JP2915629B2 - Photovoltaic element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is constructed by laminating a non-single-crystal semiconductor material containing silicon atoms and a transparent electrode of an oxide such as indium oxide, tin oxide or indium-tin oxide. And a photovoltaic element such as a photovoltaic cell and a photosensor. In particular, the present invention relates to a material using an amorphous silicon-based semiconductor material (including a microcrystalline silicon-based semiconductor material) and a polycrystalline silicon-based semiconductor material as a non-single-crystal semiconductor material.

[0002]

2. Description of the Related Art Transparent electrodes are important components related to the performance of photovoltaic devices. Conventionally, such a transparent electrode uses indium oxide, tin oxide, and indium-tin oxide, and has been deposited in a film shape by a spray method, a vacuum deposition method, an ion plating method, a sputtering method, or the like.

[0003] The light transmittance and specific resistance of the transparent electrode thus deposited are parameters directly related to the performance of the photovoltaic element. Further conditions for depositing a transparent electrode,
For example, the substrate temperature, the degree of vacuum, the deposition rate, and the like are important parameters that affect the quality of the semiconductor layer film of the photovoltaic element adjacent to the transparent electrode. The relationship between recent photovoltaic devices and transparent electrodes is described in "Optical absorption of transparent conducting oxides and power dissipation in a-Si: H pin solar cells measured by photothermal deflection spectroscopy" F. Leblanc, J. Perrin et. al. Technical digest of the international PVSEC-5. Kyoto, Japan, 1990, 253. and "Improvement of interface properties of TCO / p-layer in pin-type amorphous silicon solar cells" Y. Ashida, N. Ishiguro et.al Technical digest of the international PVSEC-5. Considered in Kyoto, Japan, 1990,367.

As a method of reducing the resistance of a transparent electrode, a transparent electrode in which an indium oxide film and a tin oxide film are laminated is described in Japanese Patent Application Laid-Open No. 54-134396.

[0005]

The above-mentioned conventional photovoltaic element has excellent characteristics, but further improvement in characteristics is desired.

It is an object of the present invention to provide a photovoltaic device having more excellent characteristics than conventional photovoltaic devices. That is, an object of the present invention is to provide a photovoltaic device having a transparent electrode made of indium oxide, tin oxide, or indium-tin oxide, which has a lower resistance.

It is another object of the present invention to provide a photovoltaic device having a transparent electrode having a higher transmittance. Furthermore, as photovoltaic devices have become widely used in general, the usage environment of photovoltaic devices has also become diverse,
Depending on the use environment, there is a problem that a layer is peeled off between a transparent electrode and a layer that is in close contact with the transparent electrode. It is to provide a photovoltaic element having good properties.

In addition, another object of the present invention is to provide a photovoltaic element which is less likely to be short-circuited even after a long heat cycle. An object of the present invention is to provide a photovoltaic element in which the flexibility of a transparent electrode is improved and cracks are less likely to occur. It is an object of the present invention to provide a photovoltaic element in which a non-single-crystal silicon-based semiconductor layer deposited on a transparent electrode is reduced in an abnormal amount and a uniform non-single-crystal silicon-based semiconductor layer is deposited. It is another object of the present invention to provide a photovoltaic element having stable characteristics.

Another object of the present invention is to improve the yield in producing a photovoltaic element.

[0010]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems and achieve the object of the present invention, and have found that the following configuration is optimal. It is. The present invention provides at least a silicon substrate on a conductive substrate.
P-type composed of non-single-crystal semiconductor material containing silicon atoms
-Single-crystal silicon-based semiconductor including layers, i-type layers and n-type layers
A layer provided on the non-single-crystal silicon-based semiconductor layer.
Device with transparent electrode laminated on it
In the transparent electrode, 1 ppm or more and 100 ppm
With a conductive oxide containing an alkali metal with the following content
A photovoltaic element characterized by being formed
You. Furthermore, the present invention relates to a method for manufacturing a transparent
A p-type layer made of a non-single-crystal semiconductor material containing
A non-single-crystal silicon-based semiconductor layer including an i-type layer and an n-type layer
And a photovoltaic device on which a conductive layer is laminated.
In the power element, the transparent substrate and the non-single-crystal silicon
A transparent electrode is provided between and
And the transparent electrode is 1 ppm or more and 100 ppm or less.
Formed with conductive oxide containing alkali metal with the following content
The present invention relates to a photovoltaic element characterized by being formed.
Furthermore, the present invention relates to a method for producing the above photovoltaic element.
The sputtering using the target containing the alkali metal.
Using a tarring method or a deposition source containing the alkali metal
Photovoltaic forming the conductive oxide by vacuum evaporation method
The present invention relates to a method for manufacturing a force element.

[0011]

The operation of the photovoltaic element of the present invention will be described. FIG. 1 and FIG. 2 are schematic explanatory diagrams for explaining the layer configuration of the photovoltaic element of the present invention. The photovoltaic device of the present invention shown in FIG. 1 includes a conductive light reflecting layer 102, a reflection increasing layer 103, and an n-type (or p-type) non-single-crystal silicon-based semiconductor layer on an opaque conductive substrate 101. A first conductivity type layer 104, an i-type (substantially intrinsic) non-single-crystal silicon-based semiconductor layer 105, and a p-type (or n-type) non-single-crystal silicon-based semiconductor layer. The second conductivity type layer 106 is formed of an oxide, and a transparent electrode 107 containing an alkali metal in the oxide and a current collecting electrode 108 are sequentially laminated. Irradiation light 109 is applied to the photovoltaic element from the transparent electrode 107 side.

The photovoltaic element of the present invention shown in FIG. 2 has a tandem structure, and is composed of a current collecting electrode 208 and an oxide facing down a conductive substrate 201 which is a transparent substrate. Transparent electrode 20 containing an alkali metal
7, a conductive type layer 206b which is a p-type (or n-type) non-single-crystal silicon-based semiconductor layer, i-type (substantially intrin
sic) i-type layer 2 which is a non-single-crystal silicon-based semiconductor layer
05b, an n-type (or p-type) non-single-crystal silicon-based semiconductor layer 204b, and a p-type (or n-type) non-single-crystal silicon-based semiconductor layer 206a, i
I-type layer 205a which is a non-single-crystal (substantially intrinsic) silicon-based semiconductor layer, n-type (or p-type)
Conductive type layer 204 which is a non-single-crystal silicon-based semiconductor layer
a, a reflection increasing layer 203, a conductive light reflecting layer 202, and a conductive layer (or / and a protective layer) 210 are sequentially laminated.

Further, although not shown, a triple photovoltaic element in which three pin units are stacked is also a photovoltaic element suitable for the present invention. Next, the transparent electrode will be described. In the photovoltaic device of the present invention, tin oxide,
In the case of a transparent electrode containing an alkali metal in indium oxide or indium-tin oxide, the crystal grain size of the oxide constituting the transparent electrode increases, and the dispersion of the crystal grain size decreases. Furthermore, since the alkali metal acts on the transparent electrode as a dopant, the distortion of the transparent electrode can be reduced. With this, the specific resistance or series resistance of the transparent electrode can be reduced (lower resistance), and the transmittance of the transparent electrode can be improved.

[0014] In addition, by adding an alkali metal to the transparent electrode, the crystal form of the oxide constituting the transparent electrode can be made relatively smooth.
The surface properties of the transparent electrode can be improved, and the flexibility can be improved to prevent cracks. In particular, when the transparent electrode is deposited on the semiconductor layer, the adhesion between the semiconductor layer and the transparent electrode is greatly improved, and peeling can be prevented. Further, when a non-single-crystal silicon-based semiconductor layer is deposited on the transparent electrode, abnormal deposition of the non-single-crystal silicon-based semiconductor layer can be reduced, and a uniform non-single-crystal silicon-based semiconductor layer can be deposited. Can be. Therefore thin p
Even if a mold layer (or n-type layer) is deposited, it is possible to reduce electrical leakage during durability and prevent short circuit.
As a result, photovoltaic power and photocurrent can be increased,
Characteristics such as average photoelectric conversion efficiency and durability characteristics of the photovoltaic element are stabilized and improved. In addition, the yield when producing photovoltaic elements is improved.

Although the details of the transparent electrode used in the photovoltaic element of the present invention are unknown, the deposition temperature of the high-quality transparent electrode at the time of formation of the transparent electrode depends on the alkali metal involved in the crystal growth of the oxide. It is conceivable that the properties are lowered, and good quality characteristics can be obtained even at a relatively low temperature. For deposition of the transparent electrode used in the photovoltaic element of the present invention, a sputtering method or a vacuum deposition method is the most suitable deposition method.

As a sputtering apparatus suitable for depositing a transparent electrode used in the photovoltaic element of the present invention, there is a DC magnetron sputtering apparatus. FIG. 3 is a schematic explanatory view showing an example of an apparatus for producing a transparent electrode used for the photovoltaic element of the present invention, which shows a production apparatus (DC magnetron sputtering apparatus) using a DC magnetron sputtering method.

In FIG. 3, the target 304 is insulated from the deposition chamber 301 by an insulating support 305. In addition, the gas introduction valves 314 and 315 are connected to a gas cylinder such as an N ₂ / O ₂ gas or an unillustrated gas cylinder such as an argon (Ar) gas. In order for these gases to flow into the deposition chamber 301, first, the heater 30
3, the substrate 302 is heated to 350 ° C.
The inside is evacuated by a vacuum pump (not shown), and when the reading of the vacuum gauge 312 reaches a desired value, the gas introduction valve 31
4 and 315 are gradually opened, and each gas is supplied to the deposition chamber 30.
1 At this time, the mass flow controllers 316 and 317 adjust the flow rate of each gas to a desired value, and conductance while watching the vacuum gauge 312 so that the pressure in the deposition chamber 301 becomes a desired value. The opening of the valve (butterfly type) 313 is adjusted. Thereafter, the voltage of the DC power supply 306 is set, DC power is introduced to the target 304 to generate a DC glow discharge, and then the shutter 307 is opened to start production of a transparent electrode on the substrate 302, and When the electrode is manufactured, the shutter 307 is closed, the output of the DC power supply 306 is turned off, and the DC glow discharge is stopped. Next, gas introduction valve 3
15, the flow of Ar gas into the deposition chamber 301 is stopped, the opening of the conductance valve 313 is adjusted so that the pressure in the deposition chamber 301 becomes a desired value, and the transparent electrode is heat-treated for one hour. Then, the fabrication of the transparent electrode containing the alkali metal is completed.

In a DC magnetron sputtering apparatus, when a transparent electrode made of tin oxide used for the photovoltaic element of the present invention is deposited on a substrate, the target is metal tin (Sn), tin oxide (SnO ₂ ), or the like. A target containing an alkali metal, an oxide of an alkali metal, an alkali metal salt, or the like is used. When a transparent electrode made of indium oxide used for the photovoltaic device of the present invention is deposited on a substrate, the target is metal indium (I).
A target in which an alkali metal, an oxide of an alkali metal, or an alkali metal salt is contained in n) or indium oxide (In ₂ O ₃ ) is used. Furthermore, when a transparent electrode made of indium-tin oxide used for the photovoltaic device of the present invention is deposited on a substrate, the target is metal tin, metal indium or an alloy of metal tin and metal indium,
A target in which an alkali metal, an oxide of an alkali metal, or an alkali metal salt is added to tin oxide, indium oxide, indium-tin oxide, or the like is used in appropriate combination.

The transparent electrode used in the photovoltaic device of the present invention
Contained as an alkali metal suitable for the purpose of the present invention
Are lithium (Li), sodium (Na), potassium
(K). Addition of alkali metal to target
In addition to the metallic state,
Are lithium fluoride (LiF), lithium chloride (LiC)
l), lithium bromide (LiBr), lithium iodide (Li
I), lithium chlorate (LiCO_Three ), Lithium oxide
(Li_Two O), lithium peroxide (Li_Two O_Two ), Nitriding
Titanium (Li _Three N), methyl lithium (Li (CH
_Three )), Organic lithium and the like. With sodium
Is sodium fluoride (NaF), sodium hydrogen fluoride
(NaHF_Two ), Sodium chloride (NaCl), hypochlorite
Sodium citrate (NaClO), sodium chlorite
(NaClO_Two ), Sodium chlorate (NaClO)
_Three ), Sodium perchlorate (NaClO)_Four ), Nato bromide
Lithium (NaBr), sodium oxide (Na_Two O), charcoal
Sodium acid (Na_Two CO_Three ) And the like. Kariu
In potassium, potassium fluoride (KF), potassium hydrogen fluoride (K
HF_Two ), Potassium chloride (KCl), potassium chlorate
(KCLO_Three ), Potassium perchlorate (KClO)_Four ), Smell
Potassium oxide (KBr), potassium oxide (K_Two O), peracid
Potassium iodide (K_Two O_Two ), Potassium trioxide (K_Two O
_Three ), Potassium carbonate (K_Two CO_Three ) And the like.

The content of the alkali metal contained in the transparent electrode used in the photovoltaic device of the present invention is approximately 1 pp.
The preferred range is from m to 100 ppm. Further, the content of the alkali metal contained in the target to make the transparent electrode contain 1 ppm or more and 100 ppm or less of the alkali metal largely depends on the sputtering conditions, but it is generally 100 pp.
m is preferred.

When the transparent electrode used in the photovoltaic device of the present invention is deposited by a sputtering method, the substrate temperature is an important factor, and a preferable range is from 25 ° C. to 600 ° C. In particular, the transparent electrode used in the photovoltaic device of the present invention exhibits excellent characteristics at a low temperature of 25 ° C. to 250 ° C. as compared with the conventional technology. In addition, when a transparent electrode used in the photovoltaic device of the present invention is deposited with a sputtering property, argon gas (Ar), neon gas (Ne), xenon gas (X
e) and an inert gas such as helium gas (He), and particularly, Ar gas is the most suitable. It is preferable to add oxygen gas (O ₂ ) to the inert gas as needed. Particularly when a metal is targeted, oxygen gas (O ₂ ) is essential.

Further, when sputtering the target with the above-mentioned inert gas or the like, the pressure in the discharge space is 0.1 to 50 m in order to perform the sputtering effectively.
torr is mentioned as a preferable range. In addition, as a power supply in the case of the sputtering method, a DC power supply or a high-frequency power supply is suitable. A suitable range of the electric power during sputtering is 10 to 1000 W.

The formation speed of the transparent electrode used in the photovoltaic element of the present invention depends on the pressure in the discharge space and the discharge power, and the optimum formation speed is in the range of 0.1 to 100 ° / sec. In the photovoltaic device of the present invention, it is preferable that the layer thickness of the transparent electrode containing an alkali metal is formed so as to satisfy the conditions of the antireflection film. As a specific layer thickness of the transparent electrode, 500Å to 3000Å
Is a preferred range.

A second method suitable for forming the transparent electrode used in the photovoltaic element of the present invention is a vacuum deposition method. FIG. 5 is a schematic explanatory view showing an example of an apparatus for producing a transparent electrode used for the photovoltaic element of the present invention, which shows a production apparatus (vacuum vapor deposition apparatus) using a vacuum vapor deposition method. In FIG. 5, a gas introduction valve 510 is connected to a gas cylinder such as an O ₂ gas (not shown).

In order for the gas in the gas cylinder to flow into the deposition chamber 501, first, the substrate 5 is heated by the heater 503.
02 was heated to 350 ° C., and the inside of the deposition chamber 501 was evacuated by a vacuum pump (not shown). When the reading of the vacuum gauge 508 became a desired value, the gas introduction valve 510 was gradually opened to open the gas in the gas cylinder. Is caused to flow into the deposition chamber 501.
At this time, the gas flow rate is adjusted by the mass flow controller 511 so as to be a desired value, and the conductance valve (butterfly type) 509 is checked while watching the vacuum gauge 508 so that the pressure in the deposition chamber 501 becomes a desired value. Adjust the opening. Then, the heater 50 is supplied from the AC power supply 506.
5 to heat the vapor deposition source 504, and then open the shutter 507 to start producing a transparent electrode on the substrate 502. When the transparent electrode is produced, the shutter 50 is opened.
7, the output of the AC power supply 506 is turned off, the gas introduction valve 510 is closed, the flow of gas into the deposition chamber 501 is stopped, and the production of the transparent electrode containing an alkali metal is completed.

In the vacuum vapor deposition method, a vapor deposition source suitable for forming a transparent electrode used in the photovoltaic device of the present invention is metal tin, metal indium, or an indium-tin alloy to which the above-mentioned alkali metal-containing substance is added. Is mentioned. The content of the alkali metal is approximately 10
0 ppm or less is a suitable range. The substrate temperature when forming the transparent electrode used in the photovoltaic device of the present invention is in a range of 25 ° C to 600 ° C.

Further, when forming the transparent electrode used in the photovoltaic device of the present invention, the pressure of the deposition chamber is reduced to the order of 10 ⁻⁶ torr or less, and then oxygen gas (O ₂ ) is added to 5 × 10 ⁻⁵ torr.
It is necessary to introduce into the deposition chamber in the range of ９9 × 10 ⁻⁴ torr. By introducing oxygen in this range, the metal vaporized from the evaporation source reacts with oxygen in the gas phase to form a good transparent electrode.

The preferable range of the formation rate of the transparent electrode under the above conditions is 0.1 to 100 ° / sec.
When the forming rate is less than 0.1 ° / sec, the productivity is reduced, and when the forming rate is more than 100 ° / sec, the film becomes coarse,
The transmittance, conductivity and adhesion are reduced. Next, the conductivity type layer (p-type layer or n-type layer) will be described.

In the photovoltaic device of the present invention, the p-type layer or the n-type layer is an important layer that affects the characteristics of the photovoltaic device. Examples of the amorphous material (denoted as a-) of the p-type layer or the n-type layer of the photovoltaic device of the present invention (microcrystalline material (denoted as μc-) are also included in the category of the amorphous material). For example, a-Si: H, a-Si: HX, a-SiC: H,
a-SiC: HX, a-SiGe: H, a-SiGe
C: H, a-SiO: H, a-SiN: H, a-SiO
N: HX, a-SiOCN: HX, μc-Si: H, μ
c-SiC: H, μc-Si: HX, μc-SiC: H
X, μc-SiGe: H, μc-SiO: H, μc-S
iGeC: H, μc-SiN: H, μc-SiON: H
X, μc-SiOCN: HX, etc., a p-type valence electron controlling agent (Group III atoms B, Al, Ga, In, Tl in the periodic table)
And n-type valence electron control agents (Group V atoms P, As,
Sb, Bi) is added at a high concentration, and a polycrystalline material (denoted as Poly−) is, for example, p-type.
poly-Si: H, poly-Si: HX, poly-
SiC: H, poly-SiC: HX, poly-Si
Ge: H, poly-Si, poly-SiC, pol
p-type valence electron controlling agent (periodic table No. II)
Materials to which a group I atom B, Al, Ga, In, or Tl) or an n-type valence electron controlling agent (group V atom P, As, Sb, or Bi in the periodic table) is added at a high concentration.

In particular, the p-type layer or the n-type layer on the light incident side may be a crystalline semiconductor layer that absorbs less visible light or a-SiC: H, a-SiO:
An amorphous semiconductor layer such as H, a-SiN: H is suitable.
The optimum amount of addition of Group III atoms of the periodic table to the p-type layer and addition of Group V atoms of the periodic table to the n-type layer is 0.1 to 50 atomic%.

Further, 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 n
This improves the doping efficiency of the mold layer. The optimum amount of hydrogen atoms or halogen atoms added to the p-type layer or the n-type layer is 0.1 to 40 atomic%. In particular, when the p-type layer or the n-type layer is crystalline, the optimal amount of hydrogen atoms or halogen atoms is 0.1 to 8 atomic%. Further, those having a large content of hydrogen atoms and / or halogen atoms at each interface side of the p-type layer / i-type layer and the n-type layer / i-type layer are mentioned as a preferable distribution form. Is preferably 1.1 to 2 times the content in the bulk as the content of the hydrogen atom and / or the halogen atom. As described above, by increasing the content of hydrogen atoms or halogen atoms near each interface between the p-type layer / i-type layer and the n-type layer / i-type layer, the defect level and mechanical strain near the interface can be reduced. Thus, the photovoltaic power and the photocurrent of the photovoltaic device of the present invention can be increased.

The p-type layer and the n-type layer of the photovoltaic element of the present invention preferably have an activation energy of 0.2 eV or less, and most preferably have an activation energy of 0.1 eV or less. The specific resistance is preferably 100 Ωcm or less, and most preferably 1 Ωcm or less. Further, the thickness of the p-type layer and the n-type layer is preferably 10 to 500 °, and 30 to 1 °.
00Å is optimal.

The source gas suitable for depositing the p-type or n-type layer of the photovoltaic device of the present invention includes a gasizable compound containing silicon atoms, a gasizable compound containing germanium atoms, and a carbon atom. And the like, and a gaseous compound containing the compound, and a mixed gas of the compound. Specific examples of the gasizable compounds containing silicon atoms include SiH ₄ , SiH ₆ , SiF ₄ , and SiH ₄ .
FH ₃ , SiF ₂ H ₂ , SiF ₃ H, Si ₃ H ₈ , Si
_{D 4, SiHD 3, SiH 2} D 2, SiH 3 D, SiF
_{D 3, SiF 2 D 2,} SiD 3 H, Si 2 D 3 H 3, and the like.

Specific examples of the gasifiable compound containing a germanium atom include GeH ₄ , GeD ₄ , and GeF _4.
, GeFH ₃ , GeF ₂ H ₂ , GeF ₃ H, GeHD ₃
, GeH ₂ D ₂ , GeH ₃ D, GeH ₆ , GeD _{6 and the} like. The specific compounds which can be gasified contains carbon _{atoms, CH 4, CD 4, C} n H 2n + 2 (n is an integer), C _n H _{2n (n} is an _{integer), C 2 H 2, C} 6 H ₆ ,
CO ₂ , CO and the like can be mentioned.

As the nitrogen-containing gas, N ₂ , NH ₃ , N
D ₃ , NO, NO ₂ , and N ₂ O. O ₂ , CO, CO ₂ , NO, NO ₂ , N ₂
O, CH ₃ CH ₂ OH, CH ₃ OH and the like. In the present invention, 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.

In the present invention, an output for introducing a Group III atom is used.
Specific examples of substances that can be used effectively as
Is B for boron atom introduction._Two H₆ , B_Four H_Ten, B_Five 
H₉, B_Five H₁₁, B₆ H_Ten, B₆ H₁₂, B₆ H₁₄Etc water
Boron iodide, BF_Three , BCl_ThreeAnd other boron halides
Can be In addition, AlCl_Three , GaCl
_Three , InCl_Three , TlCl_Three And the like.
In particular, B_TwoH₆ , BF_ThreeIs suitable.

In the present invention, a starting material for introducing a group V atom is used.
To be effectively used as a substance, specifically,
You need PH_Three , P_Two H_Four Phosphorus hydride, PH_Four 
I, PF_Three , PF_Five , PCl_Three , PCl_Five , PBr_Three ,
PBr_Five , PI_Three And the like. this
In addition, AsH_Three , AsF_Three , AsCl_Three , AsBr_Three,
AsF_Five , SbH_Three , SbF_Three , SbF_Five , SbCl
_Three , SbCl_Five , BiH _Three , BiCl_Three , BiBr_Three etc
Can also be mentioned. In particular, PH_Three , PF_Three Suitable for
I have.

The p-type or n-type layer deposition method suitable for the photovoltaic device of the present invention is a high-frequency plasma CVD method or a microwave plasma CVD method. In particular, when depositing by a high-frequency plasma CVD method, a capacitively-coupled high-frequency plasma CVD method is suitable. When depositing a p-type layer or an n-type layer by the high frequency plasma CVD method, the substrate temperature in the deposition chamber is 100 to 350 ° C., the internal pressure is 0.1 to 10 torr,
The optimum conditions are a high frequency power of 0.05 to 1.0 W / cm ² and a deposition rate of 0.1 to 30 ° / sec.

The compound capable of being gasified is H ₂ , H
It may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the sediment. In particular, microcrystalline semiconductors and a-Si
C: a layer having a small light absorption or a wide band gap, such as H,
Alternatively, when a crystalline layer such as poly-Si: H or poly-Si: CH is deposited, it is preferable to dilute the source gas by 2 to 100 times with hydrogen gas and to introduce relatively high frequency power. It is preferred. As a high frequency, 1 MHz to 100 MHz is a suitable range,
In particular, a frequency near 13.56 MHz is optimal.

When a p-type layer or an n-type layer suitable for the present invention is deposited by a microwave plasma CVD method, the microwave plasma CVD apparatus uses a waveguide in a deposition chamber through a dielectric window (alumina ceramics or the like). The method of introducing microwaves is suitable. When a p-type layer or an n-type layer suitable for the present invention is deposited by microwave plasma CVD, the substrate temperature in the deposition chamber is 100 to 400 ° C., and the internal pressure is 0.5 to 30 m.
torr, microwave power is 0.01 to 1 W / cm
^{3. The} preferred range of the microwave frequency is 0.5 to 10 GHz.

The compound capable of being gasified is H ₂ , H
The gas may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the deposition chamber. In particular, microcrystalline semiconductors and a-Si
C: a layer having a small light absorption or a wide band gap, such as H,
Alternatively, when depositing a crystalline layer such as poly-Si: H, poly-Si: CH, the source gas is diluted 2 to 100 times with hydrogen gas, and a relatively high microwave power is introduced. Is preferred.

In addition, a preferable deposition rate in the case of the microwave plasma CVD method is 1 to 200 °. Next, the i-type layer will be described. In the photovoltaic device of the present invention, the i-type layer is an important layer that generates and transports carriers with respect to irradiation light.

As the i-type layer of the photovoltaic element of the present invention,
Only p-type and only n-type layers can be used. As the i-type layer of the photovoltaic device of the present invention, an amorphous material (a-
For example, a-Si: H, a-Si: H
X, a-SiC: H, a-SiC: HX, a-SiG
e: H, a-SiGe: HX, a-SiGeC: HX, and the like.

In particular, as the i-type layer, the above-mentioned amorphous material is added with a Group III atom and / or a Group V atom of the periodic table as a valence electron controlling agent to be made intrinsic (int).
rinsic) materials are mentioned as suitable. The hydrogen atoms (H, D) or the halogen atoms (X) contained in the i-type layer work to compensate for the dangling bonds of the i-type layer, and the product of the mobility of the carrier and the lifetime in the i-type layer is calculated. It is to improve. 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, thereby improving the photovoltaic power, photocurrent and photoresponsiveness of the photovoltaic element. It is something with. hydrogen atoms contained in the i-type layer or /
The optimum content of halogen atoms is 1 to 40 atomic%. In particular, p-type layer / i-type layer, n-type layer / i
A preferred distribution form includes a large distribution of hydrogen atoms and / or halogen atoms on each interface side of the mold layer. The content of hydrogen atoms and / or halogen atoms near the interface is within the bulk. 1.1 to 2 of the content of
A double range is mentioned as a preferred range.

The thickness of the i-type layer greatly depends on the structure of the photovoltaic element (for example, single cell, tandem cell, triple cell) and the band gap of the i-type layer.
1.0 μm is mentioned as the optimum layer thickness. In addition, it is preferable that the band gap of the i-type layer is designed to be wide at each interface side of the p-type layer / i-type layer and the n-type layer / i-type layer. By designing in this manner, the photovoltaic power and the photocurrent of the photovoltaic element can be increased, and furthermore, it is possible to prevent light deterioration or the like when used for a long time.

The source gas suitable for depositing the i-type layer of the photovoltaic device of the present invention includes a gasizable compound containing silicon atoms, a gasizable compound containing germanium atoms, and a gas containing carbon atoms. Compounds that can be
And a mixed gas of the compounds. Specific examples of the gasizable compounds containing silicon atoms include SiH ₄ , SiH ₆ , SiF ₄ , SiFH ₃ , and SiH ₄ .
F ₂ H ₂ , SiF ₃ H, Si ₃ H ₈ , SiD ₄ , SiH
D ₃ , SiH ₂ D ₂ , SiH ₃ D, SiFD ₃ , SiF
_{2 D 2, SiD 3 H,} Si 2 D 3 H 3, and the like.

Specific examples of the gasifiable compound containing a germanium atom include GeH ₄ , GeD ₄ and GeF _4.
, GeFH ₃ , GeF ₂ H ₂ , GeF ₃ H, GeHD ₃
, GeH ₂ D ₂ , GeH ₃ D, GeH ₆ , GeD _{6 and the} like. The specific compounds which can be gasified contains carbon _{atoms, CH 4, CD 4, C} n H 2n + 2 (n is an integer), C _n H _{2n (n} is an _{integer), C 2 H 2, C} 6 H _{6 and the} like.

In the present invention, the substance introduced into the i-type layer for controlling the valence electrons of the i-type layer includes the periodic table II.
Group I and Group V atoms are included. In the present invention, those which can be effectively used as a starting material for introducing a group III atom, specifically, those for introducing a boron atom include B ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B ₅ H _11, B ₅ H
_{10, B 6 H 12, B} 6 borohydride of H _14, etc., BF _3, BC
and boron halides such as l ₃ . In addition, AlCl ₃ , GaCl ₃ , InCl ₃ , Tl
Cl _{3 and the} like can also be mentioned.

In the present invention, a starting material for introducing a group V atom is used.
To be effectively used as a substance, specifically,
You need PH_Three , P_Two H_Four Phosphorus hydride, PH_Four 
I, PF_Three , PF_Five , PCl_Three , PCl_Five , PBr_Three ,
PBr_Five , PI_Three And the like. this
In addition, AsH_Three , AsF_Three , AsCl_Three , AsBr_Three,
AsF_Five , SbH_Three , SbF_Three , SbF_Five , SbCl
_Three , SbCl_Five , BiH _Three , BiCl_Three , BiBr_Three etc
Can also be mentioned.

The amount of Group III and Group V atoms introduced into the i-type layer for controlling the conductivity type is as follows:
1000 ppm or less is mentioned as a preferable range.
Examples of the method for depositing the i-type layer suitable for the present invention include a high-frequency plasma CVD method and a microwave plasma CVD method. In the case of the high frequency plasma CVD method, a capacitively coupled high frequency plasma CVD apparatus is particularly suitable.

When the i-type layer is deposited by the high frequency plasma CVD method, the substrate temperature in the deposition chamber is 100 to 350 ° C.
Internal pressure is 0.1-10 torr, high frequency power is 0.05
~ 1.0 W / cm ² , deposition rate is 0.1 ~ 30〜 / sec
c is mentioned as an optimal condition. 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 sediment.

In particular, when depositing a layer having a wide band gap such as a-SiC: H, it is preferable to dilute the source gas 2 to 100 times with hydrogen gas and to introduce a relatively high frequency power. It is. A high frequency of 1 MHz to 100 MHz is a suitable range, and a frequency near 13.56 MHz is particularly optimal. When an i-type layer suitable for the present invention is deposited by a microwave plasma CVD method, a microwave plasma CVD apparatus introduces a microwave into a deposition chamber through a waveguide through a dielectric window (alumina ceramics or the like). Is suitable.

When an i-type layer suitable for the present invention is deposited by microwave plasma CVD, the substrate temperature in the deposition chamber is 1
Preferred ranges are 00 to 400 ° C., an internal pressure of 0.5 to 30 mtorr, a microwave power of 0.01 to 1 W / cm ³ , and a microwave frequency of 0.5 to 10 GHz. Further, the compound capable of being gasified is H ₂ , He,
The gas may be appropriately diluted with a gas such as Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

In particular, when a layer having a wide band gap such as a-SiC: H is deposited, it is preferable to dilute the source gas by 2 to 100 times with hydrogen gas and to introduce a relatively high microwave power. It is. In addition, a preferable deposition rate for microwave plasma CVD is 1 to 200 °.

Next, the conductive substrate will be described. The conductive substrate may be a conductive material, or may be a substrate formed of an insulating material or a conductive material and subjected to conductive treatment. Examples of the conductive support include NiCr, stainless steel, Al, Cr, Mo, Au,
Metals such as Nb, Ta, V, Ti, Pt, Pb, Sn and the like, and alloys thereof are exemplified.

Examples of the electrically insulating support include films or sheets of synthetic resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, etc., glass, ceramics, and the like.
Paper etc. are mentioned. It is preferable that at least one surface of these electrically insulating supports is subjected to conductive treatment, and a photovoltaic layer is provided on the conductive-treated surface side.

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

[0058]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. (Example 1) A photovoltaic device of the present invention was manufactured by a DC magnetron sputtering method and a microwave glow discharge decomposition method.

First, a transparent electrode containing an alkali metal was formed on a substrate by a DC magnetron sputtering method manufacturing apparatus shown in FIG. The substrate 302 is 50 m
It is made of barium borosilicate glass having an m-square and a thickness of 1 mm (7059, manufactured by Corning Incorporated). The target 304 has a composition of 85: 15: 0.005 in molar ratio of indium (In), tin (Sn) and sodium (Na), and is insulated from the deposition chamber 301 by the insulating support 305.

The gas introduction valves 314 and 315 are respectively provided with an oxygen (O ₂ ) gas cylinder (not shown) and argon (Ar)
Connected to gas cylinder. First, the heater 30
3, the substrate 302 is heated to 350 ° C.
The inside is evacuated by a vacuum pump (not shown), and when the reading of the vacuum gauge 312 becomes about 1 × 10 ⁻⁵ torr, the gas introduction valves 314 and 315 are gradually opened to supply O ₂ gas and Ar gas to the deposition chamber. It flowed into 301. At this time, the respective mass flow controllers 316 and 316 are controlled so that the O ₂ gas flow rate is 20 sccm and the Ar gas flow rate is 20 sccm.
17, the opening of the conductance valve (butterfly type) 313 was adjusted while watching the vacuum gauge 312 so that the pressure in the deposition chamber 301 became 2 mtorr. Thereafter, the voltage of the DC power supply 306 is set to −400 V, DC power is introduced to the target 304 to generate a DC glow discharge, and then the shutter 307 is opened to open the substrate 30.
The production of the transparent electrode was started on No. 2, and when the transparent electrode having a layer thickness of 70 nm was produced, the shutter 307 was closed, the output of the DC power supply 306 was turned off, and the DC glow discharge was stopped. Next, the gas introduction valve 315 is closed to stop the flow of Ar gas into the deposition chamber 301, and the pressure in the deposition chamber 301 is reduced to 1 t.
The opening of the conductance valve 313 was adjusted so as to be orr, and the transparent electrode was heat-treated for 1 hour to complete the production of the transparent electrode containing an alkali metal.

Next, the raw material gas supply device 102 shown in FIG.
A non-single-crystal silicon-based semiconductor layer was formed on the transparent electrode by a manufacturing apparatus based on a microwave glow discharge decomposition method including a deposition apparatus 1000 and a deposition apparatus 1000. Gas cylinder 1071 in the figure
A raw material gas for manufacturing the non-single-crystal silicon-based semiconductor layer of the present invention is sealed in each of the gas cylinders 1 to 1076. Specifically, each is made of SiH ₄ gas (purity 9
9.999%) cylinder 1071, H ₂ gas (99.99% purity)
999%) cylinder 1072, B ₂ H ₆ gas (purity 99.99%, diluted to 10% with H ₂ gas, hereinafter referred to as “B ₂ H ₆
/ H ₂ ") cylinder 1073, 1 with H ₂ gas
PH ₃ gas (purity 99.99%, hereinafter abbreviated as “PH ₃ / H ₂ ”) cylinder diluted to 0%, CH ₄ gas (purity 99.9999%) cylinder 1074, and 1076 are Ge
The H ₄ gas (purity 99.99%) cylinder is 1075. In addition, gas cylinders 1071 to 107
When attaching 6, each gas is supplied to the valve 1051
From 1056, it is introduced into the gas piping of the inflow valves 1031 to 1036.

The substrate 1004 is transparent by the method described above.
An electrode was produced. First, the gas cylinder 1071
More SiH_Four H from gas and gas cylinder 1072_Two gas,
B from gas cylinder 1073_Two H₆/ H_Two Gas, gas bon
PH from BE 1074 _Three / H_Two Gas, gas cylinder 1075
More CH_Four GeH from gas and gas cylinder 1076_Four gas
Is introduced by opening valves 1051 to 1056,
Each gas pressure is adjusted to about 2 kg /
cm^Two Was adjusted.

Next, it is confirmed that the inflow valves 1031 to 1036 and the leak valve 1009 of the deposition chamber 1001 are closed.
After confirming that the auxiliary valve 1008 is opened, the conductance (butterfly type) valve 1007 is fully opened, and the inside of the deposition chamber 1001 and the gas pipe is evacuated by a vacuum pump (not shown). 1x1
When the pressure reached 0 ^-4 torr, the auxiliary valve 1008 and the outflow valves 1041 to 1046 were closed.

Next, the inflow valves 1031 to 1036 are gradually
Open each gas and use each mass flow controller 1
021 to 1026. Film formation as above
Is completed, a p-type layer, an i-type
A layer and an n-type layer were formed. To make a p-type layer,
Substrate 1004 is heated to 350 ° C. by heater 1005
Heat and gradually open outflow valves 1041 to 1043
And SiH_Four Gas, H_TwoGas, B_Two H₆ / H_Two Gas
Through the inlet pipe 1003 into the deposition chamber 1001.
Was. At this time, SiH_Four Gas flow rate 10 sccm, H_Two 
Gas flow rate 100sccm, B_Two H₆ / H_Two Gas flow
Each mass flow controller to be 5sccm
-1021 to 1023. In the deposition chamber 1001
Check the vacuum gauge 1006 so that the pressure becomes 20 mtorr.
While adjusting the opening of conductance valve 1007
Was. Then, the power of the microwave power supply (not shown) is increased by 400 m.
W / cm^Three And a waveguide (not shown) and a waveguide 1010
Through the dielectric window 1002 and into the deposition chamber 1001.
Microwave glow discharge caused by introduction of microwave power
To start the production of a p-type layer on the transparent electrode,
Stop microwave glow discharge when p-type layer is fabricated
Outflow valves 1041 to 1043 and auxiliary valve 1
008 is closed to stop the gas flow into the deposition chamber 1001.
Thus, the fabrication of the p-type layer was completed. Next, an i-type layer is formed.
The substrate 1004 by the heater 1005
Heat to 0 ° C. and drain valves 1041, 1042 and supplement
Open the auxiliary valve 1008 gradually and set the SiH_Four Gas, H_Two 
Gas is introduced into the deposition chamber 1001 through the gas introduction pipe 1003.
Let in. At this time, SiH_Four Gas flow is 100sc
cm, H _Two Each so that the gas flow rate is 200 sccm
Adjusted by mass flow controllers 1021 and 1022
did. The pressure in the deposition chamber 1001 becomes 5 mtorr
While watching the vacuum gauge 1006
The opening of 1007 was adjusted. Next, the high frequency of the bias power supply
Wave bias of 100 mW / cm^Three Substrate, DC bias
Set 75V to 1004 and set the bias rod 1012
Was applied. Then, the power of the microwave power supply (not shown) is
100mW / cm^Three And the waveguide and waveguide (not shown)
1010 and the deposition chamber 100 through the dielectric window 1002.
Microwave glow discharge by introducing microwave power into 1
And the production of an i-type layer on the p-type layer is started, and a layer thickness of 4
Microwave glow was performed when an i-type layer of
Stop discharging, turn off the output of the bias power supply 1011,
Preparation of the layer was completed.

In order to form an n-type layer, the substrate 1004 is added.
Heated to 300 ° C by heat heater 1005,
Grab 1044 is gradually opened and SiH_Four Gas, H_Two gas,
PH _Three / H_Two Gas is deposited through a gas introduction pipe 1003 in a deposition chamber.
1001. At this time, SiH_Four Gas flow
Is 30 sccm, H_Two Gas flow rate 100 sccm, PH
_Three / H_Two Each mass was adjusted so that the gas flow rate became 6 sccm.
With flow controllers 1021, 1022, 1024
It was adjusted. The pressure in the deposition chamber 1001 is 10 mtorr
Conductance while looking at the vacuum gauge 1006 so that
The opening of the valve 1007 was adjusted. After that,
Power of microwave power supply is 50mW / cm^ThreeSet to
The waveguide, waveguide section 1010 and dielectric window 1002 shown in FIG.
Microwave power is introduced into the deposition chamber 1001 through the
A microwave glow discharge is generated to form an n-type layer on the i-type layer.
Was started, and an n-type layer having a layer thickness of 10 nm was produced.
The microwave glow discharge is stopped, and the outflow valves 1041, 1
042, 1044 and the auxiliary valve 1008 are closed,
Stop the gas flow into the deposition chamber 1001 and create an n-type layer.
finished.

When producing each layer, it goes without saying that the outflow valves 1041 to 1046 other than the necessary gas are completely closed, and the respective gases are discharged into the deposition chamber 1001 and outflow valve 1041. Outflow valves 1041 to 1046 are closed, auxiliary valve 1008 is opened, and conductance valve 100
7 was fully opened, and the operation of once evacuating the system to a high vacuum was performed as needed.

Next, on the n-type layer, Al was used as a back electrode.
Was vapor-deposited by 2 μm to produce a photovoltaic device (designated as device No. 1). Table 1 shows the conditions for manufacturing the above photovoltaic element.

[0068]

[Table 1] (Comparative Example 1) A conventional photovoltaic element was manufactured in the same manner as in Example 1. First, a transparent electrode was formed on a substrate using a target having a composition different from that of Example 1 by a DC magnetron sputtering method manufacturing apparatus shown in FIG.

The target 308 has a composition of 85:15 in molar ratio of indium (In) and tin (Sn), and is insulated from the deposition chamber 301 by the insulating support 309. In the same manner as in Example 1, the substrate 302 was heated to 350 ° C., and O ₂ gas and argon gas were introduced into the deposition chamber 301 at 20 sccm, and the pressure in the deposition chamber 301 was adjusted to 2 mtorr. Then, the DC power supply 310
Is set to −400 V, and D
C power is introduced to generate a DC glow discharge, and then the shutter 311 is opened to start production of a transparent electrode on the substrate 302. When a transparent electrode having a layer thickness of 70 nm is produced, the shutter 311 is closed. The output of the power supply 310 was turned off to stop DC glow discharge. Next, gas introduction valve 3
15 is closed, the flow of Ar gas into the deposition chamber 301 is stopped, and the pressure in the deposition chamber 301 becomes 1 torr.
The opening of the conductance valve 313 was adjusted, and the transparent electrode was heat-treated for one hour to complete the production of the transparent electrode.

Next, a p-type layer, an i-type layer, an n-type layer and a back electrode were formed on the transparent electrode under the same manufacturing conditions as in Example 1 to manufacture a photovoltaic element (element No. ratio). 1). The initial characteristics and durability characteristics of the photovoltaic elements manufactured in Example 1 (element No. 1) and Comparative Example 1 (element No. ratio 1) were measured. The initial characteristics were measured by measuring the photovoltaic elements manufactured in Example 1 (element No. 1) and Comparative Example 1 (element No. ratio 1) by AM-1.5 (100).
mW / cm ² ) The sample was installed under light irradiation, and the measurement was performed by using a short-circuit current and a series resistance obtained by measuring VI characteristics. As a result of the measurement, Comparative Example 1 (element No. ratio 1)
Example 1 (element No. 1) for the photovoltaic element of
The photovoltaic element of No. 1 was excellent in short circuit current by 1.03 times and in series resistance by 1.3 times.

The measurement of the durability characteristics was performed in the same manner as in Example 1 (element no.
The photovoltaic elements fabricated in Example 1) and Comparative Example 1 (element No. ratio 1) were left in a dark place with a humidity of 85%, and the temperature was 85 ° C.
Heat cycle for 4 hours and -40 ° C for 30 minutes
The measurement was performed based on the change in photoelectric conversion efficiency after 0 times. As a result of the measurement, the photovoltaic element of Example 1 (element No. 1) exhibited a decrease in photoelectric conversion efficiency of 1.07 times that of the photovoltaic element of comparative example 1 (element No. ratio 1). It was excellent.

From the above measurement results, the photovoltaic device using the transparent electrode containing the alkali metal of the present invention (device N
o. Actual 1) is a conventional photovoltaic element (element number ratio 1).
It turned out to have excellent characteristics. (Example 2) A transparent electrode, a p-type layer, an i-type layer, an n-type layer, a transparent electrode, a p-type layer, an n-type layer, A photovoltaic device having a back electrode was prepared (device No. 2-1).
To 9).

The manufactured photovoltaic element (element No. 2-
1 to 9) were measured for initial characteristics and durability characteristics in the same manner as in Example 1. Table 2 shows the results. As can be seen from Table 2, the photovoltaic devices using the transparent electrode containing the alkali metal of the present invention (device Nos. 2-1 to 9) are different from the conventional photovoltaic devices (device No. ratio 1). On the other hand, it turned out to have excellent characteristics.

[0074]

[Table 2] (Example 3) A photovoltaic element of the present invention was manufactured in the same manner as in Example 1. First, a transparent electrode containing an alkali metal non-uniformly in a layer thickness direction was formed on a substrate by a DC magnetron sputtering method manufacturing apparatus shown in FIG.

The target 304 has a composition of 85: 15: 0.005 in molar ratio of indium (In), tin (Sn) and sodium (Na).
Was 85:15 in molar ratio of indium (In) and tin (Sn). As in the first embodiment, the substrate 30
2 was heated to 350 ° C., and O ₂ gas was
0 sccm and 20 sccm of argon gas were introduced, and the pressure in the deposition chamber 301 was adjusted to 2 mtorr. Thereafter, the voltage of the DC power supply 306 is set to −400 V, DC power is introduced to the target 304, and the voltage of the DC power supply 310 is set to −350 V to set the target 30.
8, power is introduced to cause a DC glow discharge, and then
The shutters 307 and 311 are opened to start production of a transparent electrode on the substrate 302, and at the same time, the voltage of the DC power supply 310 is gradually increased at a constant rate from -350V to -450V.
Then, the voltage was changed from -450 V to -350 V, and a transparent electrode having a layer thickness of 70 nm was formed.
7 and 311 were closed, the outputs of the DC power supplies 306 and 310 were turned off, and the DC glow discharge was stopped. Next, the gas introduction valve 315 is closed, the flow of Ar gas into the deposition chamber 301 is stopped, and the opening of the conductance valve 313 is adjusted so that the pressure in the deposition chamber 301 becomes 1 torr.
The transparent electrode was heat-treated for 1 hour to complete the production of the transparent electrode containing the alkali metal in the layer thickness direction non-uniformly.

Next, a p-type layer, an i-type layer, an n-type layer, and a back electrode were formed on the transparent electrode under the same manufacturing conditions as in Example 1 to manufacture a photovoltaic element (element No. 3). The manufactured photovoltaic element (element No. 3) was measured for initial characteristics and durability characteristics in the same manner as in Example 1. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 3 (element No. 3) was 1.05 times as large as that of the photovoltaic element of comparative example 1 (element No. ratio 1). The resistance is 1.
The photovoltaic element (element No. 3) using the transparent electrode containing the alkali metal of the present invention (element No. 3) is 4 times better and has a durability property of 1.08 times better.
o. It was found that the composition had excellent characteristics with respect to the ratio 1).

Example 4 A transparent electrode and an n-type layer were formed on a substrate under the same manufacturing conditions as in Example 3 except that the n-type layer, the i-type layer, and the p-type layer were formed as shown in Table 3. , An i-type layer, a p-type layer, and a back electrode were fabricated to fabricate a photovoltaic device (designated as device No. 4).

[0078]

[Table 3] Comparative Example 2 A transparent electrode, an n-type layer, an i-type layer, and a p-type layer were formed on a substrate under the same manufacturing conditions as in Example 4 except that a transparent electrode was formed on the substrate under the same manufacturing conditions as Comparative Example 1. A mold layer and a back electrode were prepared to produce a photovoltaic element (designated as element No. ratio 2).

The initial characteristics and the durability characteristics of the photovoltaic elements manufactured in Example 4 (element No. 4) and Comparative Example 2 (element No. ratio 2) were measured in the same manner as in Example 1. Done. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 4 (element No. actual 4) was 1.03 times as large as that of the photovoltaic element of comparative example 2 (element No. ratio 2), The resistance is 1.25 times better and the durability is 1.07 times better.
The photovoltaic element using the transparent electrode containing an alkali metal of the present invention (element No. 4) has superior characteristics to the conventional photovoltaic element (element No. ratio 2). found.

Example 5 Under the same manufacturing conditions as in Example 3,
A transparent electrode containing an alkali metal in a layer thickness direction non-uniformly was formed on a substrate, and a p-type layer and an i-type were formed on the transparent electrode using CH ₄ gas and GeH ₄ gas under the manufacturing conditions shown in Table 4. Layer, n
After forming a p-type layer, a p-type layer, an i-type layer, and an n-type layer, a ZnO thin film is deposited on the n-type layer as a reflection increasing layer by a DC magnetron sputtering method to a thickness of 1 μm. A 300 nm silver thin film was deposited by a sputtering method, and a back electrode was formed on the silver thin film in the same manner as in Example 3 to prepare a photovoltaic element (indicated as Element No. 5).

[0081]

[Table 4] (Comparative Example 3) A transparent electrode, a p-type layer, an i-type layer, and an n-type were formed on a substrate under the same manufacturing conditions as in Example 5 except that a transparent electrode was formed on the substrate under the same manufacturing conditions as Comparative Example 1. Layer, p-type layer, i
A photovoltaic element was produced by producing a mold layer, an n-type layer, a reflection increasing layer, a light reflection layer, and a back electrode (designated as element number ratio 3).

The initial characteristics and the durability characteristics of the photovoltaic elements produced in Example 5 (element No. 5) and Comparative Example 3 (element No. ratio 3) were measured in the same manner as in Example 1. Done. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 5 (element No. 5) was 1.04 times as large as that of the photovoltaic element of comparative example 3 (element No. ratio 3), The resistance is 1.32 times better and the durability is 1.08 times better.
The photovoltaic element using the transparent electrode containing an alkali metal of the present invention (element No. 5) has superior characteristics to the conventional photovoltaic element (element No. ratio 3). found.

Example 6 A photovoltaic device of the present invention was manufactured by a vacuum evaporation method and a microwave glow discharge decomposition method. First, the manufacturing apparatus of the vacuum evaporation method shown in FIG.
A transparent electrode containing an alkali metal was formed on a substrate.

The substrate 502 is made of barium borosilicate glass (7059, manufactured by Corning Incorporated) of 50 mm square and 1 mm thick.
It is made. The evaporation source 504 has a composition of indium (I
n), tin (Sn) and sodium (Na) in a molar ratio of 50: 50: 0.005. The gas introduction valve 510 is connected to an O ₂ gas cylinder (not shown).

First, the substrate 50 is heated by the heater 503.
2 was heated to 350 ° C., and the inside of the deposition chamber 501 was evacuated by a vacuum pump (not shown).
^When the pressure reached ^-5 torr, the gas introduction valve 510 was gradually opened to allow the O ₂ gas to flow into the deposition chamber 501. At this time, the mass flow controller 511 adjusts the flow rate of the O ₂ gas to 10 sccm, and
Vacuum gauge 50 so that the internal pressure becomes 0.3 mtorr.
While watching 8, conductance valve (butterfly type) 5
09 opening was adjusted. After that, power is supplied from the AC power supply 506 to the heater 505 to heat the evaporation source 504, and then the shutter 507 is opened to start production of a transparent electrode on the substrate 502. After manufacturing, the shutter 507 is closed and the AC power supply 50 is closed.
6, the gas introduction valve 510 was closed, the flow of gas into the deposition chamber 501 was stopped, and the production of the transparent electrode containing an alkali metal was completed.

Next, a p-type layer, an i-type layer, an n-type layer, and a back electrode were formed on the transparent electrode under the same manufacturing conditions as in Example 1 to manufacture a photovoltaic element (element No. 6). Comparative Example 4 A conventional photovoltaic element was manufactured in the same manner as in Example 6. The evaporation source 5 whose composition is 50:50 in molar ratio of indium (In) and tin (Sn).
A transparent electrode was manufactured under the same manufacturing conditions as in Example 6, except that the p-type layer, the i-type layer, and the n-type layer were formed on the transparent electrode under the same manufacturing conditions as in Example 1. A back electrode was fabricated to produce a photovoltaic device (designated as device No. ratio 4).

The initial characteristics and the durability characteristics of the photovoltaic elements produced in Example 6 (element No. 6) and Comparative Example 4 (element No. ratio 4) were measured in the same manner as in Example 1. Done. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 6 (element No. 6) was 1.03 times that of the photovoltaic element of comparative example 4 (element No. ratio 4), 1.33 times better resistance and 1.06 times better durability.
The photovoltaic element using the transparent electrode containing an alkali metal of the present invention (element No. 6) has superior characteristics to the conventional photovoltaic element (element No. ratio 4). found.

(Example 7) A conductive substrate made of stainless steel (SUS430BA) of 50 mm square and 1 mm thick and having a mirror-finished surface was used, and a light was applied on the conductive substrate by DC magnetron sputtering. 300 nm silver thin film as reflection layer, 1 μm ZnO thin film as reflection enhancement layer
m was deposited. Next, an n-type layer, an i-type layer, and a p-type layer were formed on the conductive substrate under the manufacturing conditions shown in Table 5. further,
A transparent electrode was formed on the p-type layer under the same conditions as in Example 6 except that the substrate temperature was set to 200 ° C., and Al was deposited as a current collecting electrode on the transparent electrode by vacuum evaporation to a thickness of 2 μm. A photovoltaic device was produced (designated as device No. 7).

[0089]

[Table 5] (Comparative Example 5) Under the same manufacturing conditions as in Example 7, a light reflecting layer, a reflection increasing layer, an n-type layer, an i-type layer, and a p-type layer were formed on a conductive substrate. A transparent electrode was formed on the p-type layer under the same conditions as in Comparative Example 4 except that the above conditions were used. Further, as in Example 7, a current collecting electrode was formed to prepare a photovoltaic element (element No. . Ratio 5).

The initial characteristics and the durability characteristics of the photovoltaic devices manufactured in Example 7 (element No. 7) and Comparative Example 5 (element No. ratio 5) were measured in the same manner as in Example 1. Done. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 7 (element No. actual 7) was 1.04 times larger than that of the comparative example 5 (element No. ratio 5), The resistance is 1.34 times better and the durability is 1.08 times better.
The photovoltaic element using the transparent electrode containing an alkali metal of the present invention (element No. 7) has superior characteristics to the conventional photovoltaic element (element No. ratio 5). found.

Example 8 A photovoltaic device of the present invention was manufactured by a DC magnetron sputtering method and a high-frequency glow discharge decomposition method. First, a transparent electrode containing an alkali metal was produced on a substrate under the same production conditions as in Example 1.

Next, the source gas supply device 102 shown in FIG.
A non-single-crystal silicon-based semiconductor layer was formed on the transparent electrode by a manufacturing apparatus including a high-frequency glow discharge decomposition method and a deposition apparatus 1100. The substrate 1104 is a substrate on which the above-described transparent electrode is manufactured. In the figure, gas cylinder 1071
The same source gas as in Example 1 is sealed in each of the gas cylinders of Nos. 1 to 1076, and each gas is supplied to the mass flow controllers 1021 to 1026 by the same operation procedure as in Example 1.
Introduced within.

After the preparation for the film formation was completed as described above, a p-type layer, an i-type layer, and an n-type layer were formed on the substrate 1104. In order to form a p-type layer, the substrate 1104 is heated to 300 ° C. by the heater 1105, and the outflow valves 1041 to 1043 and the auxiliary valve 1108 are gradually opened, and the SiH ₄ gas, the H ₂ gas, and the B ₂ H ₆ / H ₂ gas was introduced into the deposition chamber 1101 through the gas introduction pipe 1103. At this time, the flow rate of the SiH ₄ gas is 2 sccm,
The mass flow controllers 1021 to 1023 adjusted the H ₂ gas flow rate to 50 sccm and the B ₂ H ₆ / H ₂ gas flow rate to 1 sccm. The opening of the conductance valve 1107 was adjusted while watching the vacuum gauge 1106 so that the pressure in the deposition chamber 1101 became 1 torr. After that, the high frequency power source power (not shown) was increased to 200 mW / c.
m ³ , high-frequency power was introduced into the cathode 1102 through the high-frequency matching box 1112, high-frequency glow discharge was generated, and the formation of a p-type layer on the transparent electrode was started to form a p-type layer having a thickness of 5 nm. By the way, the high-frequency glow discharge was stopped, the outflow valves 1041 to 1043 and the auxiliary valve 1108 were closed, the flow of gas into the deposition chamber 1101 was stopped, and the production of the p-type layer was completed.

Next, in order to produce an i-type layer, the substrate 110
4 was heated to 300 ° C. by the heater 1105, and the outflow valves 1041, 1042 and the auxiliary valve 1108 were heated.
Was gradually opened, and SiH ₄ gas and H ₂ gas were caused to flow into the deposition chamber 1101 through the gas introduction pipe 1103. At this time, the mass flow controllers 1021 and 1022 adjusted the flow rates of the SiH ₄ gas to ₂ sccm and the flow rate of the H ₂ gas to 20 sccm. The opening of the conductance valve 1107 was adjusted while watching the vacuum gauge 1106 so that the pressure in the deposition chamber 1101 became 1 torr. Thereafter, the power of a high-frequency power supply (not shown) was increased to 5 mW / cm.
Set to ³ , high-frequency power is introduced into the cathode 1102 through the high-frequency matching box 1112 to generate a high-frequency glow discharge, and start manufacturing an i-type layer on the p-type layer.
When the i-type layer having a thickness of 400 nm was produced, the high-frequency glow discharge was stopped, and the production of the i-type layer was completed.

Next, in order to form an n-type layer, the substrate 110
4 was heated to 250 ° C. by a heater 1105, and the outflow valve 1044 was gradually opened, so that SiH ₄ gas, H ₂
Gas and B ₂ H ₆ / H ₂ gas were caused to flow into the deposition chamber 1101 through the gas introduction pipe 1103. At this time, SiH ₄
Gas flow rate ₂ sccm, H ₂ gas flow rate 20 sccm,
Each of the mass flow controllers 1021, 1022, and 102 is controlled such that the flow rate of the B ₂ H ₆ / H ₂ gas is 1 sccm.
Adjusted at 24. The pressure in the deposition chamber 1101 is 1 torr
The opening of the conductance valve 1107 was adjusted while watching the vacuum gauge 1106 so as to obtain r. Thereafter, the power of the high-frequency power supply is set to 5 mW / cm ³ (not shown), high-frequency power is introduced into the cathode 1102 through the high-frequency matching box 1112, and a high-frequency glow discharge is generated.
Production of an n-type layer was started on the mold layer, and when an n-type layer having a layer thickness of 10 nm was produced, high-frequency glow discharge was stopped, and outflow valves 1041, 1042, 1044 and auxiliary valve 11 were formed.
08, to stop the gas flow into the deposition chamber 1101,
The fabrication of the n-type layer was completed.

When forming each layer, it goes without saying that the outflow valves 1041 to 1046 other than the necessary gas are completely closed, and the respective gases are discharged into the deposition chamber 1101 and outflow valve 1041. Outflow valves 1041 to 1046 are closed, auxiliary valve 1108 is opened, and further conductance valve 1107
Was fully opened, and an operation of once evacuating the system to a high vacuum was performed as needed.

Next, a back electrode was deposited on the n-type layer in the same manner as in Example 1 to fabricate a photovoltaic element (designated as element No. 8). Are shown in Table 6.

[0098]

[Table 6] (Comparative Example 6) Except for using the same transparent electrode as Comparative Example 1,
Under the same fabrication conditions as in Example 8, a p-type layer, i
A photovoltaic element was produced by producing a mold layer, an n-type layer and a back electrode (designated as element number ratio 6).

The initial characteristics and the durability characteristics of the photovoltaic elements manufactured in Example 8 (element No. 8) and Comparative Example 6 (element No. ratio 6) were measured in the same manner as in Example 1. Done. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 8 (element No. actual 8) was 1.04 times larger than that of the photovoltaic element of comparative example 6 (element ratio No. 6), and the series The resistance is 1.27 times better, the durability is 1.07 times better,
The photovoltaic element using the transparent electrode containing the alkali metal of the present invention (element No. 8) has superior characteristics to the conventional photovoltaic element (element No. ratio 6). found.

Example 9 In the same manner as in Example 7 and Comparative Example 5, 100 photovoltaic elements were manufactured. Abnormal deposition, delamination and cracking of the photovoltaic element were measured with an optical microscope (Versmet-2, Union).
Was observed at a magnification of 50 to 500 times. The yield of the photovoltaic element was determined by measuring current and voltage.

In the photovoltaic device of the present invention, abnormal deposition, delamination and cracking were each reduced by 10% as compared with the comparative example. The yield of the photovoltaic device of the present invention was improved by 3% as compared with the comparative example.

[0102]

According to the photovoltaic device of the present invention comprising a non-single-crystal silicon-based semiconductor layer having a transparent electrode containing an alkali metal, the series resistance related to the transparent electrode is reduced and the transmittance is increased. In addition, the adhesion between the semiconductor layer and the transparent electrode was improved, the leakage during durability was reduced, and the durability characteristics of the photovoltaic element were improved.

Further, when a photovoltaic element comprising a non-single-crystal silicon-based semiconductor layer having a transparent electrode containing an alkali metal is deposited on a flexible substrate, the photovoltaic element can be formed even when the substrate is distorted. Cracks of the power element do not occur.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram for explaining a layer configuration of a photovoltaic element of the present invention.

FIG. 2 is a schematic configuration diagram for explaining a layer configuration of a photovoltaic device of the present invention.

FIG. 3 is a schematic explanatory view showing an example of an apparatus for manufacturing a transparent electrode used for a photovoltaic element of the present invention, which is a manufacturing apparatus using a DC magnetron sputtering method.

FIG. 4 is a schematic explanatory view showing an example of an apparatus for manufacturing a non-single-crystal silicon-based semiconductor layer used for a photovoltaic element of the present invention, showing a manufacturing apparatus by a glow discharge method using microwaves.

FIG. 5 is a schematic explanatory view showing an example of an apparatus for producing a transparent electrode used for a photovoltaic element of the present invention, showing a production apparatus by a vacuum evaporation method.

FIG. 6 is a schematic explanatory view showing an example of an apparatus for manufacturing a non-single-crystal silicon-based semiconductor layer used for a photovoltaic element of the present invention, which shows a manufacturing apparatus by a glow discharge method using a high frequency.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 Conductive substrate 102 Light reflective layer (conductive) 103 Reflection increasing layer 104 Conductive type layer (n-type or p-type) 105 i-type layer 106 Conductive type layer (p-type or n-type) 107 Transparent electrode 108 Current collecting electrode 109 Irradiation light 201 Conductive substrate 202 Light reflective layer (conductive) 203 Reflection increasing layer 204a, 204b Conductive type layer (n-type or p-type) 205a, 205bi i-type layer 206a, 206b Conductive type layer (p-type or n-type) 207 Transparent electrode 208 Current collecting electrode 209 Irradiation light 210 Conductive layer (or / and protective layer) 301 Deposition chamber 302 Substrate 303 Heater 304, 308 Target 305, 309 Insulating support 306, 310 DC power supply 307, 311 Shutter 312 Vacuum Total 313 Conductance valve 314, 315 Gas introduction valve 316, 3 17 Mass flow controller 501 Deposition chamber 502 Substrate 503 Heating heater 504 Evaporation source 505 Heating heater 506 AC power supply 507 Shutter 508 Vacuum gauge 509 Conductance valve 510 Gas introduction valve 511 Mass flow controller 1000 Deposition apparatus by microwave glow discharge decomposition method 1001 Deposition chamber 1002 Dielectric window 1003 Gas introduction pipe 1004 Substrate 1005 Heater 1006 Vacuum gauge 1007 Conductance valve 1008 Auxiliary valve 1009 Leak valve 1010 Waveguide section 1011 Bias power supply 1012 Bias rod 1020 Source gas supply device 1021 to 1026 Mass flow controller 1031 to 1036 Gas inflow valve 1041-1046 Gas outflow valve 1051-1056 Gas cylinder valves 1061 to 1066 Pressure regulators 1071 to 1076 Raw material gas cylinders 1100 Film forming apparatus by high-frequency glow discharge decomposition method 1101 Deposition chamber 1102 Cathode 1103 Gas introduction tube 1104 Substrate 1105 Heater 1106 Vacuum gauge 1107 Conductance valve 1108 Auxiliary valve 1109 Leak valve 1112 High frequency matching box

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 31/04 H01L 21/28

Claims (11)

(57) [Claims] 1. A non-single-crystal silicon-based semiconductor layer including a p-type layer, an i-type layer, and an n-type layer made of a non-single-crystal semiconductor material containing at least silicon atoms is provided on a conductive substrate, In a photovoltaic device in which a transparent electrode is stacked on and in contact with the non-single-crystal silicon-based semiconductor layer, the transparent electrode is formed of a conductive oxide containing an alkali metal in a content of 1 ppm or more and 100 ppm or less. A photovoltaic element, characterized in that: 2. The conductive oxide is indium oxide,
The photovoltaic device according to claim 1, wherein the photovoltaic device is a material selected from tin oxide and indium-tin oxide. 3. The photovoltaic device according to claim 1, wherein the conductive substrate is a substrate provided with a conductive thin film on a support made of an insulating material. 4. The thickness of the transparent electrode is 500 to 300.
The photovoltaic device according to claim 1, wherein the photovoltaic device has a current of 0A. 5. The photovoltaic device according to claim 1, wherein the alkali metal is unevenly distributed in a thickness direction of the conductive oxide. 6. A non-single-crystal silicon-based semiconductor layer including a p-type layer, an i-type layer, and an n-type layer made of a non-single-crystal semiconductor material containing at least silicon atoms is provided on a transparent substrate. In a photovoltaic device in which a conductive layer is stacked thereover, a transparent electrode is provided between the transparent substrate and the non-single-crystal silicon-based semiconductor layer in contact therewith, and the transparent electrode is 1 ppm or more. A photovoltaic element comprising a conductive oxide containing an alkali metal at a content of 100 ppm or less. 7. The conductive oxide is indium oxide,
The photovoltaic device according to claim 6, which is a material selected from tin oxide and indium-tin oxide. 8. The transparent electrode has a thickness of 500Å300.
7. The photovoltaic device according to claim 6, wherein the angle is 0 [deg.]. 9. The photovoltaic device according to claim 6, wherein the alkali metal is unevenly distributed in a thickness direction of the conductive oxide. 10. The method for manufacturing a photovoltaic device according to claim 1, wherein the conductive oxide is formed by a sputtering method using a target containing the alkali metal or a vacuum deposition method using a deposition source containing the alkali metal. A method for manufacturing a photovoltaic element that forms 11. The method of manufacturing a photovoltaic device according to claim 6, wherein the conductive oxide is formed by a sputtering method using a target containing the alkali metal or a vacuum deposition method using a deposition source containing the alkali metal. A method for manufacturing a photovoltaic element that forms