is preferable for performing
Listed as a range. The deposition rate of the transparent electrode is
The optimum deposition rate depends on the pressure and discharge power in the space
Is in the range of 0.01 to 10 nm / sec.

Suitable vapor deposition sources for depositing transparent electrodes in the vacuum vapor deposition method include metal tin, metal indium, and indium-tin alloy. Moreover, the range of 25 ° C. to 600 ° C. is a suitable range for the substrate temperature when depositing the transparent electrode. Further, it is necessary to introduce oxygen gas (O ₂ ) and deposit at a pressure of 5 × 10 ⁻⁵ Torr to 9 × 10 ⁻⁴ Torr. By introducing oxygen in this range, the metal vaporized from the vapor deposition source reacts with oxygen in the vapor phase to deposit a good transparent electrode. The preferable deposition rate range of the transparent electrode under the above conditions is 0.01 to 10 nm / sec. Deposition rate is 0.0
If it is less than 1 nm / sec, the productivity will decrease and 10 nm /
If it is larger than sec, a rough film is formed and the transmittance, the conductivity and the adhesion are lowered.

The layer thickness of the transparent electrode is preferably deposited under the conditions satisfying the conditions of the antireflection film. As a specific layer thickness of the transparent electrode, 50 to 500 nm is mentioned as a preferable range. Current collector electrode In order to allow more light to enter the i-type layer, which is a photovoltaic layer, and to efficiently collect the generated carriers in the electrode, the shape of the current collector electrode (the shape viewed from the light incident direction), and Material is important. Usually, a comb-shaped collector electrode is used, and the line width, the number of wires, etc. 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. . The line width is usually about 0.1 mm to 5 mm. The material of the collector electrode is Fe, Cr, Ni, Au, Ti, P
d, Ag, Al, Cu, AlSi, C (graphite)
Etc. are used, and Ag, Cu, A, which usually has a small specific resistance,
Metals such as 1, Cr, C, and alloys thereof are suitable.

The layer structure of the collector electrode may be composed of a single layer, or may be composed of a plurality of layers.

It is desirable that these metals are formed by a vacuum vapor deposition method, a sputtering method, a plating method, a printing method or the like.

In the case of forming by a vacuum evaporation method, a mask having a current collecting electrode shape is brought into close contact with the transparent electrode, and a desired metal evaporation source is evaporated in a vacuum by electron beam or resistance heating,
A collecting electrode having a desired shape is formed on the transparent electrode.

In the case of forming by the sputtering method, a mask having a current collecting electrode shape is brought into close contact with the transparent electrode, Ar gas is introduced into a vacuum, DC is applied to a desired metal sputter target, and glow discharge is generated. By letting
A metal is sputtered to form a collector electrode having a desired shape on the transparent electrode.

In the case of forming by a printing method, Ag paste, Al paste and carbon paste are printed by a screen printing machine.

The layer thickness of these metals is from 10 nm to
0.5 mm is mentioned as a suitable layer thickness.

Next, the power generation system of the present invention will be described.

The power generation system of the present invention comprises: the photovoltaic element of the present invention; and the voltage and / or current of the photovoltaic element to monitor the electric power from the photovoltaic element to a storage battery and / or an external load. It is composed of a control system for controlling supply, and a storage battery for storing power from the photovoltaic element and / or supplying power to an external load. Figure 1
3 is 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 1303, and a backflow prevention diode (CD) 130 is used.
4. A voltage control circuit (constant voltage circuit) 1305 that monitors the voltage and controls the voltage, a storage battery 1302, a load 1301 and the like.

For modularization, an adhesive sheet and a nylon sheet may be placed on a flat plate, and an adhesive sheet and a fluororesin sheet may be placed on the sheet and vacuum laminated. 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 battery and a flywheel energy storage unit.

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

The power generation system using such a photovoltaic element 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 time, and the photovoltaic power can be applied even when the irradiation light applied to the solar cell fluctuates. Since it functions sufficiently as an element, it exhibits excellent stability.

[0219]

The present invention will be described in more detail with reference to the following examples, but it goes without saying that the present invention is not limited to these examples.

Example 1 Using the deposition apparatus shown in FIG. 6, a solar cell of FIG. 1-b having germanium atoms in the i-type layer was produced. The n-type layer 112 was formed by the RFPCVD method.

First, the substrate 111 was manufactured. A stainless steel substrate having a thickness of 0.5 mm and 50 × 50 mm ² was ultrasonically cleaned with acetone and isopropanol and dried with warm air. A light reflection layer of Ag having a thickness of 0.3 μm and a 35 μm thick light reflection layer on the surface of the stainless steel substrate at room temperature using the sputtering method.
A ZnO reflection-increasing layer having a layer thickness of 1.0 μm is formed at 0 ° C.,
The manufacture of the substrate 111 is completed.

Next, the deposition apparatus 400 can carry out both the MWPCVD method and the RFPCVD method, and can also carry out the sputtering of alkaline earth metal at the same time. Using this, each semiconductor layer was formed on the reflection increasing layer.

A raw material gas supply device (not shown) is connected to the deposition device 400 through a gas introduction pipe. The raw material gas cylinders were all refined to ultra-high purity, and SiH
₄ gas cylinder, SiF ₄ gas cylinder, CH ₄ gas cylinder, GeH ₄ gas cylinder, GeF ₄ gas cylinder, SnH
₄ gas cylinders, PH ₃ / H ₂ (dilution: 100ppm)
Gas cylinder, B ₂ H ₆ / H ₂ (dilution: 100 ppm)
Gas cylinder, H ₂ gas cylinder, He gas cylinder, O ₂ /
He gas cylinder, N ₂ / He gas, Mg heated to 100 ℃ (NO ₃₎ connecting the liquid cylinder of ₂ · 6H ₂ O.
The He gas cylinder is connected to the liquid cylinder, and He gas can be bubbled. Mg was used for the target 416, it was attached to the target electrode 418, and an RF power source was used for the target power source 414.

Next, the back surface of the substrate 111 on which the reflection layer and the reflection increasing layer are formed is brought into close contact with the heater 405, the leak valve 409 in the deposition chamber 401 is closed, the conductance valve 407 is fully opened, and vacuum exhaust (not shown) is performed. The inside of the deposition chamber 401 was evacuated by a pump until the pressure became about 1 × 10 ⁻⁵ Torr.

After the preparation for film formation is completed as described above, the RFn type layer 1 made of μc-Si is formed on the substrate 111.
12, the i-type layer 114 made of a-SiC, the RFp-type layer 115 made of a-SiC, and the MWp-type layer 116 made of a-SiC were sequentially formed.

In order to form the RFn-type layer 112 made of μc-Si, H ₂ gas is introduced into the deposition chamber 401, the flow rate is adjusted to 300 sccm by the mass flow controller, and the pressure in the deposition chamber 401 is adjusted. The conductance valve 407 was adjusted to 1.0 Torr. Heater 405 so that the temperature of substrate 111 is 350 ° C.
Was set, and when the substrate temperature became stable, SiH ₄ gas and PH ₃ / H ₂ gas were caused to flow into the deposition chamber 401.
At this time, the SiH ₄ gas flow rate is ₂ sccm, the H ₂ gas flow rate is 100 sccm, and the PH ₃ / H ₂ gas flow rate is 200 sccm.
cm, and the pressure in the deposition chamber 401 was adjusted to 1.0 Torr. The power of the RF power source was set to 0.02 W / cm ³ , RF power was introduced to the bias electrode 410 to cause glow discharge, the shutter 415 was opened, and the substrate 11
1, the formation of the RF n-type layer 112 is started, and the layer thickness is 20 nm.
When the RF n-type layer 112 is formed, the shutter 41
5 is closed, RF power is turned off, glow discharge is stopped, RF
The formation of the n-type layer 112 is completed. Si into the deposition chamber 401
After stopping the inflow of H ₄ gas and PH ₃ / H ₂ and continuing to flow H ₂ gas into the deposition chamber 401 for 5 minutes, the inflow of H ₂ is also stopped and the inside of the deposition chamber 401 and the gas pipe is 1 × 10 5. ^-5 To
It was evacuated to rr.

The i-type layer 114 made of a-SiGe is MW.
Simultaneous PCVD method and alkaline earth metal sputtering
Formed by doing. First, H₂ 30 gas
Introduced 0 sccm, pressure 0.01 Torr, substrate 11
The temperature of 1 was set to 350 ° C. Stable substrate temperature
By the way, SiH_Four Gas, GeH_Four Gas, He gas
Flow in, SiH_Four Gas flow rate is 130 sccm, Ge
H_Four Gas flow rate is 20 sccm, He gas flow rate is 150 s
ccm, H₂ The gas flow rate was 150 sccm, and the deposition chamber 4
Adjust the pressure in 01 to 0.01 Torr
It was Next, the power of the RF power source is 0.32 W / cm³ Set to
And applied to the bias electrode. After that, MW not shown
The power of the power supply is 0.20 W / cm³ Set to the dielectric window 4
MW power is introduced into the deposition chamber 401 through the
-A discharge has occurred. Next, set the target power to 20
Set to 0W, open the target shutter 417, R
Formation of the i-type layer 114 was started on the Fn-type layer 112. Ma
Connect the computer connected to the flow controller
Using SiH according to the change pattern shown in FIG. _Four 
Gas flow rate, GeH_Four Change the gas flow rate to obtain a layer thickness of 300n
When the i-type layer of m is formed, the shutter and the target are
Close the shutter, MW power supply, RF power supply, target
The power supply 414 is turned off to stop the glow discharge, and the i-type layer 114
Finished formation. SiH_Four Gas, GeH_Four Gas, He gas
Stop the flow rate for 5 minutes, H₂ After continuing to flow the gas, H
₂ Also stop the inflow of gas, in the deposition chamber 401 and the gas pipe
1 x 10^-FiveEvacuated to Torr.

To form the RF p-type layer 115 made of a-SiC, H ₂ gas was introduced at 300 sccm, the pressure was 1.0 Torr, and the substrate temperature was 200 ° C. When the substrate temperature becomes stable, SiH ₄ gas, CH
₄ gas and B ₂ H ₆ / H ₂ gas are caused to flow into the deposition chamber 401, SiH ₄ gas flow rate is 5 sccm, CH ₄ gas flow rate is 1 sccm, H ₂ gas flow rate is 100 sccm, and B ₂ H ₆
/ H ₂ gas flow rate is 200 sccm, pressure is 1.0 Torr
It was adjusted to be r. RF power 0.06W
/ Cm ³ , glow discharge is generated, the shutter is opened, formation of the RFp type layer 115 on the i-type layer 114 is started, and the shutter 415 is closed when the RFp type layer 115 having a layer thickness of 10 nm is formed, The RF power supply was turned off, the glow discharge was stopped, and the formation of the RF p-type layer 115 was completed. SiH ₄ gas, CH ₄ gas, B ₂ H ₆ / in the deposition chamber 401
Stopping the flow of H ₂ gas for 5 minutes, after which continued to flow H ₂ gas, stopping the inflow of the H ₂ gas, the deposition chamber 401 and the gas pipes were evacuated to 1 × 10 ^-5 Torr.

A MWp type layer 116 made of a-SiC is formed.
H to make₂ Introduce gas at 500 sccm and deposit chamber
The pressure inside 401 is 0.02 Torr, the substrate temperature is 200
The temperature was set to be ° C. Where the substrate temperature is stable
And SiH_Four Gas, CH_Four Gas, B₂ H₆ / H₂ Gas
Let it flow. At this time, SiH_Four Gas flow rate is 10 scc
m, CH_Four Gas flow rate is 2 sccm, H₂ Gas flow rate is 10
0 sccm, B₂ H₆ / H ₂ Gas flow rate is 500scc
m and the pressure were adjusted to 0.02 Torr. So
After that, the power of the MW power source (not shown) is 0.40 W / cm.³ 
And introduce MW power through the dielectric window 413,
Glow discharge is generated, the shutter 415 is opened, and RF
The formation of the MW p-type layer 116 was started on the p-type layer 115.
When the MWp type layer 116 having a layer thickness of 10 nm is formed,
Close the shutter 415, turn off the MW power, and release the glow.
The electricity was stopped and the formation of the MW p-type layer 116 was completed. SiH_Four 
Gas, CH_Four Gas, B₂ H₆ / H₂ Stop the flow of gas,
5 minutes, H₂ After continuing to flow the gas, H₂ Gas inflow
Stop the deposition chamber 401 and the gas pipe to 1 x 10^-FiveT
Evacuate to orr and close auxiliary valve 408.
The valve 409 was opened to leak the deposition chamber 401.

Next, the transparent electrode 1 is formed on the MWp type layer 116.
As No. 17, ITO having a layer thickness of 70 nm was vacuum deposited by a vacuum deposition method.

Next, a mask having comb-shaped holes is placed on the transparent electrode 117, and Cr (40 nm) / Ag (1000 n
A comb-shaped collector electrode made of m) / Cr (40 nm) was vacuum deposited by the vacuum deposition method.

[0232] Thus, the production of the solar cell was completed. This solar cell will be referred to as SC Ex 1 hereinafter, and the RFn type layer 1
12, i-type layer 114, RFp-type layer 115, MWp-type layer 1
The conditions for forming 16 are shown in Table 1.

[0233]

[Table 1] Comparative Example 1-1 When forming the i-type layer 114, as shown in FIG.
A solar cell (SC ratio 1-1) was produced under the same conditions as in Example 1 except that the SiH ₄ gas flow rate and the GeH ₄ gas flow rate were changed in accordance with the above procedure.

(Comparative Example 1-2) When forming the i-type layer 114, a solar cell was formed under the same conditions as in Example 1 except that the SiH ₄ gas flow rate was 130 sccm and the GeH ₄ gas flow rate was 20 sccm. (SC ratio 1-2) was produced.

Comparative Example 1-3 A solar cell (SC ratio 1-3) was prepared under the same conditions as in Example 1 except that the RFp type layer 115 was not formed and the MWp type layer 116 had a layer thickness of 20 nm. did.

The solar cell (SC Ex 1) and (SC ratio 1-
1) to (SC ratio 1 to 3) were prepared in 6 pieces, and initial photoelectric conversion efficiency (photovoltaic power / incident light power), vibration deterioration,
Photodegradation, vibration degradation when applying a forward bias voltage, and photodegradation were measured.

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 VI characteristic. As a result of the measurement, for (SC Ex 1), (SC Ratio 1-
The initial photoelectric conversion efficiencies of 1) to (SC ratio 1-3) are as follows.

(SC ratio 1-1) 0.89 times (SC ratio 1-2) 0.91 times (SC ratio 1-3) 0.92 times For the measurement of vibration deterioration, the initial photoelectric conversion efficiency was measured in advance. Installed solar cells in a dark place with a humidity of 50% and a temperature of 25 ° C.
AM1.5 (100 mW / cm ² ) after adding for 0 hours
It was determined by the rate of decrease in photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after vibration deterioration test / initial photoelectric conversion efficiency).

The photodegradation was measured by installing a solar cell whose initial photoelectric conversion efficiency had been measured in advance in an environment of a humidity of 50% and a temperature of 25 ° C. and applying AM1.5 (100 mW / cm ² ) light to 5 times.
AM1.5 (100 mW / cm ² ) after irradiation for 00 hours
The rate of decrease in photoelectric conversion efficiency under irradiation (photoelectric conversion efficiency after photodegradation test / initial photoelectric conversion efficiency) was used. As a result of the measurement, for (SC Ex 1), (SC ratio 1-1) to (SC
The rate of decrease in photoelectric conversion efficiency after photodeterioration and the rate of decrease in photoelectric conversion efficiency after vibration deterioration of ratio 1-3) were as follows.

Vibration deterioration Optical deterioration (SC ratio 1-1) 0.89 times 0.86 times (SC ratio 1-2) 0.90 times 0.87 times (SC ratio 1-3) 0.91 times 0.1. A 88 times forward bias was applied to measure vibration deterioration and light deterioration. Two solar cells whose initial photoelectric conversion efficiencies were measured in advance were placed in a dark place at a humidity of 50% and a temperature of 25 ° C., and a forward bias voltage of 0.8 V was applied. The above vibration was applied to one solar cell to measure the vibration deterioration, and the other solar cell was irradiated with light of AM1.5,
The photodegradation was measured. As a result of the measurement, with respect to (SC Ex. 1), the rate of decrease in photoelectric conversion efficiency after vibration deterioration of (SC ratio 1-1) to (SC ratio 1-3) and the decrease in photoelectric conversion efficiency after light deterioration. The rates are as follows.

Vibration deterioration Photodegradation (SC ratio 1-1) 0.87 times 0.86 times (SC ratio 1-2) 0.89 times 0.90 times (SC ratio 1-3) 0.88 times 0. 89 times Next, the state of delamination was observed using an optical microscope.
Delamination was not observed in (SC Ex 1), (SC ratio 1-1), and (SC ratio 1-2), but slight delamination was observed in (SC ratio 1-3).

Next, using a glass substrate and a stainless substrate,
A sample was prepared in which the SiH ₄ flow rate and the GeH ₄ flow rate were constant over time. An i-type layer was prepared under the same conditions as in Example 1 except that the flow rate was constant and the layer thickness was 1 μm, and the samples were used for bandgap measurement and analysis. further,
Several samples with different flow rates were prepared.
The band gap (Eg) of the glass substrate sample was obtained using a spectrophotometer, and further, the Ge content of the stainless substrate sample was analyzed using an Auger electron spectroscopy analyzer. The relationship between the Ge content in the i-type layer and the band gap was obtained using the results of both. In addition, the solar cell (SC Ex 1), (SC
When the Ge content in the layer thickness direction of the ratio 1-3) was determined, it was as shown in FIG. 7-c. Further, when the change in the band gap was obtained by using the relationship between the Ge content and the band gap described above, the result was as shown in FIG. 7-c. Similarly (S
When the changes in the Ge content and the band gap in the layer thickness direction of the C ratio 1-1) were obtained, it was as shown in FIG. 7-d.
Similarly, when the Ge content (SC ratio 1-2) is obtained,
It was found that the Ge content did not change in the layer thickness direction and was constant, and the band gap was 1.51 (eV). As described above, it was found that the changes in the Ge content and the band gap with respect to the layer thickness direction depend on the GeH ₄ gas flow rate introduced.

Further, the vibration deterioration and the light deterioration in the high temperature environment and the vibration deterioration and the light deterioration in the high humidity environment were measured, and (SC Ex 1) was from (SC Ratio 1-1) to (SC Ratio 1).
-3) had better characteristics. Furthermore, when a forward bias is applied in the above environment, (SC
Ex. 1) had better characteristics than (SC ratio 1-1) to (SC ratio 1-3).

As described above, the solar cell of this embodiment (SC Ex 1) is the same as the conventional solar cells (SC ratio 1-1) to (SC ratio 1).
It was found that it has more excellent characteristics than that of (3).

Example 2 A solar cell (SC Ex 2) in which the Ge content and the alkaline earth metal content in the i-type layer were changed as shown in FIG. 3-b was produced. A solar cell (SC Ex 2) was produced under the same conditions as in Example 1 except that the GeH ₄ gas flow rate monotonously increased with respect to time, the SiH ₄ gas flow rate monotonically decreased with respect to time, and the target power monotonically decreased. did. When the change in the band gap in the layer thickness direction was obtained by the same method as in Example 1, it was found that the change was as shown in FIG. When the same measurement as in Example 1 was carried out, the solar cell of this example (SC Ex 2) exhibited further excellent characteristics as compared with the conventional solar cells (SC ratio 1-1) to (SC ratio 1-3). Found to have.

Example 3 A photodiode having the layer structure shown in FIG. 1-c was produced.

First, the substrate 121 was manufactured. A glass substrate with a thickness of 0.5 mm and 20 × 20 mm ² is ultrasonically cleaned with acetone and isopropanol, dried with warm air, and a layer thickness of 0.1 μm is formed on the glass substrate surface at room temperature by a vacuum deposition method.
Then, the Al light reflecting layer was formed, and the fabrication of the substrate 121 was completed.

M is formed on the substrate 121 in the same manner as in the first embodiment.
Wn type layer (a-SiC) 122, RFn type layer (a-Si)
C) 123, i-type layer (a-SiGe) 124, and RFp-type layer (μc-SiC) 125 were sequentially formed. Table 2 shows the layer forming conditions of the semiconductor layer.

Next, the transparent electrode 127 and the current collecting electrode 128 similar to those in Example 1 were formed on the RF p-type layer 127.

[0250]

[Table 2] (Comparative Example 3-1) When forming the i-type layer 124, FIG.
7D, the SiH ₄ gas flow rate and the GeH ₄ gas flow rate are changed with time, and the band gap is changed as shown in FIG.
D ratio 3-1) was produced.

(Comparative Example 3-2) A photodiode (PD ratio 3--) was formed under the same conditions as in Example 3 except that the RFn type layer 123 was not formed and the MWn type layer 122 had a layer thickness of 40 nm.
2) was produced.

First, the on / off ratio (photocurrent / dark current measurement frequency of 10 kHz when irradiated with AM1.5 light) of the manufactured photodiode was measured. This is called an initial on / off ratio. Next, the same measurement as in Example 1 was performed for the on / off ratio. As a result, the photodiode (PD Ex 3) of this example was compared to the conventional photodiode (PD Ratio 3).
-1), (PD ratio 3-2), it was found that it has more excellent characteristics.

Example 4 A solar cell of FIG. 1-b having a nip type structure was manufactured by reversing the stacking order of the n type layer and the p type layer. As in Example 1, the RF p-type layer (μc
-Si), i-type layer (a-SiGe), RFn-type layer (a-
SiC) and a MWn type layer (a-SiC) were formed. When forming the i-type layer, as shown in FIG. 7-b, SiH ₄ gas flow rate,
The GeH ₄ gas flow rate was changed with time so that the position where the Ge content became maximum was closer to the p-type layer than the center position of the i-type layer. The layer forming conditions of the semiconductor layer are shown in Table 3.

A solar cell (SC Ex 4) was manufactured under the same conditions as in Example 1 except for the semiconductor layer and the substrate.

[0255]

[Table 3] (Comparative Example 4-1) A solar cell (SC ratio 4) was formed under the same conditions as in Example 4 except that the SiH ₄ gas flow rate and the GeH ₄ gas flow rate were changed with time as shown in FIG. −
1) was produced.

(Comparative Example 4-2) No RFn-type layer was formed,
A solar cell (SC ratio 4-2) was produced under the same conditions as in Example 4 except that the layer thickness of the MWn type layer was 20 nm.

When the same measurement as in Example 1 was performed, it was confirmed that the solar cell of this example (SC Ex 4) was a conventional solar cell (SC).
It was found that the characteristics were more excellent than those of the ratio 4-1) and (SC ratio 4-2).

Example 5 A solar cell was prepared in which the i-type layer 114 was made to contain fluorine, and the fluorine content was minimum near the interface. When forming the i-type layer 114, GeH ₄
GeF ₄ gas was introduced in place of the gas, and the SiH ₄ gas flow rate and the GeF ₄ gas flow rate were changed with time as in Example 1, and the fluorine content changed as shown in FIG. A solar cell changing like 7-c was obtained. Other than this, it produced on the same conditions as Example 1. When the same measurement as in Example 1 was performed, it was found that the solar cell (SC Ex 5) of this example had further excellent characteristics than (SC Ex 1).

Example 6 A solar cell having a maximum hydrogen content near the interface between the RFp type layer 115 and the MWp type layer 116 was produced. When forming the RF p-type layer 115, R
When the F power was changed with time and the MW p-type layer 116 was formed, the MW power was changed with time to obtain a hydrogen content change pattern as shown in FIG. Other than this, it produced on the same conditions as Example 1. When the same measurement as in Example 1 was performed, it was found that the solar cell (SC Ex 6) of this example had further excellent characteristics than (SC Ex 1).

Example 7 A solar cell in which the content of the valence electron control agent is maximum near the interface between the MWp type layer 116 and the RFp type layer 115 was produced. MWp type layer 116 and R
When forming the Fp type layer 115, the source gas of the valence electron control agent introduced was changed with time to obtain a change pattern of the content of B atoms as shown in FIG. 9-a. Other than this, it produced on the same conditions as Example 1. When the same measurement as in Example 1 was performed, it was found that the solar cell (SC Ex 7) of this example had further excellent characteristics than (SC Ex 1).

Example 8 has the structure of FIG. 1-a, and
The content of the valence electron control agent in the i-type layer 104 is changed in the layer thickness direction.
Changes smoothly, and the p-type layer 105 side and the n-type layer 103
Made a solar cell (SC Ex 8) with a high content on the side
Made When forming the i-type layer 104, PH ₃ / H₂ gas
Flow rate, B₂ H₆ / H₂ By changing the gas flow rate with time,
Conducted except that the contents of the child and B atom are as shown in Fig. 9-c.
A solar cell (SC Ex 8) was produced under the same conditions as in Example 1. Half
The same material as in Example 1 was used except for the conductor layer. Example 1
When the same measurement was performed, the manufactured solar cell (SC
8) has better characteristics than (SC Ex 1)
I understood.

(Example 9) A solar cell (SC Ex 9) was prepared in which the MWp type layer 116 and the RFp type layer 115 contained fluorine.

When forming the MWp-type layer 116 and the RFp-type layer 115, SiF ₄ gas is newly introduced, and the flow rate is changed with time to change the fluorine content in the layer thickness direction as shown in FIG. I did it.

Other conditions were the same as in Example 1. When the same measurement as in Example 1 was performed, it was found that the manufactured solar cell (SC Ex. 9) had further excellent characteristics than (SC Ex. 1).

(Embodiment 10) A-SiS is formed on the i-type layer 114.
Using n, a solar cell containing an alkaline earth metal was produced by the MWPCVD method. First, the target 416, the target electrode 418, and the target shutter 417 in FIG. 6 were removed from the deposition chamber 401. i-type layer 114
SnH ₄ gas was used in place of GeH ₄ gas when forming Mg, and Mg (NO 2) was bubbled newly with He gas.
₃₎ Using ₂ · 6H ₂ O / He gas. When forming the i-type layer 114, SiH ₄ is formed with a change pattern similar to that of FIG.
The gas flow rate is changed with time, and the SnH ₄ gas flow rate is shown in FIG.
The same as that of the GeH ₄ gas flow rate of
_{(NO 3) 2 · 6H 2} O / He gas flow rate is temporally varied, alkaline earth metal content was set at Figure 7-a. Otherwise, the solar cell (S
C ex. 10) was produced.

(Comparative Example 10-1) When forming the i-type layer 114, the same conditions as in Example 10 except that the SiH ₄ gas flow rate and the SnH ₄ gas flow rate were temporally constant and 120 sccm and 30 sccm, respectively. With solar cells (SC ratio 1
0-1) was produced.

(Comparative Example 10-2) A solar cell (SC ratio 10-2) was prepared under the same conditions as in Example 10 except that the RFp type layer 115 was not formed and the layer thickness of the MWp type layer 116 was 20 nm.
Was produced.

When the same measurement as in Example 1 was performed, the solar cell of this example (SC Ex. 10) showed that the conventional solar cell (S
It was found that the characteristics were further superior to those of C ratio 10-1) and (SC ratio 10-2).

Example 11 As an alkaline earth metal,
Contains both Lilium, Magnesium and Calcium
A solar cell was manufactured. First, as the target 416
BeF₂ , MgF₂, CaF₂ Mix 1: 2: 1
Target power when forming the i-type layer
By changing over time, the change pattern of Ge content,
Change pattern of Lucari earth metal content is shown in Figure 3-c.
Other than that, the solar cell (SC Ex 11) was used under the same conditions as in Example 1.
It was made. Further, find the band gap in the layer thickness direction.
It turns out that it looks like Figure 4-c.
It was When the same measurement as in Example 1 was performed,
The solar cell (SC Ex 11) is a conventional solar cell (SC ratio 1
0-1), more excellent characteristics than (SC ratio 10-2)
Found to have. (Example 12) Fig. 2-c
As shown, between the RF n-type layer 103 and the i-type layer 104,
First and second R between the RF p-type layer 105 and the i-type layer
A solar cell having the F-i layers 131 and 132 was manufactured.
Implemented except that two RF-i layers 131 and 132 are formed
A solar cell was prepared in the same manner as in Example 8. RF-i layer 1
31 and 132 are made of a-Si, SiH_Four Gas flow rate
2 sccm, SiF_Four Gas flow rate is 0.5 sccm, H ₂ 
Gas flow rate is 50 sccm, pressure in deposition chamber is 1.0To
rr, RF power to be introduced is 0.01 W / cm³ , Substrate temperature
The temperature was 270 ° C. and the layer thickness was 20 nm. Production
The solar cell (SC Ex 12) is even better than (SC Ex 8)
It has been found that it has excellent characteristics.

Example 13 A triple type solar cell shown in FIG. 10 was produced using the deposition apparatus of FIG. 6 using the MWPCVD method.

First, the substrate 801 was manufactured. As in Example 1, a 50 × 50 mm ² stainless steel substrate was ultrasonically cleaned with acetone and isopropanol and dried. A light reflection layer of Ag having a layer thickness of 0.3 μm was formed on the surface of the stainless steel substrate by using the sputtering method. At this time, the substrate temperature was set to 350 ° C. and the substrate surface was made uneven (textured). A substrate thickness of 350 ° C. and a layer thickness of 2.0
A μm ZnO reflection enhancing layer was formed.

Next, the preparation for film formation was completed in the same manner as in Example 1. A first MWn type layer (μc-Si layer thickness 10 μm) 802 is formed on the substrate 801 by the same method as in Example 1, and further a first RFn type layer (a-Si layer thickness 10 μm).
m) 803, first i-type layer (a-SiGe) 804, first RFp-type layer (a-Si layer pressure 10 nm) 805, first MWp-type layer (μc-Si layer thickness 10 nm) 806,
Second RF n-type layer (μc-Si) 807, second i-type layer (a-Si) 808, second RF p-type layer (a-SiC)
Layer thickness 10 nm) 809, second MWp type layer (μc-S
iC layer thickness 10 nm) 810, third RFn type layer (a
-SiC) 811, the third i-type layer (a-SiC) 81
2, third RF p-type layer (a-SiC layer thickness 10 nm) 8
13, third MWp type layer (μc-SiC layer thickness 10n
m) 814 was sequentially formed. Target power supply 414 is D
C power source was exchanged, each semiconductor layer was made to contain Mg, DC power was changed with time, and the change in content in the layer thickness direction was changed as shown in FIG.
Like Further, SiF ₄ gas was newly introduced into each semiconductor layer to change the fluorine content in each semiconductor layer in the layer thickness direction as shown in FIG. When forming the first i-type layer, Si
The H ₄ gas flow rate and the GeH ₄ gas flow rate were changed with time as shown in FIG. 7-a. In the other layers, the layers formed by the MWPCVD method change the MW power with time to form R
When forming the layers formed by the FPCVD method, the RF power was changed with time so that the distribution of the hydrogen content of each layer was as shown in FIG. 8C. Next, a transparent electrode similar to that in Example 1 was formed on the third MWp type layer. Next, a collector electrode similar to that of Example 1 was formed on the transparent electrode by a vacuum vapor deposition method. This is the end of the production of the triple solar cell (SC Ex 13).

(Comparative Example 13-1) When forming the first i-type layer 804, as shown in FIG. 7-b, SiH ₄ gas flow rate, Ge
A solar cell (SC ratio 13-1) was produced under the same conditions as in Example 13 except that the H ₄ gas flow rate was changed with time.

(Comparative Example 13-2) First RF n-type layer 80
3, first RF p-type layer 805, second RF p-type layer 80
9 and the third RF p-type layer 813 are not formed, and the first MWn-type layer 802, the first MWp-type layer 806, and the second M-type layer 806 are formed.
A solar cell (SC ratio 13-2) was produced under the same conditions as in Example 13 except that the layer thicknesses of the Wp type layer 810 and the third MWp type layer 814 were set to 20 nm.

When the same measurement as in Example 1 was carried out, the solar cell of this example (SC Ex 13) was further improved than the conventional solar cells (SC ratio 13-1) and (SC ratio 13-2). It has been found to have excellent properties.

Example 14 The tandem solar cell of FIG. 11 was produced using the deposition apparatus using the roll-to-roll method of FIG.

First, the substrate 901 has a length of 300 m and a width of 30 c.
A long stainless steel sheet having m and a thickness of 0.1 mm and having both surfaces mirror-polished was used. A light reflection layer made of Ag having a layer thickness of 0.3 μm was continuously formed on the surface of the stainless steel substrate by a sputtering apparatus using a roll-to-roll method at a substrate temperature of 350 ° C., and further at a substrate temperature of 350 ° C., a layer thickness of 2. 0μ
The reflection increasing layer made of ZnO of m was continuously formed. Board 9
The 01 surface was found to be textured as in Example 13.

FIG. 12 is a schematic view of an apparatus for continuously forming semiconductor layers using the roll-to-roll method. This apparatus includes a substrate delivery chamber 1010 and a plurality of deposition chambers 1001-10.
09 and a substrate winding chamber 1011 are sequentially arranged, and a separation passage 1012 is connected between them, and a long substrate 901 passes through them, and a substrate delivery chamber 1010 is formed.
The substrate can be continuously moved from the substrate winding chamber 1011 to the substrate winding chamber 1011, and at the same time when the substrate 901 is moved, the semiconductor layers can be simultaneously formed in the deposition chambers. 10
50 is a view of the deposition chambers seen from above.
01 to 1009 have a source gas inlet 1014 and a source gas exhaust port 1015, an RF electrode 1016 or a microwave applicator 1017 is attached as necessary, and a halogen lamp heater 1018 for heating the substrate 901 is installed inside. Has been done. A source gas supply device similar to that of the first embodiment is connected to the source gas inlet 1014, and the deposition chambers 1001 to
An exhaust port 1015 for the raw material gas is provided at 009, and a vacuum exhaust pump such as an oil diffusion pump or a mechanical booster pump is connected to each exhaust port 1015. An RF power source is connected to each RF electrode, and a MW power source is connected to the microwave applicator. i
A bias electrode 1031 and a target electrode 1030 are arranged in deposition chambers 1003 and 1007 which are chambers for depositing mold layers, and an RF power source is connected to each as a power source. Further, Be was used as a target.

Reference numeral 1040 is a side view of the i-type layer deposition chamber. By arranging a target having a surface area smaller than the substrate area in the deposition chamber substantially in the center of the deposition chamber,
The amount of alkaline earth metal to be sputtered per unit time is set so that the central portion 104 of the substrate is more than the peripheral portion 1041 of the substrate.
It was increased by 2. By doing so, the change in the alkaline earth metal content in the layer thickness direction becomes as shown in FIG.

The separation passage 1012 connected to the deposition chamber has an inlet 1019 through which scavenging gas flows.

The substrate delivery chamber 1010 is provided with a delivery roll 1020 and a guide roll 1021 for applying an appropriate tension to the substrate and keeping it always horizontal.
011 includes a winding roll 1022 and a guide roll 10.
There are 23.

First, the substrate on which the light reflection layer and the reflection increasing layer are formed is wound around a delivery roll and set in the substrate delivery chamber 1010, and after passing through each deposition chamber, the end of the substrate 901 is taken up by the substrate winding roll 1022. Wrap around. The entire apparatus is evacuated by a vacuum exhaust pump (not shown), the lamp heater in each deposition chamber is turned on, and the substrate temperature in each deposition chamber is set to a predetermined temperature. When the pressure of the entire apparatus becomes 1 mTorr or less, H ₂ gas is introduced from the scavenging gas inlet 1019, and the substrate is wound in the winding roll 1022 while moving in the direction of the arrow. In the same manner as in Example 1, each source gas is caused to flow into each deposition chamber. At this time, each deposition chamber 1001
The flow rate of the H ₂ gas flowing into each separation passage or the pressure in each deposition chamber is adjusted so that the source gas flowing into 1009 does not diffuse into other deposition chambers. Next, RF electric power or MW electric power is introduced to cause glow discharge to form the respective semiconductor layers.

A first MWn type layer (μc-Si layer thickness 20 nm) 902 is formed on the substrate in the deposition chamber 1001, and a first RFn type layer (a-Si layer thickness 10 nm) 903 is formed in the deposition chamber 1002. In the deposition chamber 1003, the first i-type layer (a
-SiGe layer thickness 180 nm) 904, deposition chamber 1004
And the first RF p-type layer (a-Si layer thickness 10 nm) 90
5. In the deposition chamber 1005, the first MWp type layer (μc-Si
Layer thickness 10 nm) 906, second RFn in deposition chamber 1006
Mold layer (μc-Si layer thickness 20 nm) 907, deposition chamber 10
No. 07 second i-type layer (a-Si layer thickness 250 nm) 90
8. In the deposition chamber 1008, the second RF p-type layer (a-SiC
Layer thickness 10 nm) 909, second MWp in deposition chamber 1009
A mold layer (μc-SiC layer thickness 10 nm) 910 was sequentially formed. Beryllium is contained in the first i-type layer 904 and the second i-type layer 908, and the change in the content in the layer thickness direction is shown in FIG.
-C. SiH ₄ gas and SiF are used to form the semiconductor layer.
_Four gases were used, and fluorine was contained in all semiconductor layers. The raw material gas inlet 1014 of the deposition chamber 1003 for forming the first i-type layer 904 is divided into a plurality of portions, and SiH ₄ gas, SiF ₄ gas, and GeH ₄ gas were introduced from the respective inlets. When forming the i-type layer, the change pattern of the GeH ₄ gas flow rate with respect to the substrate transport direction is indicated by the arrow 102.
Each mass flow controller was adjusted so that a change pattern like 6 was obtained. By doing this, i
The change in the Ge content of the mold layer in the layer thickness direction was as shown in FIG. When the transfer of the board is completed, all MW
The power supply, the RF power supply, and the target power supply were turned off, the glow discharge was stopped, and the inflow of the raw material gas and the sweep gas was stopped. The entire device was leaked and the wound substrate 901 was taken out.

Next, the second MWp type layer 910 was placed on the second MWp type layer 910 at 170 ° C. using a sputtering apparatus used in the roll-to-roll method.
Then, a transparent electrode 919 made of ITO having a layer thickness of 70 nm was continuously formed.

Next, a part of this substrate 901 is set to 50 mm × 5.
Cut to a size of 0 mm and make a layer thickness of 5μ by screen printing.
m, a carbon paste having a line width of 0.5 mm was printed, and a silver paste having a layer thickness of 10 μm and a line width of 0.5 mm was printed thereon to form a collector electrode 812.

Thus, the production of the tandem solar cell (SC Ex 14) using the roll-to-roll method was completed.

(Comparative Example 14-1) A solar cell was manufactured under the same conditions as in Example 14 except that the GeH ₄ gas flow rate was kept constant in the substrate transport direction when the first i-type layer 904 was produced. (SC ratio 14-1) was produced.

(Comparative Example 14-2) First RF n-type layer 90
3, the first RFp-type layer 905 and the second RFp-type layer 909 are not formed, and the layer thickness of the first MWn-type layer 902 is 3
0 μm, first MWp type layer 906, and second MWp
A solar cell (SC ratio 14-2) was produced under the same conditions as in Example 14 except that the mold layer 910 had a layer thickness of 20 nm.

When the same measurement as in Example 1 was carried out, the solar cell of the present invention (SC Ex. 14) was found to be the same as the conventional solar cell (S).
It was found that the characteristics are further superior to those of C ratio 14-1) and (SC ratio 14-2).

Example 15 A tandem solar cell manufactured by using the deposition apparatus shown in FIG. 12 was modularized, applied to a power generation system, and subjected to a field test.

50 mm not irradiated with light prepared in Example 14
65 x 50mm triple solar cells (SC Ex 14)
I prepared a piece. E on a 5.0 mm thick aluminum plate
Put an adhesive sheet made of VA (ethylene vinyl acetate), put a nylon sheet on it, and put 6 on it.
Five solar cells were arranged and serialized and parallelized. An EVA adhesive sheet was placed thereon, a fluororesin sheet was placed thereon, and vacuum lamination was performed to form a module. The initial photoelectric conversion efficiency of the manufactured module was measured by the same method as in Example 1. An external light that was turned on at night was used as the load 1301 by connecting to the circuit showing the power generation system in FIG. The entire system is a storage battery 1302,
And the power of the module 1303. This power generation system will be referred to as (SBS Ex 15).

(Comparative Example 15) 65 conventional tandem solar cells (SC ratio 14-1) and (SC ratio 14-2) which were not irradiated with light were modularized in the same manner as in Example 15 to perform initial photoelectric conversion. The efficiency was measured. This module was connected to the same power generation system as in Example 15. These power generation systems (SBS ratio 15-1), (SBS ratio 15-
2).

Each module was installed at an angle at which sunlight could be condensed most. The measurement of the field test was performed by measuring the photoelectric conversion efficiency after one year and determining the deterioration rate (photoelectric conversion efficiency after one year / initial photoelectric conversion efficiency).

As a result, the power generation system (SBS Ex. 15) using the solar cell of the present invention is the same as the conventional power generation system (SB
It was found that the initial photoelectric conversion efficiency and the field durability were more excellent than those of S ratio 15-1) and (SBS ratio 15-2).

(Example 16) A photovoltaic element in which the semiconductor layer shown in the figure contains oxygen and / or nitrogen atoms was produced.

Example 16-1 When forming an i-type layer,
O ₂ / He gas is 100 sccm, N ₂ / He gas is 2
A solar cell (SC Ex 16-1) was produced under the same conditions as in Example 1 except that 0 sccm was introduced.

(Example 16-2) When forming the RF-i layer, O ₂ / He gas was ₂ sccm and N ₂ / He gas was 1 sccm.
A solar cell (SC Ex 16-2) was produced under the same conditions as in Example 1 except that sccm was introduced.

[0298] When forming (Example 16-3) MWp-type layer, when O ₂ / the He gas 100 sccm, N ₂ / the He gas was introduced 20 sccm, to form a RFp-type layer, O ₂
/ He gas ₂ sccm, N ₂ / He gas 1 sccm
A solar cell (SC Ex 16-3) was produced under the same conditions as in Example 1 except that the solar cell was introduced.

When the same measurement as in Example 1 was carried out,
It was found that the solar cells of (SC Ex 16-1) to (SC Ex 16-3) have characteristics that are even better than (SC Ex 1).

When the concentrations of oxygen atoms and nitrogen atoms of these solar cells produced were examined by SIMS, it was found that the concentrations of the source gas (O) and the source gas (N) were almost the same as those of the introduced source gas (Si). It was found to be contained.

Example 17 Using the deposition apparatus shown in FIG. 6, a solar cell of FIG. 1-b containing carbon in the i-type layer was produced. The n-type layer 112 was formed by the RFPCVD method.

First, a substrate was prepared in the same manner as in Example 1, and then RFn made of μc-Si was formed on the substrate 111.
Type layer 112, i-type layer 114 made of a-SiC, a-S
RF p-type layer 115 made of iC, M made of a-SiC
The Wp type layer 116 was sequentially formed.

In order to form the RFn type layer 112 made of μc-Si, H ₂ gas is introduced into the deposition chamber 401, and the mass flow controller is adjusted so that the flow rate is 300 sccm. The conductance valve 407 was adjusted to 1.0 Torr. Heater 405 so that the temperature of substrate 111 is 350 ° C.
Was set, and when the substrate temperature became stable, SiH ₄ gas and PH ₃ / H ₂ gas were caused to flow into the deposition chamber 401.
At this time, the SiH ₄ gas flow rate is ₂ sccm, the H ₂ gas flow rate is 100 sccm, and the PH ₃ / H ₂ gas flow rate is 200 sccm.
cm, and the pressure in the deposition chamber 401 was adjusted to 1.0 Torr. The power of the RF power source was set to 0.02 W / cm ³ , RF power was introduced to the bias electrode 410 to cause glow discharge, the shutter 415 was opened, and the substrate 11
1, the formation of the RF n-type layer 112 is started, and the layer thickness is 20 nm.
When the RF n-type layer 112 is formed, the shutter 41
5 is closed, RF power is turned off, glow discharge is stopped, RF
The formation of the n-type layer 112 is completed. Si into the deposition chamber 401
After stopping the inflow of H ₄ gas and PH ₃ / H ₂ and continuing to flow H ₂ gas into the deposition chamber 401 for 5 minutes, the inflow of H ₂ is also stopped and the inside of the deposition chamber 401 and the gas pipe is 1 × 10 5. ^-5 To
It was evacuated to rr.

The i-type layer 114 made of a-SiC is MWP.
Simultaneous CVD and alkaline earth metal sputtering
Formed by doing. First, H₂ 300 gas
sccm is introduced, the pressure is 0.01 Torr, the substrate 111
The temperature was set to 350 ° C. Substrate temperature is stable
By the way, SiH_Four Gas, CH_Four Gas, He gas flow
Insert, SiH_Four Gas flow rate is 120 sccm, CH_Four Moth
Flow rate is 30 sccm, He gas flow rate is 150 scc
m, H₂ The gas flow rate is 150 sccm, and the deposition chamber 401
The pressure inside was adjusted to 0.01 Torr. Next
And RF power of 0.32W / cm³ Set to
Applied to the ear electrode. After that, the MW power supply (not shown)
Power 0.20 W / cm³ Set the dielectric window 413 to
MW power is introduced into the deposition chamber 401 through the
Caused. Next, set the target power to 200W
Set, open target shutter 417, RFn type
Formation of the i-type layer 114 was started on the layer 112. Masflo
-Using a computer connected to the controller,
SiH according to the change pattern shown in FIG._Four gas
Flow rate, CH_Four By changing the gas flow rate, i with a layer thickness of 300 nm
When the mold layer is formed, the shutter and target
Close the switch, MW power supply, RF power supply, target power supply 4
Turn off 14 to stop glow discharge and form i-type layer 114.
finished. SiH _Four Gas, CH_Four Gas, He gas flow rate
Stop, 5 minutes, H₂ After continuing to flow the gas, H₂ Of gas
Stop the inflow, 1x1 in the deposition chamber 401 and the gas pipe.
0^-FiveEvacuated to Torr.

To form the RF p-type layer 115 made of a-SiC, H ₂ gas was introduced at 300 sccm, the pressure was 1.0 Torr, and the substrate temperature was 200 ° C. When the substrate temperature becomes stable, SiH ₄ gas, CH
₄ gas and B ₂ H ₆ / H ₂ gas are caused to flow into the deposition chamber 401, SiH ₄ gas flow rate is 5 sccm, CH ₄ gas flow rate is 1 sccm, H ₂ gas flow rate is 100 sccm, and B ₂ H ₆
/ H ₂ gas flow rate is 200 sccm, pressure is 1.0 Torr
It was adjusted to be r. RF power 0.06W
/ Cm ³ to cause glow discharge, open the shutter, start forming the RFp-type layer 115 on the i-type layer 104, and close the shutter 415 when the RFp-type layer 115 having a layer thickness of 10 nm is formed, The RF power supply was turned off, the glow discharge was stopped, and the formation of the RF p-type layer 115 was completed. SiH ₄ gas, CH ₄ gas, B ₂ H ₆ / in the deposition chamber 401
Stopping the flow of H ₂ gas for 5 minutes, after which continued to flow H ₂ gas, stopping the inflow of the H ₂ gas, the deposition chamber 401 and the gas pipes were evacuated to 1 × 10 ^-5 Torr.

A MW p-type layer 116 made of a-SiC is formed.
H to make₂ Introduce gas at 500 sccm and deposit chamber
The pressure inside 401 is 0.02 Torr, the substrate temperature is 200
The temperature was set to be ° C. Where the substrate temperature is stable
And SiH_Four Gas, CH_Four Gas, B₂ H₆ / H₂ Gas
Let it flow. At this time, SiH_Four Gas flow rate is 10 scc
m, CH_Four Gas flow rate is 2 sccm, H₂ Gas flow rate is 10
0 sccm, B₂ H₆ / H ₂ Gas flow rate is 500scc
m and the pressure were adjusted to 0.02 Torr. So
After that, the power of the MW power source (not shown) is 0.40 W / cm.³ 
And introduce MW power through the dielectric window 413,
Glow discharge is generated, the shutter 415 is opened, and RF
The formation of the MW p-type layer 116 was started on the p-type layer 115.
When the MWp type layer 116 having a layer thickness of 10 nm is formed,
Close the shutter 415, turn off the MW power, and release the glow.
The electricity was stopped and the formation of the MW p-type layer 116 was completed. SiH_Four 
Gas, CH_Four Gas, B₂ H₆ / H₂ Stop the flow of gas,
5 minutes, H₂ After continuing to flow the gas, H₂ Gas inflow
Stop the deposition chamber 401 and the gas pipe to 1 x 10^-FiveT
Evacuate to orr and close auxiliary valve 408.
The valve 409 was opened to leak the deposition chamber 401.

Next, the transparent electrode 1 is formed on the MWp type layer 116.
As No. 17, ITO having a layer thickness of 70 nm was vacuum deposited by a vacuum deposition method.

Next, a mask having comb-shaped holes is placed on the transparent electrode 117, and Cr (40 nm) / Ag (1000 n
A comb-shaped collector electrode made of m) / Cr (40 nm) was vacuum deposited by the vacuum deposition method.

[0309] Thus, the production of the solar cell was completed. Hereinafter, this solar cell will be referred to as (SC Ex. 17), and RFn
Mold layer 112, i-type layer 114, RFp-type layer 115, MWp
Table 4 shows the conditions for forming the mold layer 116.

[0310]

[Table 4] (Comparative Example 17-1) When forming the i-type layer 114, FIG.
-B under the same conditions as in Example 17, except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were changed over time.
C ratio 17-1) was produced.

(Comparative Example 17-2) A solar cell was formed under the same conditions as in Example 17 except that the SiH ₄ gas flow rate was 130 sccm and the CH ₄ gas flow rate was 20 sccm when the i-type layer 114 was formed. (SC ratio 17-2) was produced.

Comparative Example 17-3 A solar cell (SC ratio 1-3) was prepared under the same conditions as in Example 17 except that the RFp type layer 115 was not formed and the MWp type layer 116 had a layer thickness of 20 nm. did.

Solar cell (SC Ex 17) and (SC ratio 17
-1) to (SC ratio 17-3) were produced in six pieces, respectively, and in the same manner as in Example 1, initial photoelectric conversion efficiency (photovoltaic power / incident optical power), vibration deterioration, light deterioration, and forward bias voltage. Vibration deterioration and light deterioration during application were measured.

As a result of the measurement of the initial photoelectric conversion efficiency, (SC ratio 17-1) to (SC ratio 17-) for (SC actual 17)
The initial photoelectric conversion efficiency of 3) is as follows.

(SC ratio 17-1) 0.86 times (SC ratio 17-2) 0.87 times (SC ratio 17-3) 0.88 times Further, as a result of measurement of vibration deterioration and light deterioration, (SC Fruit 1
7), (SC ratio 17-1) to (SC ratio 17-
The reduction rate of the photoelectric conversion efficiency after the photodegradation and the reduction rate of the photoelectric conversion efficiency after the vibration degradation of 3) are as follows.

Vibration deterioration Light deterioration (SC ratio 17-1) 0.86 times 0.84 times (SC ratio 17-2) 0.87 times 0.85 times (SC ratio 17-3) 0.87 times As a result of measurement of vibration deterioration and light deterioration by applying a forward bias of 86 times, (SC ratio 17-1) to (SC actual 17) to
The decrease rate of the photoelectric conversion efficiency after vibration deterioration (SC ratio 17-3) and the decrease rate of the photoelectric conversion efficiency after light deterioration were as follows.

Vibration deterioration Optical deterioration (SC ratio 17-1) 0.83 times 0.84 times (SC ratio 17-2) 0.86 times 0.86 times (SC ratio 17-3) 0.85 times The state of delamination was observed using an 85 times optical microscope. In (SC Ex. 17), (SC ratio 17-1) and (SC ratio 17-2), no layer delamination was observed, but in (SC ratio 17-3) a slight layer delamination was observed.

Next, using a glass substrate and a stainless substrate,
A sample was prepared in which the SiH ₄ flow rate and the CH ₄ flow rate were constant over time. An i-type layer was prepared under the same conditions as in Example 17 except that the flow rate was constant and the layer thickness was 1 μm, and the samples were used for bandgap measurement and analysis. further,
Several samples with different flow rates were prepared.
The band gap (Eg) of the glass substrate sample was obtained using a spectrophotometer, and the C content of the stainless substrate sample was analyzed using an Auger electron spectroscopy analyzer. The relationship between the C content in the i-type layer and the band gap was obtained using the results of both. Moreover, when the carbon content with respect to the layer thickness direction of the solar cells (SC Ex 17) and (SC ratio 17-3) was obtained using an Auger electron spectroscopy analyzer, it was as shown in FIG. 17-c. Further, when the change in the band gap was obtained by using the above relationship between the C content and the band gap, it was as shown in FIG. 17-c. Similarly, changes in carbon content and band gap in the layer thickness direction (SC ratio 17-1) were obtained, and the result was as shown in FIG. 17-d. Similarly, when the C content (SC ratio 17-2) was determined, the carbon content did not change in the layer thickness direction, was constant in the layer thickness direction, and the band gap was 1.92.
It was found to be (eV). As described above, it was found that the changes in the carbon content and the band gap in the layer thickness direction depend on the CH ₄ gas flow rate introduced.

As described above, the solar cell of this embodiment (SC Ex 17) is the same as the conventional solar cells (SC ratio 17-1) to (SC).
It has been found that it has characteristics further superior to the ratio 17-3).

Example 18 The C content in the i-type layer is as shown in FIG.
A solar cell (SC Ex 18) that changed like 4-b was produced. Example 1 except that the CH ₄ gas flow rate monotonously decreases with time and the SiH ₄ gas flow rate monotonically increases.
A solar cell (SC Ex 18) was produced under the same conditions as in 7. When the change in the band gap in the layer thickness direction was obtained by the same method as in Example 17, it was found that the change was as shown in FIG. 15-b. When the same measurement as in Example 17 was performed, the solar cell of this example (SC Ex 18) exhibited further superior characteristics than the conventional solar cells (SC ratio 17-1) to (SC ratio 17-3). Found to have.

Example 19 A photodiode having the layer structure shown in FIG. 1-c was produced.

First, the substrate 121 was manufactured. A glass substrate with a thickness of 0.5 mm and 20 × 20 mm ² is ultrasonically cleaned with acetone and isopropanol, dried with warm air, and a layer thickness of 0.1 μm is formed on the glass substrate surface at room temperature by a vacuum deposition method.
Then, the Al light reflecting layer was formed, and the fabrication of the substrate 121 was completed.

In the same manner as in Example 17, the MWn type layer (a-SiC) 122 and the RFn type layer (aS) were formed on the substrate 121.
The iC) 123, the i-type layer (a-SiC) 124, and the RFp-type layer (μc-SiC) 125 were sequentially formed. Table 5 shows the layer forming conditions of the semiconductor layer.

Next, the transparent electrode 127 and the collector electrode 128 similar to those in Example 17 were formed on the RF p-type layer 125.

[0325]

[Table 5] Comparative Example 19-1 When forming the i-type layer 124, FIG.
17b except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate are temporally changed, and the band gap is changed as shown in FIG. 17-d. ) Was produced. (Comparative Example 19-2) When forming the i-type layer 124, SiH
₄ gas flow rate 130sccm, CH ₄ gas flow rate 20s
A photodiode (PD ratio 19-2) was produced under the same conditions as in Example 19 except that the c content was kept constant in ccm and the C content and the band gap in the layer thickness direction were kept constant.

(Comparative Example 19-3) A photodiode (PD ratio 1 was obtained under the same conditions as in Example 19 except that the RFn type layer 123 was not formed and the MWn type layer 122 had a layer thickness of 40 nm.
9-3) was produced.

First, the on / off ratio (photocurrent / dark current measurement frequency when irradiated with AM1.5 light of 10 kHz) of the manufactured photodiode was measured. Next, when the same measurement as in Example 1 was performed for the on / off ratio, the photodiode (PD actual 19) of this example was more than the conventional photodiodes (PD ratio 19-1) to (PD ratio 19-3). It was found to have even better properties.

Example 20 A solar cell of FIG. 1-b having a nip type structure in which the stacking order of the n type layer and the p type layer was reversed was produced. As in Example 1, the RF p-type layer (μ
c-Si), i-type layer (a-SiC), RFn-type layer (a-
SiC) and a MWn type layer (a-SiC) were formed. i
When forming the type layer, the SiH ₄ gas flow rate and the CH ₄ gas flow rate are temporally changed as shown in FIG. 17-b so that the position where the carbon content becomes the minimum is the p-type layer from the central position of the i-type layer. I tried to lean closer. Table 6 shows the layer forming conditions of the semiconductor layer.

The layers other than the semiconductor layer and the substrate were the same as those of Example 17.
A solar cell (SC Ex 20) was produced under the same conditions as described above.

[0330]

[Table 6] (Comparative Example 20-1) A solar cell (SC ratio 2) was formed under the same conditions as in Example 20 except that the SiH ₄ gas flow rate and the CH ₄ gas flow rate were changed with time as shown in FIG. 17-a when forming the i-type layer.
0-1) was produced.

(Comparative Example 20-2) When forming an i-type layer,
Example 2 except that the SiH ₄ gas flow rate was 130 sccm, the CH ₄ gas flow rate was 20 sccm, and the time was constant.
A solar cell (SC ratio 20-2) was produced under the same conditions as 0.

Comparative Example 20-3 Example 2 was repeated except that the RFn type layer was not formed and the MWn type layer had a layer thickness of 20 nm.
A solar cell (SC ratio 20-3) was produced under the same conditions as 0.

When the same measurement as in Example 17 was carried out,
It was found that the solar cell (SC Ex 20) of this example has further excellent characteristics than the conventional solar cells (SC ratio 20-1) to (SC ratio 20-3).

(Example 21) Fluorine was contained in the i-type layer 114, and a solar cell having a minimum fluorine content near the interface was produced. When the i-type layer 114 is formed, CF ₄ gas is newly introduced, and the fluorine content is changed as shown in FIG. 5-a, and the C content is changed as shown in FIG. 17-c. Obtained. Except for this, it was manufactured under the same conditions as in Example 17. When the same measurement as in Example 17 was performed, it was found that the solar cell (SC Ex. 21) of this example had further excellent characteristics than (SC Ex. 17).

(Embodiment 22) RFp type layer 115, MWp
A solar cell having a maximum hydrogen content near the interface of the mold layer 116 was produced. When forming the RF p-type layer 115,
When the RF power was changed with time to form the MW p-type layer 116, the MW power was changed with time to obtain a hydrogen content change pattern as shown in FIG. Except for this, it was manufactured under the same conditions as in Example 17. When the same measurement as in Example 17 was performed, it was found that the solar cell (SC Ex 22) of this example had further excellent characteristics than (SC Ex 17).

Example 23 Valence serving as a donor in the i-type layer
Including both a child control agent and a valence electron control agent that serves as an acceptor.
Valence electron control in the vicinity of the interface between the MWp type layer and the RFp type layer.
A solar cell having the maximum content of the control agent was produced.
When forming the i-type layer, PH is newly added.₃/ H₂, B ₂H₆/ H₂
Gas is introduced and the flow rate is changed with time, as shown in Fig. 9-a.
The content of P atom and B atom was changed. MWp type layer,
And when forming the RF p-type layer, B₂H₆/ H₂Gas flow rate
By changing the time, the content of B atom as shown in FIG.
A pattern was obtained. Otherwise, under the same conditions as in Example 17,
It was made. When the same measurement as in Example 17 was performed,
The solar cell of the example (SC Ex 23) is from (SC Ex 17)
Was found to have even better properties.

Example 24 The structure has the structure shown in FIG. 1-a, the content of the valence electron control agent in the i-type layer 104 changes smoothly in the layer thickness direction, and the content is large near the interface. A solar cell (SC Ex 24) that has become i-type layer 104
A solar cell (SC Ex 24) was produced under the same conditions as in Example 17, except that the RF power was changed with time to form the hydrogen atom content shown in FIG. The same material as in Example 1 was used except for the semiconductor layer. When the same measurement as in Example 17 was performed, the solar cell produced (SC Ex 24)
Was found to have even better properties than (SC Ex. 17).

(Example 25) MWp type layer 116, RFp
Solar cell in which the mold layer 115 contains fluorine (SC Ex 2
5) was produced.

When the MWp type layer 116 and the RFp type layer 115 are formed, BF ₃ / H ₂ gas is newly introduced and the flow rate is changed with time to show the change in the fluorine content in the layer thickness direction. -C. Further, the B ₂ H ₆ / H ₂ gas flow rate was also changed with time, and the change of the B content in the layer thickness direction was set as shown in FIG. 9-c.

Other conditions were the same as in Example 17. When the same measurement as in Example 17 was performed, it was found that the manufactured solar cell (SC Ex. 25) had further excellent characteristics than (SC Ex. 17).

Example 26 A solar cell containing an alkaline earth metal was prepared by using MWPCVD method using a-SiGeC for the i-type layer. First, the target of FIG.
The target electrode and target shutter were removed from the deposition chamber. In the formation of the i-type layer, newly used bubbled with _{Mg (NO 3) 2 · 6H} 2 O / He gas in He gas, the time to change the CH _4, GeH ₄ gas flow rate as shown in FIG. 16-a, _{mg (NO 3) 2 · 6H} 2 O / He gas flow rate be temporally varied, alkaline earth metal content 7
-A. A solar cell (SC Ex 26) was produced under the same conditions as in Example 17 except for this.

(Comparative Example 26-1) When forming an i-type layer,
A solar cell (SC ratio 26-1) was produced under the same conditions as in Example 26 except that the CH ₄ gas flow rate and the GeH ₄ gas flow rate were constant over time and were 5 sccm and 7 sccm, respectively.

Comparative Example 26-2 Example 2 was repeated except that the RFp type layer was not formed and the MWp type layer had a layer thickness of 20 nm.
A solar cell (SC ratio 26-2) was produced under the same conditions as in No. 6.

When the same measurement as in Example 17 was carried out,
In this example, it was found that the solar cell (SC Ex 26) had more excellent characteristics than the conventional solar cells (SC ratio 26-1) and (SC ratio 26-2).

Example 27 A solar cell containing beryllium, magnesium, and calcium as alkaline earth metals was prepared. First, the target 416 was replaced with a mixture of BeF ₂ , MgF ₂ , and CaF ₂ in a ratio of 1: 2: 1. When forming the i-type layer, the target power was changed with time to change the alkaline earth metal. A solar cell (SC Ex 27) was produced under the same conditions as in Example 17, except that the change pattern of the content was changed to FIG. 14-c. When the same measurement as in Example 17 was performed, the solar cell (SC
Actual 27) is a conventional solar cell (SC ratio 17-1) to (S).
It has been found that it has a more excellent characteristic than the C ratio 17-3).

(Example 28) As shown in FIG. 2-c, R
The RF p-type layer 10 is provided between the Fn-type layer 103 and the i-type layer 104.
A solar cell having RF-i layers 131 and 132 between the 5 and the i-type layer 104 was manufactured. Two RF-i layers 131, 1
A solar cell was produced in the same manner as in Example 24 except that 32 was formed. The RF-i layers 131 and 132 are made of a-Si, the SiH ₄ gas flow rate is 2 sccm, the SiF ₄ gas flow rate is 0.5 sccm, and the H ₂ gas flow rate is 50 sccm.
The pressure in the deposition chamber is 1.0 Torr, the RF power to be introduced is 0.01 W / cm ³ , the substrate temperature is 270 ° C., and the layer thickness is 20.
It was formed under the condition of nm. Fabricated solar cell (SC Ex 2
It was found that 8) had even better characteristics than (SC Ex 24).

Example 29 A triple type solar cell shown in FIG. 10 was produced using the deposition apparatus of FIG. 6 using the MWPCVD method.

First, the substrate 80 is manufactured in the same manner as in the thirteenth embodiment.
1 is manufactured, and then the first MWn-type layer (μc-Si layer thickness 10 μm is formed on the substrate 801 by the same method as in Example 17.
m) 802 to form a first RF n-type layer (a-S
i layer thickness 10 μm) 803, first i-type layer (a-SiG)
e) 804, first RF p-type layer (a-Si layer pressure 10 n)
m) 805, the first MWp type layer (μc-Si layer thickness 10)
nm) 806, second RF n-type layer (μc-Si) 80
7, second i-type layer (a-Si) 808, second RFp-type layer (a-SiC layer thickness 10 nm) 809, second MWp
Mold layer (μc-SiC layer thickness 10 nm) 810, third R
Fn-type layer (a-SiC) 811, third i-type layer (a-
SiC) 812, a third RFp type layer (a-SiC layer thickness 10 nm) 813, a third MWp type layer (μc-SiC).
A layer thickness of 10 nm) 814 was sequentially formed.

The target power supply 414 was replaced with a DC power supply, each semiconductor layer was made to contain Mg, and the DC power was changed with time to change the content in the layer thickness direction as shown in FIG. 14-c. Further, SiF ₄ gas was newly introduced into each semiconductor layer to change the fluorine content in each semiconductor layer in the layer thickness direction as shown in FIG. When forming the third i-type layer, the SiH ₄ gas flow rate and the CH ₄ gas flow rate were changed with time as shown in FIG. 17-a. In the other layers, the layers formed by the MWPCVD method change the MW power with time during formation, and RFPCVD is performed.
When forming the layers formed by the method, the RF power was changed with time during formation so that the distribution of the hydrogen content of each layer was as shown in FIG. Next, a transparent electrode similar to that in Example 17 was formed on the third MWp type layer. Then, Example 17 was formed on the transparent electrode.
A current collecting electrode similar to the above was formed by a vacuum evaporation method. This completes the production of the triple solar cell (SC Ex 29).

(Comparative Example 29-1) When forming the third i-type layer 804, as shown in FIG. 17-b, SiH ₄ gas flow rate, C
A solar cell (SC ratio 29-1) was produced under the same conditions as in Example 29 except that the H ₄ gas flow rate was changed with time.

(Comparative Example 29-2) The third i-type layer 804 was formed.
When forming, SiH_Four Gas flow rate is 130 sccm, CH
_Four The gas flow rate is set to 20 sccm and the time is constant.
Otherwise, the solar cell (SC ratio 29-
2) was produced.

(Comparative Example 29-3) First RF p-type layer 80
5, the second RF p-type layer 809 and the third RF p-type layer 813 are not formed, and the first MW p-type layer 806 and the second M p-type layer 806 are not formed.
A solar cell (SC ratio 29-3) was produced under the same conditions as in Example 29 except that the layer thicknesses of the Wp type layer 810 and the third MWp type layer 814 were 20 nm.

When the same measurement as in Example 17 was carried out,
It has been found that the solar cell (SC Ex 29) of the present invention has more excellent characteristics than the conventional solar cells (SC ratio 29-1) to (SC ratio 29-3).

Example 30 A tandem solar cell shown in FIG. 11 was manufactured using the deposition apparatus using the roll-to-roll method shown in FIG.

First, the substrate 901 is manufactured in the same manner as in the fourteenth embodiment.
A light-reflecting layer and a reflection-increasing layer were continuously formed on the top. Next, RF power or MW power was introduced into each deposition chamber to cause glow discharge, and each semiconductor layer was formed.

First MWn type in substrate deposition chamber 1001
A layer (μc-Si layer thickness 20 nm) 902, and further
In the deposition chamber 1002, the first RFn type layer (a-Si layer thickness
10 nm) 903, the first i-type layer (a
-Si layer thickness 250 nm) 904, first in deposition chamber 1004
1 RF p-type layer (a-Si layer thickness 10 nm) 905, stack
In the stacking chamber 1005, the first MWp type layer (μc-Si layer thickness 1
0 nm) 906, second RFn-type layer in deposition chamber 1006
(A-SiC layer thickness 20 nm) 907, deposition chamber 1007
And the second i-type layer (a-SiC layer thickness 200 nm) 90
8. In the deposition chamber 1008, the second RF p-type layer (a-SiC
Layer thickness 10 nm) 909, second MWp in deposition chamber 1009
Mold layer (μc-SiC layer thickness 10 nm) 910 is sequentially formed
did. The first i-type layer 904 and the second i-type layer 908 have a base.
Fig. 1 shows the change of the content in the layer thickness direction by containing Lilium.
4-c. SiH for semiconductor layer formation_Four Gas and Si
F_Four Use a gas to contain fluorine in all semiconductor layers.
It was Further, the deposition chamber 10 for forming the second i-type layer 908 is formed.
The raw material gas inlet of 07 is divided into multiple
From the entrance of SiH_Four Gas, CH_Four Let gas in, i
When forming the mold layer, CH _Four Gas flow rate in the substrate transfer direction
Contrary to the arrow 1026, the change pattern is opposite to the flow rate at both ends.
So that there is more and less in the center,
Adjusted with rollers. By doing this, the i-type layer
The change in the carbon content in the layer thickness direction is as shown in Fig. 14-c.
It was When the board has been transported, all MW
Turn off the source, RF power, and target power to stop glow discharge
Therefore, the inflow of raw material gas and sweep gas was stopped. The entire device
Then, the wound substrate 901 was taken out.

Next, 170 ° C. is formed on the second MWp type layer 910 by using a sputtering device used in the roll-to-roll method.
Then, a transparent electrode 919 made of ITO having a layer thickness of 70 nm was continuously formed.

Next, a part of this substrate 901 is set to 50 mm × 5.
Cut to a size of 0 mm and make a layer thickness of 5μ by screen printing.
m, a carbon paste having a line width of 0.5 mm was printed, and a silver paste having a layer thickness of 10 μm and a line width of 0.5 mm was printed thereon to form a collector electrode 812.

Thus, the production of the tandem solar cell (SC Ex 30) using the roll-to-roll method was completed.

(Comparative Example 30-1) A solar cell was manufactured under the same conditions as in Example 30, except that the CH ₄ gas flow rate was kept constant in the substrate transport direction when the first i-type layer 904 was produced. (SC30-1) was produced.

(Comparative Example 30-2) First RF p-type layer 90
5 and the second RF p-type layer 909 were not formed, and the solar cell () was formed under the same conditions as in Example 30 except that the first MWp-type layer 906 and the second MWp-type layer 910 had a layer thickness of 20 nm. SC ratio 30-2) was produced.

When the same measurement as in Example 17 was carried out,
It was found that the solar cell of the present invention (SC Ex 30) has further excellent characteristics than the conventional solar cells (SC ratio 30-1) and (SC ratio 30-2).

(Example 31) A tandem solar cell manufactured by using the deposition apparatus shown in FIG. 12 was modularized and applied to a power generation system to perform a field test.

Light-irradiated 50 mm produced in Example 30
65 x 50mm triple solar cells (SC 30)
Individual pieces were prepared and modularized in the same manner as in Example 15. Example 1 shows the initial photoelectric conversion efficiency of the manufactured module.
It was measured in the same manner as in 7. An external light that was turned on at night was used as the load 1301 by connecting to the circuit showing the power generation system in FIG. The entire system is operated by the power of the storage battery 1302 and the module 1303. This power generation system is called (SBS Ex 31).

(Comparative Example 31) A conventional tandem type solar cell (SC ratio 30-1) and 65 (SC ratio 30-2) which were not irradiated with light was modularized in the same manner as in Example 15 to perform initial photoelectric conversion. The efficiency was measured. This module was connected to the same power generation system as in Example 31. These power generation systems (SBS ratio 31-1), (SBS ratio 31-
2).

[0366] Each module was installed at an angle at which sunlight could be most concentrated. The measurement of the field test was performed by measuring the photoelectric conversion efficiency after one year and determining the deterioration rate (photoelectric conversion efficiency after one year / initial photoelectric conversion efficiency).

As a result, the power generation system (SBS Ex 31) using the solar cell of the present invention is the same as the conventional power generation system (SB
It was found that the initial photoelectric conversion efficiency and the field durability were more excellent than those of the S ratio 31-1) and (SBS ratio 31-2).

(Example 32) A photovoltaic element containing oxygen and / or nitrogen atoms in the semiconductor layer shown in the figure was produced.

(Example 32-1) When forming an i-type layer,
O ₂ / He gas is 100 sccm, N ₂ / He gas is 2
A solar cell (SC Ex 32-1) was produced under the same conditions as in Example 17 except that 0 sccm was introduced.

(Example 32-2) When forming the RF-i layer, ₂ sccm of O ₂ / He gas and 1 of N ₂ / He gas were used.
A solar cell (SC Ex 32-2) was produced under the same conditions as in Example 17 except that sccm was introduced.

[0371] When forming (Example 32-3) MWp-type layer, when O ₂ / the He gas 100 sccm, N ₂ / the He gas was introduced 20 sccm, to form a RFp-type layer, O ₂
/ He gas ₂ sccm, N ₂ / He gas 1 sccm
A solar cell (SC
Example 32-3) was produced.

When the same measurement as in Example 17 was carried out,
It was found that the solar cells of (SC Ex 32-1) to (SC Ex 32-3) have further excellent characteristics than (SC Ex 17).

When the concentrations of oxygen atoms and nitrogen atoms of these solar cells produced were examined by SIMS, it was found that the concentrations of the source gas (O) and the source gas (N) were almost the same as those of the introduced source gas (Si). It was found to be contained.

As described above, it was proved that the effect of the photovoltaic device of the present invention was exhibited regardless of the device structure, device material, and device manufacturing conditions.

[0375]

INDUSTRIAL APPLICABILITY The photovoltaic device of the present invention prevents recombination of photoexcited carriers, improves the open-circuit voltage and the carrier range of holes, improves the sensitivity of short-wavelength light and long-wavelength light, and performs photoelectric conversion. Efficiency is improved.

Further, the photovoltaic element of the present invention can suppress light deterioration and vibration deterioration. The photovoltaic element of the present invention can suppress optical deterioration and vibration deterioration even when a forward bias is applied.

Further, in the photovoltaic element of the present invention, the layers are not separated even when the photovoltaic element is placed in the above environment.

Furthermore, according to the method for forming a photovoltaic element of the present invention, the deposition rate of the photovoltaic element can be increased, and the efficiency of using the raw material gas is high, so that the productivity can be dramatically improved. it can.

Moreover, the power generation system of the present invention has high field durability.

[Brief description of drawings]

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

FIG. 2 is a conceptual diagram showing an example of the layer structure of the photovoltaic element of the present invention.

FIG. 3 is a graph showing changes in the alkaline earth metal and germanium contents in the layer thickness direction.

FIG. 4 is a graph showing changes in bandgap in the layer thickness direction.

FIG. 5 is a graph showing changes in fluorine content in the layer thickness direction.

FIG. 6 is a conceptual diagram showing an example of a deposition apparatus.

FIG. 7 is a graph showing changes over time in SiH ₄ gas and GeH ₄ gas flow rates and changes in Ge content and band gap in the layer thickness direction.

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

FIG. 9 is a graph showing changes in the valence electron control agent in the layer thickness direction.

FIG. 10 is a conceptual diagram showing an example of a layer structure of a triple solar cell.

FIG. 11 is a conceptual diagram showing an example of a layer structure of a tandem solar cell.

FIG. 12 is a conceptual diagram showing an example of a deposition apparatus using a roll-to-roll method.

FIG. 13 is a block diagram showing an example of a power generation system.

FIG. 14 is a graph showing changes in the alkaline earth metal and carbon contents in the layer thickness direction.

FIG. 15 is a graph showing changes in bandgap in the layer thickness direction.

FIG. 16 is a graph showing changes over time in GeH ₄ gas and CH ₄ gas flow rates and changes in C content and band gap in the layer thickness direction.

FIG. 17 is a graph showing changes over time in the flow rates of SiH ₄ gas and CH ₄ gas, changes in C content, and changes in band gap in the layer thickness direction.

[Explanation of symbols]

 101,111,121 substrate, 102,122 MWn type layer, 103,123 RFn type layer, 104,114,124 i type layer, 105,115 RFp type layer, 106,116 MWp type layer, 107,117,127 transparent Electrode, 108, 118, 128 current collecting electrode, 112 n-type layer, 125 p-type layer, 131 first RF-i layer, 132 second RF-i layer, 400 deposition apparatus, 401 deposition chamber, 402 vacuum gauge , 403 RF power supply, 404 substrate, 405 heater, 406 waveguide, 407 conductance valve, 408 auxiliary valve, 409 leak valve, 410 bias electrode, 411 gas introduction tube, 412 applicator, 413 dielectric window, 414 sputter power supply, 415 Shutter, 416 Target, 417 Target Shutter , 418 target electrode, 901 substrate, 1001 to 1009 deposition chamber, 1010 substrate delivery chamber, 1011 substrate winding chamber, 1012 separation passage, 1014 source gas inlet, 1015 source gas exhaust port, 1016 RF electrode, 1017 microwave applicator , 1018 lamp heater, 1019 scavenging gas inlet, 1010 substrate feeding chamber, 1020 feeding roll, 1021, 1023 guide roll, 1022 winding roll, 1030 target electrode, 1031 bias electrode.

Claims (24)

[Claims] 1. A p-type layer, an i-type layer, and an n-type layer containing a non-single crystal silicon semiconductor material containing hydrogen are laminated on a substrate, and the i-type layer is germanium, tin, and carbon. Containing at least one of the above and an alkaline earth metal,
In the photovoltaic device formed by the microwave plasma CVD method, the p-type layer and / or the n-type layer is
The RF doping layer has a stacked structure of an MW doping layer formed by a microwave plasma CVD method and an RF doping layer formed by an RF plasma CVD method, and the RF doping layer is between the MW doping layer and the i-type layer. , The content of germanium, tin or carbon contained in the i-type layer changes smoothly in the layer thickness direction, and the maximum value of the content is from the central position of the i-type layer to the p-type. A photovoltaic element characterized in that it is located on the mold layer side. 2. The content of the alkaline earth metal contained in the i-type layer changes smoothly in the layer thickness direction and is minimized in the vicinity of at least one of the interfaces. The photovoltaic element described. 3. The alkaline earth metal is beryllium,
The photovoltaic element according to claim 1 or 2, which contains at least one of magnesium and calcium. 4. The light according to claim 1, wherein the i-type layer contains both a valence electron control agent serving as a donor and a valence electron control agent serving as an acceptor. Electromotive force element. 5. The photovoltaic element according to claim 4, wherein the content of the valence electron control agent is maximized in the vicinity of at least one interface. 6. The i-type layer, MW doping layer and RF
The photovoltaic element according to any one of claims 1 to 5, wherein the content of the hydrogen is maximum in the vicinity of at least one interface in at least one of the doping layers. 7. The i-type layer, MW doping layer and RF
7. The photovoltaic device according to claim 1, wherein at least one of the doping layers contains oxygen and / or nitrogen atoms. 8. The i-type layer, MW doping layer and RF
The photovoltaic element according to claim 1, wherein at least one layer of the doping layers contains fluorine. 9. The photovoltaic element according to claim 8, wherein the content of fluorine is minimum near at least one interface. 10. The MW doping layer and / or R
The photovoltaic element according to any one of claims 1 to 9, wherein the content of the valence electron control agent in the F doping layer is maximized in the vicinity of at least one interface. 11. The MW-doped layer and / or R
The photovoltaic element according to any one of claims 1 to 10, wherein the F doping layer contains an alkaline earth metal. 12. The content of the alkaline earth metal contained in the MW-doped layer or the RF-doped layer changes smoothly in the layer thickness direction, and becomes the minimum in the vicinity of at least one interface. The photovoltaic element according to claim 11. 13. The photovoltaic element according to claim 11, wherein the alkaline earth metal contains at least one of beryllium, magnesium and calcium. 14. An i-type RF-formed by an RF plasma CVD method between the i-type layer and the RF doping layer.
The photovoltaic element according to any one of claims 1 to 13, which has an i layer. 15. The photovoltaic element according to claim 14, wherein the RF-i layer contains both a valence electron control agent serving as a donor and a valence electron control agent serving as an acceptor. 16. The photovoltaic element according to claim 15, wherein the content of the valence electron control agent contained in the RF-i layer is maximum near at least one interface. 17. The photovoltaic element according to claim 14, wherein the hydrogen content of the RF-i layer is maximized near at least one interface. 18. The RF-i layer contains oxygen or / and nitrogen atoms.
The photovoltaic element according to any one of 1. 19. The photovoltaic element according to claim 14, wherein the RF-i layer contains fluorine. 20. The photovoltaic element according to claim 19, wherein the content of fluorine contained in the RF-i layer is minimum near at least one interface. 21. The photovoltaic element according to claim 14, wherein the RF-i layer contains an alkaline earth metal. 22. The content of the alkaline earth metal contained in the RF-i layer changes smoothly in the layer thickness direction and is at a minimum in the vicinity of at least one interface. Photovoltaic device according to. 23. The photovoltaic element according to claim 21, wherein the alkaline earth metal contains at least one of beryllium, magnesium and calcium. 24. The photovoltaic element according to any one of claims 1 to 23, the voltage or / and the current of the photovoltaic element is monitored, and the photovoltaic element to a storage battery and / or an external load. A power generation system comprising a control system for controlling power supply from a power element and a storage battery for storing power from the photovoltaic element and / or supplying power to an external load. .