JPH06204521A - 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 crystal 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 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. In particular, the present invention relates to a photovoltaic element in which a doping layer and an i-type layer are formed by a microwave plasma CVD method (MWPCVD method). Further, the present invention relates to a photovoltaic element in which a semiconductor layer made of a non-single-crystal silicon-based 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 is excellent in raw material gas utilization efficiency. For example, as an example of forming the i-type layer by the MWPCVD method, ◆ "a-Si solar cell by microwave plasma CVD method", Kazufumi Azuma, Takeshi Watanabe, Juichi Shimada, Proceedings of the 50th Annual Meeting of the Applied Physics Society of Japan. pp. 566. Etc. In this photovoltaic element, the i-type layer is MWP
By forming it by the CVD method, an i-type layer having a high quality and a high deposition rate is obtained.

An example of forming the doping layer by the MWPCVD method is, for example, "High Efficiency Amorphous Solar Cell Employing".
ECR-CVD Produced p-Type Microcrystalline SiC Fil
m ", Y.Hattori, D.Kruangam, T.Toyama, H.Okamotoand YH
amakawa, Proceedings of the International PVSEC-3
Tokyo Japan 1987 pp.171. ◆ "HIGH-CONDUCTIVE WIDE BAND GAP P-TYPE a-SiC: HP
REPARED BY ECR CVD ANDITS APPLICATION TO HIGH EFFI
CIENCY a-Si BASIS SOLAR CELL ", Y.Hattori, D.Kruang
am, K.Katou, Y.Nitta, H.Okamoto and Y.Hamakawa, Proce
edings of 19th IEEE Photovoltaic Specialists Confer
ence 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 laminated, many defect levels occur at the interface, and therefore a photovoltaic device 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. ◆ "Characteristic stabilization 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.

Further, studies are underway on a non-single crystal silicon semiconductor layer containing fluorine and a photovoltaic element using the same. For example, ◆ "The chemical and configurational basis of high
efficiency amorphousphotovoltaic cells ", Ovshinsk
ySR, Proceedings of 17th IEEE Photovoltaic Speci
alists Conference 1985 pp.1365. ◆ "Preraration and properties of sputtered a-Si:
H: F films ", Beyer.W, Chevallier.J, Reichelt.K, Sol
ar Energy Material, vol.9, No2, pp.229-2451983. ◆ "Development of the scientific and technical ba
sis for integrated amorphous silicon modules.Res
erch on a-Si: F: H (B) alloys and module testing at IE
T-CIEMAT. ", Gutierrez MT, P Delgado L, Photovalt.
Power Gener., Pp.70-75 1988. ◆ "The effect of fluorine on the photovaltaic pro
perties of amorphous silicon ", Konagai.M, Nishigat
aK, Takahashi.K, Komoro.K, Proceedings of 15th IE
EE Photovaltaic Specialists Conference 1981 pp.90
6. etc. In these examples, the photodegradation phenomenon and thermal stability are also referred to. No relationship is mentioned. Further, in these examples, a good-quality doping layer was obtained, but a photovoltaic element having high photoelectric conversion efficiency has not yet been obtained.

In the above conventional photovoltaic device, when the MWPCVD method is used for both formation of the i-type layer and formation of the doping layer, recombination of photoexcited carriers near the p / i interface and the n / i interface. It is desired to improve the open circuit voltage and the carrier range of holes. Further, the photovoltaic element in which the doping layer and the i-type layer are formed by the MWPCVD method has a problem that the photoelectric conversion efficiency is lowered (photo-deteriorated) when the photovoltaic element is irradiated with light.

Furthermore, 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 is lowered (vibration deterioration) when placed in an environment where there is vibration for a long period of time. Furthermore, in the above photovoltaic element, the photodegradation and the vibration degradation were remarkable when placed in a high humidity 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 semiconductor layer containing fluorine has a problem that the layer is easily peeled off as compared with a layer containing no fluorine.

[0010]

In view of the above-mentioned drawbacks, the technical problem of the present invention is to provide a conventional photovoltaic device having an improved deposition rate, which is a photovoltaic device having an improved photoelectric conversion efficiency. Is to provide. Another object of the present invention is to provide a photovoltaic element that suppresses optical deterioration and vibration deterioration.

A further object of the present invention is to suppress optical deterioration and vibration deterioration 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 light deterioration and vibration deterioration of the photovoltaic element when the photovoltaic element is placed in a high humidity environment. Furthermore, the present invention provides the following when a forward bias is applied to a photovoltaic element:
The purpose is to suppress light deterioration and vibration deterioration.

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. Furthermore,
It is an object of the present invention to provide a power generation system using a photovoltaic element that achieves the above object. Still another object of the present invention is to provide a photovoltaic device having excellent productivity.

[0013]

The present invention has been made in order to solve the conventional problems and achieve the above object, and as a result,
It has been found. That is, the photovoltaic element of the present invention is configured by laminating a p-type layer, an i-type layer, and an n-type layer made of a non-single crystal silicon semiconductor material containing hydrogen on a substrate, and the i-type layer Is an alkaline earth metal-containing photovoltaic element formed by a microwave plasma CVD method, wherein the p-type layer and / or the n-type layer is a microwave-formed MW doping layer and an RF plasma CVD method. The RF doping layer is formed so as to be sandwiched between the MW doping layer and the i-type layer, and further contains the alkaline earth metal of the i-type layer. It is characterized in that the amount and the hydrogen content change smoothly in the thickness direction.

The photovoltaic element of the present invention is a p-type layer made of a non-single-crystal silicon semiconductor material containing hydrogen, i
And an i-type layer containing an alkaline earth metal, the microwave plasma C
In the photovoltaic device formed by the VD method, the p-type layer and / or the n-type layer has a laminated structure of a MW doping layer formed by microwave and an RF doping layer formed by RF plasma CVD method. Configured and the RF
The doping layer is arranged so as to be sandwiched between the MW doping layer and the i-type layer, and the i-type layer further contains both a valence electron control agent that serves as a donor and a valence electron control agent that serves as an acceptor. To do.

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

A preferred form of the present invention is the i-type layer,
At least one layer of the RF doping layer, the MW doping layer, and the RF-i layer contains fluorine, and the fluorine content changes smoothly in the layer thickness direction, and the content is near the interface of at least one of the layers. Is the smallest photovoltaic element. In addition, a preferred embodiment of the present invention is the above R
The hydrogen content of at least one of the F-doped layer, the MW-doped layer, the RF-i layer, and the i-type layer changes smoothly in the layer thickness direction, and the hydrogen content of the layer is near at least one interface. Is the maximum photovoltaic element.

A desirable mode of the present invention is that the content of the valence electron control agent serving as a donor contained in at least one of the RF doping layer, the MW doping layer, the RF-i layer and the i-type layer or / The content of the valence electron control agent serving as an acceptor changes smoothly in the layer thickness direction, and the content is maximized in the vicinity of at least one interface of the layer.

Also, a desirable mode of the present invention is a photovoltaic element, wherein at least one of the RF doping layer, the MW doping layer and the RF-i layer contains an alkaline earth metal. is there. A desirable mode of the present invention is that the content of the alkaline earth metal contained in at least one of the RF doping layer, the MW doping layer, the RF-i layer and the i-type layer changes smoothly in the layer thickness direction. In addition, the photovoltaic element has a minimum content near at least one interface.

A desirable mode of the present invention is a photovoltaic element in which tin atoms are contained in the i-type layer and / or the RF-i layer, and the layer is made of amorphous silicon / tin. Also, a desirable mode of the present invention is the i-type layer, the RF-i layer, the MW.
The photovoltaic device according to the above, wherein at least one of the doping layer and the RF doping layer contains oxygen and / or nitrogen atoms.

Further, the power generation system of the present invention monitors the voltage and / or current of the photovoltaic element and the voltage and / or current of the photovoltaic element to supply power from a storage battery and / or an external load change the photovoltaic element. It is characterized by comprising a control system for controlling, and a storage battery for storing power from the photovoltaic element and / or supplying power to an external load.

[0021]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1-a is a schematic explanatory view showing an example of the photovoltaic element of the present invention. In FIG. 1-a, the photovoltaic device of the present invention is a substrate 101, MWPCVD.
Formed by the method and having an n-type conductivity type MWn-type layer 10
2. RF n-type layer 103 formed by RFPCVD method and having n-type conductivity, i-type layer 104 formed by MWPCVD method and containing alkaline earth metal element, RFPCVD
RF p-type layer 10 formed by a method and having a p-type conductivity type
5. MW p-type layer 106 having p-type conductivity and formed by MWPCVD method, transparent electrode 107, and current collecting electrode 10.
It is composed of 8 etc.

FIG. 1-b is another example of a schematic explanatory view of the photovoltaic element of the present invention. 1B, the photovoltaic device of the present invention includes a substrate 111, an n-type layer 112 having an n-type conductivity type, an i-type layer 114, an RFp-type layer 115, a MWp-type layer 116, a transparent electrode 117, and a collector. It is composed of the electric electrode 118 and the like. FIG. 1-c is another example of a schematic explanatory view of the photovoltaic element of the present invention. 1C, the photovoltaic device of the present invention includes a substrate 121, a MWn type layer 122, an RFn type layer 123, an i type layer 124, and a p type layer 1 having p type conductivity.
25, a transparent electrode 127, a collector electrode 128, and the like.

1A to 1C, the n-type layer and the p-type layer are formed by the RFPCVD method or the MWPCVD method, but the RFPCVD method is preferable. Further, in addition to the pin-type photovoltaic device as shown in FIGS. 1-a to 1-c, there is also a nip-type photovoltaic device in which the stacking order of the n-type layer and the p-type layer is reversed. Good. Further, FIG.
In a photovoltaic device having a pin structure as shown in FIG. 1-c, RFP is provided between a doping layer and an i-type layer having a laminated structure.
FIG. 1 having an i-type (RF-i layer) formed by a CVD method.
Photovoltaic devices such as -d to Fig. 1-f may be used.

Further, the doping layer having the laminated structure of the present invention is, for example, RFp type layer / MWp type layer / RFp type layer / i type layer, i type layer / RFn type layer / MWn type layer / RFn type layer, and the like. (RF / MW) _n / RF type may have a laminated structure composed of three or more layers, or MWp type layer / R
It may be a (MW / RF) _n type laminated structure such as Fp 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. Further, the photovoltaic element of the present invention is n
It may be a stack of nip structures such as an ipnip structure and a nipnipnip structure. In the photovoltaic device of the present invention, when forming the MW doping layer and the i-type layer, M
Since the WPCVD method is used, the deposition rate is high, the throughput can be improved, the utilization efficiency of the source gas can be improved, and the productivity is excellent.

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. MWPCVD
Since the doping layer (MW doping layer) formed by the method is formed at a deposition rate of 2 nm / sec or more,
The introduced valence electron control agent is not 100% activated, and even if a dangling bond is generated, an inactive valence electron control agent terminates it, so that the characteristics of the photovoltaic element, especially the decrease in open circuit voltage are reduced. It is thought that it can be suppressed.

Further, since there is an RF doping layer between the i-type layer formed by the MWPCVD method and the MW doping layer, the interface state 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 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 is increased, and when the layer is laminated with the i-type layer, the interface state of each layer is reduced. In particular, when the deposition rate of the i-type layer is 5 nm / sec or more, the surface level of the i-type layer is not sufficiently relaxed immediately after the glow discharge is excited by microwaves or immediately after the glow discharge is stopped, so that the surface level is It is increasing.

By forming the i-type layer on the RF-doped layer having a low deposition rate, the initial film of the i-type layer immediately after the glow discharge is affected by the underlying layer, the packing density becomes high, 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, on the surface of the i-type layer, RF with a slow deposition rate
It is considered that by forming the doping layer, the surface level of the i-type layer can be reduced by the annealing due to the diffusion of hydrogen atoms that occurs simultaneously with the formation of the semiconductor layer by RFPCVD.

Further, by making the content of the valence electron control agent of the RF doping layer higher than that of the inside of the i-type layer and lower than the content of the valence electron control agent of the doping layer formed by the MWPCVD method, The open circuit voltage and fill factor of the electromotive force 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, the local flexibility is increased by providing the RF doping layer between the MW doping layer and the i-type layer whose constituent element ratios are very different from each other.
The internal stress between the W-doped layer and the i-type layer can be relaxed, the generation of defect levels due to the internal stress can be prevented, and the photoelectric conversion of the photovoltaic element can be performed even when it is left under vibration for a long time. It is considered that the decrease in efficiency can be suppressed. This is particularly effective when the hydrogen content is high at both interfaces of the RF doping layer.

Further, the photovoltaic element of the present invention is resistant to photodegradation. Generally, there are many weak bonds near the interface of the doping layer, and light causes
It is believed that the characteristics of the photovoltaic device are deteriorated because the weak bond is broken. In the case of the present invention, by introducing a large number of valence electron control agents in the vicinity of the interface between the PF doping layer and the MW doping layer, even if dangling bonds are generated by light irradiation, they are not activated. It is believed that it reacts with the agent and guarantees a dangling bond. An example shown in FIG. 12 is given as a variation pattern of the content of the valence electron control agent in the layer thickness direction. In FIG. 12, (B content) shows the content of the valence electron control agent which becomes an acceptor, and (P content) shows the content of the valence electron control agent which becomes a donor.

FIG. 12-a shows an example in which the content is maximized at both interfaces of the doping layer and the content is steeply sloped at the interface on the light incident side. It is particularly effective for a photovoltaic device having an i-type layer having a small band gap.
FIG. 12-b is an example in which the content is maximized at the light incident side interface of the doping layer and is minimized at the opposite interface so that the content has a steep gradient. It is particularly effective for a photovoltaic device having an i-type layer having a small band gap. FIG. 12-c is an example in which the content is maximized at both interfaces of the doping layer and the content has a steep gradient on both interface sides. It is particularly effective when light is entered from the p-type layer side. It is particularly effective for a photovoltaic device having an i-type layer made of a material having a large band gap.

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 weak bonds are broken by the light irradiation to form dangling bonds, it is considered that these react with unactivated valence electron control agents to compensate dangling bonds.

Further, it is considered that there are many weak bonds particularly near the interface of the i-type layer. 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 to compensate the dangling bonds. Therefore, even when the light intensity applied to the photovoltaic element is weak, the probability of trapping photoexcited electrons and holes is reduced because the defect level is compensated by the valence electron control agent. As described above, since the dark current during reverse bias is small, a 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 element 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, Si / SiC) is formed between the i-type layer and the doping layer.
Etc.) is particularly effective. 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 example shown in FIG. 2 can be given as a pattern of changes in the content of the valence electron control agent in the layer thickness direction. In FIG. 2, (B content) shows the content of the valence electron control agent which becomes an acceptor, and P content shows the content of the valence electron control agent which becomes a donor. In FIG. 2-a, the content is maximized on the p-type layer side and the n-type layer side of the i-type layer, and is minimized on the p-type layer side inside the bulk of the i-type layer, and on the p-type layer side. This is an example in which there is a steep gradient. 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 in the nip-type photovoltaic element, 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. 2B shows that the i-type layer has the maximum content on the p-type layer side and the minimum content on the n-type layer side, and the p-type layer side has a steep gradient of the content. It is an example. In particular, p
It is effective when light is incident from the mold layer side. nip
When light is incident from the n-type layer side in a type photovoltaic element, 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.

In FIG. 2C, the i-type layer is maximized on the p-type layer side and the n-type layer side, and the content is steeply sloped on the p-type layer side and the n-type layer side. Here 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 in the nip-type photovoltaic element, the pattern may be reversed with respect to the layer thickness direction. The change pattern as shown in FIG. 2C 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. 2-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 distribution of the valence electron control agent can be applied to each semiconductor layer. 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.
When an alkaline earth metal is contained in an i-type layer made of a non-single-crystal silicon semiconductor material, the alkaline earth metal donates electrons to the main constituent elements of the i-type layer such as silicon, germanium, tin, and carbon, and ionizes. . 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 photo-degradation and vibration-degradation tend to be strong.

Therefore, in the present invention, by containing a relatively large amount of alkaline earth metal in the weak electric field region and as little as possible in the strong electric field region, ionized alkali is generated even if photo-induced defects and vibration deterioration occur. It is thought that earth metals combine to compensate. Further, it is desirable to reduce the alkaline earth metal content as much as possible in a strong electric field region where photo-induced defects and vibration-induced defects are less likely 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. Further, the above effect is obtained when the hydrogen content and the fluorine content in the i-type layer change in the layer thickness direction as described below, or when the valence electron control agent serving as a donor and the valence electron control agent serving as an acceptor are used. When both are contained in the i-type layer, it becomes stronger. Hereinafter, 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 with reference to the drawings.

In FIG. 2-a or FIG. 6-a, the alkaline earth metal content is drastically changed on the p-type layer side, and the minimum value of the content is on the n-type layer side inside the bulk. in this case,
The change pattern of the valence electron control agent or the hydrogen content with respect to the layer thickness direction is preferably that shown in FIG. 2-a or FIG. 6-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. 2-b or FIG. 6-b shows an example in which the p-type layer side is slowly changed to the n-type layer side, and the minimum alkaline earth content is at the interface with the p-type layer. In this case, the change pattern of the valence electron control agent or hydrogen content with respect to the layer thickness direction is preferably that shown in FIG. 2-b or FIG. 6-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.

FIG. 2-c or FIG. 6-c is an example in which the alkaline earth content changes drastically 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 valence electron control agent or the hydrogen content in the layer thickness direction is as shown in FIG.
-C or that of FIG. 6-c is preferred. p / i interface, n /
It is particularly effective when the i interface is composed of a heterojunction. In the present invention, the alkaline earth metal content varies in the layer thickness direction, but the maximum content (Cm
It is desirable that ax) is 3 × 10 ¹⁸ cm ⁻³ or less and the minimum value (Cmin) is 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 addition, the photovoltaic device of the present invention can improve the photoelectric conversion efficiency by changing the hydrogen content of the i-type layer smoothly in the layer thickness direction. That is, for example, as shown in FIG. 6-a, the place where the hydrogen content is increased on the p-type layer side and the n-type layer side of the i-type layer and the hydrogen content is minimized is set on the p-type layer side inside the bulk. As a result, as shown in FIG. 6-d, the band gap of the i-type layer is n-side,
The maximum and minimum on the mold layer side are on the p-type layer side inside the bulk. For this reason, the electric field in the conduction band is increased on the p-type layer side of the i-type layer, the electrons and holes are efficiently separated, and the recombination of electrons and holes near the interface between the p-type layer and the i-type layer is performed. Can be reduced. In addition, it is possible to prevent electrons from being diffused back into the p-type layer. Further, the electric field in the valence band increases from the i-type layer toward the n-type layer, and recombination of electrons and holes excited on the n-type layer side of the i-type layer can be reduced.

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. Further, by containing more hydrogen atoms 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 specific to the vicinity of 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, S
It is particularly effective when it is made of i / SiC). Generally, there are many interface states at the heterojunction interface,
It is considered that internal stress exists. 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.

It is generally known that the band gap increases as the hydrogen content in the i-type layer made of an amorphous silicon semiconductor material increases. Hereinafter, with reference to the drawings, an example of a desirable change pattern of the hydrogen content of the i-type layer in the photovoltaic device of the present invention, which is considered from the change of the band gap in the layer thickness direction, will be described.

In FIG. 6-a, as described above, the hydrogen content is drastically 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. 6-d, and when light is incident from the p-type layer side, a high electric field near the interface between the p-type layer and the i-type layer and the interface between the n-type layer and the i-type layer. The high electric field in the vicinity can be used more effectively, and the collection efficiency of electrons and holes photoexcited in the i-type layer can be improved.

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 band cap of the i-type layer is small. Further, it is particularly effective when the p / i interface is a heterojunction. FIG. 6-b shows an example in which the hydrogen content is slowly changed from the p-type layer side to the n-type layer side, and the minimum value of the content is at the interface with the p-type layer. In this case, the band gap is as shown in FIG. 6-e, the electric field of the valence band can be increased over the entire region of the i-type layer, the carrier range for holes can be particularly improved, and the fill factor can be increased. Can be improved. Also n
In the case of making the light enter 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 band gap of the i-type layer is small.

FIG. 6-c 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. In this case, the band gap becomes as shown in FIG. 6-f, 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, the back diffusion of electrons to the p-type layer can be suppressed. it can. Further, the electric field in the valence band can be strengthened on the i-type tank side and the n-type layer side, and in particular, the 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 large band gap. That is, in FIG. 6-c, when light is incident from the p-type layer side, the i-type layer having a large band gap cannot sufficiently absorb the light, and the photoexcited carriers near the interface between the i-type layer and the n-type layer are recombined. Without being separated by the strong electric field near the interface, 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. 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.

The effect of the i-type layer has been described above. However, changing the hydrogen content in the layer thickness direction is R
F doping layer, MW doping layer, RF-i described later
It can also be applied to layers. The i-type layer, MW doping layer, RF doping layer, RF- of the photovoltaic element of the present invention
By including fluorine in the i layer, it is possible to suppress photodegradation and vibration degradation when the photovoltaic element is left in a high temperature environment for a long period of time. 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 is large. 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 fluorine content is preferably 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 of 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 photoelectric conversion efficiency can be improved. Further, by including fluorine in the doping layer, a microcrystalline silicon-based semiconductor material can be obtained at a relatively low voltage, so that a doping layer made of a microcrystalline silicon-based semiconductor material is formed without adversely affecting the base layer. It is possible to reduce the interface state. Therefore, the photoelectric conversion efficiency can be improved.

In the photovoltaic device of the present invention, the MW doping layer is formed by the MWPCVD method, so that a particularly good doping layer can be obtained. Further, 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 light deterioration in high temperature and high humidity environment, vibration deterioration) is further improved. It can be further demonstrated. Further, the semiconductor layer is not peeled off even when the photovoltaic element is placed in the above environment.

Hereinafter, 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 with reference to the drawings. In FIG. 3-a, 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. 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 shows an example in which the maximum value of the fluorine content is at the interface with the p-type layer by slowly changing it from the p-type layer side to the n-type layer side. In this case, the change pattern of the hydrogen content in the layer thickness direction is preferably that shown in FIG. 6-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.
FIG. 3C is 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. Further, in the photovoltaic device 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 device, that is, the tail state at the minimum band gap. It is preferable that the slope and the slope of the tail state at the maximum band gap are smoothly continuous.

In the photovoltaic device of the present invention, the photoelectric conversion efficiency can be further improved by providing the i-type layer (RF-i layer) formed by the RFPCVD method between the RF doping layer and the i-type layer. It is a thing. Further, by containing a valence electron control agent in a larger amount than the inside of the i-type layer, the open circuit voltage and fill factor of the photovoltaic element can be improved.

For example, in FIG. 1-d, R in FIG.
An RF-i layer is provided between the Fp type layer and the i type layer. Further, in FIG. 1-e, the RF-i layer is provided between the RF n-type layer and the i-type layer in FIG. 1-a. Further, in FIG. 1-f, 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 so that the gas 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 starting glow discharge by microwaves is affected by the base, and has a high packing density and a small dangling bond. Therefore, it is considered that the surface level decreases.

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 diffusion of hydrogen atoms which occurs at the same time when the RF-i layer is formed. It is thought to be possible. Also RF
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 layer. Although the details of the mechanism are unknown, in the case of the present invention, both the valence electron control agent serving as a donor and the valence electron control agent serving as an acceptor are contained in the RF-i layer, and they are not 100% activated. .
As a result, it is considered that even if dangling bonds are generated by light irradiation, they react with the unactivated valence electron control agent to compensate dangling bonds. In addition, the photovoltaic device of the present invention has a low photoelectric conversion efficiency even if it is exposed to vibration for a long time. The detailed mechanism of this is unknown, but 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 made of amorphous silicon tin (a-SiSn).
Sn atoms are covalently bonded to silicon (Si) atoms to obtain an amorphous silicon-based semiconductor material having a small band gap, and amorphous silicon-germanium (a-Si)
The same bandgap can be obtained with a smaller Sn content compared to the Ge atom content of Ge). Therefore a-S
It is considered that iSn 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. 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.

Further, at least one of the i-type layer, the RF-i layer, the MW doping layer and the RF doping layer may contain oxygen or / and nitrogen atoms. By containing a small amount (1% or less) of oxygen or / and nitrogen atoms in the i-type layer and the RF-i layer, vibration deterioration of the photovoltaic element can be suppressed. The detailed mechanism is not clear, but the i-type layer, RF
-It is considered that the internal stress of the 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.

The content of oxygen and / or nitrogen atoms is preferably changed in the layer thickness direction, and a more preferable change is that the content is increased in the vicinity of one interface. Although the photovoltaic device having the pin structure has been described above, the photovoltaic device in which the pin structure such as the pinpin structure or the pinpinpin structure is stacked, or n
The present invention can also be applied to a photovoltaic device in which a nip structure such as an ipnip structure or a nipnipnip structure is laminated.

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 / M
Wn type layer / RFn type layer / RFp type layer / MWp type layer / RF
It is desirable to form a junction having a structure such as a p-type layer.

FIG. 4 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,
A shutter 415, a target 416, a target shutter 417, a microwave power source (not shown), a vacuum exhaust pump, a raw material gas supply device, and the like are included. The raw material gas supply device (not shown) includes a raw material gas cylinder, a valve, and a mass flow controller.

The photovoltaic element of the present invention is manufactured as follows. First, the substrate 404 is brought into close contact with the heater 405 installed in the deposition chamber 401 of FIG. 4, and the inside of the deposition chamber is sufficiently evacuated to 10 ⁻⁵ Torr or less. A turbo molecular pump or an oil diffusion pump is suitable for this exhaust. After exhausting the inside of the deposition chamber sufficiently, H ₂ , H
A gas such as e or 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, the heater 405 is turned on, and the substrate is heated to 100 to 100%.
Heat to 500 ° C. 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. Also, 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. Particularly, a frequency around 2.45 GHz is 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 transmitted through the waveguide 406 and introduced into the deposition chamber from the applicator 412 through the dielectric window 413. 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 the substrate is taken out from the deposition chamber after being sufficiently purged with a gas such as H ₂ , He or Ar. 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. 4, a target electrode 409, to which a sputtering target 416 is closely attached, is installed in a deposition chamber, and a target power source 414 is installed in the target electrode. Connect. 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 of incorporating the alkaline earth metal into the semiconductor layer, a target is 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 device of the present invention, RF power as well as MW power may be introduced into the deposition chamber. In this case, the MW power to be introduced is 1 for the source gas to be introduced into the deposition chamber.
It is desirable that the power is smaller than the MW power required for 00% decomposition, and the preferable range of the RF power introduced at the same time is 0.01 to 2 W / cm ³ . A preferable range of RF power is 1 to 100 MHz. Especially 13.56 MHz is optimum. Further, it is preferable that the fluctuation of the RF frequency is within ± 2% and the waveform is smooth. It is appropriately selected depending on the area ratio between the area of the RF electrode for supplying RF power and the area of ground. However, especially when the area of the RF electrode for supplying RF power is smaller than the area of ground, the RF power is It is better to ground the self-bias (DC component) on the power supply side for supply. Alternatively, a DC voltage may be applied to the bias electrode. The preferred range of DC voltage is 30 to 300
It is about V. RF power and DC power may be applied to the bias electrode at the same time.

The details of the deposition meganism of the preferred method of depositing the i-type layer described above are unknown, but it is considered as follows. A semiconductor layer is formed by causing a MW power lower than the MW power required for 100% decomposition of the source gas to act on the source gas and an RF power higher than the MW power to act on the source gas at the same time as the MW power. It is considered that the active species suitable for the above can be selected. Furthermore, when the pressure in the deposition chamber when decomposing the source gas is 50 mTorr or less, the average free path of the active species suitable for forming a good quality semiconductor layer is sufficiently long, so that the gas phase reaction is suppressed as much as possible. Conceivable. And again the pressure in the deposition chamber is 50
It is considered that in the state of 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, in the case of the MWPCVD method, the potential difference between the plasma and the substrate is small, but the potential difference between the plasma and the substrate (+ on the plasma side and − on the substrate side) is increased by introducing RF power at the same time as the MW power. can do. Since the plasma potential is positively high with respect to the substrate, active species decomposed by MW power are deposited on the substrate, and at the same time + ions accelerated by the plasma potential collide with the substrate and relax on the substrate surface. It is considered that the reaction is promoted and a good quality semiconductor layer is obtained. 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 10 hours or more for a long time.

In the ordinary RFPCVD method, a raw material gas containing fluorine (eg, 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 raw material 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 when the alkaline earth metal content is desired to be increased, 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. Furthermore, in the case of applying DC power, it is sufficient to apply a large negative DC voltage applied to the target electrode where it is desired to increase the alkaline earth metal content, and to reduce the alkaline earth metal content. Sometimes DC applied to the target electrode
It is sufficient to apply a small voltage having a negative polarity.

When the semiconductor layer does not contain an alkaline earth metal, the target shutter may be closed. 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 hydrogen content contained in the semiconductor layer in the layer thickness direction,
The RF power applied to the bias electrode may be increased when the hydrogen content is desired to be increased, and the RF power applied to the bias electrode may be decreased when the hydrogen content is desired to be decreased. Although the detailed mechanism is still unknown,
It is considered that when the RF power applied to the bias electrode is increased, the plasma potential rises and hydrogen ions are further accelerated toward the substrate, so that more hydrogen is contained in the semiconductor layer. Furthermore, in the case of applying DC power at the same time as RF power, a large DC voltage applied to the bias electrode with a positive polarity may be applied where it is desired to increase the hydrogen content, and when the hydrogen content is desired to be reduced, The DC voltage applied to the bias electrode may be a positive voltage with a small polarity. Although the detailed mechanism remains unknown, increasing the RF power applied to the bias electrode raises the plasma potential and causes more hydrogen ions to accelerate toward the substrate, resulting in more of the i-type layer. It is considered to contain hydrogen.

As another method of changing the hydrogen content contained in the semiconductor layer in the layer thickness direction, a halogen lamp or a xenon lamp is provided in the deposition chamber, and these lamps are turned on during the formation of the semiconductor layer. The substrate temperature is temporarily raised by flashing. that time,
When it is desired to reduce the hydrogen content, the number of flushes per unit time is increased to temporarily raise the substrate temperature, and where the hydrogen content is desired to be increased, the number of flushes per unit time is decreased to reduce the substrate temperature. Can 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 of changing the hydrogen content contained in the semiconductor layer in the layer thickness direction, a source gas containing fluorine and a source gas containing hydrogen are introduced at the time of forming the semiconductor layer, and the source gas of each source gas is changed. The 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. Further, 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 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., and the pressure is 0.1.
-10 torr, RF power 0.01-5.0 W / cm
^{2. The} optimum deposition rate is 0.1 to ² nm / sec. 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 within 2%.

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, in order to prevent the source gas for containing each valence electron control agent in the semiconductor layer from diffusing into another deposition chamber and mixing into another semiconductor layer, A gas gate is used. 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 introduced into each separation passage to prevent mutual diffusion of the source gases. ing.

The alkaline earth metal used in the present invention is
Beryllium, magnesium, calcium, strontium, and barium are preferable, and beryllium, magnesium, and calcium having a small ionic radius are preferably used. In the above-mentioned method for forming a semiconductor layer, when an alkaline earth metal is sputtered to be contained in the semiconductor layer, the following metal, compound or mixture thereof is suitable as a 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.

In order to gasify, what is liquid at room temperature
Enclose the compound in a liquid cylinder and use an inert gas such as He or Ar.
It is obtained by bubbling with water and is solid at room temperature.
Nono encapsulates the compound in a liquid cylinder and heats the liquid cylinder.
Then, melt the compound and bubble with an inert gas such as He or Ar.
Obtained by ringing. Beriliu in the semiconductor layer
As the compound for containing the bismuth, Be (NO₃)
₂・ 3H₂O, Be (CH₃)₂, Be (C
₂H_Five)₂, Be (C₃H₇)₂, Be (C_FourH₉)₂
Etc.

As a compound for containing magnesium in the semiconductor layer, Mg (NO ₃ ) ₂ .6H ₂ O, M
_{g (CH 3 COO) 2,} MgSO 4 · 7H 2 O , and the like. As the compound for containing calcium in the semiconductor layer, Ca (ClO ₃ ) ₂ .2H ₂ O, Ca
_{Br 2 · 6H 2 O, CaI} · 6H 2 O, Ca (NO 3)
₂ · 4H ₂ O, and the like.

Examples of the compound for containing strontium in the semiconductor layer include SrCl ₂ .6H ₂ O and the like. Examples of the compound for containing barium in the semiconductor layer include Ba (OH) ₂ .8H ₂ O and the like. Further, in the above method for forming a semiconductor layer by the MWPCVD method or the RFPCVD method, the following gas or a compound that can be gasified by bubbling is suitable as a source gas.

The semiconductor layer was made to contain silicon atoms.
As a raw material gas for_Four(H includes deuterium D
Mu), SiX_Four(X: halogen atom), SiX_nH_4-n
(N is an integer), Si₂X_nH_6-n, And the like. Total
It is referred to as “source gas (Si)”. Especially SiH_Four, S
iD_Four, Si₂H₆Is suitable. Fluorine in the semiconductor layer
As a source gas for containing atoms, F is₂, Si
F _Four, Si₂F₆, GeF_Four, CF_Four, C₂F₆, C₂
ClF_Five, CClF₃, CHF₃, C₃F₈, NF₃,
PF_Five, BF₃, SF_FourEtc. Collectively, "Hara
Gas (F) ". Especially SiF_Four, GeF_Four, PF
_Five, BF₃Is suitable. Including carbon atoms in the semiconductor layer
CH as the source gas to have_Four, (H is heavy water
(Including element D), C_nH_{2n + 2}(N is an integer), C_nH_2n, C
X_Four(X is a halogen atom), C_nX_{2n + 2}, C_nX_2n, C
₂H₂, C₆H₆Etc. Collectively, "raw materials
(C) ". Especially CH_Four, CD_Four, C₂H₂Is suitable
is doing.

Including germanium atoms in the semiconductor layer
GeH is used as a source gas for _Four, (H is deuterium D
Including), Ge_nH_{2n + 2}, GeX_Four(X is halogen source
Child), and the like. Collective term "raw material gas (Ge)"
And Especially GeH_Four, GeD _FourIs suitable. semiconductor
As a raw material gas for containing tin atoms in the layer,
SnH_Four, (H includes deuterium D), Sn_nH_{2n + 2}, S
nX_Four(X is a halogen atom), SnR_Four(R: alkyl
Group), SnX_nR_4-nEtc. Collectively "raw materials
Gas (Sn) ”. Especially SnH_Four, SnD_Four, Sn
(CH₃)_FourIs 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. As a source gas for introducing a group III atom of the periodic table into the semiconductor layer, B ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , BF ₃ , B (CH ₃ )
₃ , B (C ₂ H ₅ ) ₃ , BCl ₃ , AlCl ₃ , Al
(CH _{3) 3,} may be mentioned GaCl _3, InCl _3, TlCl _3, and the like. Collectively, "source gas (II
I) ”. In particular B ₂ H ₆ , B (CH ₃ ) ₃ , B (C
₂ H ₅ ) ₃ and Al (CH ₃ ) ₃ are 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 , Sb
F 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.

Introduction of Group VI atom of the periodic table into the semiconductor layer
As a raw material gas for₂S, SF_Four, SF₆,
CS₂, H₂Se, SeF₆, TeH₂, TeF₆,
(CH₃ )₂Te, (C₂H_Five)₂Te etc. are mentioned.
Collectively referred to as "source gas (VI)". Especially H₂S,
(C₂H_Five)₂Te is suitable. Oxygen source in the semiconductor layer
As a raw material gas for containing the child, O₂, C
O₂, CO, NO, NO₂, N₂O, H₂O, CH₃C
H₂OH, CH₃OH etc. are mentioned. Collectively "raw materials
Gas (O) ”. Especially O₂, NO are suitable.

Source gases for containing nitrogen atoms in the semiconductor layer include N ₂ , NO, NO ₂ , N ₂ O and NH.
₃ etc. Collectively referred to as "source gas (N)". N ₂ and NH ₃ are particularly suitable. Further, these source gases may be appropriately diluted with a gas such as H ₂ , D ₂ , He, Ar or the like and introduced into the deposition chamber.

Next, the structure of the photovoltaic element of the present invention will be described in detail. 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, for example, NiCr, stainless steel, Al, Cr, M
Examples thereof include metals such as o, Au, 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,
Examples thereof include synthetic resins such as cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene and polyamide, or 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. These insulating supports have a conductive layer formed on at least one surface thereof, and the semiconductor layer of the present invention is formed on the surface having the conductive layer formed thereon.

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, In₂O₃, ITO (In₂O₃+ Sn
O₂), A conductive layer made of a material such as ZnO or an alloy thereof.
To form a synthetic resin sheet such as polyester film
If present, NiCr, Al, Ag, Pb, Zn, N on the surface
i, Au, Cr, Mo, Ir, Nb, Ta, V, Ti,
Forming a conductive layer made of a material such as Pt or an alloy thereof,
For stainless steel, NiCr, Al, Ag, Cr, M
o, Ir, Nb, Ta, V, Ti, Pt, Pb, In₂
O₃, ITO (In ₂O₃+ SnO₂), ZnO, etc.
A conductive layer made of a material or its alloy is formed.

Examples of the forming method include a vacuum vapor deposition method, a sputtering method and a screen printing method. The surface shape of the support is smooth or the peak height is 300 to 1000 at maximum.
It is desirable that the roughness is nm. The thickness of the substrate is appropriately determined so that a desired photovoltaic element can be formed, but when flexibility as a photovoltaic element is required, it is within a range in which the function as a support is sufficiently exerted. It can be made as thin as possible. However, it is usually 10 μm or more in terms of mechanical strength and the like in terms of production and handling of the support.

Preferred substrate forms in the photovoltaic element of the present invention are 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 visible 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, Sn on the light reflecting layer is preferable.
O ₂ , In ₂ O ₃ , ITO, TiO ₂ , CdO, Cd ₂
This is to form a conductive layer (reflection-increasing layer) made of SnO ₄ , Bi ₂ O ₃ , MoO ₃ , Na _x WO _3, or the like. Suitable methods for depositing the light reflection increasing layer include vacuum vapor deposition, sputtering, spraying, spin-on and dipping. As for 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 layer thickness range is 50 nm.
-10 micrometers is mentioned. Further, in order to texture the reflection enhancing layer, it is preferable to raise the substrate temperature at the time of forming the reflection enhancing layer to 200 ° C. or higher. 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-
Examples include SiN, μc-SiON, μc-SiCON, and the like. 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-SiON, μc-SiCON, poly-Si, p
Poly-SiC is 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 in at least one interface. Further, the contained hydrogen (H, D) and fluorine serve to guarantee dangling bonds and improve the doping efficiency. The optimum content of hydrogen and fluorine is 0.1 to 30 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 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 preferably 0.2 eV or less, and most preferably 0.1 eV or less. The specific resistance is 100Ωc
m or less is preferable, and 1 Ωcm or less is optimal. Further, the layer thickness is preferably 1 to 50 nm, and most preferably 3 to 30 nm.

In the case of forming a crystalline semiconductor material having a small light absorption or an amorphous semiconductor layer having a wide band gap as described above, the source gas is 2 to 100 times as much as a gas such as H ₂ , D ₂ and He. It is preferred to dilute and 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 an amorphous silicon semiconductor material,
Alternatively, it is composed of a microcrystalline silicon semiconductor material or a polycrystalline silicon semiconductor material. As the amorphous silicon semiconductor material, a-Si, a-SiC, a-SiG
e, a-SiGeC, a-SiO, a-SiN, a-S
iON, a-SiCON, etc. are raised.

As the microcrystalline silicon-based semiconductor material, μ
c-Si, μc-SiC, μc-SiGe, μc-Si
O, μc-SiGeC, μc-SiN, μc-SiO
N, μc-SiOCN, and the like. Polycrystalline silicon-based semiconductor materials include poly-Si and poly-
SiC, poly-SiGe, etc. are mentioned. In particular, a crystalline semiconductor material with little light absorption or an amorphous semiconductor layer with a wide bandgap is suitable for the RF doping layer on the light incident side. Specifically, a-SiC, a-SiO, a-S
iN, a-SiON, a-SiCON, μc-Si, μ
c-SiC, μc-SiO, μc-SiN, μc-Si
ON, μc-SiOCN, poly-Si, poly-
SiC is 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. In addition, the contained hydrogen (H, D) and fluorine function to compensate dangling bonds and improve the doping efficiency.

Hydrogen and fluorine contents are 0.1 to 25 at
% Can be mentioned as the optimum amount. 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 is large on the interface side, and the hydrogen content in the vicinity of the interface is preferably in the range of 1.1 to 3 times that in the bulk. 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. Introduction amount of oxygen and nitrogen atoms is 0.1
ppm to 20%, 0.1 pp when contained in a trace amount
The preferable range is m to 1%.

Regarding the electrical characteristics, the activation energy is preferably 0.2 eV or less, and most preferably 0.1 eV or less. The specific resistance is preferably 100 Ωcm or less, and most preferably 1 Ωcm or less. Further, the layer thickness is preferably 1 to 50 nm, and optimally 5 to 20 nm.
If a crystalline semiconductor material having a small light absorption as described above or an amorphous semiconductor layer having a wide band gap is formed, H ₂ ,
It is preferable to dilute the raw material gas 2 to 100 times with a gas such as D ₂ or He 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, and the i-type layer is made of an amorphous silicon semiconductor material containing hydrogen.
-Si, a-SiC, a-SiGe, a-SiGeC,
a-SiSn, a-SiSnC, a-SiSnGe, a
-SiSnGeC etc. are mentioned.

As the i-type layer of the photovoltaic element of the present invention,
It contains silicon, hydrogen, and an alkaline earth metal, and the hydrogen content and the alkaline earth metal content change smoothly in the layer thickness direction. Further, as a desirable variation, a valence electron controlling agent (group V or 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 both contained. It is more preferable that the valence electron control agent is increased on the p-type layer side and the n-type layer side.

Further, it is preferable to contain a p-type valence electron control agent and an n-type valence electron control agent so as to compensate each other. The amounts of the group III atom, the group V atom, and the group VI atom introduced into the i-type layer were 5 and 5, respectively.
A preferred range is 00 ppm or less. 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 lifetime in the i-type layer. . 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. Hydrogen and fluorine content of the i-type layer is 1 to 30 at
% Is mentioned as the optimum content. 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. 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. Introduction amount of oxygen and nitrogen atoms is 0.1p
A preferable range is pm to 1%.

The layer thickness of the i-type layer depends on the structure of the photovoltaic element (example
For example, single cell, tandem cell, triple cell) and
It depends largely on the band gap of the i-type layer, but is 0.05 to
The optimum layer thickness is 1.0 μm. I of the present invention
The mold layer has a deposition rate of 2.5 nm / sec or more.
There are few tail states on the valence band side,
The tilt of ilstate is 60 meV or less, and
The density of unbonded hands by spin resonance (ESR) is 10¹⁷/
cm ³It is the following.

The MWCVD method is used to form the i-type layer, preferably RF power is simultaneously introduced in the MWPCVD method as described above, and more preferably M mode as described above.
RF power and DC bias are introduced simultaneously in the WPCVD method. When forming a mold layer made of a-SiC having a wide band gap, it is ₂ to 10 with a gas such as H ₂ , D ₂ and He.
It is preferable to dilute the source gas to 0 times and introduce a relatively high MW power. RF-i layer In the photovoltaic device of the present invention, the RF-i layer is an important layer for generating and transporting carriers for irradiation light.

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 a-Si and a.
-SiC, a-SiO, a-SiN, a-SiGe, 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-S.
iSn, μc-SiO, μc-SiN, μc-SiO
N, μc-SiOCN and the like can be mentioned.

As shown in FIG. 1-d, 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. As shown in FIG. 1-e, the RF-i layer on the side opposite to the light incident side is a-Si, a-SiGe, a.
By using a semiconductor material such as -SiSn, 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 function to compensate dangling bonds in the i-type layer, and R
It is intended to improve the product of carrier mobility and lifetime in the F-i layer. 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 control agent (group V atom and / or group VI atom of the periodic table) serving as a donor and a valence electron control 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. The amount of introduction of the group III atom, the group V atom, and the group VI atom of the periodic table introduced into the RF-i layer is preferably 600 ppm or less as a preferable range, and the content is increased at least at one interface. Is desirable.

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 layer thickness of the RF-i layer is 0.5 to 30.
The optimum layer thickness is nm or less, the tail state on the valence band side is small, the slope of the tail state is 55 meV or less, and the electron spin resonance (E
The density of dangling bonds by SR) is 10 ¹⁷ / cm ³ or less. Transparent electrode Indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), ITO (In ₂ O ₃ + SnO ₂ ) are suitable materials for the transparent electrode, and these materials may contain fluorine. .

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 a sputtering method, the substrate temperature is an important factor, and 20 ° C. to 600 ° C. is mentioned as a preferable range. Further, as a gas for sputtering when depositing the transparent electrode by a sputtering method, an inert gas such as Ar gas can be used. Further, it is preferable to add oxygen gas (O ₂ ) to the inert gas as needed. Especially when a metal is used as a target, oxygen gas (O ₂ ) is essential. Further, when the target is sputtered with the inert gas or the like, the pressure in the discharge space is set to 0.
1-50 mtorr is mentioned as a preferable range.
The deposition rate of the transparent electrode depends on the pressure in the discharge space and the discharge power, and the optimum deposition rate is 0.01 to 10 nm.
The range is / sec.

Suitable vapor deposition sources for depositing transparent electrodes in the vacuum vapor deposition method include metallic tin, metallic indium, and
An indium-tin alloy is mentioned. 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 in the range of 5 × 10 ⁻⁵ torr to 9 × 10 ⁻⁴ torr. By introducing oxygen in this range, the metal vaporized from the vapor deposition source reacts with oxygen in the vapor phase to deposit a good transparent electrode. 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 conditions that satisfy 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. These metals are preferably formed by a vacuum vapor deposition method, a sputtering method, a plating method, a printing method, or the like. When forming by the vacuum deposition method, a mask having a collector electrode shape is adhered to the transparent electrode, and a desired metal deposition source is evaporated in a vacuum by electron beam or resistance heating to form the desired shape on the transparent electrode. The collector electrode is formed.

In the case of forming by the sputtering method, a mask in the shape of a collecting electrode 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. When 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
A suitable layer thickness is 0.5 nm. Next, the power generation system will be described. The power generation system of the present invention is
The photovoltaic element of the present invention, the voltage of the photovoltaic element, and / or
Alternatively, a control system that monitors current and controls supply of power from the photovoltaic element to a storage battery and / or an external load, and storage of power from the photovoltaic element and / or supply of power to an external load And a storage battery for performing.

FIG. 10 shows an example of a power supply system of the present invention, which is a basic circuit for charging and power supply using a photovoltaic element. In this circuit, the photovoltaic element of the present invention is used as a solar cell module and a backflow prevention diode (C
D), a voltage control circuit (constant voltage circuit) that monitors the voltage and controls the voltage, a storage battery, a load, and the like.
To form a module, an adhesive sheet and a nylon sheet are placed on a flat plate, and the photovoltaic elements of the present invention are further arranged on the flat sheet, serialized and parallelized, and further, an adhesive sheet and fluorine It is advisable to place a resin sheet and vacuum laminate.

A silicon diode, a Schottky diode, or the like is suitable as the backflow prevention diode. Examples of the storage battery include a nickel cadmium battery, a rechargeable silver oxide battery, a lead storage battery and a flywheel energy storage unit. The voltage control circuit is approximately equal to the output of the solar cell until the battery is fully charged, and when the battery is fully charged, the charging control IC stops the charging current.

A 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 element of the present invention as a solar cell can be stably used for a long period of time, and is sufficient as a photovoltaic element even when the irradiation light applied to the solar cell changes. It exhibits excellent stability because it functions as a.

[0128]

Embodiments of the present invention will now be described in more detail with reference to the drawings. The photovoltaic element of the present invention will be described in detail by making a solar cell and a photodiode made of a non-single crystal silicon-based semiconductor material, but the present invention is not limited thereto.

Example of Claim 2 (Example 1) Using the deposition apparatus shown in FIG. 4, a solar cell having the structure shown in FIG. 1-b was produced. The n-type layer was formed by the RFPCVD method. First, a substrate was manufactured. Thickness 0.5 mm,
A 50 × 50 m stainless steel substrate was ultrasonically cleaned with acetone and isopropanol, and dried with warm air. Layer thickness 0.3 on the surface of stainless steel substrate at room temperature using the sputtering method.
μm Ag light reflection layer and a layer thickness of 1.0 at 350 ° C.
A reflection-increasing layer of ZnO having a thickness of μm was formed, and the fabrication of the substrate was completed.

Next, the deposition apparatus 400 can carry out both the MWPCVD method and the RFPCVD method, and can 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 source gas supply device (not shown) is connected to the deposition device through a gas introduction pipe. All of the raw material gas cylinders were refined to ultra-high purity. SiH ₄ gas cylinders SiF ₄ gas cylinders, CH ₄ gas cylinders, GeH ₄ gas cylinders, GeF ₄ gas cylinders, SnH ₄ gas cylinders,
PH ₃ / H ₂ (dilution: 100 ppm) 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 (NO) heated to 100 ° C.
₃₎ Connect fluid cylinders ₂ · 6H ₂ O. A He gas cylinder different from the He gas cylinder is connected to the liquid cylinder, and He gas can be bubbled. Mg was used as the target, was attached to the target electrode, and the target power source was the RF power source.

Next, the back surface of the substrate 404 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 a vacuum not shown is shown. The inside of the deposition chamber 401 was evacuated by the exhaust pump until the pressure became about 1 × 10 ⁻⁵ Torr. After the preparation for film formation is completed as described above, RFn made of μc-Si is formed on the substrate 404.
Type layer, i-type layer made of a-Si, R made of a-SiC
An Fp type layer and an MWp type layer made of a-SiC were sequentially formed.

To form the RFn-type layer made of μc-Si, H ₂ gas was introduced into the deposition chamber 401 and the flow rate was 30%.
The mass flow controller adjusted the pressure to 0 sccm, and the conductance valve adjusted the pressure in the deposition chamber to 1.0 Torr. Substrate 404 temperature is 3
The heater 405 was set to 50 ° C., 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 P
The H ₃ / H ₂ gas flow rate was adjusted to 200 sccm, and the pressure inside the deposition chamber was adjusted to 1.0 Torr. The power of the RF power source was set to 0.02 W / cm ³ , the RF power was introduced to the bias electrode 410 to cause glow discharge, the shutter was opened, the formation of the RFn type layer on the substrate was started, and the layer thickness 20
After forming the RFn-type layer of nm, the shutter was closed, the RF power supply was turned off, the glow discharge was stopped, and the formation of the RFn-type layer was completed. SiH ₄ gas in the deposition chamber, PH ₃ /
Stopping the flow of H _2, 5 minutes, after which continued to flow H ₂ gas into the deposition chamber, the flow of H ₂ is also stopped, and vacuum evacuating the deposition chamber and the gas in the pipe up to 1 × 10 ^-5 Torr.

The i-type layer made of a-Si is formed by the MWPCVD method.
And alkaline earth metal sputtering at the same time
Formed by. First, H₂ Conduct gas at 300 sccm
The pressure is 0.01 Torr and the temperature of the substrate 404 is 3
It was adjusted to 50 ° C. Where the substrate temperature is stable
And SiH_Four Gas, He gas, B₂ H₆ / H₂ Gas, P
H₃ / H₂ Inflow gas, SiH_Four Gas flow rate is 150
sccm, He gas flow rate is 150 sccm, H₂ Gas flow
The amount is 150 sccm, B₂ H₆ / H₂ Gas flow rate is 2sc
cm, PH₃ / H₂ Gas flow rate is 2 sccm, deposition chamber
Adjust the pressure inside 401 to 0.01 Torr
It was Next, the power of the RF power source is 0.32 W / cm³Set to
And applied to the bias electrode. After that, MW
Source power 0.20 W / cm³To the dielectric window 41.
Introduce MW power into the deposition chamber through 3 to generate glow discharge.
Raised. Next, set the target power to 200W.
Open the target shutter 416,
Then, the i-type layer was formed on the RF n-type layer. Layer thickness
After forming the i-type layer of 300 nm, the shutter,
Close the target shutter, MW power supply, RF power supply,
Power off to stop glow discharge and form i-type layer
Finished. SiH_Four Gas, He gas, B₂ H₆ / H₂ Moth
Su, PH₃ / H₂ Stop gas inflow for 5 minutes H₂ Gas
After continuing to flow, H ₂ Stop the inflow of gas, and
1 x 10 inside the piping^-FiveEvacuated to Torr.

To form an RF p-type layer made of a-SiC, H ₂ gas was introduced at 300 sccm and the pressure was 1.0.
Torr and the substrate temperature were set to 200 ° C. When the substrate temperature is stable, SiH ₄ gas, CH ₄ gas,
B ₂ H ₆ / H ₂ gas is caused to flow into the deposition chamber 401, and Si
H ₄ gas flow rate is 5 sccm, CH ₄ gas flow rate is 1 sccc
m, H ₂ gas flow rate was 100 sccm, B ₂ H ₆ / H ₂ gas flow rate was 200 sccm, and pressure was adjusted to 1.0 Torr. RF power of 0.06W / cm ³
, Glow discharge, open the shutter,
The formation of the RF p-type layer on the i-type layer was started. Layer thickness 10 nm
When the RF p-type layer is formed, the shutter is closed and R
The F power source was turned off to stop the glow discharge, and the formation of the RF p-type layer was completed. SiH ₄ gas, CH ₄ gas in the deposition chamber,
The inflow of B ₂ H ₆ / H ₂ gas was stopped, H ₂ gas was continued to flow for 5 minutes, then the inflow of H ₂ gas was stopped, and the deposition chamber and the gas pipe were evacuated to 1 × 10 ⁻⁵ Torr. .

A MWp type layer made of a-SiC is formed.
To H₂ Gas is introduced at 500 sccm and pressure in the deposition chamber is increased.
Force of 0.02 Torr and substrate temperature of 200 ℃
Set to. SiH when the substrate temperature is stable_Four Moth
Su, CH_Four Gas, B₂ H₆ / H ₂ Gas was flowed in. This
When, SiH_Four Gas flow rate is 10 sccm, CH_Four Gas flow
2 sccm, H₂ Gas flow rate is 100 sccm, B₂ 
H₆ / H₂ Gas flow rate is 500 sccm, pressure is 0.02
It was adjusted to be Torr. After that, MW not shown
The power of the power supply is 0.40 W / cm³Set the dielectric window to
MW power is introduced through the
To open the MWp type layer on the RFp type layer.
did. When a MWp type layer having a layer thickness of 10 nm is formed,
Close the shutter and turn off the MW power to stop glow discharge.
Therefore, the formation of the MWp type layer was completed. SiH_Four Gas, CH_Four 
Gas, B₂ H₆ / H₂ Stop gas inflow for 5 minutes, H₂ 
After continuing to flow the gas, H₂ Stop gas inflow, deposit chamber
1 × 10 inside and inside gas pipe ^-FiveVacuum exhaust to Torr
Then close the auxiliary valve 408 and open the leak valve 409.
Then, the deposition chamber leaked.

Next, ITO having a layer thickness of 70 nm was vacuum-deposited on the MWp type layer by a vacuum vapor deposition method as a transparent electrode. Next, a mask with comb-shaped holes was placed on the transparent electrode, and Cr (4
A comb-shaped collector electrode composed of 0 nm) / Ag (1000 nm) / Cr (40 nm) was vacuum-deposited by a vacuum deposition method.

The fabrication of the solar cell was completed as described above. This solar cell will be called (SC Ex 1), and Table 1 shows the conditions for forming the RFn-type layer, the i-type layer, the RFp-type layer, and the MWp-type layer. (Comparative Example 1-1) A solar cell (SC ratio 1-1) was produced under the same conditions as in Example 1 except that PH ₃ / H ₂ gas was not introduced when forming the i-type layer.

Comparative Example 1-2 When forming the i-type layer, B
_A solar cell (SC ratio 1-2) was produced under the same conditions as in Example 1 except that ₂ H ₆ / H ₂ gas was not introduced. (Comparative Example 1-3) A solar cell (SC ratio 1-3) was produced under the same conditions as in Example 1 except that the RFp type layer was not formed and the layer thickness of the MWp type layer was 20 nm.

Solar cells (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 V-1 characteristic. As a result of the measurement, (SC ratio 1−) (SC ratio 1−
The initial photoelectric conversion efficiencies of 1) to (SC ratio 1-3) are as follows. (SC ratio 1-1) 0.94 times (SC ratio 1-2) 0.92 times (SC ratio 1-3) 0.93 times For the measurement of vibration deterioration, the initial photoelectric conversion efficiency was measured in advance. The solar cell is installed in a dark place with a humidity of 50% and a temperature of 25 ° C, and a vibration with an oscillation frequency of 60 Hz and an amplitude of 0.1 mm is 50
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).

Photodegradation was measured by setting a solar cell whose initial photoelectric conversion efficiency had been measured in advance in an environment of humidity 50% and temperature 25 ° C. and irradiating AM-1.5 (100 mW / cm ² ). The rate of decrease in photoelectric conversion efficiency (photoelectric conversion efficiency after vibration deterioration test / initial photoelectric conversion efficiency) was used. As a result of the measurement,
(SC ratio 1) to (SC ratio 1-1) to (SC ratio 1-
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.

[0141] A forward bias was applied and vibration deterioration and light deterioration were measured. 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, the reduction rate of the photoelectric conversion efficiency after the vibration deterioration of (SC ratio 1-1) to (SC ratio 1-3) and the reduction rate of the photoelectric conversion efficiency after the light deterioration with respect to (SC Ex 1) Became as follows.

[0142] The state of delamination was observed using an optical microscope. In (SC Ex 1-1) and (SC Ratio 1-1) (SC Ratio 1-2), no layer separation was observed, but in (SC Ratio 1-3), slight layer separation was observed.

Next, a secondary ion mass spectrometer (SIMS)
(SC Ex 1), (SC Ratio 1-1) to
The contents of P (phosphorus) and B (boron) of (SC ratio 1-3) were calculated as follows. Also, vibration deterioration in a high temperature environment, light deterioration, and vibration deterioration in a high humidity environment, and light deterioration were measured. Similarly, (SC Ex 1) is (SC Ratio 1-1) to (SC Ratio 1-3). Had better properties than.

Further, a forward bias was applied in the above environment.
In the same manner, (SC Ex 1) is (SC Ratio 1-1) to (S
It had characteristics superior to C ratio 1-3). That's all
The solar cell of this embodiment (SC Ex 1) is a conventional solar cell.
Even better than (SC ratio 1-1) to (SC ratio 1-3)
It was found to have the following characteristics. (Example 2) Content of valence electron control agent in i-type layer is layer thickness
It changes smoothly and has a large content on the p-type layer side.
A positive battery (SC Ex 2) was produced. PH₃ / H₂ Gas flow
Quantity, B ₂ H₆ / H₂ As shown in Fig. 5, change the gas flow rate with time.
Under the same conditions as in Example 1 except that the solar cell (SC
2) was produced. First, by SIMS as in the first embodiment.
When the contents of P and B were calculated, it was as shown in Fig. 2-a.
I found out. The same measurement as in Example 1 was performed
By the way, the solar cell of (SC Ex 2) is more than that of (SC Ex 1)
It was found to have even better properties.

Example 3 A photodiode (PD Ex 3) having the layer structure shown in FIG. 1-c was produced. First, a substrate was manufactured. Ultrasonic cleaning a 0.5 × 20 mm × 20 × 20 mm ² glass substrate with acetone and isopropanol, drying with warm air, and light reflection of Al with a layer thickness of 0.1 μm on the glass substrate surface at room temperature by vacuum deposition. The layers were formed and the fabrication of the substrate was completed.

The MWn type layer (a-SiC), RFn type layer (a-SiC), i type layer (a-Si), and RFp type layer (μc-SiC) were formed on the substrate in the same manner as in Example 1. It was formed sequentially. Table 2 shows the layer forming conditions of the semiconductor layer. Next, RF
A transparent electrode and a collector electrode similar to those in Example 1 were formed on the p-type layer. (Comparative Example 3-1) A photodiode (PD ratio 3-1) was produced under the same conditions as in Example 3 except that PH ₃ / H ₂ gas was not introduced when forming the i-type layer.

(Comparative Example 3-2) When forming the i-type layer, B
A photodiode (PD ratio 3-2) was produced under the same conditions as in Example 3 except that ₂ H ₆ / H ₂ gas was not introduced. (Comparative Example 3-3) A photodiode (PD ratio 3-3) was produced under the same conditions as in Example 3 except that the RFn type layer was not formed and the MWn type layer had a layer thickness of 40 nm.

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 of the measurement, the photodiode (PD Ex 3) of this embodiment is the same as the conventional photodiode (P
It was found that the characteristics were further superior to those of D ratio 3-1) to (PD ratio 3-3).

Example 4 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 (μc
-Si), i-type layer (a-Si), RFn-type layer (a-Si)
C), a MWn type layer (a-SiC) was formed. When forming the i-type layer, the target power was changed with time to change the alkaline earth metal content in the layer thickness direction as shown in FIG. The layer forming conditions of the semiconductor layer are shown in Table 3.

A solar cell (SC4) was produced under the same conditions as in Example 1 except for the semiconductor layer and the substrate. (Comparative Example 4-1) A solar cell (SC ratio 4-1) was produced under the same conditions as in Example 4 except that PH ₃ / H ₂ gas was not introduced when forming the i-type layer.

(Comparative Example 4-2) When forming the i-type layer, B
_A solar cell (SC ratio 4-2) was produced under the same conditions as in Example 4 except that ₂ H ₆ / H ₂ gas was not introduced. (Comparative Example 4-3) A solar cell (SC ratio 4-3) was produced under the same conditions as in Example 4 except that the RFn type layer was not formed and the MWn type layer had a layer thickness of 20 nm.

Example 4-1 When forming an i-type layer, R
A solar cell (SC Ex 4-1) was produced under the same conditions as in Example 4 except that the F power was changed with time. Next, using a glass substrate and a silicon wafer, applying a constant RF power,
Other than that, an i-type layer having a thickness of 1 μm was formed on a glass substrate and a silicon wafer under the same conditions as in Example 1 to obtain samples for bandgap measurement and infrared absorption spectrum measurement.
Furthermore, several samples with various RF powers were prepared. The band gap (Eg) of the glass substrate sample produced using a spectrophotometer was determined, and the infrared absorption spectrum of the silicon wafer sample was measured to measure the hydrogen content. The relationship between the hydrogen content in the i-type layer and the band gap was obtained using the results of both.

Next, a secondary ion mass spectrometer (SIM
When the hydrogen content in the layer thickness direction of the manufactured (SC Ex 4-1) was obtained using S), it was found that the result was as shown in FIG. 6-a. Further, when the change in the bandgap in the layer thickness direction was obtained using the relationship between the hydrogen content and the bandgap, it was found that it was as shown in FIG. 6-d.

Similarly (SC Ex 4), (SC Ratio 4-1)
When the hydrogen content of (SC ratio 4-3) was determined, it was found that the hydrogen content did not change in the layer thickness direction and was constant, and the band gap was 1.73 (eV). Thus, it was found that the changes in the hydrogen content and the band gap with respect to the layer thickness direction depend on the RF power to be introduced.

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 Ex.
It was found that the characteristics are further superior to those of the ratios 4-1) to (SC ratio 4-3). Also, (SC Ex 4-1) is (S
It was found that it had even better characteristics than C Ex 4). (Example 5) A solar cell was produced in which the fluorine content of the i-type layer changed smoothly in the layer thickness direction, and the content was minimized near the interface with the RFp-type layer. When forming the i-type layer,
The SiF ₄ gas flow rate was monotonically increased from 1 sccm to 20 sccm to obtain a change pattern of fluorine content 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 (SC Ex 5) had further excellent characteristics than (SC Ex 1).

Example 6 A solar cell having a maximum hydrogen content near the interface between the MWp type layer and the RFp type layer was produced. At the time of forming the RF p-type layer, the RF power was changed with time to obtain a hydrogen content change pattern as shown in FIG. 6-b. When the MW p-type layer was formed, the MW power was changed with time to obtain a hydrogen content change pattern as shown in FIG. 6-c. 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 it has even better characteristics than Ex 1).

Example 7 A solar cell in which the content of the valence electron control agent was maximum near the interface between the MWp type layer and the RFp type layer was produced. When forming the MWp type layer and the RFp type layer, the source gas of the valence electron control agent introduced was changed with time to change the content of B atoms as shown in FIG. 12-c.
Other than this, it produced on the same conditions as Example 1. When the same measurement as that of Example 1 was performed, it was found that (SC Ex 7) had further excellent characteristics than (SC Ex 1).

Example 8 A solar cell was prepared in which the MWp type layer and the RFp type layer contained fluorine, and the fluorine content was minimum near the interface. When forming the MWp type layer and the RFp type layer, SiF ₄ gas was newly introduced and the flow rate was changed with time to obtain a change pattern of the fluorine content 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 (SC Ex 8) had even better characteristics than (SC Ex 1).

Example 9 A solar cell having the structure shown in FIG. 1-a was produced. As in Example 1, the MWn type layer (μc-Si), the RFn type layer (a-Si), and the i type layer (a) were formed on the substrate.
-Si), RFp type layer (a-SiC), MWp type layer (μ
c-SiC) was sequentially laminated. When forming the i-type layer, B
_{The 2} H ₆ / H ₂ gas flow rate and the PH ₃ / H ₂ gas flow rate are changed with time, and the changes in the B and P contents in the layer thickness direction are shown in FIG.
-C. The same material as in Example 1 was used except for the semiconductor layer. The manufactured solar cell (SC Ex 9) is (SC
It was found that it has even better characteristics than Ex 1).

(Example 10) Use of a-SiGe for the i-type layer
, Containing alkaline earth metal using MWPCVD method
The prepared solar cell was produced. First, the target,
Target electrode and target shutter from the deposition chamber
Removed. When forming the i-type layer, a new GeH _Four With gas
Mg bubbling with He gas (NO₃ )₂ ・ 6H₂ O
/ He gas was introduced. GeH_Four Gas flow rate is 30 scc
m, and Mg (NO₃ )₂ ・ 6H₂ O / He gas flow rate is
Figure 2 shows that the alkaline earth metal content changes with time.
The thickness of the i-type layer was set to 250 nm so as to be b. other
The same conditions as in Example 1 were applied to the solar cell (SC Ex 10).
Was produced.

Comparative Example 10-1 When forming the i-type layer,
A solar cell (SC ratio 10-1) was produced under the same conditions as in Example 10 except that PH ₃ / H ₂ gas was not introduced. (Comparative Example 10-2) When forming the i-type layer, B ₂ H ₆ / H
_A solar cell (SC ratio 10-2) was produced under the same conditions as in Example 10 except that ₂ gas was not introduced.

Comparative Example 10-3 Example 1 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 10-3) was produced under the same conditions as 0. When the same measurement as in Example 1 was performed, the solar cell of this example (SC Ex 10) was a conventional solar cell (SC ratio 10).
It was found that it has more excellent characteristics than -1) to (SC ratio 10-3).

Example 11 A solar cell was prepared in which a-SiSn was used for the i-type layer and beryllium, magnesium, and calcium were contained as alkaline earth metals. First, as a target, BeF ₂ , MgF ₂ , Ca
F ₂ was exchanged with a mixture of 1: 2: 1, an Al (CH ₃ ) ₃ (trimethylaluminum TMA) liquid cylinder was connected to the raw material gas supply device, and TMA was bubbled with He gas to thereby remove He. TMA / H diluted with
The e-gas was allowed to flow into the deposition chamber. When forming the i-type layer, the SiH ₄ gas flow rate was set to 110 sccm, and SiF ₄ was added.
Gas flow rate is 20 sccm, SnH ₄ gas flow rate is 20 sc
cm, PH ₃ / H ₂ gas flow rate 1 sccm, TMA / H
A solar cell (SC Ex 11) under the same conditions as in Example 1 except that the gas flow rate of e was 10 sccm, the target power was changed with time, and the change pattern of the alkaline earth metal content was as shown in FIG. Was produced.

(Comparative Example 11-1) When forming an i-type layer,
A solar cell (SC ratio 11-1) was produced under the same conditions as in Example 11 except that PH ₃ / H ₂ gas was not introduced. (Comparative Example 11-2) When forming an i-type layer, TMA / He
A solar cell (SC ratio 11-2) was produced under the same conditions as in Example 11 except that gas was not introduced.

Comparative Example 11-3 Example 1 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 11-3) was produced under the same conditions as in 1. When the same measurement as in Example 1 was performed, the solar cell of this example (SC Ex 11) showed that the conventional solar cell (SC ratio 1
It was found that it has more excellent characteristics than 1-1) to (SC ratio 11-3).

Example 12 Between the RF p-type layer and the i-type layer,
FIG. 1-f having a PR-i layer between the RF n-type layer and the i-type layer.
The solar cell of was produced. Other layers are the same as in Example 9.
A solar cell was produced by the method. The two RF-i-type layers are a-
Made of Si, SiH_Four Gas flow rate is 2 sccm, H₂ Moth
Flow rate is 50 sccm, PH₃ / H₂ Gas flow rate is 0.2
sccm, B ₂ H₆ / H₂ Gas flow rate is 0.5 sccm,
The pressure inside the deposition chamber is 1.0 Torr, and the RF power to be introduced is
0.01 W / cm³, Substrate temperature is 270 ° C, layer thickness is 20
It was formed under the condition of nm. Fabricated solar cell (SC Ex 1
2) has better characteristics than (SC Ex 9)
I understood.

Example 13 A triple type solar cell shown in FIG. 7 was produced using the deposition apparatus of FIG. 4 using the MWPCVD method. First, a substrate was manufactured. As in Example 1, a 50 × 50 mm ² stainless steel substrate was ultrasonically cleaned with acetone and isopropanol and dried. A layer thickness of 0.3 is formed on the surface of the stainless steel substrate by using the sputtering method.
A light reflection layer of Ag of Ag was formed. At this time, the substrate temperature is set to 350 ° C., and the substrate surface is uneven (textured).
I chose A ZnO reflection increasing layer having a layer thickness of 2.0 μm was formed thereon at a substrate temperature of 350 ° C.

Next, the preparation for film formation was completed in the same manner as in Example 1. In the same manner as in Example 1, the first MWn was formed on the substrate.
A type layer (μc-Si layer thickness 10 μm) is formed, and a first RFn type layer (a-Si layer thickness 10 μm) and a first i layer are formed.
Type layer (a-SiGe), first RFp type layer (a-Si)
Layer thickness 10 nm), first MWp type layer (μc-Si layer thickness 10 nm), second RFn type layer (μc-Si), second i type layer (a-Si), second RFp type layer (A-SiC
Layer thickness 10 nm), second MWp type layer (μc-Sic layer thickness 10 nm), third RFn type layer (a-SiC), third
I-type layer (a-SiC), third RFp-type layer (a-S)
iC layer thickness 10 nm), third MWp type layer (μc-Si)
A C layer thickness of 10 nm) was sequentially formed.

At the time of forming the first i-type layer, the second i-type layer and the third i-type layer, the flow rates were changed with time so that the P and B contents were as shown in FIG. 2-a. In other layers, the MW power was changed with time in the layer formed by the MWPCVD method, and the RF power was changed in the layer formed by the RFPCVD method with time, so that the distribution of the hydrogen content in each layer was changed as shown in FIG.
I tried to be like. The target power supply is replaced with a DC power supply, and the target power (DC
The electric power) was changed so that the magnesium content was as shown in FIG.

Next, on the third MWp type layer, the same as in Example 1.
Transparent electrodes and collector electrodes were formed. Triple type thick
The fabrication of the positive battery (SC Ex 13) was completed. (Comparative Example 13-1) First i-type layer, second i-type layer, and
And when forming the third i-type layer,₃ / H ₂ Gas inflow
Solar cells (SC
Ratio 13-1) was produced.

Comparative Example 13-2 When forming the first i-type layer, the second i-type layer, and the third i-type layer, B ₂ H ₆ /
A solar cell (SC ratio 13-2) was produced under the same conditions as in Example 13 except that H ₂ gas was not introduced. (Comparative Example 13-3) The first RFn-type layer, the first RFp-type layer, the second RFp-type layer, and the third RFp-type layer were not formed, and the first MWn-type layer and the first RFn-type layer were formed. MWp type layer, second M
A solar cell (SC ratio 1 was obtained under the same conditions as in Example 13 except that the layer thicknesses of the Wp type layer and the third MWp type layer were 20 nm.
3-3) was produced. When the same measurement as in Example 1 was performed, the solar cell of the present example (SC Ex 13) had better characteristics than the conventional solar cells (SC ratio 13-1) to (SC ratio 13-3). Found to have.

Example 14 The tandem solar cell shown in FIG. 8 was produced using the deposition apparatus using the roll-to-roll method shown in FIG. First, the substrate is 300m long and 30c wide
A long stainless steel sheet having m and a thickness of 0.1 mm and having both surfaces mirror-polished was used. A light-reflecting layer made of Ag having a layer thickness of 0.3 μm was continuously formed on this stainless steel substrate in 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. 0 μm
And a reflection increasing layer made of ZnO was continuously formed. It was found that the substrate surface was textured as in Example 13.

FIG. 9 is a schematic view of a continuous semiconductor layer forming apparatus using the roll-to-roll method. This apparatus includes a substrate delivery chamber 910, a plurality of deposition chambers 901 to 909,
Substrate winding chambers 911 are sequentially arranged, and a separation passage 912 is connected between them, and a long substrate 913 is continuously moved from the substrate delivery chamber to the substrate winding chamber through these. Further, the semiconductor layers can be simultaneously formed in the deposition chambers simultaneously with the movement of the substrate. Reference numeral 950 is a view of the deposition chamber viewed from above. Each deposition chamber has a source gas inlet 914 and a source gas exhaust port 915, so that respective semiconductor layers can be simultaneously formed. 950 is a view of the deposition chamber viewed from above, each deposition chamber has a source gas inlet 914 and a source gas exhaust port 915, and an RF electrode 916 or a microwave applicator 917 is attached as necessary,
Further, a halogen lamp heater 918 for heating the substrate is installed inside. Further, a raw material gas supply device similar to that of the first embodiment is connected to the raw material gas inlet 914, each raw material gas exhaust port is provided in each deposition chamber, and each exhaust port has an oil diffusion pump and a mechanical booster. A vacuum exhaust pump such as a pump is connected. An RF power source is connected to each RF electrode, and a MW power source is connected to the microwave applicator. A bias electrode 931 and a target electrode 930 are arranged in deposition chambers 903 and 907 which are i-type layer deposition chambers, and an RF power source is connected to each as a power source. Further, Be was used as a target. 940 is a side view of the deposition chamber for the i-type layer, in which a target having a surface area smaller than the substrate area in the deposition chamber is disposed substantially in the center of the deposition chamber to sputter an alkaline earth metal per unit time. Is larger in the board central portion 942 than in the board peripheral portion 941. By doing so, the change in alkaline earth metal content in the layer thickness direction is shown in Fig. 2-c.
become that way. The separation passage connected to the deposition chamber has an inlet 919 through which scavenging gas flows. In the substrate delivery chamber, there are a delivery roll 920 and a guide roll 921 for applying an appropriate tension to the substrate and always keeping the substrate horizontal. In the substrate take-up chamber, a winding roll 922 and a guide roll 92 are provided.
There are three.

First, the substrate on which the light reflection layer and the reflection increasing layer are formed is wound around a delivery roll, set in a substrate delivery chamber, passed through each deposition chamber, and then the end of the substrate is wrapped around a substrate winding roll. 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 919, and the substrate is taken up by a take-up roll while moving in the direction of the arrow in the figure. In the same manner as in Example 1, each source gas is caused to flow into each deposition chamber. At this time, the flow rate of the H ₂ gas flowing into each separation passage or the pressure of each deposition chamber is adjusted so that the source gas flowing into each deposition chamber does not diffuse to the other deposition chambers.

Next, RF power or MW power is introduced to cause glow discharge to form the respective semiconductor layers. In the deposition chamber 901, the first MWn type layer (μc−
Si layer thickness 20 nm) is further formed, and a first RFn type layer (a-Si layer thickness 10 nm) is deposited in the deposition chamber 902, and a first i type layer (a-SiGe layer thickness 180 n is deposited in the deposition chamber 903.
m), a first RFp type layer (a-Si layer thickness 10 nm) in the deposition chamber 904, and a first MWp type layer (μc) in the deposition chamber 905.
-Si layer thickness 10 nm), second RFn in deposition chamber 906
Type layer (μc-Si layer thickness 20 nm), second i-type layer (a-Si layer thickness 250 nm) in deposition chamber 907, deposition chamber 90
8 the second RF p-type layer (a-SiC layer thickness 10 nm),
A second MWp-type layer (μc-SiC layer thickness 10 nm) was sequentially formed in the deposition chamber 909. Beryllium was contained in the first i-type layer and the second i-type layer, and the change in the content in the layer thickness direction was as shown in FIG. When forming the first i-type layer and the second i-type layer, PH ₃ / H ₂ gas, B ₂ H ₆
/ H ₂ gas was separately introduced through inlets 924 and 925 so that a large amount of valence electron control agent could be introduced near the interface of the i-type layer. In addition, a large amount of H ₂ gas from the separation passage
Since it is supplied to the deposition chamber for the i-type layer and the second i-type layer, the amount of fluorine is small near the interface, and the change in the fluorine content in the layer thickness direction is as shown in FIG. When the transfer of the substrate was completed, all MW power supplies, RF power supplies, and target power supplies were turned off, glow discharge was stopped, and inflow of raw material gas and scavenging gas was stopped. The entire apparatus was leaked and the wound substrate was taken out. Then, a transparent electrode made of ITO having a layer thickness of 70 nm was continuously formed at 170 ° C. on the second MWp type layer by a sputtering device using a roll-to-roll method.

Next, a part of this substrate is set to 50 mm × 50 mm.
The size is cut, and a screen printing method is used to print a carbon paste having a layer thickness of 5 μm and a line width of 0.5 mm, and a silver paste having a layer thickness of 10 μm and a line width of 0.5 mm is printed thereon.
A collector electrode was formed. This completes the production of a tandem solar cell (SC Ex 14) using the roll-to-roll method. When the change in the content of the valence electron control agent in the layer thickness direction was obtained using SIMS, it was found that the change was as shown in FIG.

(Example 14-1) A solar cell was prepared under the same conditions as in Example 14 except that PH ₃ / H ₂ gas was not introduced when forming the first i-type layer and the second i-type layer. Battery (SC
Example 14-1) was produced. (Example 14-2) A solar cell under the same conditions as in Example 14 except that B ₂ H ₆ / H ₂ gas was not introduced when forming the first i-type layer and the second i-type layer. (SC Ex 14-
2) was produced.

(Comparative Example 14-1) The first RFn type layer, the first RFp type layer and the second RFp type layer were not formed,
Example 1 except that the thickness of the first MWn type layer was 30 nm, the layer thickness of the first MWp type layer, and the layer thickness of the MWp type layer were 20 nm.
A solar cell (SC ratio 14-1) was produced under the same conditions as in No. 4.

When the same measurement as in Example 1 was performed, it was confirmed that the solar cell (SC Ex 14) of this Example had a solar cell (SC ratio 14-1), (SC Ex 14-1), and (SC Ex 14). −
It has been found that it has even better properties than 2). (Example 15) A tandem solar cell manufactured by using the deposition apparatus shown in FIG. 9 was modularized, applied to a power generation system, and subjected to a field test.

50 mm of non-irradiated light produced 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.

[0181] An external light which was turned on at night was used as a load, which was connected to the circuit showing the power generation system. The entire system is operated by the storage battery and the power of the module.
This power generation system will be referred to as (SBS Ex 15). (Comparative Example 15) The initial photoelectric conversion efficiency was measured by using 65 tandem-type solar cells (SC ratio 14-1) that were not irradiated with light to form a module in the same manner as in Example 15. This module was connected to the same power generation system as in Example 15.

These power generation systems (SBS ratio 15-
I will call it 1). Each module was installed at the angle that could collect the most sunlight. In the field test, the photoelectric conversion efficiency after one year was measured and the deterioration rate (1
This was done by calculating the photoelectric conversion efficiency after a year / initial photoelectric conversion efficiency). As a result, the power generation system (SBS Ex 15) using the solar cell of the present invention has more excellent initial photoelectric conversion efficiency and field durability than the conventional power generation system (SBS ratio 15-1). Do you get it.

Example 16 A photovoltaic element containing oxygen and / or nitrogen atoms in the semiconductor layer was produced. When forming the (Example 16-1) i-type layer, O ₂ / He gas 100sccm, N ₂ / He gas 20sccm solar cell under the same conditions as in Example 1 except that the introduction (SC16
Fruit-1) was produced.

(Example 16-2) When forming an RF-i layer type layer, a solar cell () was formed under the same conditions as in Example 1 except that ₂ sccm of O ₂ / He gas and 1 sccm of N ₂ / He gas were introduced. SC Ex 16-2) was produced. When forming the (Example 16-3) MWp-type layer, O ₂ / H
e gas at 100 sccm, N ₂ / He gas at 20 sccc
A solar cell (SC Ex 16-3) was prepared under the same conditions as in Example 1 except that O ₂ / He gas was introduced at ₂ sccm and N ₂ / He gas was introduced at 1 sccm when the RF p-type layer was formed. .

When the same measurement as in Example 1 was carried out, it was found that these solar cells had further superior characteristics to the solar cell (SC Ex 1). When the concentrations of oxygen atoms and nitrogen atoms of these fabricated solar cells were examined by using 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). I found out that Example of Claim 1 (Example 17) Using the deposition apparatus shown in FIG. 4, a solar cell having the structure shown in FIG. 1-b was produced. The n-type layer was formed by the RFPCVD method.

First, a substrate was prepared in the same manner as in Example 1, and subsequently, RF consisting of μc-Si was formed on the substrate 404.
An n-type layer, an i-type layer made of a-Si, an RFp type layer made of a-SiC, and a MWp type layer made of a-SiC were sequentially formed. To form an RFn-type layer made of μc-Si,
H ₂ gas was introduced into the deposition chamber 401, and the flow rate was 300 sc
Adjust with a mass flow controller to be cm,
The conductance valve was adjusted so that the pressure in the deposition chamber was 1.0 Torr. Substrate 404 temperature is 350 ° C
The heater 405 was set so that the temperature became stable, 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 PH ₃ /
The H ₂ gas flow rate was 200 sccm, and the pressure inside the deposition chamber was 1.
It was adjusted to be 0 Torr. The power of the RF power source is set to 0.02 W / cm ³ and the bias electrode 410 is set to RF.
Electric power was introduced to cause glow discharge, the shutter was opened, the formation of the RFn type layer on the substrate was started, and the layer thickness was 20 nm.
When the RF n-type layer is formed, the shutter is closed and R
The F power supply was turned off, the glow discharge was stopped, and the formation of the RFn-type layer was completed. After stopping the inflow of SiH ₄ gas and PH ₃ / H ₂ into the deposition chamber and continuing to flow the H ₂ gas into the deposition chamber for 5 minutes, the inflow of H ₂ was stopped and the inside of the deposition chamber and the gas pipe was 1 × 10 5. Evacuated to ^-5 Torr.

The i-type layer made of a-Si was formed by simultaneously performing the MWPCVD method and the sputtering of alkaline earth metal. First, 300 sccm of H ₂ gas is introduced, the pressure is 0.01 Torr, and the temperature of the substrate 404 is 3
It was adjusted to 50 ° C. When the substrate temperature became stable, SiH ₄ gas and He gas were introduced, and the SiH ₄ gas flow rate was 150 sccm and the He gas flow rate was 150 sccc.
m, H ₂ gas flow rate is 150 sccm, and deposition chamber 401
The pressure inside was adjusted to 0.01 Torr. Next, the power of the RF power source was set to 0.32 W / cm ³ and applied to the bias electrode. Then, the power of an MW power source (not shown) was set to 0.20 W / cm ³ , and the MW power was introduced into the deposition chamber through the dielectric window 413 to cause glow discharge. Next, set the power of the target power supply to 200 W, open the target shutter 416, open the shutter,
Formation of the i-type layer was started on the RF n-type layer. Using a computer connected to the RF power supply and the target power supply,
According to the change pattern shown in 1-a, the RF power and the target power are changed to form an i-type layer having a layer thickness of 300 nm, the shutter and the target shutter are closed, and the MW power source, the RF power source, and the target power source are turned off to glow. The discharge was stopped and the formation of the i-type layer was completed. SiH ₄ gas,
After stopping the inflow of He gas and continuing to flow H ₂ gas for 5 minutes, the inflow of H ₂ gas was stopped and the deposition chamber and the gas pipe were evacuated to 1 × 10 ⁻⁵ Torr.

To form the RFp type layer made of a-SiC, H ₂ gas was introduced at 300 sccm and the pressure was 1.0.
Torr and the substrate temperature were set to 200 ° C. When the substrate temperature is stable, SiH ₄ gas, CH ₄ gas,
B ₂ H ₆ / H ₂ gas is caused to flow into the deposition chamber 401, and Si
H ₄ gas flow rate is 5 sccm, CH ₄ gas flow rate is 1 sccc
m, H ₂ gas flow rate was 100 sccm, B ₂ H ₆ / H ₂ gas flow rate was 200 sccm, and pressure was adjusted to 1.0 Torr. RF power of 0.06W / cm ³
, Glow discharge, open the shutter,
The formation of the RF p-type layer on the i-type layer was started. Layer thickness 10 nm
When the RF p-type layer is formed, the shutter is closed and R
The F power source was turned off to stop the glow discharge, and the formation of the RF p-type layer was completed. SiH ₄ gas, CH ₄ gas, B in the deposition chamber
The inflow of ₂ H ₆ / H ₂ gas was stopped, the H ₂ gas was kept flowing for 5 minutes, and then the inflow of H ₂ gas was stopped, and the deposition chamber and the gas pipe were evacuated to 1 × 10 ⁻⁵ Torr.

To form the MWp type layer made of a-SiC, H ₂ gas was introduced at 500 sccm, and the pressure inside the deposition chamber was set to 0.02 Torr and the substrate temperature was set to 200 ° C. When the substrate temperature became stable, SiH ₄ gas, CH ₄ gas, and B ₂ H ₆ / H ₂ gas were introduced. At this time, SiH ₄ gas flow rate is 10 sccm, CH ₄ gas flow rate is ₂ sccm, H ₂ gas flow rate is 100 sccm, and B ₂
H ₆ / H ₂ gas flow rate is 500 sccm, pressure is 0.02
It was adjusted to be Torr. After that, MW not shown
The power of the power supply was set to 0.40 W / cm ³ , MW power was introduced through the dielectric window to cause glow discharge, the shutter was opened, and formation of the MWp type layer on the RFp type layer was started. When a MWp type layer having a layer thickness of 10 nm is formed,
The shutter was closed, the MW power was turned off to stop the glow discharge, and the formation of the MWp type layer was completed. SiH ₄ gas, CH ₄
Gas, B ₂ H ₆ / H ₂ gas flow is stopped, H ₂
After continuing to flow the gas, the inflow of H ₂ gas was stopped, the deposition chamber and the gas pipe were evacuated to 1 × 10 ⁻⁵ Torr, the auxiliary valve 408 was closed, the leak valve 409 was opened, and the deposition chamber was leaked. did.

Next, on the MWp type layer, ITO having a layer thickness of 70 nm was vacuum-deposited by a vacuum vapor deposition method as a transparent electrode. Next, a mask with comb-shaped holes was placed on the transparent electrode, and Cr (4
A comb-shaped collector electrode composed of 0 nm) / Ag (1000 nm) / Cr (40 nm) was vacuum-deposited by a vacuum deposition method. This completes the production of the solar cell. This solar cell will be referred to as (SC Ex 17), and Table 1 shows the conditions for forming the RFn-type layer, the i-type layer, the RFp-type layer, and the MWp-type layer.

(Comparative Example 17-1) When forming an i-type layer,
A solar cell (SC ratio 17-1) was produced under the same conditions as in Example 17, except that the RF power and the target power were constant over time. (Comparative Example 17-2) A solar cell (SC ratio 17-2) was produced under the same conditions as in Example 17, except that the RFp type layer was not formed and the layer thickness of the MWp type layer was 20 nm.

Solar cell (SC Ex 17) and (SC ratio 17
-1) and (SC ratio 17-2) were produced by 6 pieces respectively, and initial photoelectric conversion efficiency (photovoltaic power / incident optical power), vibration deterioration, light deterioration, and vibration deterioration at the time of applying a forward bias voltage,
The photodegradation was measured in the same manner as in Example 1. As a result of the measurement of the initial photoelectric conversion efficiency, (SC ex. 17) (SC ratio 1
The initial photoelectric conversion efficiencies of 7-1) and (SC ratio 17-2) are as follows. (SC ratio 17-1) 0.95 times (SC ratio 17-2) 0.96 times As a result of measurement of vibration deterioration and optical deterioration, (SC ratio 17-1), (SC ratio 17-1), (SC ratio 17) The rate of decrease in photoelectric conversion efficiency after photodegradation and the rate of decrease in photoelectric conversion efficiency after vibration degradation of Comparative 17-2) were as follows.

[0193] As a result of measuring the vibration deterioration and the light deterioration by applying a forward bias, (SC ratio 17-
1), (SC ratio 17-2), the rate of decrease in photoelectric conversion efficiency after vibration deterioration and the rate of decrease in photoelectric conversion efficiency after light deterioration were as follows.

[0194] The state of delamination was observed using an optical microscope. In (SC Ex 17-1) and (SC ratio 17-1), no delamination was observed, but in (SC ratio 17-2), delamination was slightly observed.

Next, using a glass substrate and a silicon wafer, an i-type layer sample was prepared under the same conditions as in Example 17 except that the SiH ₄ gas flow rate and the SiF ₄ gas flow rate were made constant over time and the layer thickness was 1 μm. Was produced. Furthermore, the total flow rate of SiH ₄ gas and SiF ₄ gas is the same, and Si
Samples with different flow rates of H ₄ gas and SiF ₄ gas were prepared. The band gap (Eg) of the glass substrate sample produced using a spectrophotometer was determined, and the hydrogen content of the silicon wafer sample was measured using a secondary ion mass spectrometer (SIMS). As a result, it was found that the band gap in the i-type layer depends on the hydrogen content.

Further, it was prepared by using SIMS (SC
When the change in the hydrogen content and the change in the alkaline earth metal content in the layer thickness direction of Ex. 17) were obtained, FIG.
It became like. Further, when the change in the band gap in the layer thickness direction was obtained by using the relationship between the hydrogen content and the band gap, it was as shown in FIG. 11-c.

Similarly, when the hydrogen content and the alkaline earth metal content of (SC ratio 17-1) were determined, the band gap did not change in the layer thickness direction and was constant, and the band gap was 1.73 ( eV). Similarly, when the hydrogen content and the alkaline earth metal content of (SC ratio 17-2) were obtained, the change in the hydrogen content with respect to the layer thickness direction was the same result as in FIG. 11-b, and the change in the band gap was obtained. Also produced the same results as in FIG. 11-c.

Thus, the hydrogen content in the layer thickness direction,
It was found that the change in the band gap and the band gap depended on the introduced RF power, and the change in the alkaline earth metal content in the layer thickness direction depended on the introduced target power. Further, vibration deterioration and light deterioration in a high temperature environment, and vibration deterioration and light deterioration in a high humidity environment were measured. Similarly, (SC ex. 17) was (SC ratio 17-1), (SC ex.
It had better characteristics than 7-2).

Further, even when the forward bias is applied in the above environment, (SC Ex 17) becomes (SC Comp Ex 17-1),
(SC ratio 17-2) had better characteristics. As described above, it was found that the solar cell (SC Ex 17) of the present example had more excellent characteristics than the conventional solar cells (SC ratio 17-1) and (SC ratio 17-2). (Example 18) In Example 17, when the i-type layer was formed,
A solar cell (SC Ex 18) in which the alkaline earth metal content and the hydrogen content were changed as shown in FIG. 6-b was produced by changing the change patterns of the RF power and the target power. When the same measurement as in Example 17 was performed, the solar cell of (SC Ex 18) was similar to that of (SC Ex 17), but the conventional solar cells (SC ratio 17-1) and (SC ratio 17-2) Was found to have even better properties.

Example 19 A photodiode (PD Ex 3) having the layer structure shown in FIG. 1-c was produced. First, a substrate was manufactured. Ultrasonic cleaning a 0.5 × 20 mm × 20 × 20 mm ² glass substrate with acetone and isopropanol, drying with warm air, and light reflection of Al with a layer thickness of 0.1 μm on the glass substrate surface at room temperature by vacuum deposition. The layers were formed and the fabrication of the substrate was completed.

MWn was formed on the substrate in the same manner as in Example 17.
The type layer (a-SiC), the RFn type layer (a-SiC), the i-type layer (a-Si), and the RFp-type layer (μc-SiC) were sequentially formed. Further, when forming the i-type layer, the RF power and the target power were temporally changed to change the alkaline earth metal content and the hydrogen content as shown in FIG. 6-c. Was produced. Table 5 shows the layer forming conditions of the semiconductor layer. Next, a transparent electrode and a collector electrode similar to those in Example 17 were formed on the RF p-type layer.

(Comparative Example 19-1) When forming an i-type layer,
A photodiode (PD ratio 19-1) was produced under the same conditions as in Example 19 except that the RF power and the target power were not changed with time as in Comparative Example 17-1. (Comparative Example 19-2) A photodiode (PD ratio 19-2) was produced under the same conditions as in Example 19 except that the RFn type layer was not formed and the MWn type layer had a layer thickness of 40 nm.

The on / off ratio (photocurrent / dark current measurement frequency of 10 kHz when irradiated with AM1.5 light) of the manufactured photodiode was measured. Furthermore, the same measurement as in Example 17 was performed for the on / off ratio. As a result, it was found that the photodiode (PD Ex 19) of the present example had better characteristics than the conventional photodiodes (PD ratio 19-1) and (PD ratio 19-2).

Example 20 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 17, the RF p-type layer (μc-Si), the i-type layer (a-Si), and the RF n-type layer (a) were formed on the substrate.
-SiC) and a MWn type layer (a-SiC) were formed. i
When forming the mold layer, the target electric power was changed with time to change the alkaline earth metal content in the layer thickness direction as shown in FIG. 6-a. Table 6 shows the layer forming conditions for the semiconductor layer.

The layers other than the semiconductor layer and the substrate were the same as in Example 17.
A solar cell (SC Ex 20) was produced under the same conditions as described above. (Comparative Example 20-1) When forming an i-type layer, Comparative Example 17-
Similar to Example 1, except that the RF power and the target power are not changed with time, the solar cell (SC
Ratio 20-1) was produced.

Comparative Example 20-2 Example 2 was repeated except that the RFn type layer was not formed and the layer thickness of the MWn type layer was 20 nm.
A solar cell (SC ratio 20-2) was produced under the same conditions as 0. When the same measurement as in Example 17 was performed, the solar cell of this example (SC Ex 20) was a conventional solar cell (SC ratio 2
It was found that it has more excellent characteristics than 0-1) and (SC ratio 20-2).

(Example 21) i-type layer, MWp-type layer, RF
The p-type layer was made to contain fluorine, and a solar cell having a minimum content near the interface was produced. i-type layer, MWp-type layer, R
When forming the Fp type layer, SiF ₄ is newly introduced to
By changing the F ₄ gas flow rate with time, a change pattern of the fluorine content 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 (SC Ex. 21) had better characteristics than (SC Ex. 17). Moreover, delamination was not observed.

Example 22 A solar cell having the maximum hydrogen content near the interface between the MWp type layer and the RFp type layer was produced. By changing the MW power with time, a change pattern of hydrogen content as shown in FIG. 6-c was obtained. Except for this, it was manufactured under the same conditions as in Example 17. When the same measurement as that of Example 17 was performed, it was found that (SC Ex. 22) had even better characteristics than (SC Ex. 17).

(Example 23) A solar cell in which the content of the valence electron control agent was maximum near the interface between the MWp type layer and the RFp type layer was produced. The raw material gas of the valence electron control agent to be introduced was changed with time to change the content of B atoms as shown in FIG. 12-b. 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 (SC Ex. 23) had better characteristics than (SC Ex. 17).

Example 24 A solar cell having the structure of FIG. 1-a was produced. MWn on the substrate as in Example 17
The type layer (μc-Si), the RFn type layer (a-Si), the i type layer (a-Si), the RFp type layer (a-SiC), and the MWp type layer (μc-SiC) were sequentially laminated. The same material as in Example 17 was used except for the semiconductor layer. It was found that the manufactured solar cell (SC Ex. 24) had better characteristics than (SC Ex. 17).

Example 25 Using a-SiC for the i-type layer, a solar cell containing an alkaline earth metal was prepared by the MWPCVD method. First, the target, target electrode, and target shutter shown in FIG. 4 were removed from the deposition chamber. When forming the i-type layer, CH ₄ gas and H are newly added.
bubbling with e gas was _{Mg (NO 3) 2 · 6H} 2 O /
He gas was used. CH ₄ gas flow rate and _{20sccm, Mg (NO 3) 2} · 6H 2 O / He gas flow rate is temporally varied, alkaline earth metal content Figure 11-b
So that A solar cell (SC Ex 25) was manufactured under the same conditions as in Example 17 except for the above.

(Comparative Example 25-1) When forming an i-type layer,
Except that the _{Mg (NO 3) 2 · 6H} 2 O / He gas flow rate temporally constant, to prepare the solar cell (SC ratio 25-1) under the same conditions as in Example 25. (Comparative Example 25-2) A solar cell (SC ratio 25-2) was produced under the same conditions as in Example 25 except that the RFp type layer was not formed and the layer thickness of the MWp type layer was 20 nm.

When the same measurement as in Example 17 was carried out,
It was found that the solar cell (SC Ex 25) of the present example had better characteristics than the conventional solar cells (SC ratio 25-1) and (SC ratio 25-2). (Example 26) A solar cell was prepared in which a-SiGe was used for the i-type layer and beryllium, magnesium, and calcium were both contained as alkaline earth metals. First, BeF ₂ , MgF ₂ , and CaF ₂ are used as targets in a ratio of 1: 2 :.
When the i-type layer was formed by exchanging with a mixture of 1 and 1, GeF ₄ gas was newly used and the GeF ₄ gas flow rate was 30 sc.
cm was introduced and the layer thickness was set to 250 nm.
A solar cell (SC Ex 26) was produced under the same conditions as described above.

(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 RF power and the target power were not changed with time as in Comparative Example 17-1. (Comparative Example 26-2) A solar cell (SC ratio 26-2) was produced under the same conditions as in Example 26 except that the RFn type layer was not formed and the MWn type layer had a layer thickness of 20 nm.

When the same measurement as in Example 17 was carried out,
It was found that the solar cell (SC Ex 26) of the present example had more excellent characteristics than the conventional solar cells (SC ratio 26-1) and (SC ratio 26-2). (Example 27) Using a-SiSn for the i-type layer, a DC power source was connected to the target instead of the power source by the RF plasma CVD method, and a solar cell containing strontium as an alkaline earth metal was produced. First, the target is S
When replacing with r and forming an i-type layer, SnH ₄ gas was newly introduced and the DC power was changed with time to change the alkaline earth metal content as shown in FIG. 6-a. Furthermore, a solar cell (SC Ex 27) was produced under the same conditions as in Example 17 except that the SnH ₄ gas flow rate was 20 sccm.

(Comparative Example 27-1) When forming an i-type layer,
A solar cell (SC ratio 27-1) was produced under the same conditions as in Example 27, except that the RF power and the target power were set constant over time as in Comparative Example 17-1. (Comparative Example 27-2) A solar cell (SC ratio 27-2) was produced under the same conditions as in Example 27 except that the RFn type layer was not formed and the layer thickness of the MWn type layer was 20 nm.

When the same measurement as in Example 17 was carried out,
It was found that the solar cell (SC Ex 27) of the present example had better characteristics than the conventional solar cells (SC ratio 27-1) and (SC ratio 27-2). (Example 28) The solar cell of FIG. 1-f having a PR-i layer between the RF p-type layer and the i-type layer and between the RF n-type layer and the i-type layer was produced. For other layers, a solar cell was manufactured in the same manner as in Example 25. The two RF-i type layers are made of a-Si and have a SiH ₄ gas flow rate of ₂ sccm and an H ₂ gas flow rate of 5
0 sccm, pressure inside the deposition chamber is 1.0 Torr, RF power to be introduced is 0.01 W / cm ³ , substrate temperature is 270
It was formed under the conditions of the temperature of 20 ° C. and the layer thickness of 20 nm. It was found that the produced solar cell (SC Ex. 28) had even better characteristics than (SC Ex. 24).

Example 29 A triple type solar cell shown in FIG. 7 was produced using the deposition apparatus of FIG. 4 using the MWPCVD method. First, a substrate was manufactured in the same manner as in Example 13. Subsequently, a first MWn-type layer (μc-Si layer thickness 10 μm) was formed on the substrate by the same method as in Example 17, and further a first RFn-type layer (a-Si layer thickness 10 μm).
m), the first i-type layer (a-SiGe), the first RFp-type layer (a-Si layer thickness 10 nm), the first MWp-type layer (μ
c-Si layer thickness 10 nm), second RF n-type layer (μc-
Si), the second i-type layer (a-Si), the second RFp-type layer (a-SiC layer thickness 10 nm), the second MWp-type layer (μ
c-Sic layer thickness 10 nm), third RFn-type layer (a-
SiC), third i-type layer (a-SiC), third RFp
The type layer (a-SiC layer thickness 10 nm) and the third MWp type layer (μc-SiC layer thickness 10 nm) were sequentially formed. When forming each semiconductor layer, SiF ₄ gas is introduced, and
_By changing the ₄ gas flow rate and the SiF ₄ gas flow rate with time, the layer thickness direction of the hydrogen content of each layer becomes as shown in FIG. 6-c, and the fluorine content change in the layer thickness direction as shown in FIG. did.
Further, the target electric power was changed with time to change the alkaline earth metal content as shown in FIG. 6-c. Then the third MWp
A transparent electrode similar to that in Example 17 was formed on the mold layer.

Next, a collector electrode similar to that of Example 1 was formed on the transparent electrode by vacuum vapor deposition. This completes the production of the triple solar cell (SC Ex 29). (Comparative Example 29-1) A solar cell (SC ratio 29-1) was produced under the same conditions as in Example 29, except that the target power was constant over time when each semiconductor layer was formed.

(Comparative Example 29-2) First RF n-type layer, first RF p-type layer, second RF p-type layer, and third RF
The same as Example 29 except that the p-type layer was not formed, and the layer thicknesses of the first MWn-type layer, the first MWp-type layer, the second MWp-type layer, and the third MWp-type layer were 20 nm. A solar cell (SC ratio 29-2) was produced under the conditions. When the same measurement as in Example 17 was performed, the solar cell of this example (SC Ex 2
It was found that 9) had even better characteristics than the conventional solar cells (SC ratio 29-1) and (SC ratio 29-2).

Example 30 A tandem solar cell shown in FIG. 8 was produced using the deposition apparatus using the roll-to-roll method shown in FIG. After forming the light reflection layer and the light reflection increasing layer on the substrate in the same manner as in Example 14, RF power or MW power was introduced into each deposition chamber to cause glow discharge, and each semiconductor layer was formed. .

A first MWn type layer (μc-Si layer thickness 20 nm) is formed on the substrate in a deposition chamber 901, and a first RFn type layer (a-Si layer thickness 10 n) is further deposited in the deposition chamber 902.
m), the first i-type layer (a-SiGe layer thickness 180 nm) in the deposition chamber 903, and the first RFp-type layer (a) in the deposition chamber 904.
-Si layer thickness 10 nm), first MWp in deposition chamber 905
Type layer (μc-Si layer thickness 10 nm), the second RFn type layer (μc-Si layer thickness 20 nm) in the deposition chamber 906, the second i-type layer (a-Si layer thickness 250 nm) in the deposition chamber 907,
In the deposition chamber 908, the second RF p-type layer (a-SiC layer thickness 1
0 nm), the second MWp-type layer (μc-S) in the deposition chamber 909.
The iC layer thickness of 10 nm) was sequentially formed. The first i-type layer,
The raw material gas inlets of the deposition chambers 903 and 907 for forming the second i-type layer are divided into a plurality of portions, and the raw material gas was introduced from each of the inlets. When forming the first i-type layer, Si
The change pattern of the F ₄ gas flow rate with respect to the substrate transport direction is as indicated by an arrow 926, the change in the hydrogen content of the i-type layer in the layer thickness direction is as shown in FIG. 6C, and the change in the fluorine content in the layer thickness direction is It looks like Figure 3-c. When the transfer of the substrate was completed, all MW power supplies, RF power supplies, and target power supplies were turned off, glow discharge was stopped, and inflow of raw material gas and scavenging gas was stopped. The entire apparatus was leaked and the wound substrate was taken out. Then, a layer thickness of 70 at 170 ° C. is formed on the second MWp type layer by a sputtering apparatus using a roll-to-roll method.
A transparent electrode made of ITO of nm was continuously formed.

Next, a part of this substrate is set to 50 mm × 50 mm.
The size is cut, and a screen printing method is used to print a carbon paste having a layer thickness of 5 μm and a line width of 0.5 mm, and a silver paste having a layer thickness of 10 μm and a line width of 0.5 mm is printed thereon.
A collector electrode was formed. Thus, the production of a tandem solar cell (SC Ex 30) using the roll-to-roll method was completed.

(Comparative Example 30-1) When forming the first i-type layer and the second i-type layer, a target having a large surface area was used, and the alkaline earth metal content was in the layer thickness direction. A solar cell (SC ratio 30-1) was produced under the same conditions as in Example 30 except that the solar cell was made uniform. (Comparative Example 30-2) The first RFn-type layer, the first RFp-type layer, and the second RFp-type layer were not formed, and the first MWn
A solar cell (SC ratio 30-3) was produced under the same conditions as in Example 30, except that the mold layer was 30 μm, and the layer thicknesses of the first MWp type layer and the MWp type layer were 20 nm.

When the same measurement as in Example 17 was carried out,
It was found that the solar cell (SC Ex 30) of the present example had better 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 of FIG. 9 was modularized, applied to a power generation system, and subjected to a field test.

50 mm not irradiated with light prepared 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 a load, which was connected to the circuit showing the power generation system. The entire system is operated by the storage battery and the power of the module. This power generation system (SBS 3
I will call it 1).

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

Each module was installed at an angle at which sunlight could be collected 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 using the solar cell of the present invention (SBS Ex 31) is a conventional power generation system (SBS ratio 3
It was found that the initial photoelectric conversion efficiency and field durability were even better than those of 1-1) and (SBS ratio 31-2).

Example 32 A photovoltaic element containing oxygen and nitrogen atoms in the semiconductor layer was produced. (Example 32-1) when forming the i-type layer, O ₂ / He gas 100sccm, N ₂ / He gas solar under the same conditions as in Example 17 except for introducing 20sccm the cell (SC 32-1) Was produced.

(Example 32-2) When forming an RF-i layer type layer, a solar cell was formed under the same conditions as in Example 1 except that ₂ sccm of O ₂ / He gas and 1 sccm of N ₂ / He gas were introduced. SC Ex 32-2) was produced. When forming the (Example 32-3) MWp-type layer, O ₂ / H
e gas at 100 sccm, N ₂ / He gas at 20 sccc
solar cell (SC Ex 32-3) under the same conditions as in Example 17 except that O ₂ / He gas was introduced at ₂ sccm and N ₂ / He gas was introduced at 1 sccm when forming the RF p-type layer.
Was produced.

When the same measurement as in Example 17 was carried out,
It was found that these solar cells had even better characteristics than the solar cell (SC Ex 17). The concentration of oxygen atoms and nitrogen atoms of these fabricated solar cells was measured by SIMS.
Was investigated by using a source gas (Si) almost introduced
It was found that the raw material gas (O) and the raw material gas (N) were contained at about the same concentrations.

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.

[0233]

The photovoltaic device of the present invention prevents recombination of photoexcited carriers, improves open-circuit voltage and carrier range of holes, and improves sensitivity of short wavelength light and long wavelength light.
The photoelectric conversion efficiency is improved. Further, the photovoltaic element of the present invention can suppress optical 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,
Further, since the raw material gas utilization efficiency is high, the productivity can be dramatically improved. Further, the power generation system of the present invention has high field durability.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

[Brief description of drawings]

FIG. 1 is a schematic view showing a layer structure of a photovoltaic element of the present invention.

FIG. 2 is a graph showing changes in the valence electron control agent content and the alkaline earth metal content in the layer thickness direction.

FIG. 3 is a graph showing changes in fluorine content in the layer thickness direction.

FIG. 4 is a schematic view showing an example of a deposition apparatus.

FIG. 5 is a graph showing the change over time in the raw material gas flow rate of the valence electron control agent.

FIG. 6 is a graph showing changes in hydrogen content, alkaline earth metal content, and band gap in the layer thickness direction.

FIG. 7 is a graph showing the layer structure of a triple solar cell.

FIG. 8 is a schematic diagram showing a layer structure of a tandem solar cell.

FIG. 9 is a schematic view showing an example of a deposition apparatus using a roll-to-roll method.

FIG. 10 is a block diagram showing an example of a power generation system.

FIG. 11 is a graph showing changes in gas flow rate, hydrogen content, and band gap.

FIG. 12 is a graph showing changes in the content of a valence electron control agent 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 collector electrode, 109 light, 112 n-type layer 125 p-type layer 130, 131, 132 RF-i layer 400 deposition apparatus, 401 deposition chamber, 402 vacuum gauge, 403 RF power supply, 403 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 , 901 909 deposition chamber, 910 substrate delivery chamber 911 substrate winding chamber, 912 separation passage, 913 long substrate, 914 source gas inlet, 915 source gas exhaust port, 916 RF electrode, 917 microwave applicator, 918 halogen lamp Heater, 919 scavenging gas inlet / outlet, 920 delivery roll, 921, 923 guide roll, 922 winding roll, 930 target electrode, 931 bias electrode.

Claims (24)

[Claims] 1. A p-type layer, an i-type layer, and an n-type layer made of a non-single-crystal silicon semiconductor material containing hydrogen are laminated on a substrate, and the i-type layer is made of an alkaline earth metal. In a photovoltaic element containing and formed by a microwave plasma CVD method, the p-type layer and / or the n-type layer is a microwave-formed MW doping layer and an RF plasma C.
It is configured by a laminated structure with an RF doping layer formed by the VD method, and the RF doping layer is arranged so as to be sandwiched between the MW doping layer and the i-type layer, and the alkaline earth of the i-type layer is further formed. A photovoltaic element, characterized in that the metal content and the hydrogen content change smoothly in the thickness direction. 2. A p-type layer, an i-type layer, and an n-type layer made of a non-single crystal silicon semiconductor material containing hydrogen are laminated on a substrate, and the i-type layer is made of an alkaline earth metal. In a photovoltaic element containing and formed by a microwave plasma CVD method, the p-type layer and / or the n-type layer is a microwave-formed MW doping layer and an RF plasma C.
It is configured by a laminated structure with an RF doping layer formed by a VD method, and the RF doping layer is arranged so as to be sandwiched between the MW doping layer and the i-type layer, and the i-type layer serves as a donor. A photovoltaic element comprising both a valence electron control agent and a valence electron control agent serving as an acceptor. 3. The content of the valence electron control agent serving as the donor and / or the content of the valence electron control agent serving as the acceptor changes smoothly in the layer thickness direction, and the content is at least near one interface. Is maximized, the photovoltaic element according to claim 2, wherein 4. The photovoltaic element according to claim 1, wherein the alkaline earth metal is at least one element selected from beryllium, magnesium and calcium. 5. The content of the alkaline earth metal changes smoothly in the layer thickness direction, and the content is minimum near at least one interface.
The photovoltaic element according to any one of items 1 to 4. 6. The i-type layer, RF doping layer and MW
6. The hydrogen content of at least one of the doping layers changes smoothly in the layer thickness direction, and the hydrogen content is maximized in the vicinity of at least one interface. The photovoltaic element according to any one of 1. 7. The i-type layer, RF doping layer and MW
7. The photovoltaic power according to claim 1, wherein at least one of the doping layers contains fluorine, and the fluorine content is changed smoothly in the layer thickness direction. element. 8. The photovoltaic element according to claim 7, wherein the fluorine content is minimum near at least one interface. 9. The RF doping layer and / or MW
The valence electron control agent content of the doping layer changes smoothly in the layer thickness direction, and the content is maximized in the vicinity of at least one interface.
The photovoltaic element according to any one of 1. 10. The RF doping layer and / or M
The photovoltaic element according to claim 1, wherein the W doping layer contains an alkaline earth metal. 11. The RF doping layer and / or M
11. The photovoltaic element according to claim 10, wherein the content of the alkaline earth metal contained in the W-doped layer changes smoothly in the layer thickness direction and is minimum at least in the vicinity of one interface. Power element. 12. The beryllium is an alkaline earth metal,
The photovoltaic element according to claim 10 or 11, which is at least one element selected from magnesium and calcium. 13. The i-type layer is made of amorphous silicon tin containing tin atoms.
13. The photovoltaic element according to any one of 12. 14. The i-type layer, MW doping layer and R
The photovoltaic element according to any one of claims 1 to 13, wherein at least one layer of the F doping layers contains oxygen and / or nitrogen atoms. 15. An i-type layer (R) formed by an RF plasma CVD method between the i-type layer and the RF doping layer.
F-i layer) is included, The photovoltaic element of any one of Claims 1-14 characterized by the above-mentioned. 16. The photovoltaic element according to claim 15, wherein the RF-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. 17. The content of the valence electron control agent serving as a donor and / or the content of the valence electron control agent serving as an acceptor contained in the RF-i layer changes smoothly in the layer thickness direction, and at least The photovoltaic element according to claim 16, which has a maximum value in the vicinity of one interface. 18. The RF-i layer contains fluorine,
The photovoltaic content according to any one of claims 15 to 17, wherein the fluorine content changes smoothly in the layer thickness direction, and the content is minimum near at least one interface. element. 19. The RF-i layer has a hydrogen content that changes smoothly in the layer thickness direction and has a maximum value in the vicinity of at least one interface.
8. The photovoltaic element according to any one of items 8. 20. The photovoltaic element according to claim 15, wherein the RF-i layer contains an alkaline earth metal. 21. The alkaline earth metal contained in the RF-i layer has a content that varies smoothly in the layer thickness direction and is at a minimum near at least one interface. Item 21. The photovoltaic element according to Item 20. 22. The photovoltaic element according to claim 15, wherein the i-type layer RF-i layer is made of amorphous silicon / tin containing tin atoms. . 23. The RF-i layer contains oxygen and / or nitrogen atoms.
The photovoltaic element according to any one of 1. 24. The photovoltaic element according to any one of claims 1 to 23, and the light to a storage battery and / or an external load by monitoring the voltage and / or current of the photovoltaic element. Power generation comprising a control system for controlling the supply of electric power from an electromotive force element, and a storage battery for accumulating electric power from the photovoltaic element and / or supplying electric power to an external load. system.