JP2785884B2 - Photovoltaic element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of laminating a semiconductor layer made of 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. The present invention relates to a photovoltaic element such as a photovoltaic cell, an optical sensor, etc.

In particular, the present invention relates to a photovoltaic element using an amorphous silicon-based semiconductor material (including a microcrystalline silicon-based semiconductor material) or a polycrystalline silicon-based semiconductor material as a non-single-crystal semiconductor material.

[0003]

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

[0004] 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 also important parameters that affect the film quality of the semiconductor layer adjacent to the transparent electrode.

The relationship between the photovoltaic element and the transparent electrode in recent years is described as “Optical absorption of transparent conducting”.
oxides and power dissipation in a-Si: H pin solar c
ells measured by photothermal deflection spectrosc
opy "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-lay
erin pin-type amorphous silicon solar cells "Y.Ash
ida, N.Ishida, N.Ishiguro et, al.Technical digest of
The international PVSEC-5. Considered in Kyoto, Japan, 1990, 367.

Further, as a technique for 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.

However, the conventional indium oxide,
It is desired that the transparent electrodes made of tin oxide and indium-tin oxide have further lower resistance.

[0008] Further, it is desired to further improve the transmittance, photovoltaic power and photocurrent of the transparent electrode.

Further, as the photovoltaic element has been widely used in general, the operating environment of the photovoltaic element has also become diversified. Therefore, depending on the operating environment, the layer between the transparent electrode and the layer which is in close contact may be provided. There was a problem that peeling off occurred.

[0010] In addition, there is a problem that a short circuit is generated by repeating the heat cycle of the photovoltaic element for a long time.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional photovoltaic device.
An object of the present invention is to provide a photovoltaic element in which distortion of a transparent electrode is removed and photovoltaic power and photocurrent are large.

It is an object of the present invention to provide a photovoltaic device in which a non-single-crystal silicon-based semiconductor layer deposited on a transparent electrode and having a uniform non-single-crystal silicon-based semiconductor layer without abnormal deposition is provided. . It is another object of the present invention to provide a photovoltaic element having stable characteristics.

According to the present invention, structural distortion between a transparent electrode of a photovoltaic element and a semiconductor layer adjacent to the transparent electrode is small,
It is an object of the present invention to provide a photovoltaic element without delamination.

Another object of the present invention is to provide a photovoltaic device capable of producing a good yield.

[0015]

As a result of intensive studies to solve the above problems and achieve the object of the present invention, it has been found that the following configuration is optimal.

In the photovoltaic device of the present invention, at least a p-type layer, an i-type layer, and an n-type semiconductor layer made of a non-single-crystal semiconductor material containing silicon atoms are laminated on a conductive substrate, Further, in a photovoltaic element configured by laminating a transparent electrode on the semiconductor layer, the transparent electrode may be an oxide such as indium oxide, tin oxide, or indium-tin oxide containing a carbon atom. Wherein the carbon atoms are more distributed on the semiconductor layer side of the transparent electrode than on the side opposite to the semiconductor layer.

[0017]

The operation of the present invention will be described below together with the detailed structure.

FIG. 1 and FIG. 2 are schematic explanatory views of the photovoltaic element of the present invention.

The photovoltaic device of the present invention shown in FIG. 1 has a light reflecting layer (conductive) 10 on an opaque conductive substrate 101.
2. reflection enhancement layer 103, n-type (or p-type) non-single-crystal silicon-based semiconductor layer 104, i-type (substantially intrinsic)
c) Non-single-crystal silicon-based semiconductor layer 105, p-type (or n-type) non-single-crystal silicon-based semiconductor layer 106, transparent electrode 107 containing a large amount of carbon atoms on the semiconductor layer side, and current collecting electrode 108 Have been. 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,
8. Transparent electrode 20 containing a large amount of carbon atoms on the semiconductor layer side
7, p-type (or n-type) non-single-crystal silicon-based semiconductor layer 206b, i-type (substantially intrinsic) non-single-crystal silicon-based semiconductor layer 205b, n-type (or p-type)
Non-single-crystal silicon-based semiconductor layer 204b, p-type (or n-type) non-single-crystal silicon-based semiconductor layer 206a, i-type (substantially intrinsic) non-single-crystal silicon-based semiconductor layer 205a, n-type (or p-type) (A type) non-single-crystal silicon-based semiconductor layer 204a, a reflection enhancement layer 203, a light reflection layer (conductive) 202, and a conductive layer (or / and a protective layer) 210.

Although not shown, a triple photovoltaic device in which three pin units are stacked is also a photovoltaic device suitable for the present invention.

Transparent Electrode In the photovoltaic device of the present invention, the transparent electrode is a transparent electrode containing a carbon atom in tin oxide, indium oxide, indium-tin oxide, or the like.

In a transparent electrode in which a carbon atom is contained in tin oxide, 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 is increased. Becomes smaller. Further, by including carbon atoms in the transparent electrode, distortion of the transparent electrode can be reduced. In this way, the specific resistance of the transparent electrode can be reduced, and the transmittance of the transparent electrode can be improved.

In addition, by including carbon atoms in the transparent electrode, the crystal shape of the oxide constituting the transparent electrode can be made relatively smooth, and the surface properties (eg, smoothness) of the transparent electrode can be improved. Can be improved.
In particular, when the transparent electrode is deposited on the semiconductor layer, the distortion between the semiconductor layer and the transparent electrode is reduced, and the adhesion between the two is greatly improved. 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. Therefore, even if a thin p-type layer (or n-type layer) is deposited, electric leakage can be reduced. As a result, the average characteristics of the photovoltaic element are improved.

In addition, by distributing a large amount of carbon atoms on the semiconductor layer side of the transparent electrode, structural distortion due to a difference in material between the transparent electrode and the semiconductor layer can be reduced.

In the present invention, the shape of the distribution of carbon atoms contained in the transparent electrode preferably decreases substantially exponentially from near the interface between the transparent electrode and the semiconductor layer toward the inside of the transparent electrode. It is listed as. Since carbon atoms are exponentially distributed in the transparent electrode in this manner, structural distortion due to a difference in material between the transparent electrode and the semiconductor layer can be alleviated more effectively, and carbon in the transparent electrode can be reduced. A change in characteristics due to the diffusion of atoms over time can be minimized.

The preferred distribution range of the exponential distribution of carbon atoms is 3 nm to 50 nm.

Although the details of the transparent electrode containing a carbon atom of the present invention are unknown, it is considered that the carbon atom lowers the formation temperature of a good quality transparent electrode in relation to the crystal growth of the oxide. Thus, good quality characteristics can be obtained even at a relatively low temperature.

The transparent electrode containing carbon atoms of the present invention is deposited as follows.

For the deposition of the transparent electrode containing carbon atoms of the present invention, for example, a sputtering method and a vacuum deposition method are the most suitable deposition methods.

As a sputtering apparatus suitable for depositing the carbon-containing transparent electrode of the present invention, there is a DC magnetron sputtering apparatus schematically shown in FIG.

A DC magnetron sputtering apparatus schematically shown in FIG. 3 suitable for depositing a carbon-containing transparent electrode of the present invention comprises a deposition chamber 301, a substrate 302, a heater 3
03, targets 304 and 308, insulating support 30
5, 309, DC power supplies 306, 310, shutter 30
7, 311, vacuum gauge 312, conductance valve 31
3, gas introduction valves 314 and 315, mass flow controllers 316 and 317, and the like.

In a DC magnetron sputtering apparatus, when a transparent electrode made of a tin oxide containing a carbon atom of the present invention is deposited on a substrate, the target is a metal tin (Sn) or tin oxide (SnO ₂ ). A target containing an atom-containing substance is used.

When a transparent electrode made of indium oxide containing a carbon atom of the present invention is deposited on a substrate, the target may be metal indium (In), indium oxide (In ₃ O ₃ ), or the like. Is used.

Further, when the transparent electrode made of indium-tin oxide containing a carbon atom of the present invention is deposited on a substrate, the target may be metal tin, metal indium or an alloy of metal tin and metal indium, tin oxide, indium oxide. And a target in which a carbon atom-containing substance is contained in an indium-tin oxide or the like.
By preparing a plurality of targets having different carbon contents and changing the aperture ratio of the shutter with respect to the targets, the content of carbon atoms in the transparent electrode can be distributed.

As a starting material of carbon atoms contained in the target, graphite-like carbon, diamond-like carbon and the like are suitable.

When the transparent electrode of the present invention is deposited by a reactive sputtering method, the target and / or the target containing no carbon atom are appropriately combined,
As a sputtering target, a carbon atom-containing source gas is introduced into the deposition chamber, and carbon atoms can be introduced into the transparent electrode using plasma energy. At this time, by changing the introduction amount of the carbon atom-containing source gas into the deposition chamber, the carbon atom content in the transparent electrode can be introduced into a desired distribution.

Examples of a carbon atom-containing source gas suitable for the reactive sputtering method include CH ₄ , CD ₄ , and 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.

The maximum distribution concentration of the carbon atom content contained in the transparent electrode of the present invention is 1,000 ppm or less and 5 ppm.
The above is mentioned as a preferable range.

Further, the maximum distribution density is 100 in the transparent electrode.
Although the content of carbon atoms contained in the target largely depends on sputtering conditions in order to contain carbon atoms of 0 ppm or less and 5 ppm or more, the maximum distribution concentration is preferably 1000 ppm or less.

In order to make the transparent electrode contain carbon atoms having a maximum distribution concentration of 1000 ppm or less by the reactive sputtering method, the mixing ratio of the carbon atom-containing gas to the sputtering gas is preferably approximately 2000 ppm or less. It is listed as.

When depositing the carbon-containing transparent electrode of the present invention 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 containing a carbon atom of the present invention has 2
It shows superior characteristics at a low temperature of 5 ° C. to 250 ° C. as compared with the prior art. Further, when the transparent electrode containing a carbon atom of the present invention is deposited by a sputtering method, the sputtering gas such as an argon gas (Ar), a neon gas (Ne), a xenon gas (Xe), a helium gas (He), or the like. An inert gas is exemplified, and an Ar gas is particularly suitable. In addition, oxygen gas (O
It is preferable to add ₂ ) as needed. Particularly when a metal is targeted, oxygen gas (O ₂ ) is essential.

When the target is sputtered with the inert gas or the like, the pressure in the discharge space is set to 0.1 to 50 mto for effective sputtering.
rr is mentioned as a preferable range.

In addition, as a power source in the case of the sputtering method, a DC power source or an RF power source is suitable. 10 to 1000 W as electric power during sputtering
Is a suitable range.

The deposition rate of the transparent electrode containing carbon atoms of the present invention depends on the pressure in the discharge space and the discharge power, and the optimal deposition rate is in the range of 0.01 to 10 nm / sec.

The second method suitable for depositing the carbon-containing transparent electrode of the present invention is a vacuum deposition method.

As schematically shown in FIG. 5, the vacuum deposition apparatus includes a deposition chamber 501, a substrate 502, a heater 503,
It comprises an evaporation source 504, a conductance valve 509, a gas introduction valve 510, and the like.

In the vacuum deposition method, the carbon atom-containing transparent electrode of the present invention was prepared by adding the carbon atom-containing material to metal tin, metal indium, or an indium-tin alloy as a deposition source suitable for depositing the transparent electrode. Things. The content of the carbon atoms is generally within the suitable range of a maximum distribution concentration of 1000 ppm or less.

The substrate temperature when depositing the carbon-containing transparent electrode of the present invention is preferably in the range of 25 ° C. to 600 ° C.

Further, when depositing the transparent electrode containing carbon atoms of the present invention, the pressure of the deposition chamber is reduced to 10 ^-6 torr or less, and then oxygen gas (O ₂ ) is added to 5 × 10 ^-5 torr or less.
It is preferable to introduce into the deposition chamber in the range of 9 × 10 ⁻⁴ torr.

By introducing oxygen in this range, the metal vaporized from the evaporation source reacts with oxygen in the gas phase to deposit a good transparent electrode.

When the transparent electrode having a carbon atom content of the present invention is deposited by reactive evaporation, the above-mentioned evaporation source and / or the above-mentioned evaporation source which does not contain carbon atoms are supplied with the carbon atom-containing gas by 5 × in a deposition chamber. The transparent electrode may be deposited by evaporating in a state where it is introduced at 10 ^-4 torr or less. In addition, plasma may be generated by introducing RF power at the above-mentioned degree of vacuum, and vapor deposition may be performed via the plasma. At this time, by changing the introduction amount of the carbon atom-containing gas into the deposition chamber over time, the content of carbon atoms contained in the transparent electrode can be controlled to a desired distribution. Further, the amount of the carbon atoms contained in the transparent electrode can be controlled to a desired distribution by changing the deposition rate of the deposition source while keeping the amount of the carbon atom-containing gas introduced into the deposition chamber constant.

The preferable range of the deposition rate of the transparent electrode under the above conditions is 0.01 to 10 nm / sec.
When the deposition rate is less than 0.01 nm / sec, the productivity is reduced, and when the deposition rate is more than 10 nm / sec, the film becomes a coarse film, and the transmittance, the conductivity and the adhesion are reduced.

In the photovoltaic device of the present invention, it is preferable that the layer thickness of the transparent electrode containing carbon atoms is deposited so as to satisfy the conditions of the antireflection film. As a specific layer thickness of the transparent electrode, a preferable range is 50 nm to 300 nm.

P-type layer or n-type layer 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.

The p-type layer or the n-type layer of the photovoltaic device of the present invention is composed of an amorphous material (denoted as “a−”) (a microcrystalline material (denoted as “μc-”) or an amorphous material). Needless to say, it falls within the range of).
i: H, a-Si: HX, a-SiC: H, a-Si
C: HX, a-SiGe: H, a-SiGeC: H, a
-SiO: H, a-SiN: H, a-SiON: HX,
a-SiOCN: HX, μc-Si: H, μc-Si
C: H, μc-Si: HX, μc-SiC: HX, μc
-SiGe: H, μc-SiO: H, μc-SiGe
C: H, μc-SiN: H, μc-SiON: HX, μ
c-SiOCN: a p-type valence electron controlling agent (Group III atoms B, Al, Ga, In, Tl in the periodic table) or an n-type valence electron controlling agent (Group V atom P, As, Sb, B
Examples of the material to which i) is added at a high concentration include polycrystalline materials (denoted as "poly-") such as pol
y-Si: H, poly-Si: HX, poly-Si
C: H, poly-SiC: HX, poly-SiG
e: H, poly-Si, poly-SiC, poly
P-type valence electron control agents (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) in SiGe or the like. , Ri) at a high concentration.

In particular, the p-type layer or the n-type layer on the light incident side includes:
A crystalline semiconductor layer with little light absorption or an amorphous semiconductor layer with a wide band gap is suitable.

The addition amount of Group III atoms of the periodic table to the p-type layer and the addition amount of Group V atoms of the periodic table to the n-type layer are 0.1
５０50 at% is mentioned as the optimum amount.

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 To improve the doping efficiency. The number of hydrogen atoms or halogen atoms added to the p-type layer or the n-type layer is 0.
The optimum is 1 to 40 at%. In particular, 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 8 at%. Further, a preferred distribution form is one in which a large amount 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 content of the hydrogen atom and / or the halogen atom is preferably in a range of 1.1 to 2 times the content in the bulk. Thus, the p-type layer / i-type layer and the n-type layer / i
By increasing the content of hydrogen atoms or halogen atoms near each interface of the mold layer, the defect level and mechanical strain near the interface can be reduced, and the photovoltaic power and light of the photovoltaic device of the present invention can be reduced. The current can be increased.

Further, those having a large content of hydrogen atoms and / or halogen atoms at each interface side of the transparent electrode / p-type layer or the transparent electrode / n-type layer are mentioned as a preferable distribution form. The content of hydrogen atoms and / or halogen atoms in the vicinity is 1.1 to 2 times the content in the bulk.
A double range is mentioned as a preferred range. By increasing the content of hydrogen atoms or halogen atoms near each interface between the transparent electrode / p-type layer and the transparent electrode / n-type layer in this manner, 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 electric characteristics of the p-type layer and the n-type layer of the photovoltaic element of the present invention are preferably those having an activation energy of 0.2 eV or less, and most preferably those having an activation energy of 0.1 eV or less. The specific resistance is preferably 100 Ωcm or less.
Ωcm 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.

The source gas suitable for depositing the p-type layer or the n-type layer of the photovoltaic device of the present invention includes a gasizable compound containing a silicon atom, a gasizable compound containing a germanium atom, and a carbon atom. And the like, and a gaseous compound containing the compound, and a mixed gas of the compound.

Specific examples of 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 ₃ , SiD ₄ ,
SiHD ₃ , SiH ₂ D ₂ , SiH ₃ D, SiFD ₃ , Si
F ₂ D ₂ , SiD ₃ H, Si ₂ D ₂ H _{3 and the} like.

Specific examples of the gasifiable compound containing a germanium atom include GeH ₄ , GeD ₄ , GeF ₄ ,
GeFH ₃ , GeF ₂ H ₂ , GeF ₃ H, GeHD ₃ , Ge
H ₂ D ₂ , GeH ₃ D, GeH ₆ , GeD _{6 and the} like can be mentioned.

Specific examples of the gasizable compounds containing carbon atoms include 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.

As the nitrogen-containing gas, N ₂ , NH ₃ , N
D ₂ , NO, NO ₂ and N ₂ O are mentioned. 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, the substance introduced into the p-type layer or the n-type layer for controlling the valence electrons may be any of those listed in Periodic Table II.
Group I and Group V atoms are included.

In the present invention, as a starting material for introducing a group III atom, for example, B ₂ H ₆ , B ₄ H ₁₀ , B _{4
5 H 3, B 5 H 11} , B 6 H 10, B 6 H 12, B 6 H 14 hydride such as boron, can name a BF _3, BCI ₃ halogenated such as boron or the like. In addition, AlCl ₃ , GaCl ₃ , In
Cl ₃ and TlCl ₃ can also be mentioned. Especially B
₂ H ₆ and BF ₂ are suitable.

[0069] In the present invention, being effectively used as a starting material for the group V atoms introduced as the a specifically phosphorus atom introducing PH _3, P ₂ H ₄ hydrogenation such as phosphorus halides, PH ₄ I, P
F ₃ , PF ₅ , PCl ₃ , PCl ₅ , PBr ₃ , PBr ₅ , P
Halogenated phosphorus such as I ₃ and the like. In addition, AsH ₃ ,
AsF ₃ , AsCl ₃ , AsBr ₃ , AsF ₅ , SbH ₃ ,
SbF ₃ , SbF ₅ , SbCl ₃ , SbCl ₅ , BiH ₃ ,
BiCl ₃ , BiBr _{3 and the} like can also be mentioned. Especially P
H ₃ and PF ₂ are suitable.

The p-type or n-type layer deposition methods suitable for the photovoltaic device of the present invention are RF plasma CVD and μW plasma CVD.

In particular, when depositing by RF plasma CVD, a capacitively coupled RF plasma CVD is suitable.

The p-type layer or n-type layer was formed by the RF plasma CVD method.
When depositing a mold layer, the substrate temperature in the deposition chamber is 100 to
350 ° C., internal pressure 0.1 to 10 torr, RF power 0.05 to 1.0 W / cm ² , deposition rate 0.0
1-3 nm / sec is mentioned as an optimal condition.

The compounds capable of being gasified are H ₂ , H
The gas may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the sediment.

In particular, when depositing a layer having a small light absorption or a wide band gap such as a microcrystalline semiconductor or a-SiC: H, the source gas is diluted 2 to 100 times with hydrogen gas and the RF power is relatively high. It is preferable to introduce power. An RF frequency of 1 MHz to 100 MHz is a suitable range, and a frequency near 13.56 MHz is particularly optimal.

A p-type layer or an n-type layer suitable for the present invention is formed by μW
ΜW plasma CVD when depositing by plasma CVD
The equipment is a dielectric window (alumina ceramics etc.) in the deposition chamber
A method of introducing microwaves through a waveguide through a fin is suitable.

A p-type layer or an n-type layer suitable for the present invention is formed by μW
When depositing by the plasma CVD method, the substrate temperature in the deposition chamber is 100 to 400 ° C., and the internal pressure is 0.5 to 30 mtorr.
The preferable ranges of r and μW power are 0.01 to 1 W / cm ³ , and the frequency of μW is 0.5 to 10 GHz.

The compounds capable of being gasified are H ₂ , H
It may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

In particular, when depositing a layer having a small light absorption or a wide band gap such as a microcrystalline semiconductor or a-SiC: H, the source gas is diluted 2 to 100 times with hydrogen gas, and the μW power is relatively high. It is preferable to introduce power.

I-Type Layer 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 device of the present invention,
Only p-type and only n-type layers can be used.

The i-type layer of the photovoltaic element of the present invention is made of an amorphous material, for example, a-Si: H, a-Si: HX, a
-SiC: H, a-SiC: HX, a-SiGe: 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 form an intrinsic material (intr.
Insic) materials are mentioned as suitable.

The hydrogen atoms (H, D) contained in the i-type layer
Or a halogen atom (X) compensates for dangling bonds of the i-type layer.
And the product of carrier mobility and lifetime in the i-type layer
Improvement It is something to make. Also, a p-type layer / i-type layer, an n-type layer /
It works to compensate for the interface state of each interface of the i-type layer, and
Improve photovoltaic, photocurrent and photoresponse of force element
It is effective. Hydrogen atoms contained in the i-type layer
Or 1 to 40 at% of halogen atom
Listed as quantities. In particular, p-type layer / i-type layer, n-type layer /
a hydrogen atom and / or a halogen atom on each interface side of the i-type layer
And the preferred distribution form is that the content of
Hydrogen atoms and / or c near the interface.
The content of logen atoms is 1.1 to 2 times the content in the bulk
Is 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.

The basic physical properties of the i-type layer serve the purpose of the present invention.
The electron mobility is 0.01 cm^Two/
V / sec or more, hole mobility is 0.0001 cm^Two/
V / sec or more, band gap is 1.1 to 2.2e
V, localization density at the center of the forbidden zone is 10¹⁸ / Cm^Three/ EV or less
Bottom, the tilt of the Urbach tail on the valence band side is 65 meV
The following are preferred ranges. Further according to the invention
AM1.5, 100mW / cm^TwoUnder
Measure the current-voltage characteristics and use the Hecht formula for curve fitting.
And perform the transfer determined from this curve fitting.
Mobility life product of 10^{- Ten}c m^Two/ V or more is desirable
Things.

The band gap of the i-type layer is p-type layer / i
It is preferable to design so as to be wider on each interface side of the mold layer and the n-type layer / i-type layer. By designing in this way, the photovoltaic power and photocurrent of the photovoltaic element can be increased, and furthermore, photodeterioration and the like when used for a long time can be prevented.

The source gas suitable for depositing the i-type layer of the photovoltaic device of the present invention includes a gasizable compound containing a silicon atom, a gasizable compound containing a germanium atom, and a gas containing a carbon atom. 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 , and SiH ₄ .
FH ₃ , SiF ₂ H ₂ , SiF ₃ H, Si ₃ H ₃ , SiD ₄ ,
SiHD ₃ , SiH ₂ D ₂ , SiH ₃ D, SiFD ₃ , Si
F 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 , GeF ₄ ,
GeFH ₃ , GeF ₂ H ₂ , GeF ₃ H, GeHD ₃ , Ge
H ₂ D ₂ , GeH ₃ D, GeH ₆ , GeD _{6 and the} like can be mentioned.

Specific examples of gasizable compounds containing carbon atoms include 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, examples of the substance introduced into the i-type layer for controlling the valence electrons of the i-type layer include Group III atoms and Group V atoms in the periodic table.

In the present invention, as a starting material for introducing a group III atom, specifically, for introducing a boron atom, B ₂ H ₃ , B ₄ H ₁₀ , B
_{5 H 9, B 5 H 11} , B 5 H 10, B 6 H 12, B 5 H 14 , etc. borohydride, may be mentioned BF _3, BCl ₃ or the like boron halide or the like. In addition, AlCl ₃ , GaCl ₃ , I
nCl ₃ , TlCl _{3 and the} like can also be mentioned.

In the present invention, the starting material for introducing a group V atom can be effectively used, specifically, for introducing a phosphorus atom, for example, hydrogen phosphide such as PH ₃ , P ₂ H ₄ , or the like. ₄ I,
PF ₃ , PF ₅ , PCl ₃ , PCl ₅ , PBr ₃ , PBr ₅ ,
Phosphorus halides such as PI ₃ ; In addition, As
H ₃ , AsF ₃ , AsCl ₃ , AsBr ₃ , AsF ₅ , Sb
_{H 3, SbF 3, SbF 5} , SbCl 3, SbCl 5, Bi
H ₃ , BiCl ₃ , BiBr _{3 and the} like can also be mentioned.

The amount of the group III and group V atoms introduced into the i-type layer for controlling the conductivity type is 10%.
00 ppm or less is mentioned as a preferable range.

As the method for depositing the i-type layer suitable for the present invention, there are RF plasma CVD method and μW plasma CVD method. In the case of the RF plasma CVD method, a capacitively coupled RF plasma CVD apparatus is particularly suitable.

When the i-type layer is deposited by the RF plasma CVD method, the substrate temperature in the deposition chamber is 100 to 350 ° C., the internal pressure is 0.1 to 10 torr, and the RF power is 0.05.
〜１０10 W / cm ² , the deposition rate is 0.01 to 3 nm / s
ec 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 deposition chamber.

In particular, when depositing a layer having a wide band gap such as a-SiC: H, it is preferable to dilute the source gas by 2 to 100 times with hydrogen gas and to introduce a relatively high RF power. . RF frequency is 1M
Hz to 100 MHz is a suitable range, especially 13.5.
A frequency near 6 MHz is optimal.

An i-type layer suitable for the present invention is formed by a μW plasma CV
In the case of depositing by the method D, a method of introducing microwaves into a deposition chamber through a waveguide through a dielectric window (alumina ceramics or the like) is suitable for the μW plasma CVD apparatus.

An i-type layer suitable for the present invention is formed by a μW plasma CV
When depositing by the method D, the substrate temperature in the deposition chamber is 100 to
400 ° C., internal pressure 0.5-30 mtorr, μW power 0.01-1 W / cm ² , μW frequency 0.5-1
0 GHz is mentioned as a preferable range.

The compounds capable of being gasified are H ₂ , H
It may be appropriately diluted with a gas such as e, Ne, Ar, Xe, or Kr and introduced into the deposition chamber.

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 power of μW. .

Conductive Substrate The conductive substrate may be a conductive material, or may be a support formed of an insulating material or a conductive material and then subjected to a conductive treatment. As the conductive support,
For example, NiCr, stainless steel, Al, Cr, Mo, A
Examples thereof include metals such as u, Nb, Ta, V, Ti, Pt, Pb, and Sn or alloys thereof.

Examples of the electrically insulating support include films of synthetic resins such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, and polyamide, or sheets, glass, ceramics, Paper and the like. These electrically insulating supports preferably have at least one surface conductively treated,
It is desirable to provide a photovoltaic layer 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 + Sn)
To provide conductivity by providing a thin film consisting of
Alternatively, if it is a synthetic resin film such as a polyester film, NiCr, Al, Ag, Pb, Zn, Ni, A
u, Cr, Mo, Ir, Nb, Ta, V, Ti, Pt, etc., a metal thin film is provided on the surface by vacuum evaporation, electron beam evaporation, sputtering, or the like, or the surface is laminated with the metal, Provide conductivity to the surface. The support may be in the form of 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, the thickness is usually 10 μm or more from the viewpoints of production and handling of the support, mechanical strength and the like.

[0105]

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 (hereinafter abbreviated as “μW”) glow discharge decomposition method.

First, a transparent electrode containing a distribution of carbon atoms was formed on a substrate by a DC magnetron sputtering apparatus shown in FIG.

In the figure, reference numeral 302 denotes a substrate made of barium borosilicate glass (7059, manufactured by Corning Incorporated) having a size of 50 mm square and 1 mm.

In the figure, reference numeral 304 indicates that the composition is indium (I
n), tin (Sn) and carbon atom (C) in a molar ratio of 8
The target is made of 5: 15: 0.005, and is insulated from the deposition chamber 301 by the insulating support 305.

In the figure, reference numeral 308 indicates that the composition is indium (I
n) and tin (Sn) in a molar ratio of 85:15.
More insulated.

In the drawing, reference numerals 314 and 315 denote gas introduction valves, which are connected to an oxygen (O ₂ ) gas cylinder and an argon (Ar) gas cylinder (not shown), respectively.

First, the substrate 30 is heated by the heater 303.
2 was heated to 350 ° C., and the inside of the deposition chamber 301 was evacuated by a vacuum pump (not shown).
^{When the} pressure reaches ^-5 torr, the gas introduction valves 314, 3
15 is gradually opened to deposit O ₂ gas and Ar gas in the deposition chamber 301.
Allowed to flow in. At this time, the O ₂ gas flow rate was 20 sccm,
The mass flow controllers 316 and 317 adjust the Ar gas flow rate to 20 sccm, and the vacuum gauge 3 adjusts the pressure in the deposition chamber 301 to 2 mtorr.
While looking at 12, conductance valve (butterfly type)
The opening of 313 was adjusted. Thereafter, the voltage of the DC power supply 306 is set to −400 V, DC power is introduced into the target 304, and the voltage of the DC power supply 310 is further reduced to −450 V.
And DC power is introduced to the target 308, and D
A C glow discharge is generated, and then the shutters 307 and 311 are opened to start producing a transparent electrode on the substrate 302, and at the same time, the voltage of the DC power supply 310 is gradually changed at a constant rate from -450V to -350V. Then, when a transparent electrode having a layer thickness of 70 nm was produced, shutters 307 and 31 were formed.
1 is closed, the outputs of the DC power supplies 306 and 310 are turned off, and D
C 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. Was heat-treated to complete the production of a transparent electrode containing carbon atoms distributed therein.

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 μW glow discharge decomposition method including a zero and a deposition apparatus 1000.

The gas cylinders 1071 to 1076 in the figure are sealed with a source gas for producing the non-single-crystal silicon-based semiconductor layer of the present invention, and 1071 is a SiH ₄ gas (purity: 99.999%) cylinder. , 1072 H ₂ gas (99.9999% purity) cylinder, 1073 H ₃ gas diluted to 10% the B ₂ H ₆ gas (99.99% purity,
Hereinafter, a cylinder (abbreviated as “B ₂ H ₆ / H ₂ ”) 1074 is a PH ₃ gas (purity 99.9) diluted to 10% with H ₂ gas.
9%, hereinafter abbreviated as “PH ₃ / H ₂ ”) cylinder, 107
5 is a CH ₄ gas (purity 99.9999%) cylinder, 10
76 is a GeH ₄ gas (purity 99.99%) cylinder. In addition, gas cylinders 1071 to 1076 are previously determined.
When attaching the gas, each gas is supplied to the valves 1051 to 1
From 056, it is introduced into the gas piping of the inflow valves 1031 to 1036.

In the figure, reference numeral 1004 denotes a substrate on which a transparent electrode has been manufactured by the method described above.

First, SiH ₄ gas from gas cylinder 1071, H ₂ gas from gas cylinder 1072, and gas cylinder 10
B ₂ H ₆ / H ₂ gas from 73, P from gas cylinder 1074
H ₃ / H ₂ gas, CH ₄ gas from gas cylinder 1075, GeH ₄ gas from gas cylinder 1076, valve 1051
-1056 is opened and introduced, and pressure regulators 1061-10
With 66, each gas pressure was adjusted to about 2 kg / cm ² .

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). 1 × 10
^{When the} pressure reached ^-4 torr, the auxiliary valve 1008 and the outflow valves 1041 to 1046 were closed.

Next, the inflow valves 1031 to 1036 are gradually opened, and each gas is supplied to the mass flow controller 1.
021 to 1026.

After the preparation for film formation was completed as described above, p-type layers, i-type layers, and n-type layers were formed on the substrate 1004.

In order to form a p-type layer, the substrate 1004 is heated to 350 ° C. by the heater 1005, and the outflow valves 1041 to 1043 are gradually opened, and the SiH ₄ gas,
H ₂ gas and B ₂ H ₅ / H ₂ gas were introduced into the deposition chamber 1001 through the introduction pipe 1003. At this time, SiH ₄ gas flow rate 10 sccm, H ₂ gas flow rate 100 sccm, B ₂
The mass flow controllers 1021 to 1023 adjusted the H ₅ / H ₂ gas flow rate to 5 sccm.
The pressure inside the deposition chamber 1001 is adjusted to 20 mtorr while watching the vacuum gauge 1006 to conductance valve 10.
07 opening was adjusted. Thereafter, the power of a μW power supply (not shown) is set to 400 mW / cm ³ , and the deposition chamber 100 is passed through a waveguide (not shown), a waveguide 1010 and a dielectric window 1002.
1 to introduce μW electric power to generate μW glow discharge,
The production of a p-type layer on the transparent electrode was started, and when a p-type layer having a thickness of 5 nm was produced, the μW glow discharge was stopped, the outflow valves 1041 to 1043 and the auxiliary valve 1008 were closed, and the gas in the deposition chamber 1001 was introduced The flow was stopped, and the production of the p-type layer was completed.

Next, in order to form an i-type layer, the substrate 100
4 was heated to 350 ° C. by a heater 1005, and the outflow valves 1041, 1042 and the auxiliary valve 1008 were gradually opened, and SiH ₄ gas and H ₂ gas were introduced into the introduction pipe 1003.
And flowed into the deposition chamber 1001. At this time, Si
H ₄ gas flow rate is 100 sccm, H ₂ gas flow rate is 200 s
ccm each mass flow controller 1
021, 1022. The opening of the conductance valve 1007 was adjusted while watching the vacuum gauge 1006 so that the pressure in the deposition chamber 1001 was 5 mtorr. Next, the high frequency bias of the bias power supply is set to 100 mW / cm.
^{3. The} DC bias was set to 75 V with respect to the substrate 1004 and applied to the bias rod 1012. After that, the power of a μW power supply (not shown) is set to 100 mW / cm ³ , and μW power is introduced into the deposition chamber 1001 through a waveguide (not shown), a waveguide unit 1010, and a dielectric window 1002 to perform μW glow discharge. Then, the production of the i-type layer was started on the p-type layer. When the i-type layer having a thickness of 400 nm was produced, the μW glow discharge was stopped, the output of the bias power supply 1011 was turned off, and the production of the i-type layer was completed. .

In order to form an n-type layer, the substrate 1004 is heated to 300 ° C. by the heater 1005, the outlet valve 1044 is gradually opened, and the SiH ₄ gas, H ₂ gas, P
The H ₃ / H ₂ gas is supplied through the gas introduction pipe 1003 to the deposition chamber 10.
01. At this time, the flow rate of the SiH ₄ gas is 30.
sccm, H ₂ gas flow rate is 100 sccm, PH ₃ / H ₂
The mass flow controllers 1021, 1022, and 1024 adjusted the gas flow rate to 6 sccm. The opening of the conductance valve 1007 was adjusted while watching the vacuum gauge 1006 so that the pressure in the deposition chamber 1001 became 10 mtorr. After that, the power of a μW power supply (not shown) is set to 50 mW / cm ³ , and the deposition chamber 10 is passed through a waveguide, a waveguide 1010 and a dielectric window 1002 (not shown).
01, a μW glow discharge is caused to occur, a production of an n-type layer is started on the i-type layer, and when a 10 nm-thick n-type layer is produced, the μW glow discharge is stopped. , 1042, 1044 and auxiliary valve 1
008 was closed, the flow of gas into the deposition chamber 1001 was stopped, and the formation of the n-type layer was completed.

When producing the respective layers, it goes without saying that the outflow valves 1041 to 1046 other than the necessary gas are completely closed, and the respective gases are supplied into the deposition chamber 1001 and outflow valve 1041. In order to avoid remaining in the piping from to -1046 to the deposition chamber 1001, the outflow valves 1041 to 1046 are closed, the auxiliary valve 1008 is opened, and the conductance valve 100
7 is fully opened, and the operation of once evacuating the system to a high vacuum is performed as necessary.

Next, on the n-type layer, Al was used as a back electrode.
Was vapor-deposited by 2 μm to produce a photovoltaic element (element No. Ex. 1).

Table 1 shows the conditions for producing the photovoltaic element described above.

[0126]

[Table 1 (Part 1)]

[0127]

[Table 1 (Part 2)]

Comparative Example 1 A conventional photovoltaic element was manufactured in the same manner as in Example 1.

First, as shown in FIG. 3, a transparent electrode was formed on a substrate by a DC magnetron sputtering method manufacturing apparatus.

As in Embodiment 1, the substrate 302 was heated at 350 ° C.
Then, O ₂ gas and 20 sccm of the O ₂ gas and the Ar gas were introduced into the deposition chamber 301, and the pressure in the deposition chamber 301 was adjusted to 2 mtorr. Then, the DC power supply 31
0 is set to -400V and the target is set to 308
To generate DC glow discharge, then open the shutter 311 to start production of a transparent electrode on the substrate 302, and close the shutter 311 when a transparent electrode having a layer thickness of 70 nm is produced. The output of the DC power supply 310 was 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 a period of time 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 the durability of the photovoltaic elements manufactured in Example 1 (Element No. 1) and Comparative Example 1 (Element No. 1) were measured.

The measurement of the initial characteristics was performed in Example 1 (element No. 1).
The photovoltaic elements manufactured in Example 1) and Comparative Example 1 (element No. ratio 1) were placed under AM-1.5 (100 mW / cm ³ ) light irradiation, and V-1 characteristics were measured. And the short-circuit current and series resistance obtained by As a result of the measurement, the short-circuit current of the photovoltaic element of Example 1 (element No. 1) was 1.04 times that of the photovoltaic element of comparative example 1 (element No. Was 1.37 times better.

The measurement of the durability was performed in the same manner as in Example 1 (element no.
The photovoltaic elements produced in Example 1) and Comparative Example 1 (element No. ratio 1) were left in a dark place with a humidity of 85% for 4 hours at a temperature of 85 ° C. and 30 minutes at a temperature of −40 ° C. 30
The measurement was performed by changing the photoelectric conversion efficiency after the application. As a result of the measurement, in the photovoltaic element of Example 1 (element No. 1), the reduction of the photoelectric conversion efficiency was 1.09 times that of the photovoltaic element of comparative example 1 (element No. ratio 1). It was excellent.

The distribution of carbon atoms in the transparent electrode of the photovoltaic element of Example 1 (element No. 1) was analyzed by a secondary ion mass spectrometer (IMS-3F manufactured by CAMECA). It was confirmed that the content of carbon atoms was clearly reduced from the p-type layer side to the substrate side.

From the above measurement results, the photovoltaic device using the transparent electrode containing carbon atoms of the present invention (device No. 1) was different from the conventional photovoltaic device (device No. ratio 1). As a result, it was found to have excellent characteristics, and the effect of the present invention was demonstrated.

Example 2 A transparent electrode, a p-type layer, an i-type layer, and an n-type layer were formed on a substrate under the same manufacturing conditions as in Example 1 except that an alloy shown in Table 2 was used as the material of the target 304. Then, a back electrode was prepared to produce a photovoltaic element (element Nos. 2-1 to 5).

The fabricated photovoltaic element (element No. 2-
1 to 5) 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 carbon atoms of the present invention (device Nos. 2-1 to 5) are different from the conventional photovoltaic devices (device No. ratio 1). On the other hand, it was found to have excellent characteristics, and the effect of the present invention was proved.

[0139]

[Table 2]

Example 3 A transparent electrode, an n-type layer, and an i-type layer were formed on a substrate under the same manufacturing conditions as in Example 1, except that the n-type layer, the i-type layer, and the p-type layer were formed as shown in Table 3. A photovoltaic element was produced by producing a mold layer, a p-type layer, and a back electrode (element No. 3).

[0141]

[Table 3]

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

Example 3 (Element No. 3) and Comparative Example 2
The initial characteristics and the durability characteristics of the photovoltaic element manufactured in (element No. ratio 2) were measured 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 2 (element No. The photovoltaic device using the transparent electrode containing carbon atoms of the present invention (device No. 3) has 1.32 times better characteristics and 1.09 times better durability characteristics than the conventional photovoltaic device. Element (Element N
o. As compared with the ratio 2), it was found to have excellent characteristics, demonstrating the effect of the present invention.

Example 4 Under the same manufacturing conditions as in Example 1, a transparent electrode containing carbon atoms was formed on a substrate, and CH ₄ gas and GeH ₄ were formed on the transparent electrode.
After producing a p-type layer, an i-type layer, an n-type layer, a p-type layer, an i-type layer, and an n-type layer under the production conditions shown in Table 4 using a gas,
On the n-type layer, a 1 μm ZnO thin film was deposited as a reflection increasing layer by DC magnetron sputtering, and further,
As a light reflection layer, a silver thin film was deposited to a thickness of 300 nm by a DC magnetron sputtering method, and a back electrode was formed on the silver thin film in the same manner as in Example 3 to manufacture a photovoltaic element (element No. 4).

[0145]

[Table 4]

Comparative Example 3 A transparent electrode, a p-type layer, an i-type layer, and an n-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. A photovoltaic element was produced by producing a mold layer, a p-type layer, an i-type layer, an n-type layer, a reflection enhancement layer, a light reflection layer, and a back electrode (element number ratio 3).

Example 4 (Element No. 4) and Comparative Example 3
Example 1 shows a photovoltaic element manufactured using (element No. ratio 3).
The initial characteristics and the durability characteristics were measured in the same manner as described above. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 4 (element No. actual 4) was 1.07 times larger than that of the photovoltaic element of comparative example 3 (element No. ratio 3), The resistance is 1.
Forty times better and 1.09 times better in durability, the photovoltaic element using the transparent electrode containing carbon atoms of the present invention (Element No. 4) is different from the conventional photovoltaic element (Element No. 4). It was found to have excellent characteristics with respect to ratio 3), demonstrating the effect of the present invention.

Example 5 Vacuum evaporation method and microwave (hereinafter abbreviated as “μW”)
The photovoltaic device of the present invention was manufactured by the glow discharge decomposition method.

First, a transparent electrode containing carbon atoms was formed on a substrate by a manufacturing apparatus using a vacuum evaporation method shown in FIG. In the figure, reference numeral 502 denotes a substrate, which is 50 mm square and 1 mm thick.
Barium borosilicate glass (Corning Co., Ltd. 705)
9).

In the figure, reference numeral 504 denotes a composition of indium (I
This is a vapor deposition source having a molar ratio of n) to tin (Sn) of 1: 1.

In the figure, reference numeral 510 denotes a gas introduction valve, which is a CO ₂ gas (C) in which O ₂ (not shown) is diluted to 50 ppm with gas.
O ₂ / O ₂ ).

In the figure, reference numeral 512 denotes a gas introduction valve, which 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 reaches ^-5 torr, the gas introduction valves 510, 5
12 was gradually opened to allow the CO ₂ / O ₂ gas and O ₂ gas to flow into the deposition chamber 501. At this time, the CO ₂ / O ₂ gas flow rate is 3 sccm, and the O ₂ gas flow rate is 7 sccm.
The opening of the conductance valve (butterfly type) 509 was adjusted while observing the vacuum gauge 508 so that the pressure in the deposition chamber 501 was 0.3 mtorr, adjusted by the respective mass flow controllers 511 and 513. Then A
Power is supplied from the C power supply 506 to the heater 505,
The evaporation source 504 is heated, then the shutter 507 is opened, and the production of a transparent electrode on the substrate 502 is started.
The O ₂ / O ₂ gas flow rate 7sccm from 3 sccm, O ₂
Each mass flow controller 51 is changed so that the gas flow rate is changed at a fixed rate from 7 sccm to 3 sccm.
When the transparent electrode having a layer thickness of 70 nm was prepared by adjusting the values of 1, 513, the shutter 507 was closed, the output of the AC power supply 506 was turned off, and the gas introduction valves 510, 512 were closed.
The flow of gas into the deposition chamber 501 was stopped, and the production of the transparent electrode containing carbon atoms 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. 5).

Comparative Example 4 A conventional photovoltaic element was manufactured in the same manner as in Example 5.

First, a transparent electrode was formed on a substrate by a vacuum evaporation method manufacturing apparatus shown in FIG.

As in the case of the fifth embodiment, the substrate 502 was heated to 350 ° C.
12 is gradually opened, an O ₂ gas flow rate of 7 sccm is introduced into the deposition chamber 501, and the pressure in the deposition chamber 501 is reduced to 0.3 m.
Adjusted to torr. 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 and produce a transparent electrode having a layer thickness of 70 nm. When the shutter 507 is closed, the AC power supply 506 is closed.
Was turned off, the gas introduction valve 512 was closed, the gas flow into the deposition chamber 501 was stopped, and the production of the transparent electrode was completed. Further, on the transparent electrode under the same manufacturing conditions as in Example 1,
A p-type layer, an i-type layer, an n-type layer, and a back electrode were prepared to produce a photovoltaic element (element number ratio 4).

Example 5 (Element No. 5) and Comparative Example 4
The initial characteristics and the durability characteristics of the photovoltaic element manufactured with the (element number ratio 4) were measured in the same manner as in Example 1. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 5 (element No. 5) was 1.05 times as large as that of the photovoltaic element of comparative example 4 (element No. ratio 4), The photovoltaic device (element No. 5) using the transparent electrode containing carbon atoms of the present invention having a resistance of 1.40 times better and a durability characteristic of 1.08 times better than the conventional photovoltaic device Element (Element N
o. As compared with the ratio 4), it was found to have excellent characteristics, and the effect of the present invention was demonstrated.

Further, the distribution of carbon atoms in the transparent electrode of the photovoltaic element of Example 5 (element No. 5) was analyzed by a secondary ion mass spectrometer (IMS-3F manufactured by CAMECA). It was confirmed that the content of carbon atoms was clearly reduced from the p-type layer side to the substrate side.

Example 6 Stainless steel (SUS430BA) 50 mm square and 1 mm thick
A 300 nm thick silver thin film as a light reflection layer and a 1 μm thick ZnO thin film as a reflection enhancement layer were deposited on the conductive substrate by DC magnetron sputtering using a conductive substrate having a mirror-finished surface. 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.

[0161]

[Table 5]

Next, a transparent electrode was formed on the p-type layer in the same manner as in Example 5. Substrate temperature 200 ℃, CO
₂ / O ₂ gas flow rate 7 sccm, O ₂ gas flow rate 3 scc
m and the pressure in the deposition chamber 501 were adjusted to 0.3 mtorr. Then, the heater 50 is supplied from the AC power supply 506.
5, the deposition source 504 is heated, the shutter 507 is opened, and the production of the transparent electrode on the substrate 502 is started. At the same time, the CO ₂ / O ₂ gas flow rate is changed from 7 sccm to 3 sc.
cm, the O ₂ gas flow rate from 3 sccm to 7 sccm,
The mass flow controllers 511 and 513 are adjusted so as to be able to change at a constant rate. When a transparent electrode having a layer thickness of 70 nm is produced, the shutter 507 is closed.
The output of the C power supply 506 is turned off, and the gas introduction valves 510, 5
12, the gas flow into the deposition chamber 501 is stopped, and p
A transparent electrode containing carbon atoms was prepared on the mold layer, and Al was deposited on the transparent electrode as a collecting electrode by depositing Al by vacuum deposition at 2 μm to prepare a photovoltaic element (element No. 6). .

Comparative Example 5 Under the same manufacturing conditions as in Example 6, 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 temperature was changed to ° C., and a current collecting electrode was prepared and a photovoltaic element was prepared in the same manner as in Example 6 (element No. Ratio 5).

Example 6 (Element No. 6) and Comparative Example 5
The initial characteristics and the durability characteristics of the photovoltaic device manufactured with (element number ratio 5) were measured in the same manner as in Example 1. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 6 (element No. actual 6) was 1.06 times that of the photovoltaic element of comparative example 5 (element No. ratio 5), The photovoltaic element (element No. 6) using the carbon atom-containing transparent electrode of the present invention has a resistance of 1.41 times better and has a durability property of 1.08 times better than the conventional photovoltaic element. (Element N
o. As compared with the ratio 5), it was found to have excellent characteristics, and the effect of the present invention was demonstrated.

The distribution of carbon atoms in the transparent electrode of the photovoltaic device of Example 6 (element No. 6) was analyzed by a secondary ion mass spectrometer (IMS-3F manufactured by CAMECA). It was confirmed that the content of carbon atoms clearly increased from the surface side to the p-type layer side.

Example 7 A photovoltaic device of the present invention was manufactured by a DC magnetron sputtering method and a high frequency (hereinafter abbreviated as “RF”) glow discharge decomposition method.

First, a transparent electrode containing carbon atoms was manufactured on a substrate under the same manufacturing 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 based on the RF glow discharge decomposition method including the deposition apparatus 1 and the deposition apparatus 1100.

In the figure, reference numeral 1104 denotes a substrate on which the above-mentioned transparent electrode is manufactured.

In the figure, the same material gas as in Example 1 is sealed in each gas cylinder of gas cylinders 1071 to 1076, and each gas is introduced into the mass flow controllers 1021 to 1026 by the same operation procedure as in Example 1. .

After preparation for 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.

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 to open the SiH ₄ gas, H ₂ gas, B ₂ H ₄ gas introduction pipe 11
03 into the deposition chamber 1101. At this time,
SiH ₄ gas inflow ₂ sccm, H ₂ gas flow rate 50 sc
cm, and the mass flow controllers 1021 to 1023 adjusted the flow rates of the B ₂ H ₄ / H ₂ gas 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. Thereafter, the power of an RF power source (not shown) is set to 200 mW / cm ³ , RF power is introduced to the cathode 1102 through the RF matching box 1112, an RF glow discharge is generated, and a p-type layer is formed on the transparent electrode. When the p-type layer having a thickness of 5 nm was formed, the RF glow discharge was stopped, and the outflow bulb 1041
1043 and the auxiliary valve 1108 are closed, and the deposition chamber 11 is closed.
The flow of gas into 01 was stopped, and the fabrication of the p-type layer was completed.

Next, to form 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 gradually opened, and SiH ₄ gas and H ₂ gas were introduced into the gas introduction pipe 110.
3 and flowed into the deposition chamber 1101. At this time, S
iH ₄ gas flow rate ₂ sccm, H ₂ gas flow rate 20 scc
m so that each mass flow controller 102
1, 1022 was adjusted. The pressure in the deposition chamber 1101 is
The opening of the conductance valve 1107 was adjusted while watching the vacuum gauge 1106 so that the pressure became 1 torr. afterwards,
The power of the RF power source (not shown) was set to 5 mW / cm ² and R
Cathode 110 through F matching box 1112
2, RF power is introduced to cause RF glow discharge, and p
Production of an i-type layer was started on the mold layer, and when an i-type layer having a thickness of 400 nm was produced, RF glow discharge was stopped, and production of the i-type layer was completed.

Next, to form an n-type layer, the substrate 110
4 was heated to 250 ° C. by a heater 1105, the outflow valve 1044 was gradually opened, and the deposition chamber 1 was passed through a SiH ₄ gas, H ₂ gas, and B ₂ H ₆ / H ₂ gas introduction pipe 1103.
101. At this time, the flow rate of the SiH ₄ gas is 2
The mass flow controllers 1021, 1022, and 1024 adjusted the flow rates of sccm, H ₂ gas to 20 sccm, and B ₂ H ₆ / H ₂ gas to 1 sccm.
The pressure inside the deposition chamber 1101 is set to 1 torr while the conductance valve 1107 is observed while watching the vacuum gauge 1106.
The opening of was adjusted. After that, the power of the RF power source (not shown) is set to 5 mW / cm ² , and the RF matching box 111 is set.
2 to the cathode 1102 through RF power,
A glow discharge is generated to start the production of an n-type layer on the i-type layer. When an n-type layer having a thickness of 10 nm is produced, the RF glow discharge is stopped, and outflow valves 1041, 1042, 104
4 and the auxiliary valve 1108 were closed to stop the gas flow into the deposition chamber 1101, and the production of the n-type layer was completed.

When producing the respective layers, it goes without saying that the outflow valves 1041 to 1046 other than the necessary gas are completely closed, and the respective gases are supplied into the deposition chamber 1101 and outflow valve 1041. Outflow valves 1041 to 1046 are closed, auxiliary valve 1108 is opened, and conductance valve 110
7 is fully opened, and the operation of once evacuating the system to a high vacuum is performed as necessary.

Next, a back electrode was deposited on the n-type layer in the same manner as in Example 1 to produce a photovoltaic element (element No. 7).

Table 6 shows the conditions for producing the photovoltaic element described above.

[0178]

[Table 6 (Part 1)]

[0179]

[Table 6 2)]

Comparative Example 6 A p-type layer, an i-type layer, an n-type layer, and a back electrode were formed on a transparent electrode under the same manufacturing conditions as in Example 7, except that the same transparent electrode as in Comparative Example 1 was used. Thus, a photovoltaic element was manufactured (element No. ratio 6).

Example 7 (Element No. 7) and Comparative Example 6
The initial characteristics and the durability characteristics of the photovoltaic device manufactured in (element No. ratio 6) were measured in the same manner as in Example 1. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 7 (element No. 7) was 1.06 times that of the photovoltaic element of comparative example 6 (element No. ratio 6), The photovoltaic element (element No. 7) using the transparent electrode containing carbon atoms of the present invention having a resistance of 1.39 times better and a durability of 1.09 times better than the conventional photovoltaic element Element (Element N
o. As compared with the ratio 6), it was found to have excellent characteristics, and the effect of the present invention was demonstrated.

[0182]

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

In addition, since a large number of carbon atoms are distributed on the semiconductor layer side of the transparent electrode, structural distortion due to a difference in material between the transparent electrode and the semiconductor layer can be reduced.

[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 illustrating a layer configuration of a conventional photovoltaic element.

FIG. 3 is an example of an apparatus for producing a transparent electrode used in the photovoltaic element of the present invention, and is a schematic explanatory view of a production apparatus by a DC magnetron sputtering method.

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

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

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

[Explanation of symbols]

101 conductive base, 102 light reflective layer (conductive), 103 reflection enhancement layer, 104 first conductive type layer (p-type or n-type), 105 i-type layer, 106 second conductive type layer (p-type or n-type), 107 transparent electrode, 108 current collecting electrode, 109 irradiation light, 201 conductive substrate, 202 light reflecting layer (conductive), 203 reflection increasing layer, 204 first conductive type layer (p-type or n-type) 205 i-type layer, 206 second 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 gauge, 313 Conductance valve 314, 315 gas introduction valve, 316, 317 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, 512 gas introduction valve, 511, 513 Mass flow controller 1000 μW glow discharge decomposition method film forming apparatus, 1001 deposition chamber, 1002 derivative window, 1003 gas introduction tube, 1004 substrate, 1005 heating heater, 1006 vacuum gauge, 1007 conductance valve, 1008 Auxiliary valve, 1009 Leak valve, 1010 Waveguide, 1011 Bias power supply, 1012 Bias rod, 1020 Source gas supply device, 1021 to 1026 Mass flow control 1031-1036 Gas inflow valve, 1041-1046 Gas outflow valve, 1051-1056 Source gas cylinder valve, 1061-1066 Pressure regulator, 1071-1076 Source gas cylinder, 1100 Film forming apparatus by RF glow discharge decomposition method, 1101 Deposition Chamber, 1102 cathode, 1103 gas inlet tube, 1104 substrate, 1105 heating heater, 1106 vacuum gauge, 1107 conductance valve, 1108 auxiliary valve, 1109 leak valve, 1112 RF matching box.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-57-42173 (JP, A) JP-A-60-211987 (JP, A) JP-A-62-35680 (JP, A) JP-A 63-42680 310505 (JP, A) JP-A-1-261469 (JP, A) JP-A-2-168507 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 31/04

Claims (7)

(57) [Claims] 1. A photovoltaic device comprising at least a semiconductor layer made of a non-single-crystal semiconductor material containing silicon atoms laminated on a conductive substrate, and a transparent electrode laminated on the semiconductor layer. In the power element, the transparent electrode is formed of an oxide containing carbon atoms, and the carbon atoms are distributed more on the semiconductor layer side of the transparent electrode than on the side opposite to the semiconductor layer. Photovoltaic element. 2. The photovoltaic device according to claim 1, wherein said oxide is indium oxide, tin oxide, or indium-tin oxide. 3. The photovoltaic device according to claim 1, wherein the semiconductor layer is formed by laminating a p-type layer, an i-type layer, and an n-type layer. 4. The photovoltaic device according to claim 1, wherein said non-single-crystal semiconductor material is an amorphous semiconductor material. 5. The photovoltaic device according to claim 1, wherein the non-single-crystal semiconductor material is a polycrystalline semiconductor material. 6. The method according to claim 1, wherein the carbon atoms are distributed so as to decrease substantially exponentially from the interface between the transparent electrode and the semiconductor layer toward the inside of the transparent electrode. Item 2. The photovoltaic element according to Item 1. 7. The maximum distribution concentration of carbon atoms is 5 ppm to 1
The photovoltaic device according to any one of claims 1 to 6, wherein the content is 000 ppm.