JP2984430B2 - 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 photovoltaic device such as a solar cell having a transparent electrode of an oxide such as indium oxide, tin oxide or indium-tin oxide, and a photosensor.

[0002]

2. Description of the Related Art Transparent electrodes are important components related to the performance of photovoltaic devices. Conventionally, such a transparent electrode,
Indium oxide, tin oxide, and indium-tin oxide were used and deposited in a film form by a spray method, a vacuum evaporation 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 adjacent to the transparent electrode.

The relationship between the photovoltaic element and the transparent electrode in recent years is described in “Optical Absorption Option”.
transparent conducting oxi
des and power dissipation
in a-Si: H pin solar cell
s measured by phototherma
l deflection spectroscope
y "F. Lelanc, J. Perrin et.a
l. Technical digest of the
international PVSEC-5. Kyo
to. Japan 1990, 253. And "Impro
element of interface prop
rties of TCO / p-layer in p
in-type amorphous silicon
solar cells "Y. Ashida, NI
shiguro et. al. Technical d
event of the internationala
l PVSEC-5. Kyoto, Japan, 199
0,367. It is described in.

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.

[0006]

2. Description of the Related Art There is a demand for a further reduction in the resistance of the conventional transparent electrodes made of indium oxide, tin oxide and indium-tin oxide.

[0007] Further, it is desired to further improve the transmittance of the transparent electrode.

Further, as photovoltaic elements have been widely used in general, the usage environment of the photovoltaic element has been diversified, and depending on the usage environment, the layer between the transparent electrode and the layer which is in close contact with each other may be formed. There was a problem that peeling occurred.

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

[0010]

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 remove the distortion of the transparent electrode and increase the photovoltaic power and photocurrent of the photovoltaic element.

An object of the present invention is to reduce the abnormal deposition of a non-single-crystal silicon-based semiconductor layer deposited on a transparent electrode and deposit a uniform non-single-crystal silicon-based semiconductor layer. It is another object of the present invention to provide a photovoltaic element having stable characteristics.

An object of the present invention is to reduce structural distortion between a transparent electrode of a photovoltaic element and a semiconductor layer adjacent to the transparent electrode.

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

[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.

The photovoltaic device of the present invention is a photovoltaic device comprising a photoelectric conversion layer made of a non-single-crystal semiconductor material containing at least silicon atoms and a transparent electrode laminated on a substrate having a conductive surface. In the electromotive force element, the transparent electrode is made of an oxide containing a nitrogen atom, and the nitrogen atom is distributed so as to be contained more in the oxide on the semiconductor layer side. is there.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 are schematic explanatory views of a photovoltaic device according to the present invention. The photovoltaic element of the present invention shown in FIG. 1 has a light reflecting layer (conductive) 102, a reflection increasing layer 103, an n-side (or p-side) on an opaque conductive substrate 101.
(Type) non-single-crystal silicon-based semiconductor layer 104, i-type (substantially intrinsic) non-single-crystal silicon-based semiconductor layer 105, p-type (or n-type) non-single-crystal silicon-based semiconductor layer 106, semiconductor layer side And a current collecting electrode 108 containing a large amount of nitrogen atoms. Light is applied 109 to the photovoltaic element from the transparent electrode 107 side.

The photovoltaic element according to the present invention shown in FIG. 2 has a tandem structure, and has a collector electrode 20 on a transparent substrate 201.
8. Transparent electrode 20 containing a large amount of nitrogen 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) Type) non-single-crystal silicon-based semiconductor layer 204a, reflection increasing layer 203, light reflecting layer (conductive) 202, conductive layer (or / and protective layer) 21
0.

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 suitably a tin oxide, indium oxide, or a transparent electrode containing indium-tin oxide containing nitrogen atoms.

In a transparent electrode in which a nitrogen atom is contained in a tin oxide, an indium oxide, or an indium-tin oxide, the crystal system of the oxide constituting the transparent electrode is increased, and the dispersion of the crystal grain size is increased. Is considered to be smaller. Further, it is considered that the distortion of the germicidal electrode can be reduced by adding a nitrogen atom to the transparent electrode. It is considered that the specific resistance of the transparent electrode can be reduced by such a method, and the transmittance of the transparent electrode can be improved.

In addition, by making the transparent electrode contain nitrogen atoms, the crystal shape of the oxide constituting the transparent electrode can be made relatively smooth, and the surface properties of the transparent electrode can be improved. It is considered possible. 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. Further, when depositing a non-single-crystal silicon-based semiconductor layer 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, since the nitrogen atoms are more 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.

In the present invention, the shape of the distribution of nitrogen atoms contained in the transparent electrode generally decreases exponentially from near the interface between the transparent electrode and the semiconductor layer toward the inside of the transparent electrode. Preferred are mentioned. Since the nitrogen atoms are exponentially distributed in the transparent electrode as described above, structural distortion due to a difference in material between the transparent electrode and the semiconductor layer can be effectively reduced, and nitrogen atoms in the transparent electrode can be effectively reduced. It is possible to minimize the change in characteristics due to the diffusion over time.

The preferred distribution range of the exponential distribution of the nitrogen atoms is 30 ° to 500 °.

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

The transparent electrode containing a nitrogen atom of the present invention is deposited as follows.

For the deposition of the nitrogen-containing transparent electrode of the present invention, a sputtering method and a vacuum deposition method are the most suitable deposition methods.

As a sputtering apparatus suitable for depositing the nitrogen-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 nitrogen-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, 315, 316, mass flow controllers 317, 318, 319, etc.

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

When the transparent electrode made of indium oxide containing a nitrogen atom of the present invention is deposited on a substrate, the target may be a metal atom-containing substance such as metal indium (In) or indium oxide (In ₂ O ₃ ). Is used.

Further, when the transparent electrode made of indium-tin oxide containing a nitrogen 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 nitrogen atom-containing substance is contained in an indium-tin oxide or the like. By preparing multiple targets with different nitrogen contents and changing the aperture ratio of the shutter with respect to the targets,
The content of the nitrogen content in the transparent electrode can be distributed.

When the transparent electrode of the present invention is deposited by a reactive sputtering method, the target and / or the target not containing a nitrogen atom are appropriately combined,
As a target for sputtering, a source gas containing nitrogen locally can be introduced into the deposition chamber, and nitrogen atoms can be introduced into the transparent electrode using plasma energy. At this time, by changing the introduction amount of the nitrogen-containing source gas into the deposition chamber, the nitrogen atom content in the transparent electrode can be introduced into a desired distribution.

N ₂ , NH ₃ , ND ₃ , NO, and N ₂
NO ₂ and N ₂ O are mentioned.

The maximum distribution concentration of the content of nitrogen atoms 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 in the transparent electrode is 1000
In order to contain nitrogen atoms of 5 ppm or less, the content of nitrogen atoms contained in the target largely depends on sputtering conditions, but the maximum distribution concentration is preferably 1000 ppm or less.

In order to make the transparent electrode contain nitrogen atoms having a maximum distribution concentration of 1000 ppm or less by the reactive sputtering method, the mixing ratio of the nitrogen atom-containing gas to the sputtering gas is generally 2000 ppm or less. Is a preferred range.

When depositing the nitrogen-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 nitrogen atom according to 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. In the case where the transparent electrode containing a nitrogen atom of the present invention is deposited by a sputtering method, a sputtering gas such as an argon gas (Ar), a neon gas (Ne), a xenon gas (Xe), a helium gas (He), or the like is used. 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.

Further, when sputtering the target with the above-mentioned inert gas or the like, the pressure in the discharge space is set to 0.1 to 50 mtorr in order to effectively perform sputtering.
Is a preferred range.

In addition, in the case of the sputtering method, a DC power supply or an rf power supply is suitable as a power supply.
A suitable range for the electric power during sputtering is 10 to 1000 W.

The deposition rate of the nitrogen-containing transparent electrode 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 0.1 to 100 ° / sec.

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

As schematically shown in FIG. 5, the vacuum evaporation 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.

Examples of the deposition source suitable for depositing the nitrogen-containing transparent electrode of the present invention in a vacuum deposition method include metal tin, metal indium, and an indium-tin alloy to which the above-mentioned nitrogen atom-containing substance is added. Can be As the content of the nitrogen atom, a maximum distribution concentration of about 1000
ppm or less is a suitable range.

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

Further, when depositing the nitrogen-containing transparent electrode of the present invention, the pressure in the deposition chamber is reduced to 10 ⁻⁶ torr or less, and then oxygen gas (O ₂ ) is supplied to 5 × 10 ⁻⁵ torr to 9 × 10 ⁻⁵ torr.
It is necessary to introduce into the deposition chamber in the range of × 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 nitrogen-containing transparent electrode of the present invention is deposited by reactive deposition, the deposition source and / or the deposition source containing no nitrogen atom is placed in the deposition chamber by 5 × 10 5 ^{With -4} torr or less installed,
The transparent electrode may be deposited by evaporation. 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 nitrogen atom-containing gas into the deposition chamber over time, the content of nitrogen atoms contained in the transparent electrode can be controlled to a desired distribution. Further, the amount of nitrogen atoms contained in the transparent electrode can be controlled to a desired distribution by changing the deposition rate of the vapor deposition source while keeping the amount of the nitrogen 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 0.1 to 100 ° / sec. When the deposition rate is less than 0.1 ° / sec, the productivity is reduced. When the deposition rate is more than 100 ° / 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 nitrogen atoms be deposited under conditions that satisfy the conditions of the antireflection film. A preferred range of the layer thickness of the transparent electrode is from 500 ° to 3000 °.

The characteristics of the photovoltaic device can be further improved by simultaneously containing carbon atoms in the nitrogen-containing transparent electrode of the present invention.

By simultaneously containing nitrogen atoms and carbon atoms in the transparent electrode, the durability of the photovoltaic device of the present invention to a heat cycle is further improved. Further, the flexibility of the transparent electrode is further improved, and the crack of the photovoltaic element is further improved.

The amount of carbon atoms added to the transparent electrodes of the photovoltaic device of the present invention in addition to nitrogen atoms is 100 ppm.
The following are preferred ranges.

The method for introducing the carbon atoms into the transparent electrode is the same as the method for introducing the nitrogen atoms.

Carbon atoms can be contained in the transparent electrode by performing sputtering or vacuum deposition using the above-mentioned target or deposition source for depositing the transparent electrode or a deposition source containing carbon atoms. Graphite-like carbon, diamond-like carbon, or the like is suitable as a starting material of carbon atoms to be contained in the target or the evaporation source.

When the transparent electrode containing nitrogen and carbon atoms of the present invention is deposited by the reactive sputtering method, the target and / or the target not containing carbon atoms are appropriately combined, and the target for nitrogen is used as a sputtering target. In addition to the atom-containing source gas, a carbon atom-containing source gas is introduced into the deposition chamber, and the plasma energy can be used to introduce carbon atoms in addition to nitrogen atoms into the transparent electrode using plasma energy.

As the carbon atom-containing source gas suitable for the reactive sputtering method, 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, C
O ₂ , CO and the like can be mentioned.

When depositing a transparent electrode containing carbon atoms in addition to nitrogen atoms of the present invention by reactive deposition, the above-mentioned deposition source and / or the above-mentioned deposition source containing no carbon atoms are deposited with the above-mentioned gas containing carbon atoms. The transparent electrode may be deposited by evaporating in a state where 5 × 10 ⁻⁴ torr or less is introduced into the room. 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.

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 or n-type layer of the photovoltaic device of the present invention has an amorphous material (denoted as a-) or a microcrystalline material (μc
For example, a-Si: H, a-S
i: HX, a-SiC: H, a-SiC: HX, a-S
iGe: H, a-SiGeC: H, a-SiO: H, a
-SiN: H, a-SiON: HX, a-SiOCN:
HX, μc-Si: H, μc-SiC: H, μc-S
i: HX, μc-SiC: HX, μc-SiGe: H,
μc-SiO: H, μc-SiGe: H, μc-Si
N: H, μc-SiON: HX, μc-SiOCN: H
X, etc., are p-type valence electron control agents (Group III atoms B, Al, Ga, In, and Tl in the periodic table) and n-type valence electron control agents (Group V atoms P, As, and Sb in the periodic table). , Bi) at a high concentration, and a polycrystalline material (denoted as poly-) is, for example, poly-Si: H, po.
ly-Si: HX, poly-SiC: H, poly-
SiC: HX, poly-SiGe: H, poly-S
i, poly-SiC, poly-SiGe, etc., a p-type valence electron controlling agent (Group III atoms B, Al, G
a, In, Tl) and n-type valence electron controlling agents (Periodic Table No. V
Materials to which group atoms P, As, Sb, and Bi) are added in 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 in the periodic table to the p-type layer and the addition amount of Group V atoms in the periodic table to the n-type layer are set to 0.
The optimal amount is 1 to 50 at%.

The 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 amount 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 content of hydrogen atoms and / or halogen atoms is distributed on each interface side of the p-type layer / i-type layer and the n-type layer / i-type layer. The 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, a transparent electrode / p-type layer or a transparent electrode /
A preferred distribution form includes a large distribution of hydrogen atoms and / or halogen atoms at each interface side of the n-type layer, and the content of hydrogen atoms and / or halogen atoms near the interface is bulk. The range of 1.1 to 2 times the content of the above is mentioned as a preferable 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 electrical 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 0.1 eV or less. The non-resistance is preferably 100 Ωcm or less,
The optimal value is 1 Ωcm or less. Further, the layer thicknesses of the p-type layer and the n-type layer are preferably from 10 ° to 500 °, and from 30 ° to 100 °.
Is optimal.

The source gas suitable for the p-type or n-type layer no deposition 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 nitrogen atom. And the like, and a gas mixture 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 ₈ , 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.

Specific examples of the gasizable compound containing a carbon atom 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.

As the nitrogen-containing gas, N ₂ , NH ₃ , N
D ₃ , NO, NO ₂ , and N ₂ O.

As the oxygen-containing gas, 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 includes the periodic table I.
Group II and Group V atoms are included.

In the present invention, those which can be effectively used as starting materials for introducing Group III atoms, specifically, those for introducing boron atoms include B ₂ H ₆ , B ₄ H ₁₀ , and B _5. H
_{9, B 5 H 11, B} 6 H 10, B 6 H 12, B 6 H 14 hydride such as boron, BF _3, BCl _3, and halogenated boron such as equal. In addition, AlCl ₃ , GaCl ₃ , I
nCl ₃ , TlCl _{3 and the} like can also be mentioned. Especially B ₂
H ₆ and BF ₃ are suitable.

In the present invention, the starting material for introducing a group V atom is effectively used, specifically, for introducing a phosphorus atom, for example, a hydrogenated phosphorus such as PH ₃ or P ₂ H ₄ ; 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 ₃ are suitable.

The p-type or n-type layer deposition method suitable for the photovoltaic device of the present invention is an rf plasma CVD method and a μw plasma CVD method.

In particular, when depositing by the rf plasma CVD method, the capacitively coupled rf plasma CVD method 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 0.1
Å30 ° / sec is an optimum condition.

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, 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. A suitable range of the rf frequency is 1 MHz to 100 MHz, 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 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 via a waveguide is suitable.

A p-type layer or an n-type layer suitable for the present invention is 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 r and μw powers are preferably 0.01 to 1 W / cm ³ , and the μw frequency is preferably 0.5 to 10 GHz.

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 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 for generating and transporting 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. When a semiconductor layer whose hole mobility and lifetime product are smaller than electron mobility and lifetime product is used as the i-type layer, a slightly p-type layer is suitable. When a semiconductor layer whose electron mobility and lifetime product are smaller than the hole mobility and lifetime product is used as the i-type layer, only n
Mold layers are suitable.

As the i-type layer of the photovoltaic device of the present invention, an amorphous material (denoted as a-), for example, a-Si: H,
a-Si: HX, a-SiC: H, a-SiC: HX,
a-SiGe: H, a-SiGe: Hx, a-SiGe
C: HX and the like.

In particular, as the i-type layer, a group III atom or /
And a group V atom to form an intrinsic (in
(trisnic) materials are preferred.

The hydrogen atoms (H, D) or the halogen atoms (X) contained in the i-type layer work to compensate for dangling bonds of the i-type layer, and the mobility and lifetime of carriers in the i-type layer. To improve the product of Also, a p-type layer / i-type layer, an n-type layer /
It functions to compensate for the interface state of each interface of the i-type layer, and has the effect of improving the photovoltaic power, photocurrent and photoresponsiveness of the photovoltaic element. The optimal content of hydrogen atoms and / or halogen atoms contained in the i-type layer is 1 to 40 at%. In particular, p-type layer / i-type layer, n-type layer /
A preferred distribution form includes a large distribution of hydrogen atoms and / or halogen atoms on each interface side of the i-type layer, and the content of hydrogen atoms and / or halogen atoms near the interface is bulk. The range of 1.1 to 2 times the content of the above is mentioned as a preferable 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 are as follows. In order to effectively achieve the object of the present invention, the electron mobility is 0.01 cm ² / cm.
V / sec or more, hole mobility is 0.0001 cm ² /
V / sec or more, band gap is 1.1 to 2.2e
V, the localization density at the center of the forbidden band is 10 ¹⁸ / cm ³ / eV or less, and the slope of the purbachtilt on the valence band side is 65 meV.
The following are preferred ranges. Furthermore, the current-voltage characteristics of the photovoltaic device of the present invention were measured at AM 1.5 and 100 mW / cm ² , curve fitting was performed by the Hecht equation, and the mobility lifetime product obtained from the curve fitting was 10 ⁻¹⁰ cm ^2. / V or more.

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. With such a design, 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 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 , 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.

Specifically, a gas containing a germanium atom
The compound which can be converted to is GeH_Four, GeD_Four, GeF_Four,
GeFH_Three, GeF_TwoH_Two, GeF_ThreeH, GeHD_Three, Ge
H_TwoD _Two, GeH_ThreeD, GeH₆, GeD₆Etc.
You.

Specific examples of the gasizable compound containing a carbon atom 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 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 III.
Group atoms and group V atoms.

In the present invention, those which can be effectively used as starting materials for introducing Group III atoms, specifically, those for introducing boron atoms include B ₂ H ₆ , B ₄ H ₁₀ and B _5. H
_{9, B 5 H 11, B} 6 H 10, B 6 H 12, B 6 H 14 hydride such as boron, BF _3, BCl _3, and halogenated boron such as equal. 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 is effectively used, specifically, for introducing a phosphorus atom, for example, hydrogen phosphide such as PH ₃ or P ₂ H ₄ ; 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.

The amount of Group III and Group V atoms introduced into the i-type layer to control the conductivity type is 1
The preferred range is 000 ppm or less.

Examples of the method for depositing an i-type layer suitable for the present invention include rf plasma CVD and μw plasma CVD. In the case of the rf plasma CVD method, a capacitively coupled rf plasma CVD apparatus is particularly suitable.

When depositing an i-type layer 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.
１．０1.0 W / cm ² , the deposition rate is 0.1-30 A / s
ec is mentioned as an optimal condition.

Further, 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, 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. is there. The frequency of rf 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 a microwave through a waveguide into a deposition chamber 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 ³ , μw frequency 0.5-1
0 GHz is mentioned as a preferable range.

Further, 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, 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 a hydrogen gas and to introduce a relatively high μw power. is there.

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. Examples of the conductive support include NiCr, stainless steel, Al, Cr, Mo, and A.
Examples thereof include metals such as u, Nb, Ta, V, Ti, Pt, Pb, and Sn, and alloys thereof.

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 and the like. 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, N
iCr, 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
A metal thin film of u, Cr, Mo, Ir, Nb, Ta, V, Tl, Pt, etc. 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 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.

[0112]

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 nitrogen atoms in a distributed manner 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 denotes a composition of indium (In).
And a target having a molar ratio of tin (Sn) of 85:15, and is insulated from the deposition chamber 301 by the insulating support 305.

In the figure, reference numerals 314 to 316 denote gas introduction valves, each of which is an oxygen (O ₂ ) gas cylinder (not shown), an argon (Ar) gas cylinder, and 50 ppm of oxygen (O ₂ ) gas.
(N ₂ ) gas (hereinafter abbreviated as “N ₂ / O ₂ ”).

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).
^-5 Torr, gas introduction valves 314-3
16 was gradually opened to allow O ₂ gas, Ar gas, and N ₂ / O ₂ gas to flow into the deposition chamber 301. At this time, the O ₂ gas flow rate was 15 sccm, the Ar gas flow rate was 20 sccm, and N ₂ /
The mass flow controllers 317 to 319 adjust the O ₂ gas flow rate to 5 sccm, and the deposition chamber 3
Vacuum gauge 31 so that the pressure inside the pressure gauge 01 becomes 2 mTorr.
Conductance valve (butterfly type) while watching 2
Thirteen openings were adjusted. 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 start production of a transparent electrode on the substrate 302. At the same time, the O ₂ gas flow rate is changed from 15 sccm to 5 sccc.
m, N ₂ / O ₂ gas flow rate from 5 sccm to 15 sccm
Then, the mass flow controllers 517 and 519 were adjusted so as to change at a constant rate, and a transparent electrode having a layer thickness of 70 nm was produced.
The output of the C power supply 306 was turned off to stop DC glow discharge.
Next, the gas introduction valves 315 and 316 are closed to stop the flow of the Ar gas and the N ₂ / O ₂ gas into the deposition chamber 301 so that 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 containing nitrogen atoms distributed therein.

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 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 denotes a H ₂ gas (purity 99.9999%) cylinder, 1073 denotes a B ₂ H ₆ gas (purity 99.99%, purity 99.99% diluted with H ₂ gas).
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 produced 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 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 ₆ / H ₂ gas were introduced into the deposition chamber 1001 through the gas introduction pipe 1003. At this time, the flow rate of the SiH ₄ gas was 10 sccm, and the flow rate of the H ₂ gas was 100 sccc.
m and each of the mass flow controllers 1021 to 1023 were adjusted so that the flow rate of the B ₂ H ₆ / H ₂ gas was 5 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 20 mTorr. Thereafter, μW (not shown)
The power of the power supply was set to 400 mW / cm ³ , and μW power was introduced into the deposition chamber 1001 through the waveguide (not shown), the waveguide 1010, and the dielectric window 1002 to generate μW glow discharge, and the Preparation of p-type layer started, layer thickness 5n
When the p-type layer of m was produced, the μW glow discharge was stopped,
Outflow valves 1041 to 1043 and auxiliary valve 1008
Was closed, the flow of gas into the deposition chamber 1001 was stopped, and the formation 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 the heater 1005, and the outflow valves 1041, 1042 and the auxiliary valve 1008 were gradually opened to supply SiH ₄ gas and H ₂ gas to the gas introduction pipe 10.
03 into the deposition chamber 1001. At this time,
SiH ₄ gas flow rate is 100 sccm, H ₂ gas flow rate is 20
Each mass flow controller 1021 and 1022 adjusted so as to be 0 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 was 5 mTorr. Next, the high frequency (hereinafter abbreviated as “RF”) bias of the bias power supply is set to 100 mW / cm ³ , the DC bias is set to 75 V with respect to the substrate 1004, and the bias rod 10 is set.
12 was applied. Thereafter, the power of the μW power supply (not shown) is reduced by 1
Set to 00 mW / cm ³ , and a waveguide (not shown)
ΜW power was introduced into the deposition chamber 1001 through 010 and the dielectric window 1002 to generate a μW glow discharge, and an i-type layer was started to be formed on the p-type layer. The μW glow discharge was stopped, the output of the bias power supply 1011 was turned off, and the fabrication 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 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. Thereafter, the power of a μW power supply (not shown) was set to 50 mW / cm ^3, and a waveguide (not shown)
Deposition chamber 1 through waveguide 1010 and dielectric window 1002
ΜW power is introduced into 001 to generate a μW glow discharge to start the production of an n-type layer on the i-type layer. When the n-type layer having a thickness of 10 nm 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 forming each layer, it goes without saying that the outflow valves 1041 to 1046 other than the necessary gas are completely closed. Further, each gas is supplied into the deposition chamber 1001 and outflow valve 1041. Outflow valves 1041 to 1046 are closed, auxiliary valve 1008 is opened, and conductance valve 1007
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.

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 by a DC magnetron sputtering method manufacturing apparatus shown in FIG.

The substrate 302 was heated at 350 ° C.
, And O ₂ gas is introduced into the deposition chamber 301 at 20 sccm.
Alcon gas was introduced at a flow rate of 20 sccm, and the pressure in the deposition chamber 301 was adjusted to 2 mTorr. Then, DC power 3
10 is set to −400 V, and the target 304
To generate DC glow discharge, and then open the shutter 307 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 307 is closed. The output of the DC power supply 306 was turned off to stop the DC glow discharge. 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).

Example 1 (Element No. Example 1) and Comparative Example 1
The initial characteristics and the durability of the photovoltaic element manufactured in (element No. ratio 1) were measured.

The measurement of the initial characteristics was performed in Example 1 (element NO.
The photovoltaic elements manufactured in Example 1) and Comparative Example 1 (element No. ratio 1) were installed under AM-1.5 (100 mW / cm ² ) light irradiation to measure VI characteristics. 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 1.05 times that of the photovoltaic element of comparative example 1 (element NO. Was 1.40 times better.

The measurement of the durability characteristics was performed in Example 1 (element NO.
The photovoltaic elements manufactured in Example 1) and Comparative Example 1 (element No. ratio 1) were left in a dark place with a humidity of 85%, and were subjected to a heat cycle of 85 ° C. for 4 hours and a temperature of −40 ° C. for 30 minutes. 30
The measurement was performed by changing the photoelectric conversion efficiency after the application. As a result of the measurement, the photovoltaic element of Example 1 (element No. Ex. 1) showed a reduction in photoelectric conversion efficiency of 1.10 times that of the photovoltaic element of Comparative Example 1 (element No. ratio 1). It was excellent.

The distribution of nitrogen 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 nitrogen atoms was clearly reduced from the p-type layer side to the substrate side.

From the above measurement results, the photovoltaic element using the transparent electrode containing a nitrogen atom of the present invention (element No. 1) was different from the conventional photovoltaic element (element 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 the alloys shown in Table 2 were used as the material of the target 304. Then, a back electrode was prepared to produce a photovoltaic element (element Nos. 2-1 to 9).

The fabricated photovoltaic element (element NO.
1 to 9) were measured for initial properties and durability in the same manner as in Example 1. Table 2 shows the results. As can be seen from Table 2, the photovoltaic devices of the present invention (elements Nos. 2-1 to 9 using a transparent electrode containing nitrogen atoms in a distributed manner) are different from the conventional photovoltaic elements (element number ratios). In contrast to 1), it was found to have excellent characteristics, and the effect of the present invention was proved.

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. Ex. 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 Comparative Example 1, except that a transparent electrode was formed on the substrate. A mold layer and a back electrode were prepared to produce a photovoltaic element (element number 2).

Example 3 (Element No. 3) and Comparative Example 2
The initial characteristics and the durability characteristics of the photovoltaic device manufactured with (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. Actual 3) was 1.06 times as large as that of the photovoltaic element of Comparative Example 2 (element No. The characteristics are 1.
37 times better and 1.10 times better in durability, the photovoltaic device of the present invention using a transparent electrode containing nitrogen atoms distributed therein (device No. 3) is a conventional photovoltaic device. (Element NO. 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 nitrogen 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 ZnO thin film of 1 μm was deposited by a DC magnetron sputtering method as a reflection increasing layer, and further, a 300 nm silver thin film was deposited by a DC magnetron sputtering method on a light reflecting layer.
In the same manner as in the above, a back electrode was produced to produce a photovoltaic element.
(Element No. Ex . 4) Comparative Example 3 A transparent electrode, a p-type layer, and i were formed on a substrate under the same production conditions as in Example 4 except that a transparent electrode was produced on the substrate under the same production conditions as Comparative Example 1. A photovoltaic device was manufactured by forming a mold layer, an n-type 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. Ex. 4) and Comparative Example 3
The initial characteristics and the durability of the photovoltaic element manufactured with (element No. ratio 3) 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 4 (element No. 4) was 1.08 times that of the photovoltaic element of comparative example 3 (element No. ratio 3), The resistance is 1.
41 times better and 1.10 times better in durability, the photovoltaic device of the present invention using a transparent electrode containing nitrogen atoms distributed therein (device No. 4) is a conventional photovoltaic device. (Element NO. Ratio 3), it was found to have excellent characteristics, 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 nitrogen atoms in a distributed manner was formed on a substrate by a vacuum evaporation method manufacturing apparatus shown in FIG.

In the figure, reference numeral 502 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 504 denotes a composition of indium (I
There is an evaporation source having a molar ratio of n: 1 to tin (Sn) of 1: 1.

In the figure, reference numeral 510 denotes a gas introduction valve, which is an N ₂ gas (N ₂ / N) diluted to 50 ppm with an O ₂ gas (not shown).
O ₂ ) Connected to the cylinder.

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).
^-5 Torr, the gas introduction valves 510, 5
12 is gradually opened to deposit N ₂ / O ₂ gas and O ₂ gas in the deposition chamber 5.
01. At this time, the N ₂ / O ₂ gas flow was 3 seconds.
The mass flow controllers 511 and 513 adjust the flow rate of ccm and O ₂ gas to 7 sccm, respectively.
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. Thereafter, power is supplied from the AC power supply 506 to the heater 505 to heat the deposition source 504, and then the shutter 507 is opened,
Production of a transparent electrode on the substrate 502 is started, and at the same time, N ₂ /
The O ₂ gas flows into the 7 sccm from 3 sccm, the O ₂ gas flows into the 3 sccm from 7 sccm, so as to vary at a constant rate, the corresponding mass flow controllers 511,5
13, when a transparent electrode having a layer thickness of 70 nm was prepared, the shutter 507 was closed, the output of the AC power supply 506 was turned off, the gas introduction valves 510 and 512 were closed, and the flow of gas into the deposition chamber 501 was stopped. The fabrication of a transparent electrode containing atoms in a distributed manner has been 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 manufacturing apparatus of a vacuum evaporation method shown in FIG.

As in Example 5, the substrate 502 was heated to 350 ° C. by the heater 503 and the gas introduction valve 5
12 is gradually opened, an O ₂ gas flow rate of 10 sccm is introduced into the deposition chamber 501, and the pressure in the deposition chamber 501 is reduced to 0.3.
Adjusted to mTorr. 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. When the device is manufactured, the shirt star 507 is closed, and the AC power source 50 is closed.
6, 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).

The initial characteristics and durability characteristics of the photovoltaic elements manufactured in Example 5 (element No. 5) and comparative example (element No. ratio 4) were measured in the same manner as in Example 1. Was. As a result of the measurement, the short-circuit current of the photovoltaic element of Example 5 (Element No. Actual 5) was 1.07 times larger than that of Comparative Example 4 (Element No. The resistance is 1.
The photovoltaic device using the transparent electrode containing the nitrogen atoms in a distributed manner (element No. 5) of the present invention is 42 times better and the durability is 1.10 times better than the conventional photovoltaic device. (Element NO. Ratio 4), it was found to have excellent characteristics, and the effect of the present invention was demonstrated.

Further, the distribution of nitrogen 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 nitrogen atoms was clearly reduced from the p-type layer side to the substrate side.

Example 6 A 50 mm square, 1 mm thick stainless steel (SUS430B
A) using a conductive substrate made of mirror-finished surface,
A 300 nm silver thin film as a light reflecting layer and a 1 μm ZnO thin film as a reflection increasing layer were deposited on the conductive substrate by DC magnetron sputtering. 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.

Next, a transparent electrode was formed on the P-type layer in the same manner as in Example 5. Substrate temperature 200 ° C, N 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 to heat the deposition source 504, open the shutter 507, and start producing a transparent electrode on the substrate 502, and at the same time, increase the N ₂ / O ₂ gas flow rate from 7 sccm to 3 sccc.
m, and the O ₂ gas flow rate was adjusted from 3 sccm to 7 sccm at a constant rate by the respective mass flow controllers 511 and 513. When a transparent electrode having a layer thickness of 70 nm was produced, the shutter 507 was closed and the AC power supply was turned off. The output of 506 is turned off, and the gas introduction valves 510 and 512 are turned off.
Is closed to stop the gas from flowing into the deposition chamber 501, to produce a transparent electrode containing nitrogen atoms distributed on the p-type layer.
AI was applied as a current collecting electrode on the transparent electrode by vacuum evaporation to 2 μm.
m was deposited to produce a photovoltaic element (element No. Ex. 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 0 ° C.
Similarly to the above, a current collecting electrode was prepared to produce a photovoltaic element (element NO. Ratio 5).

Example 6 (Element No. Ex. 6) and Comparative Example 5
The initial characteristics and the durability characteristics of the photovoltaic device manufactured with (element ratio 5) were measured in the same manner as in Example 1. As a result of the measurement, the photovoltaic element of Example 6 (element No. 6) has a short-circuit current 1.07 times that of the photovoltaic element of Comparative Example 5 (element NO. Is 1.4
The photovoltaic element (element No. 6) using the transparent electrode of the present invention, which is four times better and has a durability of 1.11 times better, and which contains nitrogen atoms in a distributed manner, is a 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 nitrogen atoms in the transparent electrode of the photovoltaic device of Example 6 (element No. 6) was analyzed by a two-ion mass spectrometer (IMS-3F manufactured by CAMECA). It was confirmed that the content of nitrogen atoms clearly increased from the surface 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 nitrogen atoms distributed on a substrate was manufactured 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, each gas cylinder 1071 to 1076 is sealed with the same raw material gas as in the first embodiment, and each gas is introduced into the mass flow controllers 1021 to 1026 in the same operation procedure as in the first embodiment.

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.

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 flow rate of the H ₂ gas is 50 sccm, and the flow rate of the B ₂ H ₆ / H ₂ gas is 1 sccm.
Each mass flow controller 1021
Adjusted at 1023. The pressure in the deposition chamber 1101 is 1T
The opening of the conductance valve 1107 was adjusted while looking at the vacuum gauge 1106 so that the pressure became orr. Thereafter, the power of an RF power supply (not shown) was set to 200 mW / cm ³ , and R
Cathode 110 through F matching box 1112
2, an RF power was introduced to generate an RF glow discharge, and a p-type layer was formed on the transparent electrode. When a p-type layer having a thickness of 5 nm was formed, the RF glow discharge was stopped. And the auxiliary valve 1108 is closed,
The flow of gas into the deposition chamber 1101 was stopped, and the production 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 to supply SiH ₄ gas and H ₂ gas to the gas introduction pipe 11.
03 into the deposition chamber 1101. At this time,
SiH ₄ gas flow rate ₂ sccm, H ₂ gas flow rate 20 sc
cm 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,
Set the power of the RF power source (not shown) to 5mW / CM ^3, 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, and the outflow valve 1044 was gradually opened to allow SiH ₄ gas, H ₂ gas, and B ₂ H ₆ / H ₂ gas to flow into the deposition chamber 1101 through the gas introduction pipe 1103. Was. At this time, the flow rate of the SiH ₄ gas was ₂ sccm, the flow rate of the H ₂ gas was 20 sccm, and B ₂ H ₆
Each of the mass flow controllers 1021, 1022, and 1024 was adjusted so that the / H ₂ gas flow rate was 1 sccm. The pressure inside the deposition chamber 1101 becomes 1 Torr while watching the vacuum gauge 1106 while the conductance valve 1
The opening of 107 was adjusted. Thereafter, the power of an RF power source (not shown) is set to 5 mW / CM ³ , RF power is introduced to the cathode 1102 through the RF matching box 1112, RF glow discharge is generated, and an n-type layer is formed on the i-type layer. Starting, when an n-type layer having a thickness of 10 nm is formed, the RF glow discharge is stopped, and the outflow valves 1041 and 104
2, 1044 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 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 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 required.

Next, a back electrode was vapor-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.

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. Actual 7) and Comparative Example 6
Example 1 shows a photovoltaic element manufactured according to Example 1 (element number ratio 6).
The initial characteristics and durability 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 7 (element No. 7) was 1.07 times that of the photovoltaic element of Comparative Example 6 (element No. Resistance is 1.41
The photovoltaic device of the present invention (element No. 7) using a transparent electrode containing nitrogen atoms in a distributed manner and having excellent durability characteristics is 1.10 times better than the conventional photovoltaic device (element No. 7). 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.

Among the transparent electrodes in the above-described embodiments, those in which nitrogen atoms are distributed exponentially in the region of 30 to 500 ° in the thickness direction, and the maximum distribution concentration is 5 to 1000 ppm. There was something that became.

[0181]

[Table 1]

[0182]

[Table 2]

[0183]

[Table 3]

[0184]

[Table 4]

[0185]

[Table 5]

[0186]

[Table 6]

[0187]

According to the photovoltaic device of the present invention comprising a non-single-crystal silicon-based semiconductor layer having a nitrogen-containing transparent electrode, 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 amount of nitrogen 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 for explaining a layer configuration of a photovoltaic device of the present invention.

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]

Reference Signs List 101 conductive substrate 102 light reflecting layer (conductive) 103 reflection increasing layer 104 first conductive type layer (p-type or n-type) 105 i
Mold layer 106 Second conductivity 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 conductivity 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 314-316 Gas introduction valve 317-319 Mass flow controller 501 Deposition chamber 502 Substrate 503 Heater 504 Evaporation source 505 Heater 506 AC power supply 5 7 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 Dielectric window 1003 Gas introduction pipe 1004 Substrate 1005 Heater 1006 Vacuum gauge 1007 Conductance Valve 1008 Auxiliary valve 1009 Leak valve 1010 Wave guide unit 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 to 1046 Gas outflow valve 1051 to 1056 Source gas cylinder valve 1061 to 1066 Pressure Regulator 1071-1076 Source gas cylinder 1100 RF glow discharge decomposition method Deposition apparatus 1101 Deposition chamber 1102 Cathode 1103 Gas inlet tube 1104 Substrate 1105 Heater 1106 Vacuum gauge 1107 Conductance valve 1108 Auxiliary valve 1109 Leak valve 1112 RF matching box

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-225714 (JP, A) JP-A-2-219281 (JP, A) JP-A-59-181064 (JP, A) JP-A-2- 168507 (JP, A) JP-A-1-187983 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 31/04-31/078 H01L 29/40-29/51

Claims (4)

(57) [Claims] 1. A photovoltaic element comprising a photoelectric conversion layer made of a non-single-crystal semiconductor material containing at least silicon atoms and a transparent electrode laminated on a substrate having a conductive surface. A photovoltaic element, wherein the electrode is made of an oxide containing a nitrogen atom, and in the oxide, the nitrogen atom is distributed so as to be more contained in the semiconductor layer side. 2. The method according to claim 1, wherein the distribution of the nitrogen atoms is different from that of the transparent electrode and the light.
Exponential function from the interface with the electricity conversion layer toward the inside of the transparent electrode
2. The photovoltaic device according to claim 1, wherein the photovoltaic power is reduced.
Force element. 3. An exponential distribution range of the nitrogen atom.
3. The photovoltaic element according to claim 2, wherein the angle is 30 ° to 500 °. 4.
Child. 4. The transparent electrode is made of tin oxide or indium.
2. An oxide, selected from indium-tin oxide.
4. The photovoltaic device according to any one of claims 3 to 3.