JPH11261102A - Photovoltaic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photovoltaic device which is light in weight, in photovoltaic characteristic, high in photoelectric conversion efficiency, capable of easy enlargement in area, and easily manufactured at low cost. SOLUTION: A PIN photovoltaic device is equipped with an i-type semiconductor layer 105 of a PIN semiconductor junction, wherein the i-type semiconductor layer 105 is of a laminated structure, where fine crystalline silicon layers 105A that take advantages of fine crystalline silicon (μc-Si) and amorphous silicon (a-Si) layers 105B are laminated alternately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photovoltaic device made of a silicon-based non-single-crystal semiconductor material. More specifically, the present invention relates to a photovoltaic element having high photoelectric conversion efficiency and excellent durability. The photovoltaic element in the present invention includes a solar cell.

[0002]

2. Description of the Related Art In recent years, solar cells using photovoltaic elements have attracted attention as a power generation means instead of thermal power generation using fossil fuels, in view of the problem of global warming due to an increase in the concentration of carbon dioxide in the atmosphere. ing. Incidentally, several countries, including Japan, have made plans to disseminate photovoltaic power generation facilities to ordinary households with the support of the government, and those plans are already being implemented. In addition, since solar cells can generate power locally at the place, they are being used for light emission of traffic signs and for power generation at the time of emergency evacuation. For these reasons, demand for solar cells is expected to increase in the future. The photovoltaic cells used in such photovoltaic power generation facilities have high photoelectric conversion efficiency, stable power generation capacity over a long period of about 20 years, good productivity, and low cost / light generation capacity. Ki is required. As a constituent material of the solar cell, single crystal silicon, polycrystalline silicon (poly-Si), amorphous silicon (a-Si), microcrystalline silicon (μc-Si), G
aAs, CdS and the like are used. Of these, a
Amorphous semiconductors represented by -Si are:
Compared to a single crystal silicon semiconductor, it is considered promising because of its advantages such as being able to form a film with a large area, being thinner, and being able to deposit a film on any material. By the way, in the so-called amorphous solar cell (photovoltaic element) using such an amorphous semiconductor, there is a point that the photoelectric conversion efficiency and the long-term stability (long-term durability) need to be further improved. In particular, the photodegradation phenomenon of the photoelectric conversion efficiency is a difficult problem to avoid.

[0003] There are many proposals for improving the photoelectric conversion efficiency of amorphous solar cells (photovoltaic elements). For example, in the case of an amorphous solar cell (photovoltaic element) using a pin-type semiconductor junction, the characteristics of each of the p-type semiconductor layer, the i-type semiconductor layer, and the n-type semiconductor layer constituting the amorphous solar cell are described. Need to improve. For this reason, the i-type semiconductor layer is provided with amorphous silicon (a-S
It has been proposed to use microcrystalline silicon (μc-Si) containing an amorphous phase that undergoes photodegradation and a crystalline phase that does not undergo photodeterioration instead of i). For example, J. Meier, e
t. al, Proc. of MRS spring m
eating 1996 San Francisco
Describes a so-called microcrystalline solar cell using a microcrystalline film. The solar cell has a narrow band gap, is sensitive to long-wavelength light, and has a photoelectric conversion efficiency of 7.7%.
And light degradation is said to be small. From this, it can be said that a microcrystalline solar cell using a microcrystalline film has less light degradation when exposed to the sun, as compared with a normal amorphous solar cell. From these facts, it can be said that microcrystalline semiconductor materials have long-term stability and are close to amorphous silicon (a-Si) semiconductor materials in terms of cost / power generation capability. It can be said that it can be used as a constituent material.

Incidentally, amorphous silicon (a-S)
i) Although various proposals have been made with respect to a technique for forming a film or a microcrystalline silicon (μc-Si) film, a film forming technique by a glow discharge method is widely used as a practical film forming technique. Can be mentioned. When a film is formed by a film forming technique using a glow discharge method, since amorphous silicon (a-Si) has structural flexibility, its physical property constant can be controlled by selecting the composition of the source gas and the discharge conditions. An extreme example is microcrystalline silicon (μc-
Si) film. For example, silane diluted with hydrogen (Si
Glow discharge of H ₄ ) gas under high supply power
A microcrystalline Si film having a crystal phase and an amorphous phase having a particle size of 0 nm or less can be obtained.

[0005]

Conventionally, a photovoltaic element using microcrystalline silicon (μc-Si) for an i-type semiconductor layer has a low photoelectric conversion efficiency, and a μc-Si has a low light collection efficiency. Therefore, for a practically usable solar cell, the layer thickness of the i-type semiconductor made of μc-Si is 6
It is said that the thickness needs to be very large, from 00 nm to 4000 nm. However, as the thickness of the μc-Si layer is increased as described above, in the microcrystalline phase, crystal grains of different sizes and shapes grow, so that interface mismatches occur between the crystal grains and internal stress is relaxed. In addition, there is a problem in that defects are generated at the interface between crystal grains in the microcrystalline phase, and the traveling properties of carriers are deteriorated. For this reason, it is difficult to form a desired i-type semiconductor layer from microcrystalline silicon (μc-Si), and even if a desired i-type semiconductor layer can be formed, a photovoltaic element (solar cell) to be manufactured Is particularly problematic in terms of cost. In addition, since microcrystalline silicon (μc-Si) is weak n-type in a non-doped state in which impurities are not doped, when microcrystalline silicon (μc-Si) is used for an i-type semiconductor layer, boron is slightly doped. By shifting the Fermi level to near the center of the band gap, the electric field intensity in the i-type semiconductor layer is increased,
Side to prevent short circuit current from being reduced. However, the doping efficiency of μc-Si is close to 100%,
When forming a μc-Si film, B ₂ H was added to SiH ₄ during preparation.
_{6 Even in} a very small region where the amount of addition is about 1 ppm, the μc-Si characteristics in the region are greatly changed. Also,
Since microcrystalline silicon (μc-Si) has a high doping efficiency, there is a problem that it is difficult to control film formation and to obtain reproducibility.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art and provides a photovoltaic device (solar cell) using microcrystalline silicon (μc-Si) and having desired photovoltaic characteristics. The purpose is to do. Another object of the present invention is to provide microcrystalline silicon (μc-S
An object of the present invention is to provide a photovoltaic element (solar cell) that uses the microcrystalline silicon, has high carrier mobility, and has high photoelectric conversion efficiency so as to take advantage of i). Another object of the present invention is to provide a photovoltaic element (solar cell) that is lightweight, flexible, generates stable power for a long time, and has low power cost. Another object of the present invention is to
A photovoltaic device (solar cell) that can be installed on the roof of a building to perform solar power generation, or function as a night light, guide light, or ventilation facility in public facilities such as parks and road signs. To offer.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art and achieves the above object. A photovoltaic element provided by the present invention is a pin formed by stacking a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer made of a silicon-based non-single-crystal semiconductor material.
A photovoltaic device having a semiconductor junction of a type, wherein the i-type semiconductor layer is a microcrystalline i-type semiconductor layer and an amorphous i-type semiconductor layer having a thickness smaller than the thickness of the microcrystalline i-type semiconductor layer. The semiconductor device has a laminated structure in which semiconductor layers are alternately laminated. The photovoltaic element of the present invention having the above configuration includes the following first and second aspects.

[0008]

First Embodiment A photovoltaic element having a pin-type semiconductor junction formed by laminating a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer each made of a silicon-based non-single-crystal semiconductor material. Thus, the i-type semiconductor layer is a microcrystal i
A stacked structure in which semiconductor layers and amorphous i-type semiconductor layers having a thickness smaller than that of the microcrystalline i-type semiconductor layer are alternately stacked, and the microcrystalline i-type semiconductor layer has a thickness of 300 nm. To 5 μm, and the amorphous i-type semiconductor layer has a thickness of 3.0 nm to 50 nm. In this configuration, the amorphous i-type semiconductor layer having an extremely thin thickness is disposed on the p-type semiconductor layer or the n-type semiconductor layer side with respect to the microcrystalline i-type semiconductor layer. Further, the amorphous i-type semiconductor layer may be disposed on each side of the p-type and n-type semiconductor layers with the microcrystalline i-type semiconductor layer interposed therebetween. In this case, the sum of the thickness of the amorphous i-type semiconductor layer disposed on the p-type semiconductor layer side and the thickness of the amorphous i-type semiconductor layer disposed on the n-type semiconductor layer side is 6.0 nm. It is desirable that the thickness be in the range of 80 to 80 nm.

The photovoltaic device according to the first aspect of the present invention has the following functions and effects. That is, by arranging a very thin amorphous i-type semiconductor layer having a specific thickness on the non-single-crystal p-type semiconductor layer side with respect to a microcrystalline i-type semiconductor layer having a specific thickness, The photoelectric conversion efficiency is improved as compared with a photovoltaic element without an i-type semiconductor layer. This phenomenon is caused by disposing a very thin amorphous i-type semiconductor layer on the non-single-crystal p-type semiconductor layer side with respect to the microcrystalline i-type semiconductor layer, thereby forming a potential barrier at the p / i interface, and It is considered that when a directional bias is applied, electrons are excited because photoexcited electrons are prevented from flowing into the p layer and recombining. As a result, the open-circuit voltage, the short-circuit current, and the fill factor are improved, respectively. Further, by arranging an extremely thin amorphous i-type semiconductor layer on the side of the non-single-crystal p-type semiconductor layer with respect to the microcrystalline i-type semiconductor layer, the effect of improving the yield of the photovoltaic element is exhibited. Is done. Although the detailed reason for this phenomenon is unknown, it is not because the generation of leak current can be suppressed by covering the grain boundary portion precipitated on the surface of the microcrystalline i-type semiconductor layer with the amorphous i-type semiconductor layer. It is thought. In addition, by arranging an extremely thin amorphous i-type semiconductor layer having a specific thickness on the non-single-crystal n-type semiconductor layer side with respect to a microcrystalline i-type semiconductor layer having a specific thickness, The photoelectric conversion efficiency is improved as compared with a photovoltaic element without an i-type semiconductor layer. This phenomenon is caused by disposing a very thin amorphous i-type semiconductor layer on the non-single-crystal n-type semiconductor layer side with respect to the microcrystalline i-type semiconductor layer, thereby forming a potential barrier at the n / i interface, and It is considered that when a directional bias is applied, the holes are generated because photoexcited holes are prevented from flowing into the n-layer and recombining. Furthermore, it is considered that the diffusion of the impurity (P) contained in the non-single-crystal n-type semiconductor layer toward the i-type semiconductor layer can be suppressed. As a result, the open-circuit voltage, the short-circuit current, and the fill factor are improved, respectively. In the present invention, the microcrystalline i-type semiconductor layer functioning as a light absorbing layer can effectively absorb sunlight as its thickness is larger, but when it is too thick, the mobility of carriers, particularly holes, becomes poor. As a result, the characteristics of the photovoltaic element, particularly the fill factor (FF), are adversely affected. Therefore, the thickness of the microcrystalline i-type semiconductor layer in the present invention is 30
The range of 0 nm to 5 μm is optimal. With respect to the amorphous i-type semiconductor layer in the present invention, the larger the optical bandgap is, the more effective the formation of a potential barrier.
The optimal optical bandgap of the amorphous i-type semiconductor layer is 1.7 eV or more. In the present invention, boron is contained in the microcrystalline i-type semiconductor layer, and the content thereof is set to 8 ppm or less, so that the growth of the microcrystalline i-type semiconductor layer is not alienated and the hole traveling property is improved. Can be improved.

[0010]

Second Embodiment A photovoltaic device having a pin-type semiconductor junction formed by laminating a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer each made of a silicon-based non-single-crystal semiconductor material. Thus, the i-type semiconductor layer is a microcrystal i
A stacked structure in which a p-type semiconductor layer and an amorphous i-type semiconductor layer having a thickness smaller than that of the microcrystalline i-type semiconductor layer are alternately and repeatedly laminated a plurality of times; The layer has a thickness in the range of 10 nm to 50 nm and the amorphous i
The semiconductor layer has a thickness in the range of 1 nm to 5 nm, and the microcrystalline i-type semiconductor layer has a crystal grain size in the range of 2 nm to 40 nm. In this configuration,
A microcrystalline i-type semiconductor layer having a specific thickness is sandwiched between amorphous i-type semiconductor layers having a specific thickness. As described above, as the thickness increases in the microcrystalline phase, crystal grains of different sizes and shapes grow, causing interface mismatch between the crystal grains and reducing the internal stress. Defects occur at the interface between them. However, in the present invention, the internal stress between the two microcrystalline layers is reduced by inserting the amorphous layer between the microcrystalline layer and the i-type semiconductor including the microcrystalline layer / amorphous layer. The layers have a minimum internal stress. Further, the thickness of one amorphous layer is 1 nm.
The thickness of the amorphous layer is reduced even in the entire i-type semiconductor layer, and the influence of light deterioration of the i-type semiconductor layer can be suppressed. Further, by setting the crystal grain size of the microcrystalline layer to 2 nm to 40 nm, an i-type semiconductor layer having good carrier transport properties can be formed.

Each microcrystalline i-type semiconductor layer constituting the i-type semiconductor layer in the second embodiment has at least one atom selected from the group III and group V atoms of the periodic table. , So that the concentration of the atom is constant (1 × 10 ⁻⁵ atomic% or less). When, for example, B is contained in each microcrystalline i-type semiconductor layer as the group III atom, the Fermi level is pinned near midgap, and the gap level of the weak n-type i-type semiconductor layer is compensated. In addition, since the electric field spreads over the entire i-type semiconductor layer, the short-circuit current is improved, and the number of electrons flowing from the i-type semiconductor layer to the p-type semiconductor layer is reduced. Further, each amorphous i-type semiconductor layer constituting the i-type semiconductor layer contains at least one atom of the group III and group V atoms of the periodic table and the concentration of the atom in the i-type semiconductor layer. Is constant (1 × 10 ⁻⁵ atomic% or less). As the group V atom,
For example, when vanadium is contained in each amorphous i-type semiconductor layer, the corrosion resistance can be improved without deteriorating the mobility of carriers in the i-type semiconductor layer. When the photovoltaic element of the present invention is installed on a roof as a solar cell, corrosion can be prevented even in acid rain. Further, the i-type semiconductor layer according to the second aspect is such that at least one of the interfaces between the amorphous i-type semiconductor layer and the microcrystalline i-type semiconductor layer is gradually moved from the interface toward the inside of the microcrystalline i-type semiconductor layer. At least one of the Group III and Group V atoms of the periodic table with a concentration distribution that becomes higher. When the atom is Bi, for example, a short circuit in the pin junction can be prevented. That is, since the electric resistance of Bi increases as the temperature increases, Bi can be used to increase the resistance of the short-circuit portion of the pin junction of the photovoltaic element. Thereby, the area of the photovoltaic element can be increased. Further, the i-type semiconductor layer in the second aspect has at least one interface among the amorphous i-type semiconductor layer / microcrystalline i-type semiconductor layer interface, in a direction from the interface to the inside of the amorphous i-type semiconductor layer. Periodic Table II with gradually increasing concentration distribution
It can contain at least one atom from Group I and Group V atoms. When the atoms are, for example, As, the flexibility of the i-type semiconductor layer is improved, so that the photovoltaic element has improved bending strength and can be bent into a desired shape.

Hereinafter, the photovoltaic device (solar cell) of the present invention will be described in more detail with reference to the drawings. 1 to 4 are schematic cross-sectional views each showing a configuration of an example of the photovoltaic element of the present invention. FIG. 5 is a schematic cross-sectional view showing a configuration of an example of a photovoltaic element in which the i-type semiconductor layer is constituted only by the microcrystalline i-type semiconductor layer. 1 to 5,
101 is a substrate, 102 is a back electrode, 103 is a transparent conductive layer, 104 is a silicon-based non-single-crystal n-type semiconductor layer, 105
Is a silicon-based non-single-crystal i-type semiconductor layer, 106 is a silicon-based non-single-crystal p-type semiconductor layer, 107 is a transparent electrode, and 108 is a current collecting electrode. Reference numeral 105A denotes a silicon-based microcrystalline i-type semiconductor layer, and 105B, 105B-1 and 1B.
05B-2 indicates a silicon-based amorphous i-type semiconductor layer. I-type semiconductor layer 1 in the photovoltaic element shown in FIG.
Reference numeral 05 denotes a two-layer structure, in which the amorphous i-type semiconductor layer (105B-1) is arranged on the p-type semiconductor layer 106 side with respect to the microcrystalline i-type semiconductor layer. The i-type semiconductor layer 105 in the photovoltaic element shown in FIG. 2 has the same two-layer structure as that of FIG. 1, and the amorphous i-type semiconductor layer (105B-2) is a microcrystalline i-type semiconductor layer. It is arranged on the n-type semiconductor layer 104 side with respect to the type semiconductor layer. The i-type semiconductor layer 105 in the photovoltaic element shown in FIG. 3 has a three-layered structure, and has both sides of the microcrystalline i-type semiconductor layer 105A, that is, the n-type semiconductor layer 104 and the p-type semiconductor layer 106. The amorphous i-type semiconductor layers (105B-1, 105B-2) are arranged on each side of the semiconductor device. In the example of the photovoltaic element shown in FIG. 4, the i-type semiconductor layer 105 is a microcrystalline i-type semiconductor layer 105A (thickness: 10 nm to 5 nm).
And the amorphous i-type semiconductor layer 105B (thickness: 1 nm to 5 n
m) shows an example having a laminated structure in which layers are alternately and repeatedly repeated a plurality of times. I-type semiconductor layer 1 in FIG.
Reference numeral 05 denotes a laminated structure in which the amorphous i-type semiconductor layer 105B and the microcrystalline i-type semiconductor layer 105A are alternately and repeatedly laminated twice. And 105B can be arbitrarily adjusted as desired. As described above, the illustrated photovoltaic element of the present invention has a configuration in which light is incident from the side opposite to the substrate, but these may have a configuration in which light is incident from the substrate side. In the above-described photovoltaic device of the present invention, the substrate 101 has a function of supporting the device. The back electrode 102 (or the back reflection layer) is mainly made of Al, A
It is made of a metal such as g or Cu and has a function of guiding light not absorbed by the semiconductor layer to the semiconductor layer again. The transparent conductive layer 103 is made of zinc oxide, tin oxide, indium oxide, or the like, and has a function of diffusing light and preventing a short circuit. P-type, i-type, and n-type semiconductor layers (106, 10) each made of a silicon-based non-single-crystal material
5, 104) has a pin junction semiconductor layer having a photoelectric conversion function. The transparent electrode 107 (upper transparent electrode)
The semiconductor layer has a function of efficiently supplying light to the semiconductor layer and effectively guiding generated photocurrent to the current collecting electrode 108. The collecting electrode 108 has a function of collecting a photocurrent and efficiently guiding light to the semiconductor layer, and has a comb-like shape when viewed from the light incident direction.

Hereinafter, each component of the photovoltaic device of the present invention will be described in detail.

[0014]

[Substrate 101] The substrate 101 may be a single-crystal or non-single-crystal substrate, and may be a conductive or electrically insulating substrate. Further, they may be light-transmitting or non-light-transmitting, but preferably have a small amount of deformation and distortion and a desired strength. Specifically, Fe, Ni, Cr, Al, Mo, Au, N
Metals such as b, Ta, V, Ti, Pt, Pb or alloys thereof, for example, thin plates such as brass and stainless steel and composites thereof, and polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, and polyvinyl chloride Films or sheets of heat-resistant synthetic resins such as vinylidene, polystyrene, polyamide, polyimide, epoxy or composites of these with glass fibers, carbon fibers, boron fibers, metal fibers, etc., and thin plates of these metals, resin sheets, etc. Surface-coated metal thin films of different materials and / or insulating thin films of SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , AlN, etc. on the surface by sputtering, vapor deposition, plating, etc., and glass , Ceramics, etc. . If the substrate is electrically conductive such as metal, it may be used as an electrode for direct current extraction. If the substrate is electrically insulating such as synthetic resin, the surface on the side on which the deposited film is formed may be made of Al, Ag. , Pt, Au, Ni, T
i, Mo, W, Fe, V, Cr, Cu, stainless steel, brass, nichrome, SnO ₂ , In ₂ O ₃ , ZnO, so-called metal simple substance or alloy, and transparent conductive oxide (TCO) It is desirable that a surface treatment is performed in advance by a method such as vapor deposition or sputtering to form an electrode for extracting current. Of course, even if the substrate is made of an electrically conductive material such as a metal, it improves the reflectance of long-wavelength light on the substrate surface and prevents mutual diffusion of constituent elements between the substrate material and the deposited film. A different kind of metal layer or the like may be provided on the side of the substrate on which the deposited film is formed, for the purpose of performing the above. In the case where the substrate is relatively transparent and a photovoltaic element having a layer configuration in which light is incident from the side of the substrate is used, a conductive thin film such as the transparent conductive oxide or a metal thin film may be used in advance. It is desirable to deposit and form. Also,
The surface of the substrate may be a so-called smooth surface or a fine uneven surface. In the case of forming a fine uneven surface, the uneven shape is spherical, conical, pyramidal, or the like, and its maximum height (Rmax) is preferably 0.1 mm.
By setting the thickness to 05 μm or 2 μm, light reflection on the surface becomes irregular reflection, and the optical path length of the light reflected on the surface is increased. The shape of the substrate can be plate-like with a smooth surface or an uneven surface, a long belt-like shape, a cylindrical shape, or the like depending on the application, and the thickness thereof is appropriately determined so that a desired photovoltaic element can be formed. However, when flexibility is required for the photovoltaic element, or when light is incident from the side of the substrate, the thickness should be as thin as possible within a range where the function as the substrate is sufficiently exhibited. it can. However,
The thickness is usually 10 μm or more from the viewpoint of the production and handling of the substrate, the mechanical strength, and the like.

[0015]

[Back electrode 102] The back electrode 102 is an electrode disposed on the back surface of the semiconductor layer in the light incident direction. Materials for the back electrode include gold, silver, copper, aluminum, nickel, iron,
Examples include metals such as chromium, molybdenum, tungsten, titanium, cobalt, tantalum, niobium, and zirconium, and alloys such as stainless steel. Among them, metals having high reflectance, such as aluminum, copper, silver, and gold, are particularly preferable. In the case of using a metal having a high reflectance, the back electrode can also serve as a light reflecting layer that reflects light that could not be absorbed by the semiconductor layer again to the semiconductor layer. Further, the back electrode may be formed by laminating two or more kinds of materials in two or more layers. Further, the shape of the back surface electrode may be flat, but it is more preferable that the back surface electrode has an uneven shape for scattering light. By having an uneven shape that scatters light, it scatters long-wavelength light that could not be absorbed by the semiconductor layer, extends the optical path length in the semiconductor layer, improves the long-wavelength sensitivity of the photovoltaic element, and increases the short-circuit current. And the photoelectric conversion efficiency can be improved. The uneven shape that scatters light has a height difference between peaks and valleys of the unevenness of 0.2 to 2.0 μm in Rmax.
It is desirable that However, when the substrate also serves as the back electrode, the back electrode may not need to be formed in some cases.
In addition, a vapor deposition method, a sputtering method, a plating method, a printing method, or the like is used for forming the back surface electrode. When the back electrode is formed to have an uneven shape that scatters light, the formed metal or alloy film is formed by dry etching, wet etching, sandblasting, heating, or the like. In addition, the above-mentioned metal or alloy can be deposited while heating the substrate to form an uneven shape for scattering light.

[0016]

[Transparent Conductive Layer 103] The transparent conductive layer 103 is disposed between the back electrode 102 and the semiconductor layer mainly for the following purposes. First, the irregular reflection on the back surface of the photovoltaic device is improved, light is confined in the photovoltaic device by multiple interference by a thin film, the optical path length in the semiconductor layer is extended, and the short-circuit current (Jsc) of the photovoltaic device is increased. To increase. Next, it is necessary to prevent the metal of the back metal reflection layer serving as the back electrode from diffusing or migrating into the semiconductor layer to prevent the photovoltaic element from shunting. In addition, by giving the transparent conductive layer a slight resistance value, short-circuiting caused by a defect such as a pinhole in the semiconductor layer between the back electrode 102 and the transparent electrode 107 provided with the semiconductor layer interposed therebetween can be prevented. It is. That the transparent conductive layer 103 has a high transmittance in a wavelength region where the semiconductor layer can absorb,
Moderate resistivity is required. Preferably, the transmittance at 650 nm or more is 80% or more, more preferably 85% or more, and most preferably 90% or more. Also,
The resistivity is preferably 1 × 10 ⁻⁴ Ωcm or more and 1 × 10 ⁻⁴ Ωcm or more.
It is desirably ⁶ Ωcm or less, more preferably 1 × 10 ⁻² Ωcm or more and 5 × 10 ⁴ Ωcm or less. As a material of the transparent conductive layer 103, In ₂ O ₃ , SnO ₂ , I
TO (In ₂ O ₃ + SnO ₂ ), ZnO, CdO, Cd ₂ S
nO ₄ , TiO ₂ , Ta ₂ O ₅ , Bi ₂ O ₃ , MoO ₃ , Na _x
A conductive oxide such as WO ₃ or a mixture thereof is suitably used. Further, an element (dopant) that changes the conductivity may be added to these compounds.
As the element (dopant) that changes the conductivity, for example, when the transparent conductive layer 103 is ZnO, Al, In,
When B, Ga, Si, F, etc. are In ₂ O ₃ ,
Sn, F, Te, Ti, Sb, Pb, etc .;
_In the case of ₂ , F, Sb, P, As, In, Tl, T
e, W, Cl, Br, I and the like are preferably used. The transparent conductive layer 103 can be formed by various evaporation methods such as EB evaporation and sputter evaporation, various CVD methods, a spray method, a spin-on method, a dipping method, and the like. Specifically, the formation of the transparent conductive layer can be performed using, for example, a DC magnetron sputtering apparatus having a configuration as shown in FIG. The formation of the transparent conductive layer using the apparatus shown in FIG. 7 can be performed, for example, as follows. 30 in FIG.
Reference numeral 8 denotes a target of 99.99% pure zinc oxide (ZnO), which is insulated from the deposition chamber 301 by an insulating support. Using the gas introduction line 317, the Ar gas flow rate is 10 sccm, the CH ₄ / Ar gas flow rate is 5 sccm,
Opening of the conductance valve (butterfly type) while adjusting the vacuum gauge so that the flow rate of the O ₂ / Ar gas is 20 sccm and the flow rate of the N ₂ / Ar gas is 5 sccm, and the pressure in the deposition chamber 301 is 9 mTorr. To adjust.
Thereafter, the voltage of the DC power supply 311 is set to −420 V, DC power is introduced to the target 308, and a DC glow discharge is generated. Shutter 314 after 7 minutes
To start the formation of the transparent electrode layer on the substrate,
When the transparent electrode layer of μm is formed, the shutter 314 is formed.
Is closed, the output of the DC power supply 311 is turned off, and the DC glow discharge is stopped. Thereby, a transparent conductive layer containing carbon atoms, oxygen atoms, and nitrogen atoms can be formed.

[0017]

[Semiconductor layer (104, 105, 106)] The silicon-based non-single-crystal material constituting the semiconductor layer in the photovoltaic device of the present invention is a silicon-containing amorphous material,
Includes silicon-containing microcrystalline materials and silicon-containing polycrystalline materials. Particularly preferred examples of the silicon-containing amorphous material include a-Si: H (abbreviation for hydrogenated amorphous silicon), a-Si: F, a-Si: H: F, and a-Si.
Ge: H, a-SiGe: F, a-SiGe: H: F,
a-SiC: H, a-SiC: F, a-SiC: H: F
And the like. As a particularly preferable example of the silicon-containing microcrystalline material, a material obtained by forming these amorphous silicon-based materials under conditions for microcrystallization can be given. The semiconductor layer can perform valence electron control and forbidden band width control. Specifically, a raw material compound containing an element serving as a valence electron controlling agent or a forbidden band width controlling agent when forming a semiconductor layer is used alone, or mixed with the deposited film forming raw material gas or the dilution gas to form a film. What is necessary is just to introduce in space. Further, the semiconductor layer is at least partially doped with p-type and n-type by valence electron control,
Form at least one set of pin junctions. And pi
By stacking a plurality of n junctions, a so-called stack cell configuration is obtained. The semiconductor layer is formed by microwave plasma CVD, RF plasma CVD, photo CVD, thermal C
It can be performed by various CVD methods such as VD method and MOCVD method, or various vapor deposition methods such as EB evaporation, MBE, ion plating and ion beam method, sputtering method, spray method, printing method and the like. As a method adopted industrially, a plasma CVD method in which a raw material gas is decomposed by plasma and deposited on a substrate is preferably used. In addition, as the reaction device, a batch type device, a continuous film forming device, or the like can be used as desired. Hereinafter, a semiconductor layer using a silicon-based non-single-crystal semiconductor material particularly suitable for the photovoltaic device of the present invention will be described in further detail.

[0018]

[I-type semiconductor layer (intrinsic semiconductor layer)] In a photovoltaic device using a silicon-based non-single-crystal semiconductor material, the i-type layer used for a pin junction is an important layer that generates and transports carriers with respect to irradiation light. . As the i-type layer, a slightly p-type and slightly n-type layer can be used. As described above, the silicon-based non-single-crystal semiconductor material contains a hydrogen atom (H, D) or a halogen atom (X), which has an important function. That is, the hydrogen atoms (H, D) contained in the i-type layer
Alternatively, the halogen atom (X) works to compensate for dangling bonds in the layer, and improves the product of carrier mobility and lifetime in the i-type layer. Further, it works to compensate for the interface state of each interface of the p-type layer / i-type layer and the n-type layer / i-type layer, and has the effect of improving the photovoltaic power, photocurrent and photoresponsiveness of the photovoltaic element. There is something. The number of hydrogen atoms and / or halogen atoms contained in the i-type layer is 1
４０40 at% is mentioned as the optimum content. Especially,
A preferred distribution form is one in which a large content of hydrogen atoms and / or halogen atoms is distributed on each interface side of the p-type layer / i-type layer and the n-type layer / i-type layer. The preferred range of the content of hydrogen atoms and / or halogen atoms is 1.1 to 2 times the content in the bulk. Further, it is preferable that the content of hydrogen atoms and / or halogen atoms is changed in accordance with the content of silicon atoms. Amorphous silicon and microcrystalline silicon can be converted into a-Si: H, a-Si: F, a-Si: H: F,
μc-Si: H, μc-Si: F, μc-Si: H: F
It is written as. These are particularly preferable as constituent materials of the i-type semiconductor layer in the photovoltaic device of the present invention. The characteristics of the preferred i-type semiconductor layer in the photovoltaic device of the present invention include a hydrogen atom content (C _H )
1.0 to 25.0 atomic%, AM 1.5, 100 mW / c
artificial sunlight irradiation of a light conductivity of the m ² (σp) is 1.0
× 10 ⁻⁷ S / cm or more, dark conductivity (σd) is 1.0 ×
10 ^-9 S / cm or less, Urbach energy by the constant photocurrent method (CPM) is 55 me
V or less, and those having a localized level density of 10 ¹⁷ / cm ³ or less are suitably used. The feature of the i-type semiconductor layer in the photovoltaic element of the present invention is that the i-type semiconductor layer is formed from the stacked structure of the amorphous layer and the microcrystalline layer as described above, and has an advantage that the photodegradation seen in the microcrystal is small. It is characterized by good carrier mobility seen in amorphous.

[0019]

[Doping layer (p-type semiconductor layer, n-type semiconductor layer)] The doping layer (p-type semiconductor layer or n-type semiconductor layer) is also an important layer that affects the characteristics of the photovoltaic device of the present invention. Hereinafter, the p-type semiconductor layer and the n-type semiconductor layer may be abbreviated as a p-type layer and an n-type layer, respectively. Silicon-based non-single-crystal material that is a constituent material of the doping layer, that is,
Amorphous material (denoted as a-) or microcrystalline material (μ
c-) is, for example, a-Si: H, a
-Si: HX, a-SiC: H, a-SiC: HX, a
-SiGe: H, a-SiGe: HX, a-SiGe
C: H, a-SiGeC: HX, a-SiO: H, a-
SiO: HX, a-SiN: H, a-SiN: HX, a
-SiON: H, a-SiON: HX, a-SiOC
N: H, a-SiOCN: HX, μc-Si: H, μc
-Si: HX, μc-SiC: H, μc-SiC: H
X, μc-SiO: H, μc-SiO: HX, μc-S
iN: H, μc-SiN: HX, μc-SiGeC:
H, μc-SiGeC: HX, μc-SiON: H, μ
c-SiON: HX, μc-SiOCN: H, μc-S
iOCN: HX, etc., p-type valence electron control agents (Group III atoms B, Al, Ga, In, Tl) and n-type valence electron control agents (Group V atoms P, As in the periodic table) , Sb, B
Examples of the material to which i) is added at a high concentration include polycrystalline materials (denoted as poly-) such as poly-
Si: H, poly-Si: HX, poly-SiC:
H, poly-SiC: HX, poly-SiO: H,
poly-SiO: HX, poly-SiN: H, po
ly-SiN: HX, poly-SiGeC: H, po
ly-SiGeC: HX, poly-SiON: H, p
poly-SiON: HX, poly-SiOCN: H,
poly-SiOCN: HX, poly-Si, pol
y-SiC, poly-SiO, poly-SiN, etc., p-type valence electron controlling agent (Group III atom B,
Al, Ga, In, Tl) and a material to which an n-type valence electron controlling agent (Group V group atoms P, As, Sb, Bi) is added at a high concentration. In particular, the p-type layer or n on the light incident side
As the mold layer, a crystalline semiconductor layer with little light absorption or an amorphous semiconductor layer with a wide band gap is suitable. Hydrogen atoms (H, D) or halogen atoms contained in the p-type layer or the n-type layer work to compensate for dangling bonds of the p-type layer or the n-type layer, and doping of the p-type layer or the n-type layer. It improves efficiency. Suitable amounts of hydrogen atoms or halogen atoms added to the p-type or n-type layer are preferably between 0.
1 to 50 at%, more preferably 1 to 40 at% is desirable. When the p-type layer or the n-type layer is crystalline, the optimum amount of hydrogen atoms or halogen atoms is 0.1 to 10 atomic%. Regarding the electrical characteristics of the p-type layer and the n-type layer of the photovoltaic element, those having an activation energy of 0.2 eV or less are preferable, and those having an activation energy of 0.1 eV or less are optimal.
The non-resistance is preferably 100 Ωcm or less, and 1 Ωcm or less.
cm or less is optimal. Further, the thickness of the p-type layer and the n-type layer is preferably 1 to 50 nm, and most preferably 3 to 10 nm.

[0020] The doping layer of the photovoltaic device of the present invention comprises:
In the doping layer, a granular region in which the density of a group IV element as a main component is low may be discretely present. As for the doping layer, when the average height in the thickness direction of the granular region is d and the average diameter in the direction parallel to the substrate surface on which the semiconductor layer (doping layer) is formed is L, preferably 3 nm ≦ d ≦ 40 nm and 3 nm ≦ L ≦ 80 nm, more preferably 4 nm ≦ d ≦
30 nm and 4 nm ≦ L ≦ 60 nm, optimally 5 nm
≦ d ≦ 20 nm and 5 nm ≦ L ≦ 40 nm are desirable. If the size of the granular region is smaller than the above range, the light absorption of the doping layer may increase. If it is larger than the above range, the granular regions tend to be connected to each other and become continuous. As a result, the light absorption of the doping layer decreases, but the activation energy increases, and the open-circuit voltage (V
oc) may be reduced. By setting the size of the granular region in the above range, light absorption of the doping layer is reduced while maintaining low activation energy, and the open voltage (Voc) and short circuit current (Jsc) of the photovoltaic device are reduced. Can be improved. Here, the shape of the granular region may be spherical, spheroidal, three-dimensional polygonal, or irregular. The presence of the granular region in the doping layer can be analyzed by various methods. For example, it can be confirmed by observing a cross section obtained by cutting the photovoltaic element in a direction perpendicular to the substrate with a transmission electron microscope (TEM). Further, the doping layer is characterized in that the concentration of the element for expanding the optical band gap is higher in the granular region than in other portions of the doping layer. Here, when the group IV element that is the main component is Si, as the element that enlarges the optical band gap,
Examples include H, C, N, O, and a halogen element. A suitable concentration of the element that enlarges the optical band gap varies depending on the element, but is preferably in the range of% to 90%, more preferably 3% in the granular region.
~ 80% is desirable. In another portion of the doping layer, preferably, 0.1% to 50%, more preferably,
1% to 40% is desirable. The ratio of the concentration of the element that enlarges the optical bandgap in the granular region to the concentration of the other part of the doped layer is preferably 2%.
The ratio is preferably from 2 to 200 times, more preferably from 3 to 100 times.

[0021]

[Method of Forming Semiconductor Layer] A particularly preferable method for forming a silicon-based non-single-crystal semiconductor layer as a semiconductor layer of the photovoltaic device of the present invention is an RF plasma CVD method or a microwave plasma CVD method. Is a plasma CVD method using alternating current or high frequency. In the microwave plasma CVD method, a material gas such as a source gas or a diluent gas is introduced into a deposition chamber (vacuum chamber) that can be reduced in pressure,
While evacuating by a vacuum pump, the internal pressure of the deposition chamber is kept constant, microwaves oscillated by a microwave power supply are guided by a waveguide, and introduced into the deposition chamber via a dielectric window (alumina ceramics or the like). This is a method of generating a plasma of a material gas to decompose and form a desired deposited film on a substrate disposed in a deposition chamber, and forming a deposited film applicable to a photovoltaic element under a wide range of deposition conditions. can do. The semiconductor layer for the photovoltaic device of the present invention is formed by microwave plasma CVD (abbreviated as MW plasma CVD).
Method), the substrate temperature in the deposition chamber is 100 to 4
50 ° C., internal pressure 0.5-30 mTorr, microwave power 0.01-1 W / cm ³ , microwave frequency 0.1-10 GHz, deposition rate 0.05-20 nm /
sec is a preferred range. When the deposition is performed by the RF plasma CVD method, the substrate temperature in the deposition chamber is 100 to 350 ° C., and the internal pressure is 0.1 to 10 Torr.
The r and RF power are preferably 0.001 to 5.0 W / cm ³ , and the deposition rate is preferably 0.01 to ³ nm / sec. The source gas suitable for depositing the silicon-based non-single-crystal semiconductor layer particularly suitable for the photovoltaic device of the present invention includes a gasizable compound containing silicon atoms, a gasizable compound containing germanium atoms, carbon Examples thereof include a gasizable compound containing an atom, and a mixed gas of the compound. Specifically, as the gasizable compound containing a silicon atom, a chain or cyclic silane compound is used.
_{H 4, Si 2 H 6,} SiF 4, SiFH 3, SiF 2 H 2, S
iF ₃ H, Si ₃ H ₈ , SiD ₄ , SiHD ₃ , SiH
_{2 D 2, SiH 3 D,} SiFD 3, SiF 2 D 2, Si 2 D 3 H
_{3, (SiF 2) 5,} (SiF 2) 6, (SiF 2) 4, Si 2
F ₆ , Si ₃ F ₈ , Si ₂ H ₂ F ₄ , Si ₂ H ₃ F ₃ , SiC
l ₄ , (SiCl ₂ ) ₅ , SiBr ₄ , (SiBr ₂ ) ₅ , S
i ₂ Cl ₆ , SiHCl ₃ , SiH ₂ Br ₂ , SiH ₂ C
l ₂ , Si ₂ Cl ₃ F _3, etc., which are in a gas state or can be easily gasified. Examples of the gasizable compound containing a germanium atom include GeH ₄ , GeD ₄ and G
eF ₄ , GeFH ₃ , GeF ₂ H ₂ , GeF ₃ H, GeH
D ₃ , GeH ₂ D ₂ , GeH ₃ D, Ge ₂ H ₆ , Ge ₂ D _{6 and the} like. Examples of the gasizable compound containing a carbon atom include CH ₄ , CD ₄ , C _n H _{2n + 2} (n is an integer), C _n
H _2n (n is an integer), such as _{C 2 H 2, C 6 H} 6, CO 2, CO and the like. As the nitrogen-containing gas, N ₂ , NH ₃ , N
D ₃ , NO, NO ₂ , and N ₂ O. Examples of the oxygen-containing gas include O ₂ , CO, CO ₂ , NO, NO ₂ , N ₂ O, C
H ₃ CH ₂ OH, CH ₃ OH and the like can be mentioned. Examples of the substance introduced into the p-type layer or the n-type layer for controlling valence electrons include Group III atoms and Group V atoms in the periodic table. Effectively used as a starting material for introducing a Group III atom, specifically, for introducing a boron atom, B ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B ₅ H ₁₁ , B
_{6 H 10, B 6 H 12} , B 6 borohydride such as H _14, BF _3,
Examples thereof include boron halides such as BCl ₃ . In addition, AlCl ₃ , GaCl ₃ , InCl ₃ ,
TlCl _{3 and the} like can also be mentioned. Especially B ₂ H ₆ , B
F ₃ is suitable. Effectively used as a starting material for introducing a group V atom are, specifically, for introducing a phosphorus atom, phosphorus hydrides such as PH ₃ and P ₂ H ₄ , PH ₄ I, PF ₃ ,
Phosphorus halides such as PF ₅ , PCl ₃ , PCl ₅ , PBr ₃ , PBr ₅ , PI _{3 and the} like can be mentioned. In addition, AsH ₃ , A
sF ₃ , AsCl ₃ , AsBr ₃ , AsF ₅ , SbH ₃ , S
bF ₃ , SbF ₅ , SbCl ₃ , SbCl ₅ , BiH ₃ , B
iCl ₃ , BiBr _{3 and the} like can also be mentioned. Especially P
H ₃ and PF ₃ are suitable. Further, the gasifiable compound may be appropriately diluted with a gas such as H ₂ , He, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. In particular, when depositing a layer having a small light absorption or a wide band gap, such as a microcrystalline or polycrystalline semiconductor or a-SiC: H, the raw material gas is diluted with hydrogen gas and microwave power or R
Preferably, the F power introduces a relatively high power.

[0022]

[Transparent electrode 107] The transparent electrode 107 in the photovoltaic element of the present invention is an electrode on the light incident side that transmits light, and also functions as an anti-reflection film by optimizing the film thickness. The transparent electrode 107 is required to have a high transmittance in a wavelength region where the semiconductor layer can absorb light and to have a low resistivity. Preferably, 550 nm
Is 80% or more, more preferably 85%
It is desirable that it is above. The resistivity is preferably 5 × 10 ⁻³ Ωcm or less, more preferably 1 × 10 ⁻³ Ωcm.
It is desirable that the resistivity be ⁻³ Ωcm or less. The materials include In ₂ O ₃ , SnO ₂ , and ITO (In ₂ O ₃ + Sn).
O ₂ ), ZnO, CdO, Cd ₂ SnO ₄ , TiO ₂ , Ta
A conductive oxide such as ₂ O ₅ , Bi ₂ O ₃ , MoO ₃ , Na _x WO ₃ or a mixture thereof is suitably used. Further, an element (dopant) that changes the conductivity may be added to these compounds. Examples of the element (dopant) that changes the conductivity include Al, In, B, Ga, Si, F when the transparent electrode 107 is ZnO, and Sn, F when the transparent electrode 107 is In ₂ O _3. , Te, T
i, Sb, Pb, etc., and in the case of SnO ₂ , F,
Sb, P, As, In, Tl, Te, W, Cl, Br,
I and the like are preferably used. As a method for forming the transparent electrode 107, an evaporation method, a CVD method, a spray method, a spin-on method, a dipping method, or the like is suitably used.

[0023]

[Current collecting electrode 108] The current collecting electrode 108 in the photovoltaic element of the present invention is formed on a part of the transparent electrode 107 as necessary when the resistivity of the transparent electrode 107 cannot be made sufficiently low. And lowers the series resistance of the photovoltaic element. Examples of the material include metals such as gold, silver, copper, aluminum, nickel, iron, chromium, molybdenum, tungsten, titanium, cobalt, tantalum, niobium, and zirconium; alloys such as stainless steel; and conductive materials using powdered metals. Paste and the like. In addition, the ratio of the area occupied by the collecting electrode to the entire surface area of the photovoltaic element is preferably 15% or less, more preferably 10% or less, and optimally 5% or less.
A mask is used for forming the pattern of the collecting electrode 108.
As a forming method, an evaporation method, a sputtering method, a plating method, a printing method, or the like is used. When a solar cell (module or panel) having a desired output voltage and output current is manufactured using the photovoltaic device of the present invention, the photovoltaic devices of the present invention are connected in series or in parallel, A protective layer is formed on the front and back surfaces, and output output electrodes and the like are attached. When the photovoltaic elements of the present invention are connected in series, a diode for preventing backflow may be incorporated.

[0024]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

[0025]

Embodiment 1 An amorphous i-type semiconductor was formed on the non-single-crystal p-type semiconductor layer side with respect to the microcrystalline i-type semiconductor layer shown in FIG. 1 by the following procedure using the deposition film forming apparatus shown in FIG. A photovoltaic element (solar cell) in which layers were stacked was prepared. The deposited film forming apparatus shown in FIG. 6 has a three-layer structure in which a non-single-crystal i-type semiconductor layer is stacked in the order of an amorphous i-type semiconductor layer, a microcrystalline i-type semiconductor layer, and an amorphous i-type semiconductor layer. It is a device corresponding to the above, and is provided with five semiconductor layer forming vacuum devices, but it is not necessary to generate a glow discharge in all the semiconductor layer forming vacuum devices, and a desired photovoltaic element It can be used according to the layer configuration. In addition, each vacuum device for forming a semiconductor layer includes a substrate (substrate 10 shown in FIG. 1) in each discharge chamber.
(Corresponding to 1) and a discharge area adjusting plate (not shown) for adjusting the contact area between the discharge space and the discharge space, and by adjusting this, the film thickness of each semiconductor layer can be adjusted. I can do it. First, stainless steel (SU
S430BA) (a width of 40 cm,
(Thickness: 0.125 mm) was sufficiently degreased and washed, and was attached to a continuous sputtering device (not shown), and a silver electrode (silver purity: 9).
(9.99%) as a target, and a silver thin film having a thickness of 100 nm was sputter-deposited. Further, a thickness of 1.2 μm was set using a ZnO electrode (ZnO purity: 99.999%) as a target.
m ZnO thin film was sputter-deposited on the silver thin film, and a back electrode was formed on the strip substrate. Next, a bobbin around which the band-shaped substrate 250 is wound is mounted on the substrate delivery container 202 of the deposition film forming apparatus, and the band-shaped substrate is moved to the gas gate 25 on the loading side.
1. Vacuum container 203 for forming a non-single-crystal n-type semiconductor layer, vacuum device 204 for forming an amorphous i-type semiconductor layer, vacuum device 201 for forming a microcrystalline i-type semiconductor layer, vacuum for forming an amorphous i-type semiconductor layer The tension was adjusted so that the belt-shaped substrate 250 did not sag through the apparatus 205, the non-single-crystal p-type semiconductor layer forming vacuum vessel 206, and the substrate take-up vessel 207 via the unloading-side gas gate 256. Then, the substrate delivery container 20
2. Vacuum container 203 for forming a non-single-crystal n-type semiconductor layer, vacuum device 204 for forming an amorphous i-type semiconductor layer, vacuum device 201 for forming a microcrystalline i-type semiconductor layer, vacuum for forming an amorphous i-type semiconductor layer The apparatus 205, the vacuum vessel 206 for forming a non-single-crystal p-type semiconductor layer, and the substrate take-up vessel 207 are sufficiently reduced to 5 × 10 ⁻⁶ Torr or less by a vacuum exhaust system including an oil diffusion pump, a mechanical booster pump and a rotary pump (not shown). Was evacuated.

Next, while operating the vacuum evacuation system, the raw material gas of the deposited film is introduced into the discharge chamber 211 from the gas introduction pipe (not shown) under the conditions shown in Table 1 and into the gas introduction pipe (not shown) under the conditions shown in Table 2. From the gas introduction pipe (not shown) into the discharge chamber 213 under the conditions shown in Table 3, and the gas introduction pipe (not shown) under the conditions shown in Table 4. H ₂ gas 200scc the raw material gas for the deposited film into the discharging chamber 216, and from the gas inlet pipe (not shown) from
m into the discharge chamber 214 at the same time
41, 242, 243, 244, 245, and 246, the respective gas gates 251, 252, 253, 254, 255,
A hydrogen gas flow rate of 50
0 sccm was supplied. In this state, the evacuation capacity of the evacuation system is adjusted, and the pressure in the discharge chamber 211 is set to 10 mTorr.
The pressure in the discharge chambers 213, 214, 215, 216 is set to 1.
It was kept at 2 Torr. Discharge chamber 211, 21
3, 214, 215, 216, when the pressure in the substrate has been stabilized,
The movement of the belt-shaped substrate 250 in the direction of 7 was started. The substrate moving speed at this time was 100 cm / min. While moving the strip-shaped substrate 250, an infrared lamp heater (not shown) was turned on to heat the substrate 250 to a desired temperature.
Next, a high-frequency power having a frequency of 13.56 MHz is supplied from a high-frequency power supply to the discharge electrodes in the discharge chambers 213, 215, and 216 to generate glow discharge in the discharge chambers 213, 215, and 216, and to generate glow discharge in the discharge chamber 211. Microwave power of a frequency of 2.45 GHz is supplied to the applicator 230 from the microwave power supply 232 via the waveguide 231, and the discharge chamber 21 is discharged.
1, a microwave glow discharge is generated in the band-shaped substrate 250.
A non-single-crystal n-type semiconductor layer is formed on the non-single-crystal n-type semiconductor layer forming vacuum container 203, and a microcrystalline i-type semiconductor layer is formed on the microcrystalline i-type semiconductor layer forming vacuum container 201. An amorphous i-type semiconductor layer is sequentially formed in a vacuum vessel 205 for forming a layer, and a non-single-crystal p-type semiconductor layer is sequentially formed in a vacuum vessel 206 for forming a non-single-crystal p-type semiconductor. A bond was formed. At this time, the non-single-crystal n-type semiconductor layer 104 has a thickness of 20 nm and the microcrystalline i-type semiconductor layer 105 is formed by a film formation region adjusting plate (not shown) provided in each vacuum vessel.
A is fixed so that the thickness of A is 2 μm and the thickness of the non-single-crystal p-type semiconductor layer 106 is 10 nm.
During the film formation, the thickness of 05B-1 was adjusted to be 0 nm to 200 nm. Each semiconductor layer 10 is placed on the belt-shaped substrate 250.
After the formation of the strips 4 to 106, the strip-shaped substrate 250 is cooled, taken out of the continuous deposition film forming apparatus, and the transparent electrode 107 and the current collecting electrode 108 are formed on the non-single-crystal p-type semiconductor layer 106, and the strip-shaped substrate 250 is formed. Solar cell was completed. next,
The obtained band-shaped solar cell was processed into a solar cell module having a size of 36 cm × 22 cm for each film thickness of each amorphous i-type semiconductor layer 105 </ b> B- 1 using a continuous modularization device (not shown). The characteristics of the obtained solar cell module were evaluated using simulated sunlight of AM 1.5 and 100 mW / cm ² , and the amorphous i-type semiconductor layer 105B-1 was evaluated.
The relationship between the film thickness and the characteristics was examined. Table 5 shows the results.
Next, with the fabricated solar cell module kept at a substrate temperature of 50 ° C., simulated sunlight of AM 1.5, 100 mW / cm ² was irradiated for 500 hours, and a change in the conversion efficiency of the solar cell module with respect to the light irradiation time. Was examined. Table 6 shows the results. From this result, the amorphous i-type semiconductor layer 10
It was found that a conversion efficiency was high when the thickness of 5B-1 was 3.0 nm or more and 50 nm or less, and a photovoltaic element with almost no photodegradation could be produced.

[0027]

Embodiment 2 Using the deposition film forming apparatus shown in FIG. 6 in the same manner as in Embodiment 1, the microcrystalline i-type semiconductor layer shown in FIG. A photovoltaic element (solar cell) in which an amorphous i-type semiconductor layer was laminated was prepared.
First, a strip-shaped substrate 250 (width: 40 cm, thickness: 0.125 mm) made of stainless steel (SUS430BA) is sufficiently degreased and washed, mounted on a continuous sputtering device (not shown), and a silver electrode (silver purity: 99.99%) Was used as a target, and a silver thin film having a thickness of 100 nm was sputter-deposited. Further, a ZnO thin film having a thickness of 1.2 μm was sputter-deposited on the silver thin film using a ZnO electrode (ZnO purity: 99.999%) as a target to form a lower electrode on the belt-shaped substrate 250. Next, the substrate delivery container 20 of the deposition film forming apparatus
2, the bobbin around which the band-shaped substrate is wound is mounted, and the band-shaped substrate is loaded into the gas gate 251 on the loading side, the non-single-crystal n-type semiconductor layer forming vacuum container 203, the amorphous i-type semiconductor layer forming vacuum device 204, Vacuum apparatus for forming crystalline i-type semiconductor layer 20
1, through the vacuum device 205 for forming an amorphous i-type semiconductor layer, the vacuum container 206 for forming a non-single-crystal p-type semiconductor layer, and the substrate take-up container 207 through a gas gate 256 on the unloading side.
The tension was adjusted so that the belt-shaped substrate 250 did not sag.
Then, the substrate delivery container 202, the non-single-crystal n-type semiconductor layer forming vacuum container 203, the amorphous i-type semiconductor layer forming vacuum device 204, and the microcrystalline i-type semiconductor layer forming vacuum device 20
1. A vacuum device 205 for forming an amorphous i-type semiconductor layer, a vacuum container 206 for forming a non-single-crystal p-type semiconductor layer, and a substrate take-up container 207 are evacuated from an oil diffusion pump (not shown), a mechanical booster pump, and a rotary pump. Vacuum was exhausted sufficiently to 5 × 10 ⁻⁶ Torr or less by an exhaust system. Next, while operating the vacuum evacuation system, the raw material gas of the deposited film is introduced into the discharge chamber 211 from the gas introduction pipe (not shown) under the conditions shown in Table 1, and is deposited from the gas introduction pipe (not shown) under the conditions shown in Table 2. Into the discharge chamber 213 from the gas inlet tube (not shown) under the conditions shown in Table 3.
15 into the discharge chamber 216 from a gas introduction pipe (not shown) under the conditions shown in Table 4, and 200 sccm of H ₂ gas from the gas introduction pipe (not shown) to the discharge chamber 214.
At the same time, each gate gas supply pipe 241, 242, 2
43,244,245,246
Hydrogen gas at a flow rate of 500 sccm was supplied to each of 1,252,253,254,255,256 as a gate gas. In this state, the evacuation capacity of the evacuation system is adjusted, the pressure in the discharge chamber 211 is set to 10 mTorr,
The pressure in 214, 215, and 216 was maintained at 1.2 Torr. Discharge chambers 211, 213, 214, 2
When the pressure in 15, 216 became stable, the movement of the belt-shaped substrate 250 from the substrate unloading container 202 toward the substrate winding container 207 was started. The substrate moving speed at this time was 100 cm / min. Strip substrate 250
While moving the substrate, an infrared lamp heater (not shown) was turned on to heat the substrate 250 to a desired temperature.

Next, high-frequency power having a frequency of 13.56 MHz is supplied from a high-frequency power source to the discharge electrodes in the discharge chambers 213, 215, and 216 to generate glow discharge in the discharge chambers 213, 215, and 216. The microwave power supply 232 is connected to the applicator 230 in the 211 through the waveguide 231.
Supplies microwave power at a frequency of 2.45 GHz to generate microwave glow discharge in the discharge chamber 211,
The non-single-crystal n-type semiconductor layer is formed on the strip-shaped substrate 250 in the non-single-crystal n-type semiconductor layer forming vacuum container 203, and the microcrystalline i-type semiconductor layer is formed on the microcrystalline i-type semiconductor layer forming vacuum container 201. An amorphous i-type semiconductor layer is formed in a vacuum container 205 for forming an i-type semiconductor layer, and a non-single-crystal p-type semiconductor layer is formed in a vacuum container 206 for forming a non-single-crystal p-type semiconductor layer, as shown in FIG. A pin-type semiconductor junction was formed. At this time, the thickness of the non-single-crystal n-type semiconductor layer 104 is 20 nm, the thickness of the microcrystalline i-type semiconductor layer 105A is 2 μm, and the thickness of the non-single-crystal The p-type semiconductor layer 106 has a thickness of 10 nm and the amorphous i-type semiconductor layer 105
B-1 was fixed so as to have a thickness of 5.0 nm. After the semiconductor layers 104 to 106 are formed on the strip-shaped substrate 250, the strip-shaped substrate 250 is taken out from the continuous deposition film forming apparatus after cooling, and the transparent electrode 107 and the transparent electrode 107 are formed on the non-single-crystal p-type semiconductor layer 106. The collector electrode 108 was formed, and a belt-shaped solar cell was completed. Next, using a continuous modularization device (not shown), the obtained band-shaped solar cell was
It was processed into 100 solar cell modules having a size of × 22 cm.

[0029]

Comparative Example 1 A photovoltaic element (solar cell) in which the amorphous i-type semiconductor layer shown in FIG. 5 is not laminated by the following procedure using the deposited film forming apparatus shown in FIG. It was created. First, a strip-shaped substrate 250 (width: 40 cm, thickness: 0.125 mm) made of stainless steel (SUS430BA) is sufficiently degreased and washed, mounted on a continuous sputtering device (not shown), and a silver electrode (silver purity: 99.99%) Was used as a target, and a silver thin film having a thickness of 100 nm was sputter-deposited. Further, a ZnO thin film having a thickness of 1.2 μm was sputter-deposited on the silver thin film using a ZnO electrode (ZnO purity: 99.999%) as a target to form a lower electrode on the belt-shaped substrate 250. Next, the substrate delivery container 20 of the deposition film forming apparatus
2, a bobbin around which the band-shaped substrate is wound is attached, and the band-shaped substrate is loaded into the gas gate 251 on the loading side, a vacuum container 203 for forming a non-single-crystal n-type semiconductor layer, a vacuum device 204 for forming an amorphous i-type semiconductor layer, Vacuum apparatus for forming microcrystalline i-type semiconductor layer 20
1. The vacuum substrate 205 for forming an amorphous i-type semiconductor layer, the vacuum container 206 for forming a non-single-crystal p-type semiconductor layer, and the substrate 207 through the gas gate 256 on the unloading side are passed to the substrate winding container 207 so that the belt-shaped substrate 250 does not slack. Was adjusted for tension. Then, the substrate delivery container 202, the non-single-crystal n-type semiconductor layer forming vacuum container 203, the amorphous i-type semiconductor layer forming vacuum device 204, and the microcrystalline i-type semiconductor layer forming vacuum device 20
1. A vacuum device 205 for forming an amorphous i-type semiconductor layer, a vacuum container 206 for forming a non-single-crystal p-type semiconductor layer, and a substrate take-up container 207 are evacuated from an oil diffusion pump (not shown), a mechanical booster pump, and a rotary pump. Vacuum was exhausted sufficiently to 5 × 10 ⁻⁶ Torr or less by an exhaust system. Next, while operating the vacuum evacuation system, the raw material gas for the deposited film is discharged from the discharge chamber 21 through a gas introduction pipe (not shown) under the conditions shown in Table 1.
1, the raw material gas of the deposited film is introduced into the discharge chamber 213 from the gas introduction pipe (not shown) under the conditions shown in Table 2, and the raw material gas of the deposited film is discharged from the gas introduction pipe (not shown) to the discharge chamber under the conditions shown in Table 4. 216 and H ₂ gas 2 from a gas introduction pipe (not shown).
00 sccm into the discharge chamber 214 and the discharge chamber 215,
At the same time, each gate gas supply pipe 241, 242, 243,
From 244, 245, 246, each gas gate 251, 25
Hydrogen gas was supplied to 2,253,254,255,256 as a gate gas at a flow rate of 500 sccm. In this state, the evacuation capacity of the evacuation system is adjusted, and the discharge chamber 211 is adjusted.
The internal pressure was set to 10 mTorr, and the discharge chambers 213, 214,
The pressure in 215, 216 was kept at 1.2 Torr. Discharge chambers 211, 213, 214, 215, 2
When the pressure in the substrate 16 is stabilized, the substrate
From 02, the movement of the band-shaped substrate 250 was started in the direction of the substrate winding container 207. The substrate moving speed at this time is
It was 100 cm / min. With the band-shaped substrate 250 being moved, an infrared lamp heater (not shown) is turned on, and the substrate 2
50 was heated to the desired temperature.

Next, a high-frequency power having a frequency of 13.56 MHz is supplied from a high-frequency power supply to the discharge electrodes in the discharge chambers 213 and 216 to generate glow discharge in the discharge chambers 213 and 216, and the applicator in the discharge chamber 211. 230 via a waveguide 231 from a microwave power supply 232 to a frequency 2.30.
A microwave power of 45 GHz is supplied, a microwave glow discharge is generated in the discharge chamber 211, and the non-single-crystal n-type semiconductor layer is formed on the belt-shaped substrate 250 in the non-single-crystal n-type semiconductor layer forming vacuum container 203. A microcrystalline i-type semiconductor layer is formed in a vacuum vessel 201 for forming a microcrystalline i-type semiconductor layer, and a non-single-crystal p-type semiconductor layer is formed in a vacuum vessel 206 for forming a non-single-crystal p-type semiconductor layer. The pin-type semiconductor junction shown was formed. At this time, the thickness of the non-single-crystal n-type semiconductor layer 104 is 20 nm and the thickness of the microcrystalline i-type semiconductor layer 105A is 2 μm by a film formation region adjusting plate (not shown) provided in each vacuum vessel.
m, the thickness of the non-single-crystal p-type semiconductor layer 106 was fixed to be 10 nm. Each semiconductor layer 1 is placed on the belt-shaped substrate 250.
After the formation of 04 to 106, the belt-like substrate 250 was cooled, taken out of the continuous deposition film forming apparatus, and a transparent electrode 107 and a current collecting electrode 108 were further formed on the non-single-crystal p-type semiconductor layer 106. A belt-shaped solar cell was completed.
Next, using a continuous modularization device (not shown), the obtained band-shaped solar cell was sized to a size of 36 cm × 22 cm.
It was processed into zero solar cell modules.

[0031]

[Evaluation] AM1.5, 10
The characteristics were evaluated using pseudo sunlight of 0 mW / cm ² . At the same time, shunt resistance (Rsh) was measured to evaluate the degree of occurrence of leakage current. With respect to the photoelectric conversion efficiency and the shunt resistance, criteria were set for each of them to be practically usable. Those that exceeded both reference values were regarded as good products, and the yield was evaluated based on the number of good products. As a result, assuming that the number of conforming photovoltaic elements without the amorphous i-type semiconductor layer formed in Comparative Example 1 is 1, the microcrystalline i-type semiconductor layer formed in Example 2 is compared with the non-single-crystal p-type semiconductor layer. It can be seen that the yield rate of the photovoltaic element in which the amorphous i-type semiconductor layer is stacked on the non-single-crystal p-type semiconductor layer side is 1.2 with respect to the microcrystalline i-type semiconductor layer. It was found that the yield was improved in the photovoltaic element in which the amorphous i-type semiconductor layer was stacked.

[0032]

Embodiment 3 In the same manner as in Embodiment 1, the non-single-crystal n-type semiconductor layer side with respect to the microcrystalline i-type semiconductor layer shown in FIG. A photovoltaic element was formed by laminating an amorphous i-type semiconductor layer on the substrate. First, a belt-like substrate 250 made of stainless steel (SUS430BA)
(Width 40 cm, thickness 0.125 mm) was sufficiently degreased and washed, and was mounted on a continuous sputtering device (not shown), and a silver electrode (silver purity: 99.99%) having a thickness of 1
A 00 nm silver thin film was sputter deposited. Furthermore, ZnO
Using an electrode (ZnO purity: 99.999%) as a target, a 1.2 μm-thick ZnO thin film was sputter-deposited on the silver thin film to form a lower electrode on the strip substrate 250. Next, the bobbin around which the band-shaped substrate is wound is mounted on the substrate sending container 202 of the deposition film forming apparatus, and the band-shaped substrate is transferred to the gas gate 251 on the loading side, the non-single-crystal n-type semiconductor layer forming vacuum container 203, the amorphous vacuum device 204 for forming an i-type semiconductor layer,
Vacuum apparatus 201 for forming a microcrystalline i-type semiconductor layer, vacuum apparatus 205 for forming an amorphous i-type semiconductor layer, vacuum vessel 206 for forming a non-single-crystal p-type semiconductor layer, and a substrate take-up vessel 207 via a gas gate 256 on the carry-out side. Through the belt-like substrate 250
The tension was adjusted to prevent slack. Then, the substrate delivery container 202, the non-single-crystal n-type semiconductor layer forming vacuum container 203, the amorphous i-type semiconductor layer forming vacuum device 204,
An oil diffusion pump (not shown) including a vacuum device 201 for forming a microcrystalline i-type semiconductor layer, a vacuum device 205 for forming an amorphous i-type semiconductor layer, a vacuum container 206 for forming a non-single-crystal p-type semiconductor layer, and a substrate winding container 207 5 × 10 ^-6 To by vacuum evacuation system consisting of a mechanical booster pump and a rotary pump
It was evacuated sufficiently to rr or less. Next, while operating the vacuum evacuation system, the source gas of the deposited film is deposited into the discharge chamber 211 from the gas introduction tube (not shown) under the conditions shown in Table 1 and from the gas introduction tube (not shown) under the conditions shown in Table 2. The source gas for the film is deposited into the discharge chamber 213 from the gas inlet tube (not shown) under the conditions shown in Table 3, and the source gas for the film is deposited into the discharge chamber 214 from the gas inlet tube (not shown) under the conditions shown in Table 4. The raw material gas for the film is introduced into the discharge chamber 216, and 200 sccm of H ₂ gas is introduced into the discharge chamber 215 from a gas introduction pipe (not shown), and simultaneously, the respective gate gas supply pipes 241, 242, 243, and 24.
4, 245, 246, each gas gate 251, 252,
Hydrogen gas was supplied to 253, 254, 255, 256 as a gate gas at a flow rate of 500 sccm. In this state, the evacuation capacity of the evacuation system is adjusted, the pressure in the discharge chamber 211 is set to 10 mTorr, and the discharge chambers 213, 214, 21
The pressure in 5,216 was kept at 1.2 Torr. Discharge chambers 211, 213, 214, 215, 216
When the internal pressure is stabilized, the substrate delivery container 202
To the substrate take-up container 207 from the
50 moves have begun. The substrate moving speed at this time is 10
It was 0 cm / min. With the band-shaped substrate 250 being moved, an infrared lamp heater (not shown) is turned on, and the substrate 25 is turned on.
0 was heated to the desired temperature.

Next, a high-frequency power having a frequency of 13.56 MHz is supplied from a high-frequency power source to the discharge electrodes in the discharge chambers 213, 214, and 216 to generate glow discharge in the discharge chambers 213, 214, and 216, and The microwave power supply 232 is connected to the applicator 230 in the 211 through the waveguide 231.
Supplies microwave power at a frequency of 2.45 GHz to generate microwave glow discharge in the discharge chamber 211,
The non-single-crystal n-type semiconductor layer is formed on the strip-shaped substrate 250 in the non-single-crystal n-type semiconductor layer forming vacuum container 203, and the amorphous i-type semiconductor layer is formed on the amorphous i-type semiconductor layer forming vacuum container 204. A microcrystalline i-type semiconductor layer is formed in a vacuum vessel 201 for forming a crystal i-type semiconductor layer, and a non-single-crystal p-type semiconductor layer is formed in a vacuum vessel 206 for forming a non-single-crystal p-type semiconductor layer, as shown in FIG. A pin-type semiconductor junction was formed. At this time, the thickness of the non-single-crystal n-type semiconductor layer 104 is 20 nm, the thickness of the microcrystalline i-type semiconductor layer 105A is 2 μm, and the thickness of the non-single-crystal The thickness of the p-type semiconductor layer 106 is fixed at 10 nm, and the thickness of the amorphous i-type semiconductor layer 105B-2 is 0 nm to 200 nm.
During the film formation. After each of the semiconductor layers 104 to 106 is formed on the band-shaped substrate 250, the band-shaped substrate 250 is cooled, taken out of the continuous deposition film forming apparatus, and placed on the non-single-crystal p-type semiconductor layer 106 to form the transparent electrode 10
7 and the collecting electrode 108 were formed to complete a belt-like solar cell. Next, using a continuous modularization device (not shown),
The obtained band-shaped solar cell is connected to each amorphous i-type semiconductor layer 105.
Each film thickness of B-2 was processed into a solar cell module having a size of 36 cm × 22 cm. The characteristics of the obtained solar cell module were evaluated using AM1.5, 100 mW / cm ² simulated sunlight, and the amorphous i-type semiconductor layer 1 was evaluated.
The relationship between the film thickness and characteristics of 05B-2 was examined. Table 7 shows the results. Next, with the obtained solar cell module maintaining the substrate temperature at 50 ° C., AM 1.5, 100 mW /
The solar cell module was irradiated with 500 cm ² of pseudo sunlight for 500 hours, and the change in the conversion efficiency of the solar cell module with respect to the light irradiation time was examined. Table 8 shows the results. From this result, it is found that the thickness of the amorphous i-type semiconductor layer 105B-2 is 3.0 nm or more and 50 nm.
In the following, it was found that a photovoltaic element having high conversion efficiency and almost no light degradation can be produced.

[0034]

Embodiment 4 A glass substrate was placed in a discharge chamber 215 in a vacuum apparatus 205 for forming an amorphous i-type semiconductor layer in the deposition film forming apparatus shown in FIG. While changing the dilution amount, the raw material gas for the deposited film was introduced into the discharge chamber 215 from a gas introduction tube (not shown), and a single film sample of the amorphous i-type layer was formed on the glass substrate. When the optical bandgap of each sample was measured, the optical bandgap of the obtained sample was 1.65 to 1.85 eV.

In the same manner as in the first embodiment, the amorphous silicon is deposited on the non-single-crystal p-type semiconductor layer side with respect to the microcrystalline i-type semiconductor layer of FIG. 1 by the following procedure using the deposition film forming apparatus shown in FIG. A photovoltaic element in which i-type semiconductor layers were stacked was prepared. Stainless steel (SU
S430BA) (a width of 40 cm,
(Thickness: 0.125 mm) was sufficiently degreased and washed, and was attached to a continuous sputtering device (not shown), and a silver electrode (silver purity: 9).
(9.99%) as a target, and a silver thin film having a thickness of 100 nm was sputter-deposited. Further, a thickness of 1.2 μm was set using a ZnO electrode (ZnO purity: 99.999%) as a target.
A ZnO thin film having a thickness of m was sputter-deposited on the silver thin film to form a lower electrode on the belt-like substrate 250. Next, a bobbin around which the band-shaped substrate is wound is mounted on the substrate delivery container 202 of the deposition film forming apparatus, and the band-shaped substrate is moved to the gas gate 25 on the loading side.
1. Vacuum container 203 for forming a non-single-crystal n-type semiconductor layer, vacuum device 204 for forming an amorphous i-type semiconductor layer, vacuum device 201 for forming a microcrystalline i-type semiconductor layer, vacuum for forming an amorphous i-type semiconductor layer The tension was adjusted so that the belt-like substrate 250 did not sag through the apparatus 205, the non-single-crystal p-type semiconductor layer forming vacuum vessel 206, and the substrate take-up vessel 207 through the gas gate 256 on the carry-out side. Then, the substrate delivery container 20
2. Vacuum container 203 for forming a non-single-crystal n-type semiconductor layer, vacuum device 204 for forming an amorphous i-type semiconductor layer, vacuum device 201 for forming a microcrystalline i-type semiconductor layer, vacuum for forming an amorphous i-type semiconductor layer The apparatus 205, the vacuum vessel 206 for forming a non-single-crystal p-type semiconductor layer, and the substrate take-up vessel 207 are sufficiently reduced to 5 × 10 ⁻⁶ Torr or less by a vacuum exhaust system including an oil diffusion pump, a mechanical booster pump and a rotary pump (not shown). Was evacuated. Next, while operating the evacuation system,
Under the conditions shown in Table 1, the raw material gas of the deposited film is introduced into the discharge chamber 211 from a gas introduction tube (not shown), and the raw material gas of the deposited film is discharged from the gas introduction tube (not shown) into the discharge chamber 213 under the conditions shown in Table 2.
The raw material gas of the deposited film is introduced into the discharge chamber 215 from the gas introduction tube (not shown) under the conditions shown in Table 3, and the raw material gas of the deposited film is discharged from the gas introduction tube (not shown) to the discharge chamber 216 under the conditions shown in Table 4. H ₂ gas 20 into the gas inlet pipe (not shown).
0 sccm into the discharge chamber 214 at the same time, the respective gate gas supply pipes 241, 242, 243, 244, 245, 24
6, the gas gates 251, 252, 253, 254,
Hydrogen gas was supplied to each of 255 and 256 as a gate gas at a flow rate of 500 sccm. In this state, the evacuation capacity of the evacuation system is adjusted, and the pressure in the discharge chamber 211 is reduced to 10 m
At rr, the pressure in the discharge chambers 213, 214, 215, 216 was maintained at 1.2 Torr. Discharge chamber 21
When the pressures in 1, 213, 214, 215, and 216 were stabilized, the movement of the belt-shaped substrate 250 from the substrate delivery container 202 toward the substrate take-up container 207 was started. The substrate moving speed at this time was 100 cm / min. While moving the strip-shaped substrate 250, an infrared lamp heater (not shown) was turned on to heat the strip-shaped substrate 250 to a desired temperature.

Next, high-frequency power having a frequency of 13.56 MHz is supplied from a high-frequency power source to the discharge electrodes in the discharge chambers 213, 215, and 216 to generate glow discharge in the discharge chambers 213, 215, and 216. The microwave power supply 232 is connected to the applicator 230 in the 211 through the waveguide 231.
Supplies microwave power at a frequency of 2.45 GHz to generate microwave glow discharge in the discharge chamber 211,
The non-single-crystal n-type semiconductor layer is formed on the strip-shaped substrate 250 in the non-single-crystal n-type semiconductor layer forming vacuum container 203, and the microcrystalline i-type semiconductor layer is formed on the microcrystalline i-type semiconductor layer forming vacuum container 201. An amorphous i-type semiconductor layer is formed in a vacuum vessel 205 for forming an i-type semiconductor layer, and a non-single-crystal p-type semiconductor layer is formed in a vacuum vessel 206 for forming a non-single-crystal p-type semiconductor layer, as shown in FIG. A pin type semiconductor junction was formed. At this time, the film thickness of the non-single-crystal n-type semiconductor layer 104 is 20 nm and the thickness of the microcrystalline i
The semiconductor layer 105A has a thickness of 2 μm, the non-single-crystal p-type semiconductor layer 106 has a thickness of 10 nm, and the amorphous i-type semiconductor layer 10
5B-1 was fixed so that the film thickness became 5.0 nm. In addition, among the source gases introduced into the discharge chamber 215, the H ₂ gas is changed under the condition that the single film of the amorphous i-type layer is first formed, and the optical property of the amorphous i-type semiconductor layer is changed. The forbidden band width was adjusted so as to be 1.65 to 1.85 eV. After each of the semiconductor layers 104 to 106 is formed on the band-shaped substrate 250, the band-shaped substrate 250 is cooled, taken out from the continuous deposition film forming apparatus, and the transparent electrode 107 is formed on the non-single-crystal p-type semiconductor layer 106. The collector electrode 108 was formed, and a belt-shaped solar cell was completed. Next, using a continuous modularization device (not shown), the obtained band-shaped solar cell was subjected to 36 cm × 2 for each film thickness of each amorphous i-type semiconductor layer 105B-1.
It was processed into a solar cell module having a size of 2 cm. About the obtained solar cell module, AM1.5, 100
Characteristics were evaluated using mW / cm ² simulated sunlight, and the relationship between the optical bandgap and the characteristics of the amorphous i-type semiconductor layer 105B-1 was examined. Table 9 shows the results. From this result, the optical bandgap of the amorphous i-type semiconductor layer was 1.7 eV.
As described above, it was found that a photovoltaic element having high conversion efficiency can be produced.

[0037]

Fifth Embodiment In the same manner as in the first embodiment, the non-single-crystal n-type semiconductor layer side with respect to the microcrystalline i-type semiconductor layer shown in FIG. Further, a photovoltaic element in which an amorphous i-type semiconductor layer was stacked on the non-single-crystal p-type semiconductor layer side was prepared. First, stainless steel (SUS430B
A) A strip substrate 250 (width 40 cm, thickness 0.1)
25 mm) was sufficiently degreased and washed, mounted on a continuous sputtering device (not shown), and a silver electrode (silver purity: 99.99).
%) As a target, and a silver thin film having a thickness of 100 nm was sputter-deposited. Furthermore, a ZnO electrode (ZnO purity: 9)
9.999%) and 1.2 μm thick Z
An nO thin film is sputter-deposited on a silver thin film to form a strip substrate 25.
0 was formed on the lower electrode. Next, a bobbin around which the band-shaped substrate is wound is mounted on the substrate sending container 202 of the deposition film forming apparatus, and the band-shaped substrate is transferred to the gas gate 251 on the loading side, the non-single-crystal n-type semiconductor layer forming vacuum container 203, and the amorphous i. Vacuum device 204 for forming a type semiconductor layer, vacuum device 201 for forming a microcrystalline i-type semiconductor layer, vacuum device 205 for forming an amorphous i-type semiconductor layer, vacuum container 206 for forming a non-single-crystal p-type semiconductor layer,
The substrate take-up container 20 is passed through the gas gate 256 on the unloading side.
7, the tension was adjusted so that the belt-shaped substrate 250 did not sag. Then, the substrate delivery container 202, the non-single-crystal n-type semiconductor layer forming vacuum container 203, the amorphous i-type semiconductor layer forming vacuum device 204, the microcrystalline i-type semiconductor layer forming vacuum device 201, the amorphous i-type Vacuum device 2 for semiconductor layer formation
05, the vacuum container 206 for forming a non-single-crystal p-type semiconductor layer and the substrate take-up container 207 are sufficiently reduced to 5 × 10 ⁻⁶ Torr or less by a vacuum exhaust system including an oil diffusion pump, a mechanical booster pump, and a rotary pump (not shown). Evacuated. Next, while operating the vacuum evacuation system, the source gas of the deposited film is deposited into the discharge chamber 211 from the gas introduction tube (not shown) under the conditions shown in Table 1 and from the gas introduction tube (not shown) under the conditions shown in Table 2. The raw material gas for the film was introduced into the discharge chamber 213, as shown in Table 3.
The raw material gas for the deposited film is introduced into the discharge chamber 214 from a gas introduction tube (not shown) under the conditions shown in Table 4, and the source gas for the deposited film is introduced into the discharge chamber 215 from the gas introduction tube (not shown) under the conditions shown in Table 3. The raw material gas of the deposited film is introduced into the discharge chamber 216 from a gas introduction pipe (not shown) under the conditions shown in FIG. 4 and simultaneously, the respective gate gas supply pipes 241, 242, 243, 244, 245, and 2
From 46, each gas gate 251, 252, 253, 25
Hydrogen gas was supplied as a gate gas to each of 4, 255 and 256 at a flow rate of 500 sccm. In this state, the evacuation capacity of the evacuation system is adjusted to reduce the pressure in the discharge chamber 211 to 10 m.
At Torr, the pressure in the discharge chambers 213, 214, 215, 216 was maintained at 1.2 Torr. When the pressure in the discharge chambers 211, 213, 214, 215, and 216 was stabilized, the movement of the belt-shaped substrate 250 was started from the substrate delivery container 202 toward the substrate take-up container 207. The substrate moving speed at this time was 100 cm / min. While moving the strip-shaped substrate 250, an infrared lamp heater (not shown) was turned on to heat the substrate 250 to a desired temperature.

Next, the discharge chambers 213, 214, 215, 2
A frequency of 13.56 was applied to the discharge electrodes in
MHz power, and discharge chambers 213, 214,
Glow discharge is generated in the discharge chambers 211 and 216,
A microwave power having a frequency of 2.45 GHz is supplied from a microwave power supply 232 to an applicator 230 in the inside of the discharge chamber 211 through a waveguide 231 to generate a microwave glow discharge in the discharge chamber 211, and a non-single unit is formed on the strip-shaped substrate 250. A non-single-crystal n-type semiconductor layer is formed in a vacuum container 203 for forming a crystalline n-type semiconductor layer, and an amorphous i-type semiconductor layer is formed in a vacuum container 204 for forming an amorphous i-type semiconductor layer. The microcrystalline i-type semiconductor layer is formed in the vacuum container 201, the amorphous i-type semiconductor layer is formed in the amorphous i-type semiconductor layer forming vacuum container 205, and the non-single-crystal is formed in the non-single-crystal p-type semiconductor layer forming vacuum container 206. The p-type semiconductor layers were sequentially formed, and a pin-type semiconductor junction shown in FIG. 3 was formed. At this time, the non-single-crystal n-type semiconductor layer 104 is formed by a film formation region adjusting plate (not shown) provided in each vacuum vessel.
Is 20 nm, the thickness of the microcrystalline i-type semiconductor layer 105A is 2 μm, and the thickness of the non-single-crystal p-type semiconductor layer 106 is 10 n.
m, and the amorphous i-type semiconductor layer 105B-
Adjustment was made during the film formation so that the film thickness of each of No. 1 and the amorphous i-type semiconductor layer 105B-2 was 0 nm to 200 nm. After each of the semiconductor layers 104 to 106 is formed on the belt-like substrate 250, the belt-like substrate 250 is cooled and then taken out of the continuous deposition film forming apparatus, and the non-single-crystal p-type semiconductor layer 1 is formed.
06, a transparent electrode 107 and a current collecting electrode 108 were formed to complete a strip-shaped solar cell. Next, using a continuous modularization apparatus (not shown), the obtained band-shaped solar cell was formed for each film thickness of each of the amorphous i-type semiconductor layers 105B-1 and 105B-2. 36cm × 22cm
Into a solar cell module of the size AM1.5, 100mW /
The characteristics were evaluated using simulated sunlight of cm ² and the amorphous i
-Type semiconductor layer 105B-1 and amorphous i-type semiconductor layer 10
The relationship between the film thickness and characteristics of 5B-2 was examined. Table 1 shows the results.
0 is shown. Next, with the obtained solar cell module maintaining the substrate temperature at 50 ° C., AM 1.5, 100 mW /
The solar cell module was irradiated with 500 cm ² of pseudo sunlight for 500 hours, and the change in the conversion efficiency of the solar cell module with respect to the light irradiation time was examined. Table 11 shows the results. From these results, it can be seen that the amorphous i
Semiconductor layer 105B-1 and amorphous i-type semiconductor layer 105B
It was found that when the sum of the layer thicknesses of -2 and 3.0 nm or more and 80 nm or less, the conversion efficiency was high and a photovoltaic element with almost no photodegradation could be produced.

[0039]

Embodiment 6 In the same manner as in Embodiment 1, the non-single-crystal p-type semiconductor layer side with respect to the microcrystalline i-type semiconductor layer shown in FIG. A photovoltaic element was formed by laminating an amorphous i-type semiconductor layer on the substrate. First, a belt-like substrate 250 made of stainless steel (SUS430BA)
(Width 40 cm, thickness 0.125 mm) was sufficiently degreased and washed, and was mounted on a continuous sputtering device (not shown), and a silver electrode (silver purity: 99.99%) having a thickness of 1
A 00 nm silver thin film was sputter deposited. Furthermore, ZnO
Using an electrode (ZnO purity: 99.999%) as a target, a 1.2 μm-thick ZnO thin film was sputter-deposited on the silver thin film to form a lower electrode on the strip substrate 250. Next, a bobbin around which the band-shaped substrate is wound is mounted on the substrate delivery container 202 of the deposition film forming apparatus, and the band-shaped substrate is loaded with the gas gate 251 on the loading side, the non-single-crystal n-type semiconductor layer forming vacuum container 203, and the amorphous i. Vacuum device 204 for forming a type semiconductor layer, vacuum device 201 for forming a microcrystalline i-type semiconductor layer, vacuum device 205 for forming an amorphous i-type semiconductor layer, vacuum container 206 for forming a non-single-crystal p-type semiconductor layer, The tension was adjusted so that the belt-like substrate 250 was not slackened by passing the gas through the gas gate 256 to the substrate winding container 207. Then, the substrate sending container 202 and the non-single-crystal n-type semiconductor layer forming vacuum container 2
03, vacuum device for forming an amorphous i-type semiconductor layer 204, vacuum device for forming a microcrystalline i-type semiconductor layer 201, vacuum device for forming an amorphous i-type semiconductor layer 205, vacuum for forming a non-single-crystal p-type semiconductor layer The container 206 and the substrate take-up container 207 are evacuated to 5 × 10 ⁻⁶ Torr by a vacuum exhaust system including an oil diffusion pump, a mechanical booster pump, and a rotary pump (not shown).
Vacuum was exhausted sufficiently to the following. Next, while operating the vacuum evacuation system, the source gas of the deposited film is deposited into the discharge chamber 211 from the gas introduction tube (not shown) under the conditions shown in Table 1 and from the gas introduction tube (not shown) under the conditions shown in Table 2. The source gas for the film is deposited into the discharge chamber 213 from a gas inlet tube (not shown) under the conditions shown in Table 3, and the source gas for the film is deposited into the discharge chamber 215 from the gas inlet tube (not shown) under the conditions shown in Table 4. The raw material gas of the film is introduced into the discharge chamber 216 and H is supplied from a gas introduction pipe (not shown).
₂ gas 200 sccm into the discharge chamber 214 at the same time, each gate gas supply pipe 241, 242, 243, 244, 2
45, 246 from each gas gate 251, 252, 25
Hydrogen gas was supplied to 3,254,255,256 as a gate gas at a flow rate of 500 sccm. In this state, the evacuation capacity of the evacuation system is adjusted, the pressure in the discharge chamber 211 is set to 10 mTorr, and the discharge chambers 213, 214, 215,
The pressure in 216 was kept at 1.2 Torr. When the pressure in the discharge chambers 211, 213, 214, 215, and 216 is stabilized, the band-shaped substrate 25 is moved from the substrate delivery container 202 to the substrate take-up container 207.
Movement of zero started. The substrate moving speed at this time is 100
cm / min. While moving the belt-like substrate 250,
The infrared lamp heater (not shown) was turned on to heat the substrate 250 to a desired temperature.

Next, a high-frequency power having a frequency of 13.56 MHz is supplied from a high-frequency power source to the discharge electrodes in the discharge chambers 213, 215, and 216 to generate glow discharge in the discharge chambers 213, 215, and 216, and The microwave power supply 232 is connected to the applicator 230 in the 211 through the waveguide 231.
Supplies microwave power at a frequency of 2.45 GHz to generate microwave glow discharge in the discharge chamber 211,
The non-single-crystal n-type semiconductor layer is formed on the strip-shaped substrate 250 in the non-single-crystal n-type semiconductor layer forming vacuum container 203, and the microcrystalline i-type semiconductor layer is formed on the microcrystalline i-type semiconductor layer forming vacuum container 201. An amorphous i-type semiconductor layer is formed in a vacuum vessel 205 for forming an i-type semiconductor layer, and a non-single-crystal p-type semiconductor layer is formed in a vacuum vessel 206 for forming a non-single-crystal p-type semiconductor layer, as shown in FIG. A pin type semiconductor junction was formed. At this time, the non-single-crystal n-type semiconductor layer 104 has a thickness of 20 nm, the non-single-crystal p-type semiconductor layer 106 has a thickness of 10 nm, and a non-illustrated film formation region adjusting plate provided in each vacuum vessel. The thickness of the quality i-type semiconductor layer 105B-1 is fixed to be 5.0 nm, and the thickness of the microcrystalline i-type semiconductor layer 105A is 200 nm to
During the film formation, the thickness was adjusted to 10 μm. Strip substrate 25
After the semiconductor layers 104 to 106 are formed on the non-single-crystal p-type semiconductor layer 106, the transparent substrate 107 and the current collector are collected on the non-single-crystal p-type semiconductor layer 106. The electrode 108 was formed, and a belt-shaped solar cell was completed. Next, the obtained band-shaped solar cell was processed into a solar cell module having a size of 36 cm × 22 cm for each film thickness of each microcrystalline i-type semiconductor layer 105A using a continuous modularization device (not shown). Characteristics of the obtained solar cell module were evaluated using simulated sunlight of AM 1.5 and 100 mW / cm ² , and the relationship between the film thickness of the microcrystalline i-type semiconductor layer 105A and the characteristics was examined. Table 12 shows the results. From this result, the microcrystalline i-type semiconductor layer 105
It was found that a photovoltaic element having a high conversion efficiency with an A film thickness of 300 nm or more and 5 μm or less can be produced.

[0041]

Embodiment 7 In the same manner as in Embodiment 1, the non-single-crystal p-type semiconductor layer side with respect to the microcrystalline i-type semiconductor layer shown in FIG. A photovoltaic element was formed by laminating an amorphous i-type semiconductor layer on the substrate. First, a belt-like substrate 250 made of stainless steel (SUS430BA)
(Width 40 cm, thickness 0.125 mm) was sufficiently degreased and washed, and was mounted on a continuous sputtering device (not shown), and a silver electrode (silver purity: 99.99%) having a thickness of 1
A 00 nm silver thin film was sputter deposited. Furthermore, ZnO
Using an electrode (ZnO purity: 99.999%) as a target, a 1.2 μm-thick ZnO thin film was sputter-deposited on the silver thin film to form a lower electrode on the strip substrate 250. Next, a bobbin around which the band-shaped substrate is wound is mounted on the substrate delivery container 202 of the deposition film forming apparatus, and the band-shaped substrate is loaded with the gas gate 251 on the loading side, the non-single-crystal n-type semiconductor layer forming vacuum container 203, and the amorphous i. Vacuum device 204 for forming a type semiconductor layer, vacuum device 201 for forming a microcrystalline i-type semiconductor layer, vacuum device 205 for forming an amorphous i-type semiconductor layer, vacuum container 206 for forming a non-single-crystal p-type semiconductor layer, The tension was adjusted so that the belt-like substrate 250 was not slackened by passing the gas through the gas gate 256 to the substrate winding container 207. Then, the substrate sending container 202 and the non-single-crystal n-type semiconductor layer forming vacuum container 2
03, vacuum device for forming an amorphous i-type semiconductor layer 204, vacuum device for forming a microcrystalline i-type semiconductor layer 201, vacuum device for forming an amorphous i-type semiconductor layer 205, vacuum for forming a non-single-crystal p-type semiconductor layer The container 206 and the substrate take-up container 207 are evacuated to 5 × 10 ⁻⁶ Torr by a vacuum exhaust system including an oil diffusion pump, a mechanical booster pump, and a rotary pump (not shown).
Vacuum was exhausted sufficiently to the following. Next, while operating the vacuum evacuation system, the source gas of the deposited film is deposited into the discharge chamber 211 from the gas introduction tube (not shown) under the conditions shown in Table 1 and from the gas introduction tube (not shown) under the conditions shown in Table 2. The source gas for the film is deposited into the discharge chamber 213 from a gas inlet tube (not shown) under the conditions shown in Table 3, and the source gas for the film is deposited into the discharge chamber 215 from the gas inlet tube (not shown) under the conditions shown in Table 4. The raw material gas of the film is introduced into the discharge chamber 216 and H is supplied from a gas introduction pipe (not shown).
₂ gas 200 sccm into the discharge chamber 214 at the same time, each gate gas supply pipe 241, 242, 243, 244, 2
45, 246 from each gas gate 251, 252, 25
Hydrogen gas was supplied to 3,254,255,256 as a gate gas at a flow rate of 500 sccm. In this state, the evacuation capacity of the evacuation system is adjusted, the pressure in the discharge chamber 211 is set to 10 mTorr, and the discharge chambers 213, 214, 215,
The pressure in 216 was kept at 1.2 Torr. When the pressure in the discharge chambers 211, 213, 214, 215, and 216 is stabilized, the band-shaped substrate 25 is moved from the substrate delivery container 202 to the substrate take-up container 207.
Movement of zero started. The substrate moving speed at this time is 100
cm / min. While moving the belt-like substrate 250,
The infrared lamp heater (not shown) was turned on to heat the substrate 250 to a desired temperature.

Next, a high-frequency power having a frequency of 13.56 MHz is supplied from a high-frequency power source to the discharge electrodes in the discharge chambers 213, 215, and 216 to generate glow discharge in the discharge chambers 213, 215, and 216. The microwave power supply 232 is connected to the applicator 230 in the 211 through the waveguide 231.
Supplies microwave power at a frequency of 2.45 GHz to generate microwave glow discharge in the discharge chamber 211,
The non-single-crystal n-type semiconductor layer is formed on the strip-shaped substrate 250 in the non-single-crystal n-type semiconductor layer forming vacuum container 203, and the microcrystalline i-type semiconductor layer is formed on the microcrystalline i-type semiconductor layer forming vacuum container 201. An amorphous i-type semiconductor layer is formed in a vacuum vessel 205 for forming an i-type semiconductor layer, and a non-single-crystal p-type semiconductor layer is formed in a vacuum vessel 206 for forming a non-single-crystal p-type semiconductor layer, as shown in FIG. A pin type semiconductor junction was formed. At this time, the film thickness of the non-single-crystal n-type semiconductor layer 104 is 20 nm and the thickness of the microcrystalline i
The semiconductor layer 105A has a thickness of 2 μm, the non-single-crystal p-type semiconductor layer 106 has a thickness of 10 nm, and the amorphous i-type semiconductor layer 10
5B-1 was fixed so that the film thickness became 5.0 nm. Further, H ₂ -diluted B ₂ H ₆ gas was introduced into the gas to be introduced into the discharge chamber 211 in the microcrystalline i-type semiconductor layer forming vacuum vessel 201 so as to change the flow rate. The semiconductor layer contains boron atoms (B) in the range of 0 to 10 ppm. When the respective semiconductor layers 104 to 106 are formed on the belt-like substrate 250, the belt-like substrate 250
After cooling, the transparent electrode 107 and the current collecting electrode 108 were formed on the non-single-crystal p-type semiconductor layer 106 to complete a belt-shaped solar cell. Next, the obtained strip-shaped solar cell was processed into a solar cell module having a size of 36 cm × 22 cm for each microcrystalline i-type semiconductor layer 105A having a different B atom content by using a continuous modularization device (not shown). did. The characteristics of the obtained solar cell module were evaluated using simulated sunlight of AM 1.5 and 100 mW / cm ² , and the relationship between the B atom content in the microcrystalline i-type semiconductor layer 105A and the characteristics was examined. Table 13 shows the results. From this result, it was found that a photovoltaic element having high conversion efficiency with B atoms contained in the microcrystalline i-type semiconductor layer 105A of 8 ppm or less can be produced.

[0043]

Embodiment 8 A photovoltaic element (solar cell) having one pin junction as shown in FIG. 4 was produced. Specifically, a stainless SUS403BA substrate (10 × 10c
m ² , 0.2 mm thick) on the back electrode / transparent conductive layer Zn
O was first formed. Next, an n-type semiconductor layer is formed, and an a-Si: H layer / μc-Si is formed thereon as an i-type semiconductor layer.
Four layers of a layered structure were formed to form a p-type semiconductor layer. Thereafter, a transparent electrode ITO / a current collecting electrode was formed, and a solar cell was produced. Here, the back electrode was formed by a sputtering method, and the transparent conductive layer ZnO was formed by a sputtering method using an apparatus shown in FIG. The semiconductor layer is formed by an n layer, the p layer is formed by an RF plasma CVD method, the i layer is formed by a microwave plasma CVD method using a microwave plasma CVD apparatus shown in FIG. 8, and the transparent electrode is formed by a sputtering method. The collecting electrode was prepared by a vapor deposition method. Table 14 shows the conditions for forming the semiconductor layer. In the microwave plasma CVD apparatus shown in FIG. 8, reference numeral 401 denotes a deposition chamber, 402 denotes a substrate for film formation, 403 denotes a heater for heating a substrate, 404 denotes a butterfly valve, 405 denotes a microwave waveguide, 406 denotes an introduction window, and 407. Is a microwave introducing ceramic window, 408 is a bias rod, 409 is an RF power source, 410 is a plasma generation space, 411 is a shutter, 412 is a microwave, 413
Indicates an exhaust gas, 414 indicates an exhaust port, 415 indicates a source gas introduction pipe, and 416 indicates a source gas.

[0044]

Comparative Example 2 A photovoltaic element (solar cell) was produced in the same manner as in Example 8, except that the i-type semiconductor layer was formed only of a-Si: H. Table 15 shows the conditions for forming the semiconductor layer.

[0045]

[Evaluation] (1). Observation of the μc-Si layer of the i-type semiconductor layer of the photovoltaic device of Example 8 by a cross-sectional TEM photograph revealed that the layer had an average crystal grain size of 30 nm. The results are shown in Table 14. (2). For each of the photovoltaic device of Example 8 and the photovoltaic device of Comparative Example 2, initial characteristics (photoconductive characteristics,
Leak current, low illuminance open circuit voltage) were measured. When the photoelectric conversion efficiency, open-circuit voltage, and short-circuit photocurrent were measured using a solar simulator (AM 1.5, 100 mW / cm ² , surface temperature 25 ° C.), the photovoltaic element of Example 1 was 1.08 times each. , 1.14 times and 1.02 times. (3). A reliability test was performed on each of the photovoltaic device of Example 8 and the photovoltaic device of Comparative Example 2. That is, each of the photovoltaic elements is placed under high temperature and high humidity (temperature 90
(° C., humidity: 87%) in an environmental test box, taken out after 1200 hours, and measured for photoelectric conversion efficiency, open-circuit voltage, and short-circuit current in the same manner as in (2) above. The electromotive force elements are 1.08 each.
2 times, 1.03 times and 1.05 times better. (4). When a reverse bias of +1 V was applied to each of the photovoltaic device of Example 8 and the photovoltaic device of Comparative Example 2, the leak current of the photovoltaic device of Example 1 was 0.95 times smaller than that of Example 1. Was. From this, it was confirmed that the photovoltaic element of Example 1 has a small number of short circuits in the solar cell when the area is increased, and a good solar cell can be obtained. (5). Each of the photovoltaic elements of Example 8 and Comparative Example 2 was placed in an environmental test box capable of maintaining an arbitrary temperature from -10 ° C to + 90 ° C, and AM1.5, 100 at various temperatures.
The photovoltaic element was irradiated with light of mW / cm ² , and the photoelectric conversion efficiency, open-circuit voltage, and short-circuit current at that time were measured, and the temperature dependence was examined. The results are as shown in Table 16. The photovoltaic device of Example 8 had better characteristics in conversion efficiency, open-circuit voltage and short-circuit current at high temperature. Table 16
From the results of, for example, solar cells used in high-temperature areas such as tropical jungles and desert areas just below the equator,
Example 8 was found to be more desirable.

[0046]

Embodiment 9 Microcrystalline layer of i-type semiconductor layer (μc-Si layer)
A photovoltaic element (solar cell) was obtained in the same manner as in Example 8, except that 0.3 ppm of B ₂ H ₆ was added to the film forming gas of Example 1.
Table 17 shows the semiconductor layer formation conditions. In the present embodiment, the Fermi level approaches the vicinity of midgap, and the open circuit voltage can be increased. Although the amorphous layer of the i-type semiconductor layer is non-doped and weak n-type, holes move from the microcrystalline layer to the amorphous layer by forming a laminated structure with the microcrystalline layer doped with boron. Is also intrinsic, and it can be expected that the mobility of holes increases and the characteristics of the i-type semiconductor layer improve. When the distribution of B atoms in the depth direction in the microcrystalline layer was examined by SIMS, the distribution was almost constant.

[0047]

Comparative Example 3 A photovoltaic device (solar cell) was obtained in the same manner as in Example 9 except that B ₂ H ₆ was not added when the microcrystalline layer of the i-type semiconductor layer was formed. Table 18 shows the semiconductor layer formation conditions.

[0048]

[Evaluation] The photovoltaic elements of Example 9 and Comparative Example 3 were evaluated in the same manner as in Example 8 and Comparative Example 2, and the photovoltaic element of Example 9 was replaced with the photovoltaic element of Comparative Example 3. It turned out to be better. Further, in the same manner as in Example 9 and Comparative Example 3, the photovoltaic elements
When zero lot was prepared and the yield was evaluated based on the obtained photovoltaic elements, it was found that the yield of Example 9 was 20% larger than that of Comparative Example 3.

[0049]

Embodiment 10 Amorphous layer (a-Si layer) of i-type semiconductor layer
A photovoltaic element (solar cell) was obtained in the same manner as in Example 8, except that 0.3 ppm of VCl ₄ was added to the film-forming gas at the time of formation of. Table 19 shows the conditions for forming the semiconductor layer. Regarding the amorphous layer (a-Si layer) of the obtained photovoltaic element,
When the distribution of V atoms in the depth direction in the layer was examined by SIMS, the distribution was constant at 2 × 10E ¹⁶ / cm ³ .

[0050]

Comparative Example 4 When forming an amorphous layer of an i-type semiconductor layer, VCl _{4 was used.}
A photovoltaic element (solar cell) was obtained in the same manner as in Example 10, except that was not added. Table 2 shows the semiconductor layer formation conditions.
0 is shown.

[0051]

[Evaluation] The photovoltaic devices of Example 10 and Comparative Example 4 were evaluated in the same manner as in Example 8 and Comparative Example 2, and the photovoltaic device of Example 10 was replaced with the photovoltaic device of Comparative Example 4. It turned out to be better. Further, each of the photovoltaic elements of Example 10 and Comparative Example 4 was adjusted to pH
The photovoltaic element of Example 10 was superior to the photovoltaic element of Comparative Example 4 when it was immersed in an acidic water having a value of 4 and taken out after 2000 hours. I knew it was there. From these results, it is understood that the photovoltaic element (solar cell) of Example 10 has no problem of characteristic deterioration even when used for a long time under, for example, acid rain.

[0052]

Embodiment 11 In Embodiment 8, an amorphous layer (a-Si layer) is formed on an n-type semiconductor layer, and then a microcrystalline layer (μ
When forming a c-Si layer, a film forming gas (SiH ₄ +
H ( ₂ ) was added in the same manner as in Example 8 except that Bi (CH ₃ ) ₃ was added and the concentration was changed as shown in FIG. 9 as the microcrystalline layer was deposited. Solar cell). When the Bi concentration in the i-type semiconductor layer was examined by SIMS, it gradually increased from the microcrystalline layer / amorphous layer interface to the inside of the microcrystalline layer, and reached 2 × 10 ⁻⁷ atomic%. It was getting lower gradually. The obtained photovoltaic element is
Evaluation was made in the same manner as in Example 8 and Comparative Example 2, and it was found that the device was excellent as in the photovoltaic device of Example 8. Next, for the photovoltaic element,
In order to perform shunt passivation, the photovoltaic element was immersed in an acidic aqueous electrolyte solution and a negative voltage was applied. At this time, the pH was 4 and the voltage was 3V. By shunt passivation, a short-circuit portion between the transparent conductive layer of the photovoltaic element and the upper transparent electrode was removed. Observation of the portion from which the short-circuited portion was removed by shunt passivation with an optical microscope showed that only 0.64 pieces / cm ² were removed from the short-circuited portion. When the same shunt passivation treatment was applied to the photovoltaic device obtained in Comparative Example 2, the number of short-circuit removed portions was 1.1 / cm ² , and the photovoltaic device of Example 11 It was found that the one having less short-circuited portions was more suitable for increasing the area.

[0053]

Embodiment 12 In Embodiment 8, when forming an amorphous layer (a-Si layer) on an n-type semiconductor layer, a film forming gas (S
iH ₄ + H ₂ ), except that AsCl ₃ was added and its concentration was changed as shown in FIG. 10 as the amorphous layer was deposited, in the same manner as in Example 8 ) Got. When the As concentration in the i-type semiconductor layer was examined by SIMS, the As concentration was gradually increased in the inward direction of the amorphous layer from the interface between the microcrystalline layer / amorphous layer and reached 8 × 10 ⁻⁶ atomic%. , Was gradually getting lower. When the obtained photovoltaic device was evaluated in the same manner as in Example 8 and Comparative Example 2, it was found that the photovoltaic device was as excellent as the photovoltaic device of Example 8. Next, a shunt passivation test was performed on the photovoltaic device in the same manner as in Example 11;
As in the case of the photovoltaic element of No. 1, it was found that the short-circuit portion was small and the element was excellent. Further, from the results of the cross-sectional TEM photograph, it was found that the crystal grain size increased from the microcrystalline layer / amorphous layer interface to the inside of the microcrystalline layer. From this, the carrier mobility inside the microcrystalline layer was improved, and the short-circuit current was 1.1 times smaller than that of the photovoltaic element of Comparative Example 2 as measured by a solar simulator.
Had improved twice.

[0054]

Embodiment 13 In Embodiment 8, an amorphous layer (a-Si layer) is formed on an n-type semiconductor layer, and then a microcrystalline layer (μc-Si layer) is formed.
AsCl ₃ is added to the film forming gas (SiH ₄ + H ₂ ) during the formation of the amorphous layer in the cycle of forming the layer, and the concentration is changed as shown in FIG. 11 as the amorphous layer is deposited. A photovoltaic element (solar cell) was obtained in the same manner as in Example 8, except for the above. When the As concentration in the i-type semiconductor layer was examined by SIMS, the As concentration was gradually increased in the inward direction of the amorphous layer from the interface between the microcrystalline layer / amorphous layer and reached 7 × 10 ⁻⁶ atomic%. , Was gradually getting lower. When the obtained photovoltaic device was evaluated in the same manner as in Example 8 and Comparative Example 2, it was found that the photovoltaic device was as excellent as the photovoltaic device of Example 8. Then, a shunt passivation test was performed on the photovoltaic element in the same manner as in Example 11. The photovoltaic element was the same as the photovoltaic element of Example 11, with few short-circuit portions and excellent. It turned out to be. Further, from the results of the cross-sectional TEM photograph, it was found that the crystal grain size increased from the microcrystalline layer / amorphous layer interface to the inside of the microcrystalline layer. From this, the carrier mobility inside the microcrystalline layer was improved, and the short-circuit current was 1. compared with the photovoltaic element of Comparative Example 2 as measured by a solar simulator.
It was improved by a factor of one.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

[Table 3]

[0058]

[Table 4]

[0059]

[Table 5]

[0060]

[Table 6]

[0061]

[Table 7]

[0062]

[Table 8]

[0063]

[Table 9]

[0064]

[Table 10]

[0065]

[Table 11]

[0066]

[Table 12]

[0067]

[Table 13]

[0068]

[Table 14]

[0069]

[Table 15]

[0070]

[Table 16]

[0071]

[Table 17]

[0072]

[Table 18]

[0073]

[Table 19]

[0074]

[Table 20]

[0075]

[Table 21]

[0076]

As described above, the photovoltaic device (solar cell) of the present invention can be used for microcrystalline silicon (μc
-Si), an i-type semiconductor layer having a layered structure in which a layer made of the microcrystalline silicon and a layer made of amorphous silicon (a-Si) are alternately stacked to take advantage of its p-type.
Since it is used for an in-type semiconductor junction, it has particularly high carrier mobility and exhibits desired photoelectric conversion efficiency. Further, the photovoltaic element is lightweight, flexible, durable, and can stably generate power for a long period of time, and thus can be suitably used as a solar cell for power supply. In addition, the photovoltaic element can be easily increased in area, and can be manufactured relatively inexpensively.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a layer configuration of an example of a photovoltaic device of the present invention.

FIG. 2 is a schematic cross-sectional view showing a layer configuration of an example of the photovoltaic device of the present invention.

FIG. 3 is a schematic cross-sectional view showing a layer configuration of an example of the photovoltaic device of the present invention.

FIG. 4 is a schematic cross-sectional view illustrating a layer configuration of an example of the photovoltaic element of the present invention.

FIG. 5 is a schematic cross-sectional view showing a layer configuration of a photovoltaic element as a comparative example in which an i-type semiconductor layer is composed of only a microcrystalline layer.

FIG. 6 is a schematic explanatory view of a deposited film forming apparatus by a plasma CVD method.

FIG. 7 is a schematic explanatory view of a DC magnetron sputtering device.

FIG. 8 is a schematic explanatory view of a microwave plasma CVD apparatus.

FIG. 9 is a diagram showing a change in the flow rate of Bi (CH ₃ ) ₃ during film formation in Example 11.

FIG. 10 is a diagram showing a change in the flow rate of AsCl ₃ during film formation in Example 12.

FIG. 11 is a diagram showing a change in the flow rate of AsCl ₃ during film formation in Example 13.

[Explanation of symbols]

101 Substrate 102 Back electrode 103 Transparent conductive layer 104 Non-single-crystal n-type semiconductor layer 105 Non-single-crystal i-type semiconductor layer 105A Microcrystalline i-type semiconductor layer 105B, 105B-1, 105B-2 Amorphous i-type semiconductor layer 106 Non Single crystal p-type semiconductor layer 107 Transparent electrode 108 Current collecting electrode

Claims (16)

[Claims] 1. A photovoltaic device having a pin-type semiconductor junction formed by laminating a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer made of a silicon-based non-single-crystal semiconductor material, wherein The type semiconductor layer has a stacked structure in which a microcrystalline i-type semiconductor layer and an amorphous i-type semiconductor layer having a thickness smaller than the thickness of the microcrystalline i-type semiconductor layer are alternately stacked. A photovoltaic element characterized by the above-mentioned. 2. The laminated structure of the i-type semiconductor layer is a laminated structure in which the microcrystalline i-type semiconductor layer and the amorphous i-type semiconductor layer are alternately laminated, and the microcrystalline i-type semiconductor layer is Is 3
2. The photovoltaic device according to claim 1, wherein the thickness is from 00 nm to 5 μm, and the thickness of the amorphous i-type semiconductor layer is from 3.0 nm to 50 nm. 3. 3. The method according to claim 1, wherein the amorphous i-type semiconductor layer is formed of the microcrystalline i.
The photovoltaic element according to claim 2, wherein the photovoltaic element is arranged on the p-type semiconductor layer side with respect to the type semiconductor layer. 4. The method according to claim 1, wherein the amorphous i-type semiconductor layer is formed of the microcrystal i.
The photovoltaic device according to claim 2, wherein the photovoltaic element is disposed on the n-type semiconductor layer side with respect to the type semiconductor layer. 5. The laminated structure of the i-type semiconductor layer is a three-layer structure in which the amorphous i-type semiconductor layer, the microcrystalline i-type semiconductor layer, and the amorphous i-type semiconductor layer are laminated. And the total thickness of the two amorphous i-type semiconductor layers is 6.0.
The photovoltaic device according to claim 2, wherein the photovoltaic device has a thickness in a range of from about 80 nm to about 80 nm. 6. The photovoltaic device according to claim 2, wherein the optical bandgap of the amorphous i-type semiconductor layer is 1.7 eV or more. 7. The photovoltaic device according to claim 2, wherein the microcrystalline i-type semiconductor layer contains boron atoms in an amount of 8 ppm or less. 8. The laminated structure of the i-type semiconductor layer is 10n
the microcrystalline i-type semiconductor layer having a thickness of
2. The photovoltaic device according to claim 1, wherein the amorphous i-type semiconductor layer having a thickness of 5 nm to 5 nm is alternately and repeatedly laminated a plurality of times. 9. The photovoltaic device according to claim 1, wherein the microcrystalline i-type semiconductor layer has a crystal grain size in a range of 2 nm to 40 nm. 10. Each of the microcrystalline i-type semiconductor layers contains at least one atom from Group III and Group V atoms of the periodic table in the microcrystalline layer. 10. The photovoltaic device according to claim 8, wherein the concentration of the atoms is 1 × 10 ⁻⁵ atomic% or less. 11. Each of the amorphous i-type semiconductor layers contains at least one atom of Group III and Group V atoms of the periodic table in the amorphous layer. The photovoltaic device according to claim 8, wherein the concentration of the atoms in the layer is 1 × 10 ⁻⁵ atomic% or less. 12. The semiconductor device according to claim 1, wherein the i-type semiconductor layer is formed of at least one of a group III and a group III of the periodic table from at least one amorphous i-type semiconductor layer / microcrystalline i-type semiconductor layer interface to the microcrystalline i-type semiconductor layer. 9. The photovoltaic device according to claim 8, wherein at least one of group V atoms is contained in a concentration distribution in which the atomic concentration gradually increases. 13. The i-type semiconductor layer includes a group III and a group III of the periodic table from at least one amorphous i-type semiconductor layer / microcrystalline i-type semiconductor layer interface to the amorphous i-type semiconductor layer. 9. The photovoltaic device according to claim 8, wherein at least one of group V atoms is contained in a concentration distribution in which the atomic concentration gradually increases. 14. The photovoltaic device according to claim 8, wherein the thickness of each repeating unit composed of the microcrystalline i-type semiconductor layer and the amorphous i-type semiconductor layer is constant. 15. A concentration of at least one of Group III and V atoms of the periodic table contained in the microcrystalline i-type semiconductor layer, the concentration gradually increasing toward the inside of the i-type semiconductor layer. 2. A distribution having a distribution.
The photovoltaic element according to 0. 16. At least one of Group III and V atoms of the periodic table contained in the amorphous i-type semiconductor layer gradually increases toward the inside of the i-type semiconductor layer. 2. The method according to claim 1, wherein the material has a concentration distribution.
2. The photovoltaic device according to 1.