JP3029169B2 - 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 having a pin layer made of a non-single-crystal silicon-based semiconductor material and having a zinc oxide thin film layer between a base and the pin layer. The photovoltaic element is suitably applied to a solar cell, a photodiode, an electrophotographic photosensitive member, a light emitting element and the like.

[0002]

2. Description of the Related Art In recent years, photovoltaic devices using a zinc oxide (ZnO) thin film layer as a transparent conductive film have been energetically studied. For example, (i) “Optimization of Transparent and Reflecting El
ectrodes for AmorphousSilicon Solar Cells ”, Gordo
n RG, Hu J, Musher J, Giunta C, US DOE Rep. pp.44
In 1991, ZnO having a texture structure doped with fluorine was improved. (ii) “Research on amorphous silicon based thin fil
m photovoltaic devices.Task B: Research on stable
high efficiency, large area amorphous silicon base
d submodules ”, Delahoy AE, Ellls FB Jr, Kampas
FJ, Tonon T, Weakllem HA, US DOE Rep. Pp. 48 1989.
Report a solar cell using excellent high-grade doped ZnO. (iii) “Amorphous silicon pin solar cells using ind
ium doped ZnO transparent conducting coatings ”, S
ansores E, Campos J, Nair PK, Photovoltaic Sol.Ene
In rgy Conf. vol.8th No.1 pp.1008 1988, a solar cell using ZnO doped with indium is reported.

In addition, microwave plasma CVD (MWP)
A solar cell using the CVD method has also been studied as follows. (iv) "a-Si solar cell by microwave plasma CVD", Kazufumi Higashi, Takeshi Watanabe, Juichi Shimada, "Proceedings of the 50th Annual Conference of the Japan Society of Applied Physics" pp. 566, and the like. In this photovoltaic element, an i-layer having good quality and a high deposition rate is obtained by forming the i-layer by the MWPCVD method.

As an example of forming a doping layer by MWPCVD, for example, (v) “High Efficiency Amorphous Solar Cell Employin
g ECR-CVD Produced p-Type Microcrystalline SiC Fil
m ”, Y. Hattori, D. Kruangam, T. Toyama, H. Okamoto an
d Y. Hamakawa, Proceedings of the International PVSE
C-3 Tokyo Japan 1987 pp.171, (vi) “HIGH-CONDUCTIVE WIDE BAND GAP P-TYPE a-SiC:
H PREPARED BY ECR CVDAND ITS APPLICATION TO HIGH E
FFICIENCY a-Si BASIS SOLAR CELLS ”, Y. Hattori, DK
ruangam, K. Katou, Y. Nitta, H. Okamoto and Y. Hamakaw
a, Proceedings of 19th IEEE Photovoltaic Specialist
s Conference 1987 pp.689. In these photovoltaic elements, a high quality p layer is obtained by using the MWPCVD method for the p layer.

US Pat. No. 4,400,409 discloses a plasma CVD apparatus that employs a roll-to-roll method and continuously forms semiconductor layers. It is desirable that the photovoltaic element of the present invention be manufactured continuously using such an apparatus. According to this apparatus, a plurality of deposition chambers are provided, and a strip-shaped and flexible substrate is disposed along a path through which the substrates sequentially pass through the deposition chamber, and a semiconductor having a desired conductivity type is provided in the deposition chamber. It is described that a photovoltaic element having a pin junction can be continuously manufactured by continuously transporting the substrate in the longitudinal direction while forming a layer. Note that, in the specification, a gas gate is used to prevent a source gas for containing each valence electron controlling agent in a semiconductor layer from diffusing into another deposition chamber and being mixed into another semiconductor layer. Have been. Specifically, the deposition chambers are separated from each other by a slit-shaped separation passage, and each separation passage is provided with A
A scavenging gas such as r, H ₂ , He or the like is introduced to prevent mutual diffusion of each source gas.

This roll-to-roll forming method is effective in producing a photovoltaic device as in the present invention.

In the above conventional photovoltaic device, ZnO / p
Improvement in suppression of recombination of photoexcited carriers near the in-layer interface and the ZnO / substrate interface is desired. Further, in these photovoltaic elements, it is desired to improve the open-circuit voltage and the short-circuit current. Further, when light is irradiated for a long time in a high-temperature and high-humidity environment, photoelectric conversion efficiency is reduced. In addition, when vibration is applied for a long time in a high-temperature and high-humidity environment, the photoelectric conversion efficiency is reduced.

In addition, light deterioration and vibration deterioration when a bias voltage is applied in a high-temperature and high-humidity environment poses a problem. Further, in a photovoltaic element containing at least one of Ag, Al, and In in the base, there is a problem that a short circuit occurs when a bias voltage is applied in a high temperature and high humidity environment. Further, there is a problem that the ZnO thin film layer formed by the roll-to-roll method is easily peeled off when stored or transported for a long time in a rolled and wound state.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photovoltaic element which solves the above-mentioned conventional problems. That is, the object is to suppress the recombination of photoexcited carriers near the ZnO / pin layer interface and the ZnO / substrate interface. Another object is to improve the open-circuit voltage and the short-circuit current, and to improve the photoelectric conversion efficiency. It is another object of the present invention to suppress light deterioration and vibration deterioration in a high temperature and high humidity environment. Another object of the present invention is to suppress light deterioration and vibration deterioration when a bias voltage is applied in a high temperature and high humidity environment. A further object of the present invention is to prevent a photovoltaic element containing at least one element of Ag, Al, and In from being short-circuited even when a bias voltage is applied in a high temperature and high humidity environment.
It is an object of the present invention to provide a photovoltaic element which is hardly delaminated even in a rolled state.

[0010]

The present invention solves the problems of the prior art, and as a result of intensive studies to achieve the above object,
It has been found that the photovoltaic device of the present invention comprises:
In a photovoltaic device in which a zinc oxide thin film layer and a pin layer (p layer, i layer, and n layer) made of a non-single-crystal silicon-based semiconductor material are stacked on a substrate, the zinc oxide thin film layer has a surface of zero. A c-axis oriented crystalline thin film having irregularities of 1 to 1.0 μm and containing boron (B), and the content of boron takes the minimum value at the interface with the substrate, It gradually increases toward the pin layer, and the zinc oxide thin film layer
It is characterized in that a large amount of boron is contained near the crystal grain boundaries . In addition, the photovoltaic element of the present invention
Zinc oxide thin film layer, made of non-single-crystal silicon-based semiconductor material
Photovoltaic formed by laminating pin layers (p layer, i layer, n layer)
In the force element, the zinc oxide thin film layer has
C-axis oriented crystalline thin film with irregularities of ~ 1.0 μm
And containing boron (B), the content of the boron
Takes a minimum value at the interface with the substrate and moves toward the pin layer.
And the zinc oxide thin film layer is silicon
And / or germanium, and the zinc oxide thin film layer
Silicon and / or germanium in the vicinity of grain boundaries
It is characterized by high content.

A preferred embodiment of the present invention is a photovoltaic device in which the c-axis is substantially perpendicular to the surface of the substrate.

A preferred embodiment of the present invention is a photovoltaic element in which the boron content is high near the crystal grain boundary of the zinc oxide thin film layer.

In a preferred embodiment of the present invention, the zinc oxide thin film layer contains silicon and / or germanium, and the content changes in the layer thickness direction and has a minimum value at the interface with the substrate. It is a photovoltaic element gradually increasing toward.

A preferred embodiment of the present invention is a photovoltaic device in which silicon and / or germanium is contained near the crystal grain boundaries of the zinc oxide thin film layer.

A preferred embodiment of the present invention is a photovoltaic device in which the p-layer or the n-layer in contact with the zinc oxide thin film layer contains boron.

In a preferred embodiment of the present invention, the p-layer or the n-layer in contact with the zinc oxide thin film layer is formed by a microwave plasma CVD method so that boron of the layer is diffused into the zinc oxide thin film layer. This is a photovoltaic element.

In a preferred embodiment of the present invention, after forming the p-layer or the n-layer in contact with the zinc oxide thin-film layer, a plasma treatment is performed by a microwave plasma CVD method to remove boron in the layer. It is a photovoltaic element manufactured by diffusing it inside.

In a preferred embodiment of the present invention, the i-layer is formed by microwave plasma CVD to diffuse boron in the p-layer or the n-layer in contact with the zinc oxide thin film layer into the zinc oxide thin film layer. This is a photovoltaic element manufactured by the above method.

A preferred embodiment of the present invention is a photovoltaic device manufactured by diffusing silicon and / or germanium in the p layer or the n layer in contact with the zinc oxide thin film layer together with boron by the above boron diffusion method. It is.

A preferred embodiment of the present invention is the above-described photovoltaic device, wherein the substrate is a flexible band-shaped substrate, and the roll-shaped photovoltaic element can be wound.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic explanatory view of a photovoltaic device of the present invention. In FIG. 1, a photovoltaic element of the present invention includes a substrate 101, a ZnO thin film layer 102, a pin layer 103 made of a non-single-crystal silicon-based semiconductor material, and a transparent electrode 10.
4. It is composed of a collecting electrode 105 and the like.

The photovoltaic element shown in FIG. 1 is usually used by irradiating light from the transparent electrode side, but may be used by irradiating light from the back side of the substrate. In this case, the base may be made of a material that transmits light, and a light reflection layer made of a metal material may be formed on the pin layer instead of the transparent electrode.

Further, the pin layer of the photovoltaic element of the present invention
It may be a stack of pin structures such as an inpin structure and a pinpinpin structure.

The pin layer of the photovoltaic device of the present invention has n
A stack of nip structures such as an ip structure, a nipnip structure, and a nipnipnip structure may be used.

In the photovoltaic device of the present invention, the ZnO thin film layer contains boron, the content of which changes smoothly and is minimum at the interface with the substrate and gradually increases toward the pin layer. Interface between thin film layer and pin layer, ZnO
Recombination of photoexcited carriers at the interface between the thin film layer and the substrate can be reduced. Further, since the internal stress generated at the interface between the ZnO thin film layer and the pin layer and the interface between the ZnO thin film layer and the base is reduced, photodeterioration of the photovoltaic element (deterioration of element characteristics due to long-time light irradiation), Vibration deterioration (deterioration of element characteristics due to long-time vibration application) can be suppressed. It is considered that the photodeterioration of the photovoltaic element causes a weak bond to be broken by the energy of light, and this becomes a recombination center of the photoexcited carrier, thereby deteriorating the element characteristics. In addition, it is considered that vibration degradation of a photovoltaic element breaks a weak bond due to vibration energy, and this becomes a recombination center of photoexcited carriers, thereby deteriorating element characteristics. It is considered that this weak bond is localized in a region where stress is generated, and it is particularly important to reduce recombination centers generated at the interface between the ZnO thin film layer and the pin layer.

These effects are particularly prominent when the p-layer or the n-layer in contact with the ZnO thin film layer contains boron. More preferably, the ZnO thin film layer contains silicon and / or germanium, and the content changes in the layer thickness direction, and is minimum at the interface with the substrate and gradually increases toward the pin layer.

Further, when boron is contained in the ZnO thin film layer, the stability of the ZnO thin film layer in a high temperature and high humidity environment is improved, and the stability of the high temperature and high humidity characteristics of the photovoltaic device is improved. Light deterioration and vibration deterioration under high temperature and high humidity can be suppressed. More preferably, the ZnO thin film layer contains silicon and / or germanium, and the content changes in the layer thickness direction, and is minimum at the interface with the substrate and gradually increases toward the pin layer.

In addition, since boron acts as a valence electron controlling agent in the ZnO thin film, the conductivity of the film can be improved.
Moreover, the light transmittance of the ZnO thin film is not impaired. That is, when light is irradiated from the transparent electrode 104 side, light that could not be absorbed by the pin layer can be transmitted efficiently, and short-circuit current can be improved. The base 10
When irradiating light from the back side of 1, the light is efficiently pinned.
Leads to the layers.

In the present invention, a crystalline ZnO thin film having c-axis orientation is used. As a result, irregularities are formed on the surface of the ZnO thin film as shown in FIG.
It can be led to the in layer, and the short-circuit photocurrent of the photovoltaic element can be improved. That is, when light is incident from the transparent electrode side, the light is refracted on the transparent electrode surface and the pin layer surface, so that the optical path length from the incident on the pin layer to the light reaching the crystalline ZnO layer surface is extended. P, more light
Can be absorbed in the in layer. Further, when the base is made of a material that reflects light, light that could not be absorbed by the pin layer can be once again made to enter the pin layer from the base and absorbed. At that time, crystalline ZnO
Since the surface of the thin film layer 102 has irregularities, the reflected light can be refracted here, and the optical path length can be extended.
Light can be absorbed more effectively. In order to absorb visible light, the unevenness can effectively absorb visible light when the height of the peak is 0.1 to 1.0 μm.

In particular, it is desirable that each crystal grain 107 is a wurtzite type crystal and the c-axis (six rotation axis) is substantially perpendicular to the substrate. This makes p more effective
Light can be guided to the in layer. In order to make the c-axis almost perpendicular to the substrate, when forming a ZnO thin film layer by sputtering, a DC bias and / or an RF bias is applied to increase the plasma potential, or a negative DC bias is applied to the substrate. Apply. Further, in order to make the c-axis substantially perpendicular to the substrate, countless fine protrusions may be formed on the surface of the substrate. For example, an Ag thin film layer may be formed on a stainless steel support at a support temperature of 200 to 600 ° C. It is desirable that the projections are formed at substantially equal intervals.

Further, by making the crystal grain boundary 106 contain a large amount of boron, diffusion of impurities from the substrate can be prevented. That is, when a material containing an impurity (for example, a certain metal element) that adversely affects the pin layer is used for the base, the impurity must be prevented from diffusing into the pin layer. In the case of a crystalline ZnO thin film layer as shown in FIG. 1, impurities diffuse through crystal grain boundaries, which may degrade device characteristics. In particular, when a bias voltage is applied to the element for a long time, it becomes particularly noticeable, the shunt resistance becomes extremely small, and characteristics such as photoelectric conversion efficiency deteriorate. This is presumably because voids and voids are present at the crystal grain boundaries, so that impurities are easily diffused. Therefore, by adding a large amount of boron to the crystal grain boundaries, these voids and voids can be reduced and diffusion can be prevented. Further, by adding a large amount of boron to the crystal grain boundaries, dangling bonds are increased, and the diffusion is prevented by reacting with the diffused impurities. It is desirable that the content of boron is several times larger than the inside of the crystal bulk. Z
It is more preferable that silicon and / or germanium be contained in the crystal grain boundaries of the nO thin film layer.

In the present invention, p in contact with the ZnO thin film layer
Since boron is contained in the layer or the n-layer, light deterioration and vibration deterioration are suppressed. That is, defects such as dangling bonds in the p-layer or n-layer generated by irradiating the photovoltaic device of the present invention with light are converted into boron which is inactive in the p-layer or n-layer. To compensate for the defect and suppress light degradation. Similarly, boron, which inactivates defects such as dangling bonds in the p-layer or n-layer generated by applying vibration, compensates for defects such as dangling bonds and suppresses vibration deterioration. is there.

In the photovoltaic device of the present invention, the p layer or the n layer
Layer and the i-layer are formed by RF plasma CVD (RFPCVD).
Method) or microwave plasma CVD method (MWPCVD)
Method). Especially MWPCVD
According to the method, the deposition rate is high, the throughput can be improved, and the utilization efficiency of the source gas can be improved, so that the productivity can be improved. When the doping layer is formed by the MWPCVD method, a doping layer having good characteristics as a photovoltaic element can be obtained. That is, the doping layer is excellent as a doping layer because of good light transmittance, high electric conductivity, and low activation energy. Further, when formed by the MWPCVD method, a high-quality microcrystalline silicon-based semiconductor material or a high-quality amorphous silicon-based semiconductor material having a wide band gap can be relatively easily formed, which is effective as a method for forming a doping layer. The i-layer is particularly effective because the i-layer is thicker than the p-layer and the n-layer.

The ZnO thin film layer of the present invention is preferably formed by a sputtering method. Among them, a magnetron sputtering method with a high deposition rate and a microwave sputtering method described below are suitable. Microwave sputtering is a method that introduces an inert gas or a reactive gas into a vacuum vessel, irradiates the gas with microwaves to generate ions, and applies electromagnetic energy to a target to accelerate the ions. And irradiate the target surface, and sputter the target to form a deposited film on the substrate surface at high speed. The electromagnetic energy is suitably RF power.

Since the photovoltaic device of the present invention has a ZnO thin film layer and a pin layer formed on a flexible band-shaped substrate, it can be wound into a roll, and requires space for storage or transportation. And handling becomes easy. Further, the method is suitable for a manufacturing method using a roll-to-roll method, and can dramatically improve productivity. In the photovoltaic element of the present invention, since the ZnO thin film layer contains boron as described above, it is difficult for the layer to be peeled even in a rolled state.

The photovoltaic element having the pin structure has been described above.
b, a photovoltaic element in which a pin structure such as a pinpinpin structure is laminated, or a nipnip structure or ni
The present invention is also applicable to a photovoltaic element in which a nip structure such as a pnnip structure is stacked.

FIG. 2 is a schematic illustration of a deposition apparatus suitable for producing the photovoltaic device of the present invention. The deposition device 2
00 is a deposition chamber 201, a vacuum gauge 202, a bias power supply 2
03, substrate 204, heater 205, waveguide 206, conductance valve 207, valve 208, target electrode 209, bias electrode 210, gas introduction pipe 211,
It comprises an applicator 212, a dielectric window 213, a sputtering power supply 214, a base shutter 215, a target 216, a target shutter 217, a microwave power supply 219, a toroidal coil 221, a vacuum exhaust pump (not shown), a source gas supply device, and the like. The vacuum exhaust pump is connected to an exhaust port 220 shown in the figure, and the source gas supply device is composed of a source gas cylinder, a valve, and a mass flow controller, and is connected to a gas introduction pipe 211. The dielectric window is made of a material that transmits microwaves well, such as alumina ceramics, quartz, and boron nitride.

The fabrication of the photovoltaic device of the present invention is performed as follows. First, the substrate 204 is brought into close contact with the heater 205 installed in the sediment 201 in FIG. 2, and the deposition chamber is sufficiently evacuated to 1 × 10 ⁻⁵ Torr or less. A turbo molecular pump, an oil diffusion pump, or a cryopump is suitable for this exhaust. Thereafter, an inert gas such as Ar is introduced into the deposition chamber, the heater is turned on, and the substrate is heated. When the substrate temperature is stabilized at a predetermined temperature, the conductance valve 207 is adjusted to a predetermined pressure, and a method of forming a ZnO thin film layer described in detail below is performed. Next, a method of forming a pin layer described in detail below is performed. Next, the target is In ₂ O in a vacuum.
Replace with ₃ + SnO ₂ (5 wt%), introduce O ₂ gas into the deposition chamber, perform DC magnetron sputtering, and form ITO on the pin layer. Next, the deposition chamber is leaked, and a comb-shaped current collecting electrode is formed on the ITO surface by an electron beam vacuum evaporation method, thereby completing the fabrication of the photovoltaic element.

The pin layer is formed by MWPCVD or RFP
It is preferably formed by a CVD method. (A) When the pin layer is formed by the MWPCVD method When the pin layer is formed by the MWPCVD method, the source gas is introduced into the deposition chamber, the pressure is adjusted by the conductance valve 207, and the microwave is applied to the waveguide 213 and the applicator 2.
Irradiation is performed on the source gas through 12 to generate plasma. The pressure during the formation of the pin layer is a very important factor, and the pressure in the deposition chamber is preferably 0.5 to 50 mTorr. The MW power introduced into the deposition chamber is also an important factor. The MW power is appropriately determined depending on the flow rate of the source gas introduced into the deposition chamber, but is preferably in the range of 100 to 5000 W. A preferable frequency range of the MW power includes 0.5 to 10 GHz. Particularly, a frequency around 2.45 GHz is suitable. After forming the desired layer thickness, stop introducing MW power,
The deposition chamber is sufficiently evacuated and sufficiently purged with a gas such as H ₂ , He, or Ar before forming the next layer.

When forming the pin layer, RF power may be applied to the bias electrode 210 together with MW power. In this case, the MW power to be introduced is desirably smaller than the MW power required to decompose the raw material gas introduced into the deposition chamber by 100%, and the RF power simultaneously introduced is preferably larger than the MW power. desirable. A preferable range of the simultaneously introduced RF power is 200 to 1000
0W. A preferable frequency range of the RF power includes 1 to 100 MHz. Especially 13.56MHz
Is optimal. When the area of the bias electrode for RF power supply is smaller than the area of the ground, it is better to ground the self-bias (DC component) on the power supply side for RF power supply. Further, a DC voltage may be applied to the bias electrode. A preferred range of the DC voltage is 30 to 300
About V. Further, RF power and DC voltage may be simultaneously applied to the bias electrode.

(B) When a pin layer is deposited by RFPCVD, a capacitively coupled RFPCVD method is suitable. When a pin layer is formed by the RFPCVD method, a source gas is introduced into a deposition chamber, and an RF voltage is applied to a bias electrode to generate plasma. The substrate temperature is 100 to 500 ° C., the pressure is 0.1 to 10 Torr, the RF power is 1 to 2000 W,
The optimum deposition rate is 0.1 to 2 nm / sec. After the desired layer thickness is formed, the introduction of RF power is stopped, the deposition chamber is sufficiently evacuated, and the next layer is formed after sufficiently purging with a gas such as H ₂ , He, or Ar.

The following method can be used to form a ZnO thin film layer having a changed boron content. (1) In the case of forming by sputtering method RF magnetron sputtering method with high forming speed is suitable. In that case, an Ar gas is introduced into a deposition chamber in which a toroidal coil is placed around the target, a target made of ZnO: B containing boron is mounted on the target electrode 209, and the substrate temperature is set to 200 to 600 ° C.
Then, RF (1 to 100 MHz) power is applied to generate plasma to form a ZnO thin film layer on the substrate.

At this time, since the pressure in the deposition chamber is a parameter closely related to the deposition film formation speed, it is appropriately determined according to the type of gas to be introduced, the size of the deposition apparatus, and the like. Usually, it is 1 to 30 mTorr.
A predetermined amount of the above-mentioned gas is introduced into the deposition chamber from the gas cylinder via the mass flow controller, and the introduction amount is appropriately determined depending on the volume of the deposition chamber. Further, O ₂ gas may be introduced in addition to Ar gas.

To change the boron content in the layer thickness direction, the RF power may be changed over time. That is, Z
Since the RF power dependence of the sputtering rate differs between nO and boron, the boron content is high at high RF power, and the boron content is low at low RF power.

In order to increase the boron content at the crystal grain boundary, the RF power may be increased immediately before each crystal grain comes into contact with a neighboring crystal grain.

(2) Sputtering method + RFPCVD method
In the case of forming by the RF magnetron sputtering method described above,
To B_TwoH₆Gas, BF _ThreeGas containing boron such as
And the amount of introduction may be changed over time. in this case,
Using a target made of ZnO that does not contain boron
Is also good.

Further, in order to increase the boron content at the crystal grain boundary, a large amount of a gas containing boron may be flowed immediately before each crystal grain comes into contact with a neighboring crystal grain.

(3) When Forming by Microwave Sputtering Method Ar gas is introduced into the deposition chamber, the target made of ZnO: B is mounted on the target electrode 209, the substrate temperature is set to 200 to 600 ° C., and RF (1 to 100 MH
z) Apply power or DC power (100-600V). The microwave power generated from the microwave power source is transmitted, expanded in the applicator, and irradiated with the above gas through the dielectric window 213 to generate plasma to form a ZnO thin film layer on the substrate.

At this time, the pressure in the deposition chamber is a parameter closely related to the formation rate of the deposited film, and is appropriately determined according to the type of gas to be introduced, the size of the deposition apparatus, and the like. Usually, it is 0.1 to 10 mTorr. In addition, the above gas is introduced into the deposition chamber from the gas cylinder through a mass flow controller in a predetermined amount.
The introduction amount is appropriately determined depending on the volume of the deposition chamber. Further, O ₂ gas may be introduced in addition to Ar gas.

To change the boron content in the layer thickness direction, the RF power or the DC power may be changed over time. That is, since the RF power (DC power) dependency of the sputtering rate differs between ZnO and boron, the high RF power (DC power) is high.
In power, the boron content is high and the lower the boron content.

In order to increase the boron content at the crystal grain boundaries, the RF power (DC power) may be increased immediately before each crystal grain comes into contact with a neighboring crystal grain.

(4) Microwave sputtering method + MW
When forming by PCVD method In the microwave sputtering method described above, B ₂ is newly added.
A boron-containing gas such as an H ₆ gas or a BF ₃ gas may be introduced, and the introduced amount may be changed over time. In this case, a target made of ZnO containing no boron may be used.

Further, in order to increase the boron content at the crystal grain boundary, a large amount of a gas containing boron may be flowed immediately before each crystal grain comes into contact with a neighboring crystal grain.

(5) In the case of diffusing boron in the p layer or the n layer-1 After forming the ZnO thin film layer by a normal sputtering method, the p layer or the n layer in contact with the ZnO thin layer is MWPCV.
When forming by the method D, the surface temperature of the p-layer or the n-layer is raised by applying relatively high microwave power, and boron in the p-layer or the n-layer is diffused into the ZnO thin film.

In order to increase the boron content at the crystal grain boundaries, the substrate temperature may be set to 300 ° C. or higher.

(6) In the case of diffusing boron in the p-layer or the n-layer -2 The ZnO thin film layer is formed by a normal sputtering method.
After forming a p-layer or an n-layer in contact with the O thin film layer by RFPCVD, an inert gas such as an Ar gas or an H ₂ gas is introduced into the deposition chamber, and plasma is generated by microwaves to generate the p-layer or the n-layer. Is subjected to microwave plasma treatment to diffuse boron in the p layer or the n layer into the ZnO thin film layer. At this time, it is preferable to adjust the microwave power so that the boron content gradually decreases in the direction of the base.

In order to increase the boron content at the crystal grain boundaries, the substrate temperature may be set to 300 ° C. or higher.

(7) In the case of diffusing boron in the p layer or the n layer-3 The ZnO thin film layer is formed by a normal sputtering method,
O thin film layer, and the boron-containing p-layer or n-layer
After the formation by the FPCVD method, the i-layer is formed by the MWPCVD method. Due to the rise in surface temperature during formation,
The boron in the layer or n-layer is diffused into the ZnO thin film layer.
At this time, it is preferable to adjust the microwave power so that the boron content gradually decreases in the direction of the base.

In order to increase the boron content at the crystal grain boundaries, the substrate temperature may be set to 300 ° C. or higher.

(8) When Forming by Roll-to-Roll Method The substrate temperature is set to 200 to 600 ° C. in the microwave sputtering method or the ordinary sputtering method,
A boron-containing gas such as a B ₂ H ₆ gas may be newly introduced, and the introduced amount may be spatially changed with respect to the moving direction of the substrate.

Further, in order to increase the boron content at the crystal grain boundary, it is sufficient to flow a large amount of a boron-containing gas where each crystal grain comes into contact with a neighboring crystal grain.

Further, the method for containing boron and / or germanium in the ZnO thin film layer can be carried out in the same manner as in the above methods (1) to (8) for containing boron.

In the method of forming the above-mentioned pin layer, the following gases or compounds capable of being gasified by bubbling are suitable as the source gas.

As a source gas for containing silicon atoms, SiH ₄ , SiD ₄ , Si ₂ H ₆ , Si
F ₄ and Si ₂ F ₆ are suitable.

As a raw material gas for containing a fluorine atom, F ₂ , SiF ₄ , GeF ₄ , CF ₄ , PF ₅ ,
BF ₃ is suitable.

As a source gas for containing carbon atoms, CH ₄ , CD ₄ , C ₂ H ₂ and CF ₄ are suitable.

GeH ₄ , GeD ₄ , and GeF ₄ are suitable as source gases for containing germanium atoms.

As a source gas for containing a tin atom, SnH ₄ , SnD ₄ and Sn (CH ₃ ) ₄ are suitable.

As a source gas for introducing a Group III atom of the periodic table into the p layer, B ₂ H ₆ , B (CH ₃ ) ₃ ,
B (C ₂ H ₅ ) ₃ , Al (CH ₃ ) ₃ and BF ₃ are suitable.

PH ₃ , AsH ₃ , and PF ₅ are suitable as source gases for introducing Group V atoms of the periodic table into the n-layer.

A group VI atom of the periodic table is introduced into the n-layer.
As the raw material gas, H_TwoS, H _TwoSe is suitable
You.

O ₂ , CO ₂ , CO, and NO are suitable as source gases for containing oxygen atoms in the pin layer.

Source gases for containing nitrogen atoms in the pin layer include N ₂ , NO, NO ₂ , N ₂ O, NH
₃ is suitable.

Further, these source gases are used as H ₂ , D ₂ , H
It may be appropriately diluted with a gas such as e or Ar and introduced into the deposition chamber.

When the above-mentioned ZnO thin film layer containing boron is formed, ZnO or ZnO:
B is used, but Zn containing no oxygen or Zn: B may be used. Boron may be contained in the target in the form of an oxide (B ₂ O ₃ ). When a target containing no oxygen is used, it is necessary to introduce O ₂ gas into the deposition chamber.

Silicon and / or gel with boron
In the case of containing manium, ZnO: BSi (G
e), Zn: BSi (Ge) may be used. Silicon and / or
Alternatively, germanium is an oxide (SiO_Two, GeO_Two)of
It may be contained in the target in the form. In the ZnO thin film layer
As a gas introduced to contain boron, B
_TwoH₆, B (CH_Three)_Three, B (C_TwoH_Five)_Three, BF_Threeetc
Is suitable.

Hereinafter, the configuration of the present invention will be described in more detail. Substrate The substrate may be composed of a simple substance of a conductive material or an insulating material, or may be a material in which a thin film layer is formed on a support made of a conductive material or an insulating material. As the conductive material, for example, NiCr, stainless steel, Al, C
r, Mo, Au, Nb, Ta, V, Ti, Pt, Pb,
Metals such as Sn and alloys thereof are exemplified. In order to use these materials as a support, it is desirable that the material be in the form of a sheet or a roll formed by winding a belt-like sheet around a cylindrical body.

As the insulating material, polyester, polyethylene, polycarbonate, cellulose acetate,
Examples include synthetic resins such as polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, and polyamide; glass, ceramics, and paper. In order to use these materials as a support, it is desirable that the material be in the form of a sheet or a roll formed by winding a belt-like sheet around a cylindrical body.

In the photovoltaic device of the present invention, it is preferable that a conductive thin film layer is formed on one surface of the support, and a ZnO thin film layer is formed on the surface on which the conductive thin film layer is formed.

For example, in the case of glass, NiC
r, Al, Ag, Cr, Mo, Ir, Nb, Ta, V,
Ti, Pt, Pb, In ₂ O ₃ , SnO ₂ , ITO (I
n ₂ O ₃ + SnO ₂ ) or a conductive thin film layer made of an alloy thereof, and if a synthetic resin sheet such as a polyester film is used, NiCr, Al, Ag,
Pb, Zn, Ni, Au, Cr, Mo, Ir, Nb, T
a, V, Tl, Pt, etc., or a conductive thin film layer made of an alloy thereof is formed.
Al, Ag, Cr, Mo, Ir, Nb, Ta, V, T
i, Pt, Pb, In ₂ O ₃ , SnO ₂ , ITO (In
_A conductive thin film layer made of a material such as ₂ O ₃ + SnO ₂ ) or an alloy thereof is formed. As a forming method, a vacuum evaporation method,
It is formed by a sputtering method, a screen printing method, or the like.

The surface shape of the substrate is desirably smooth or uneven with a peak height of 0.1 to 1.0 μm on average. The thickness of the substrate is appropriately determined so that a desired photovoltaic element can be formed. However, when flexibility as a photovoltaic element is required, a range in which the function as a support is sufficiently exhibited is provided. Can be made as thin as possible. However,
The thickness is usually 10 μm or more from the viewpoint of production and handling of the support, mechanical strength and the like.

The preferred form of the substrate in the photovoltaic device of the present invention is such that Ag, Al, Cu, A
The purpose is to form a conductive thin film layer made of a metal having high reflectance in the near infrared to visible light such as lSi. This layer functions as a light reflection layer, and a suitable layer thickness of these metals as the light reflection layer is 10 nm to 5000 nm. In order to make the surface of the light reflection layer uneven (texture), the substrate temperature at the time of formation may be 200 ° C. or higher.

ZnO Thin Film Layer ZnO containing boron formed by the above method
The light transmittance of the thin film layer is 85% or more in the wavelength range of 400 nm to 900 nm, and the resistivity is 3 × 1.
It is less than 0 ^-4 Ω · cm. The boron content has a minimum value (Cmin) at the interface with the substrate, gradually increases in the direction of the pin layer, and has a maximum boron content (Cmax) at the crystal grain boundary. About 0.01% is suitable as Cmin, and about 5% is suitable as Cmax.

As the change pattern of the boron content in the layer thickness direction, a pattern which increases linearly from the substrate side as shown in FIG. 3A, a pattern which increases exponentially from the substrate side as shown in FIG. As shown in FIG. 3C, a material that rapidly increases near the interface with the pin layer is suitable. When silicon and / or germanium is contained in the ZnO thin film layer, the change pattern of the silicon content and the germanium content is preferably the same as the change pattern of boron.

P layer, n layer These layers are important layers that affect the characteristics of the photovoltaic element, and are made of an amorphous silicon-based semiconductor material, a microcrystalline silicon-based semiconductor material, or a polycrystalline silicon-based semiconductor material. Is done. Amorphous (abbreviated as a-) silicon-based semiconductor materials include a-Si, a-SiC, a-SiGe, a
-SiGeC, a-SiO, a-SiN, a-SiO
N, a-SiCON and the like. Microcrystalline (abbreviated as μc−) silicon-based semiconductor material includes μc-S
i, μc-SiC, μc-SiGe, μc-SiO, μ
c-SiGeC, μc-SiN, μc-SiON, μc
—SiOCN and the like. As a polycrystalline (abbreviated as poly-) silicon-based semiconductor material, poly-S
i, poly-SiC, poly-SiGe and the like.

In particular, as the layer on the light incident side, a crystalline semiconductor material with little light absorption or an amorphous semiconductor layer with a wide band gap is suitable. Specifically, a-SiC, a-
SiO, a-SiN, a-SiON, a-SiCON,
μc-Si, μc-SiC, μc-SiO, μc-Si
N, μc-SiON, μc-SiOCN, poly-S
i, poly-SiC is suitable.

The amount of the valence electron controlling agent introduced to make the conductivity type p-type or n-type is 1000 ppm to 10 ppm.
% Is mentioned as a preferable range.

The contained hydrogen (H, D) and fluorine work to compensate for dangling bonds and improve the doping efficiency. Hydrogen and fluorine content is 0.1-3
0 at% is mentioned as the optimum amount. In particular, in the case of crystallinity, 0.01 to 10 at% is mentioned as an optimum amount.

The introduction amount of oxygen and nitrogen atoms is from 0.1 ppm to
20%, 0.1ppm-1% when contained in trace amount
Is a preferable range.

As for the electric characteristics, the activation energy is 0.1.
Those having 2 eV or less are preferable, and those having 0.1 eV or less are optimal. The resistivity is preferably 100 Ωcm or less, and most preferably 1 Ωcm or less. Further, the layer thickness is 1 to
50 nm is preferred, and 3 to 30 nm is optimal.

In particular, when the above-mentioned crystalline semiconductor material having little light absorption or an amorphous semiconductor layer having a wide band gap is formed, a source gas such as H ₂ , D ₂ , He or the like is used 2 to 100 times. And introducing relatively high MW or RF power.

In the photovoltaic element of the present invention, the ZnO thin film layer contains boron, and the content gradually increases toward the pin layer.
Even if a p layer or an n layer in contact with the nO thin film layer is formed, Zn
Damage to the O thin film layer, that is, interface level can be reduced.

I-Layer In the photovoltaic device of the present invention, the i-layer is the most important layer for generating and transporting photoexcited carriers. A slightly p-type and slightly n-type layer can also be used as the i-layer, and is made of an amorphous silicon-based semiconductor material containing hydrogen.
-Si, a-SiC, a-SiGe, a-SiGeC,
a-SiSn, a-SiSnC, a-SiSnGe, a
—SiSnGeC and the like.

Hydrogen (H, D) and fluorine contained in the i-layer work to compensate for dangling bonds in the i-layer and improve the product of the carrier mobility and the lifetime in the i-layer. .
Further, it has a function of compensating the interface state of the interface, and has an effect of improving the photovoltaic power, the photocurrent and the photoresponsiveness of the photovoltaic element. The hydrogen and fluorine contents of the i-layer are 1 to 3
0 at% is mentioned as the optimum content.

The amount of oxygen and nitrogen atoms introduced is 0.1 ppm to
1% is a suitable range.

The thickness of the i-layer depends on the structure (for example, pin, pinpin, nip) of the photovoltaic element and the band gap of the i-layer, and the optimum thickness is 0.05 to 1.0 μm.

The i-layer of the present invention has a small valence band tail state, and has a tail state inclination of 60.
The density is less than meV and the density of dangling bonds by electron spin resonance (ESR) is 10 ¹⁷ / cm ³ or less.

The MWCVD method is used to form the i-layer. Preferably, RF power is simultaneously introduced in the MWPCVD method as described above.
RF power and DC power are simultaneously introduced in the PCVD method.

In the case of forming a-SiC having a wide band gap, it is preferable to dilute the source gas by a factor of 2 to 100 with a gas such as H ₂ , D ₂ , He and to introduce a relatively high MW power.

Transparent Electrode The transparent electrode is made of a material suitable for indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), and ITO (In ₂ O ₃ + SnO ₂ ). These materials contain fluorine. You may.

For forming a transparent electrode, a sputtering method and a vacuum evaporation method are optimal.

In the case of forming by a sputtering method, a target such as a metal target or an oxide target is used in appropriate combination. When forming by a sputtering method, the substrate temperature is an important factor,
00 ° C is mentioned as a preferable range. In the case where the transparent electrode is formed by a sputtering method, an inert gas such as an Ar gas may be used as a sputtering gas. It is preferable to add oxygen gas (O ₂ ) to the inert gas as needed. Particularly when a metal is targeted, oxygen gas (O ₂ ) is essential. Further, when sputtering the target with the inert gas or the like, the pressure is preferably in the range of 0.1 to 50 mTorr in order to effectively perform sputtering. The deposition rate of the transparent electrode depends on the pressure and the electric power to be introduced.
The range is from 01 to 10 nm / sec.

[0103] As vapor deposition sources suitable for forming a transparent electrode in a vacuum vapor deposition method, metal tin, metal indium,
An indium-tin alloy is exemplified. A suitable range of the substrate temperature for forming the transparent electrode is from 25 ° C. to 600 ° C. Further, it is necessary to introduce oxygen gas (O ₂ ) and form the pressure in a range of 5 × 10 ⁻⁵ Torr to 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 form a good transparent electrode. The preferable range of the deposition rate of the transparent electrode under the above conditions is 0.01 to 10 nm / sec. Deposition rate is 0.0
If it is less than 1 nm / sec, the productivity decreases, and
If it is larger than / sec, the film becomes coarse, and the transmittance, the electrical conductivity and the adhesion are reduced.

It is preferable that the layer thickness of the transparent electrode satisfies the condition of the antireflection film. As a specific layer thickness, a preferable range is 50 to 500 nm. In order to make more light incident on the i-layer, which is the photovoltaic layer of the collecting electrode, and to efficiently collect generated carriers on the electrode, the shape of the collecting electrode (the shape as viewed from the light incident direction) and the material Is important. Usually, the shape of the current collecting electrode is a comb shape, and the line width, the number of lines, and the like are as follows:
And the size, the material of the collecting electrode, and the like. The line width is usually about 0.1 mm to 5 mm. The material of the current collecting electrode is Fe, Cr, Ni, Au, Ti, P
d, Ag, Al, Cu, AlSi, C (graphite)
Ag, Cu, A having small resistivity
Metals such as l, Cr, C, and alloys thereof are suitable. The layer structure of the collecting electrode may be composed of a single layer, or may be composed of a plurality of layers.

It is desirable to form these metals by a vacuum deposition method, a sputtering method, a plating method, a printing method, or the like.

In the case of forming by a vacuum evaporation method, a mask having a shape of a collecting electrode is brought into close contact with the transparent electrode, and a desired metal evaporation source is evaporated in a vacuum by electron beam or resistance heating.
A collector electrode having a desired shape is formed on the transparent electrode.

In the case of forming by a sputtering method, a mask having the shape of a current collecting electrode is brought into close contact with the transparent electrode, Ar gas is introduced into a vacuum, DC is applied to a desired metal sputtering target, and glow discharge is generated. By letting
A metal is sputtered to form a current collecting electrode having a desired shape on the transparent electrode.

In the case of forming by a printing method, an Ag paste, an Al paste, or a carbon paste is printed by a screen printing machine.

The layer thickness of these metals is 10 nm to
A suitable layer thickness is 0.5 mm.

[0110]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the photovoltaic element of the present invention will be described in detail by manufacturing a solar cell and a photodiode made of a non-single-crystal silicon-based semiconductor material, but the present invention is not limited thereto.

Example 1 A solar cell having the structure shown in FIG. 1 was manufactured using the deposition apparatus shown in FIG.

A source gas supply device (not shown) is connected to the deposition device of FIG. 2 through a gas introduction pipe. All raw material gas cylinders have been purified to ultra-high purity.
₄ gas cylinder _, SiF ₄ gas cylinder, CH ₄ gas cylinder, GeH ₄ gas cylinder, SnH ₄ gas cylinder, PH ₃
/ H ₂ (dilution: 100 ppm) gas cylinder, B ₂ H ₆
/ H ₂ (dilution: 100 ppm) gas cylinder, H ₂ gas cylinder, and Ar gas cylinder were connected. The target is Ag
And ZnO: B (1%), each of which can be switched in vacuum to perform a sputtering method. An RF power supply was used as a bias power supply.

First, a substrate was manufactured. 0.5m thick
A 50 × 50 mm ² stainless steel plate was subjected to ultrasonic cleaning with acetone and isopropanol and dried with hot air. A DC power supply was connected as a sputtering power supply, and an Ag light reflecting layer was formed using a DC magnetron sputtering method. The stainless plate was brought into close contact with the heater of FIG. 2, and the deposition chamber was evacuated from the exhaust port 220 to which the oil diffusion pump was connected.
When the pressure reaches 1 × 10 ^-5 Torr, 50
sccm was introduced, and the pressure was adjusted with a conductance valve so as to be 7 mTorr. When the substrate temperature reached 150 ° C., an electric current was passed through the toroidal coil, and a DC power of 400 V was applied from a sputtering power supply to generate Ar plasma. The target shutter and the base shutter were opened, and when a 0.3 μm-thick Ag light reflecting layer was formed on the surface of the stainless steel plate, the two shutters were closed to extinguish the plasma, completing the manufacture of the base.

Next, a ZnO thin film layer whose boron content changes in the layer thickness direction was formed by the formation method (1). Switch the target electrode to the RF power source and supply Ar gas to the deposition chamber for 5 minutes.
0 sccm, substrate temperature 350 ° C, pressure 5mT
Orr, RF power of 300 W was applied to the target electrode from a sputtering power source to generate Ar plasma. The target shutter and the base shutter were opened. When the RF power was monotonically increased with time to form a 2.0 μm-thick boron-containing ZnO thin film layer on the surface of the Ag light reflection layer, the two shutters were closed to extinguish the plasma.

Next, an n-layer, an i-layer, and a p-layer were sequentially formed on the ZnO thin film layer. The n-layer made of a-Si and the i-layer made of a-Si were formed by RFPCVD, and the p-layer made of a-SiC was formed by MWPCVD.

To form an n-layer made of a-Si, H
₂ gas was introduced at 300 sccm, and the pressure in the deposition chamber was 1.
At 0 Torr, when the substrate temperature was stabilized at 250 ° C.,
SiH ₄ gas 2 sccm, PH ₃ / H ₂ gas 200 sc
cm, H ₂ gas 100 sccm was introduced, and the pressure in the deposition chamber was adjusted to 1.0 Torr. The power of the RF power source was set to 5 W, RF power was applied to the bias electrode, plasma was generated, the substrate shutter was opened, and Zn
The formation of the n-layer was started on the O thin film layer. When the n-layer having a thickness of 40 nm was formed, the shutter was closed, the RF power was turned off, the plasma was extinguished, and the formation of the n-layer was completed. Stop the flow of SiH ₄ gas and PH ₃ / H ₂ gas into the deposition chamber,
After continuously flowing H ₂ gas into the deposition chamber for 5 minutes, the inflow of H ₂ gas was stopped, and the deposition chamber and the inside of the gas pipe were 1 × 10 2
^The chamber was evacuated to ^-5 Torr.

To form an i-layer made of a-Si, H
₂ gas is introduced at 500 sccm and the pressure is 1.5 Torr
r, The substrate temperature was set to 250 ° C. When the substrate temperature is stabilized, SiH ₄ gas is introduced, and SiH ₄
Gas flow rate is 50 sccm, H ₂ gas flow rate is 500 scc
m and the pressure in the deposition chamber were adjusted to 1.5 Torr. Next, the power of the RF power source was set to 50 W, and applied to the bias electrode to generate plasma, the base shutter was opened, and the formation of the i-layer on the n-layer was started.
When the i-layer was formed, the shutter was closed, the RF power was turned off, the plasma was extinguished, and the formation of the i-layer was completed.
SiH ₄ stop the flow of gas, 5 minutes, after which continued to flow H ₂ gas, stopping the inflow of the H ₂ gas was evacuated deposition chamber and the gas in the pipe up to 1 × 10 ^-5 Torr.

To form a p-layer made of a-SiC,
H ₂ gas was introduced at 500 sccm, the pressure in the deposition chamber was set to 0.02 Torr, and the substrate temperature was set to 200 ° C. When the substrate temperature becomes stable, SiH ₄ gas, C
H ₄ gas and B ₂ H ₆ / H ₂ gas were introduced. At this time,
SiH ₄ gas flow rate is 10 sccm, CH ₄ gas flow rate is 2
sccm, H ₂ gas flow rate is 100 sccm, B ₂ H ₆ /
H ₂ gas flow rate 500 sccm, pressure 0.02 Torr
r was adjusted. Then, the power of the MW power supply is reduced by 5
Set to 00W, introduce MW power through the dielectric window,
Plasma is generated, the base shutter is opened, the formation of a p-layer on the i-layer is started, and when the p-layer having a thickness of 10 nm is formed, the shutter is closed, the MW power is turned off, the plasma is extinguished, and the p-layer Finished forming. SiH ₄ gas, CH
Stop the inflow of ₄ gas and B ₂ H ₆ / H ₂ gas, and
After the continuous flow of the _two gases, the flow of the H ₂ gas was stopped, and the inside of the deposition chamber and the gas pipe were evacuated to 1 × 10 ⁻⁵ Torr, and the deposition chamber was leaked.

Next, a transparent electrode having a thickness of 7 was formed on the p-layer.
0 nm of ITO was vacuum deposited by a resistance heating vacuum deposition method.
Next, a mask having a comb-shaped hole is placed on the transparent electrode, and Cr
(40 nm) / Ag (1000 nm) / Cr (40 n
m) was vacuum-deposited by an electron beam vacuum deposition method.

Thus, the production of the solar cell has been completed. This solar cell will be referred to as (SC Ex. 1).

Comparative Example 1-1 Example 1 was repeated except that the RF power was kept constant over time when the ZnO thin film layer was formed.
Under the same conditions as above, a solar cell (SC ratio 1-1) was produced.

(Comparative Example 1-2) A solar cell (SC ratio 1-1) was formed under the same conditions as in Example 1 except that ZnO containing no boron was used as a target when forming a ZnO thin film layer.
2) was produced.

(Comparative Example 1-3) A solar cell (SC ratio 1-3) was manufactured under the same conditions as in Example 1 except that the temperature of the base was 80 ° C when forming the ZnO thin film layer.

The solar cell (SC actual 1) and (SC ratio 1−
1), (SC ratio 1-2), and (SC ratio 1-3) were prepared six each, and the initial photoelectric conversion efficiency (photovoltaic power / incident light power), high-temperature high-humidity vibration deterioration, high-temperature high-humidity light Deterioration, high-temperature high-humidity vibration deterioration when bias voltage was applied, and high-temperature high-humidity light deterioration were measured.

The measurement of the initial photoelectric conversion efficiency can be obtained by placing the produced solar cell under irradiation of AM-1.5 (100 mW / cm ² ) light and measuring the V-1 characteristic.

For measurement of high-temperature high-humidity vibration deterioration, a solar cell whose initial photoelectric conversion efficiency was measured in advance was placed in a dark place with a humidity of 90% and a temperature of 70 ° C., and a vibration frequency of 60 Hz and an amplitude of 0.
After the vibration of 1 mm was applied for 500 hours, the reduction rate of the photoelectric conversion efficiency under AM-1.5 light irradiation (photoelectric conversion efficiency after high-temperature and high-humidity vibration deterioration test / initial photoelectric conversion efficiency) was performed.

For the measurement of high-temperature high-humidity light deterioration, a solar cell whose initial photoelectric conversion efficiency was measured in advance was placed in an environment with a humidity of 90% and a temperature of 70 ° C., and irradiated with AM-1.5 light for 500 hours. Later, the rate of decrease in photoelectric conversion efficiency under AM-1.5 light irradiation (photoelectric conversion efficiency after high-temperature and high-humidity light deterioration test / initial photoelectric conversion efficiency) was used.

As a result of the measurement, (SC actual 1)
Ratio 1-1), (SC ratio 1-2), (SC ratio 1-3), initial photoelectric conversion efficiency, reduction rate of photoelectric conversion efficiency after high-temperature and high-humidity light deterioration, and photoelectric conversion after high-temperature and high-humidity vibration deterioration The conversion efficiency reduction rate was as follows. These differences were mainly due to the difference between open-circuit voltage and short-circuit photocurrent.

Initial photoelectric conversion efficiency High-temperature high-humidity vibration deterioration High-temperature high-humidity light deterioration (SC actual 1) 1.00 times 1.00 times 1.00 times (SC ratio 1-1) 0.90 times 0.87 times 0 0.89 times (SC ratio 1-2) 0.87 times 0.85 times 0.87 times (SC ratio 1-3) 0.86 times 0.86 times 0.88 times First, the surface of the solar cell was examined with an electron microscope. Observed at
In (SC Ex. 1), (SC Comp. 1-1), and (SC Comp. 1-2), the surface is uneven (texture) as shown in FIG. 1, and the surface unevenness was examined using a surface roughness meter. However, it was found that the average peak height was about 0.15 μm.
The surface irregularities (SC ratio 1-3) were 0.04 μm or less.

Next, samples of the ZnO thin film layer used for the four solar cells were prepared, and the crystallinity was evaluated using an X-ray diffractometer. (SC actual 1), (SC ratio 1-1), (SC ratio 1-1) Although the composition has c-axis orientation in the ratio 1-2), the (SC ratio 1-
In 3), it was found that it did not have crystallinity.

Next, the change in the boron content in the thickness direction of the fabricated (SC Ex. 1) was determined by SIMS, and as shown in FIG. It was found that the value varied depending on the RF power of the sputtering power supply. In (SC ratio 1-1), there was no change in the layer thickness direction. In (SC ratio 1-2), boron was not detected. In (SC ratio 1-3), the same change as (SC actual 1) was obtained. Was done.

As described above, the solar cell (SC actual 1) of this embodiment is different from the conventional solar cell (SC ratio 1-1) and (SC ratio 1).
-2) and (SC ratio 1-3).

Example 2 A solar cell having the configuration shown in FIG. 1 in which the c-axis was substantially perpendicular to the substrate and the boron content was high at the crystal grain boundaries was produced. Ag in Example 1
When forming the light reflecting layer, the solar cell (S) was formed in the same manner as in Example 1 except that the substrate temperature was set to 350 ° C. and the RF power of the sputter power supply was rapidly increased immediately before each crystal grain contacted.
C Ex 2) was produced.

When the same measurement as in Example 1 was performed, the vibration degradation and light degradation were almost the same, but the solar cell of (SC Ex. 2) was more excellent in initial photoelectric conversion than (SC Ex. 1). Rate. This is because the surface irregularities were optimized and the short-circuit current was improved.

(Comparative Example 2-1) A solar cell was manufactured in the same manner as in Example 2 except that the RF power of the sputtering power supply was constant when forming the ZnO thin film layer.

(Comparative Example 2-2) A solar cell was fabricated in the same manner as in Example 2, except that a target not containing boron was used when forming the ZnO thin film layer.

(Comparative Example 2-3) A solar cell (SC ratio 2-3) similar to that of Example 2 was prepared except that the substrate temperature was set to 80 ° C when forming the ZnO thin film layer.

First, when the surface of the solar cell was observed with an electron microscope, (SC Ex. 2), (SC ratio 2-1), (SC ex.
In the ratio 2-2), the surface is uneven (texture) as shown in FIG. 1. When the surface unevenness was examined using a surface roughness meter, the average peak height was about 0.24 μm. I understood. In (SC ratio 2-3), the peak height of the unevenness was 0.05 μm or less.

When the crystallinity was examined using an X-ray diffractometer, (SC Ex. 2), (SC ratio 2-1), (SC ex.
In the ratio 2-2), it was found that there was c-axis orientation, and the c-axis was perpendicular to the substrate. (SC ratio 2-3) was found to have no orientation and no crystallinity.

Further, measurement of vibration deterioration and light deterioration was performed by applying a forward bias. Solar cells (SC actual 2), whose initial photoelectric conversion efficiency was measured in advance, (SC ratio 2-1),
(SC ratio 2-2) and (SC ratio 2-3) were measured at a humidity of 50% and a temperature of 25 ° C., and a voltage of 0.8 V was applied as a forward bias voltage to measure vibration deterioration and light deterioration. As a result of the measurement,
(SC ratio 2-1), (SC ratio 2-2), (SC ratio 2-
It was found that (SC Ex. 2) had better characteristics than 3).

Example 3 A photodiode (PD Ex. 3) having the layer configuration shown in FIG. 1 was manufactured. First, a base was produced. A 0.5 mm thick, 20 × 20 mm ² glass substrate is ultrasonically cleaned with acetone and isopropanol, dried with hot air, and the light reflection of 0.1 μm thick Al on a glass substrate surface at room temperature by a vacuum evaporation method. The layer was formed, and the production of the base was completed. In the same manner as in Example 1, a ZnO thin film layer, an n layer (a-Si: P RFPCVD method), and an i layer (a
-Si RFPCVD method), p-layer (a-SiC: BM)
WPCVD method). When the ZnO thin film layer is formed, it is performed by the formation method of (2), a target not containing boron is used, B ₂ H ₆ / H ₂ is introduced as a gas containing boron, and the flow rate is changed over time. hand,
The boron content was changed as shown in FIG. Then, p
On the layer, the same transparent electrode and current collecting electrode as in Example 1 were formed.

Comparative Example 3-1 A photodiode (PD ratio 3) was formed under the same conditions as in Example 3 except that the flow rate of the B ₂ H ₆ / H ₂ gas was not changed when the ZnO thin film layer was formed.
-1) was prepared.

(Comparative Example 3-2) A photodiode (PD ratio 3-2) was manufactured under the same conditions as in Example 3 except that B ₂ H ₆ / H ₂ gas was not introduced when forming the ZnO thin film layer. did.

(Comparative Example 3-3) A photodiode (PD ratio 3-3) was manufactured under the same conditions as in Example 3 except that the temperature of the substrate was 80 ° C. when forming the ZnO thin film layer.

The on / off ratio (photocurrent / dark current measurement frequency of 10 kHz when irradiating AM-1.5 light) of the fabricated photodiode was measured. This will be referred to as an initial on / off ratio. Next, the same measurement as in Example 1 was performed for the on / off ratio. As a result, the photodiode (PD actual 3) of this embodiment is different from the conventional photodiode (PD
It has been found that it has more excellent characteristics than (Comparative 3-1), (PD ratio 3-2), and (PD ratio 3-3).

Example 4 A solar cell (SC Ex. 4) having a boron-containing n-layer on a ZnO thin film layer was manufactured.
When forming an n-layer in Example 1, a new B ₂ H ₆ / H ₂ gas was introduced at 20 sccm, and an n-layer (μc-Si: PB RFPCVD method) and an i-layer (a- S
i RFPCVD method), p layer (a-SiC: B MWP)
CVD method). When forming a ZnO thin film layer,
This was performed by the formation method of (3), and the RF power was changed with time to change the boron content as shown in FIG. A transparent electrode and a current collecting electrode were formed in the same manner as in Example 1.

The same measurement as in Example 1 was carried out, and it was found that the solar cell (SC Ex. 4) of the present invention had more excellent characteristics than (SC Ex. 1).

(Example 5) A nip type solar cell using the ZnO thin film layer formed by the method of (5) (SC Ex. 5)
Was prepared. The ZnO thin film layer is formed at a substrate temperature of 350 ° C. using a normal RF magnetron sputtering method,
A p layer (μc-Si: B) is formed thereon by the MWPCVD method under the conditions of a SiH ₄ gas flow rate of 50 sccm, B ₂
H ₆ / H ₂ gas flow rate 500 sccm, pressure 5 mTorr,
The MW power was 300 W and the substrate temperature was 350 ° C. On it, the same i-layer, n-layer, transparent electrode and current collecting electrode as in Example 2 were formed.

The boron content in the ZnO thin film layer is shown in FIG.
SIMS revealed that the boron content was high near the grain boundaries.

When the same measurement as in Example 1 was performed, it was found that the solar cell (SC Ex. 5) had more excellent characteristics than (SC Ex. 2). Also, the same measurement as in Example 2 was performed, and it was found that (SC Ex. 5) had more excellent characteristics than (SC Ex. 2).

(Example 6) A film was formed by the method of (5),
Ni using ZnO thin film layer containing boron and silicon
A p-type solar cell (SC Ex. 6) was produced. ZnO thin film layer
Is based on standard RF magnetron sputtering
It was formed at a body temperature of 350 ° C. On top of that, the p layer is MWPCV
D method, and the formation condition is SiH_Four5 gas flow rate 0scc
m, B_TwoH ₆/ H_TwoGas flow rate 500sccm, pressure 5m
Torr, MW power 800W, substrate temperature 350 ° C
Was.

The boron content in the ZnO thin film layer is shown in FIG.
SIMS revealed that the boron content was high near the grain boundaries. Similarly, Zn
SIMS revealed that the silicon content in the O thin film layer was as shown in FIG. 3C, and that the silicon content was high near the grain boundaries.

The i-layer, the n-layer, the transparent electrode, and the current collecting electrode were manufactured under the same conditions as in Example 1. When the same measurement as in Example 1 was performed, it was found that the solar cell (SC Ex. 6) had more excellent characteristics than (SC Ex. 5). In addition, the same measurement as in Example 2 was performed, and it was found that (SC Ex. 6) had more excellent characteristics than (SC Ex. 5).

(Example 7) A film was formed by the method of (7),
A nip solar cell (SC Ex. 7) using a ZnO thin film layer containing boron, silicon, and germanium was manufactured. The ZnO thin film layer is formed at a substrate temperature of 350 ° C. using a normal RF magnetron sputtering method, the p layer is formed under the same conditions as in Example 6 except that GeH ₄ is newly introduced at 1 sccm, and the i layer is formed by the MWPCVD method. Formed with Si
H ₄ gas flow rate 150 sccm, H ₂ gas flow rate 300 sc
cm, pressure 5 mTorr, MW power 400 W, and RF power 800 W.

The boron content in the ZnO thin film layer is shown in FIG.
SIMS revealed that the boron content was high near the grain boundaries. Further Zn
SIMS revealed that the silicon content and the germanium content in the O thin film layer were as shown in FIG. 3C, and that both the silicon content and the germanium content increased near the grain boundaries.

The n-layer, transparent electrode, and current collecting electrode were manufactured under the same conditions as in Example 1. The same measurement as in Example 1 was performed, and it was found that the solar cell (SC Ex. 7) had more excellent characteristics than (SC Ex. 6). In addition, the same measurement as in Example 2 was performed, and it was found that (SC Ex. 7) had more excellent characteristics than (SC Ex. 6).

Example 8 A solar cell (SC Ex. 8) having a pinpin structure and shown in FIG. 4A was manufactured. Using a target not containing silicon, a crystalline ZnO thin film layer and an n1 layer (a-Si: PBR) were formed on a substrate by the formation method of (6).
After forming the FPCVD method, the layer thickness is 40 nm, the Ar gas flow rate is 300 sccm, the pressure is 10 mTorr, and the MW power is 6
Microwave plasma treatment was performed under the condition of 00W for 30 minutes. Subsequently, an i1 layer (a-SiGe RFPCVD method, a layer thickness of 250 nm) and a pl layer (a-SiC: B MWPCV)
D method layer thickness 10 nm), n2 layer (a-Si: P RFP)
CVD method, layer thickness 20 nm), i2 layer (a-Si MWP)
CVD method, layer thickness 150 nm), p2 layer (μc-SiC:
B MWPCVD method, layer thickness 5 nm). Z
The same layers as in Example 1 were used except for the nO thin film layer and the pinpin layer.

The boron content in the ZnO thin film layer is shown in FIG.
SIMS revealed that the boron content was high near the grain boundaries. Further Zn
SIMS showed that the silicon content in the O thin film layer was as shown in FIG. 3B, and that the silicon content increased near the grain boundaries.

(Comparative Example 8) The same procedure as in Example 8 was performed except that the microwave plasma treatment was not performed.
A pin type solar cell (SC ratio: 8) was produced.

The same measurement as in Example 1 was carried out, and it was found that the solar cell (SC Ex. 8) had more excellent characteristics than (SC ratio 8). In addition, the same measurement as in Example 2 was performed, and it was found that (SC Ex. 8) had better characteristics than (SC Comp. 8).

(Example 9) A ZnO thin film layer similar to that of Example 1 was formed on a glass substrate.
Except for flowing ₄ gas at 10 sccm, the same p
An in-layer was formed, and a solar cell (SC Ex. 9) having a light reflection layer made of Al on the pin layer was manufactured. The light reflection layer had a thickness of 0.5 μm and was formed by electron beam vacuum evaporation.

(Comparative Example 9) When forming a ZnO thin film layer,
A solar cell (SC ratio 9) was manufactured under the same conditions as in Example 9 except that a target containing no boron was used.

The same measurement as in Example 1 was carried out by irradiating light from the back surface of the glass substrate.
It was found that it had better characteristics than the ratio 9).

(Embodiment 10) Using the deposition apparatus using the roll-to-roll method of FIG. 5, the pinp of FIG.
An in-type solar cell was manufactured.

The substrate (support) has a length of 300 m and a width of 30 c.
A strip-shaped stainless steel sheet having a thickness of 0.1 mm and a thickness of 0.1 mm was used.
FIG. 5 is a schematic view of an apparatus for continuously forming photovoltaic elements using a roll-to-roll method. In this apparatus, a substrate delivery chamber 510, a plurality of deposition chambers 501 to 509, and a substrate winding chamber 511 are sequentially arranged, and a separation passage 51 is provided therebetween.
Each deposition chamber has an exhaust port, and the inside can be evacuated. The strip-shaped substrate 513 is wound up from the substrate delivery chamber to the substrate winding chamber through the deposition chamber and the separation passage. At the same time, gas can be introduced from the gas inlets of the respective deposition chambers and separation passages, and the gas can be exhausted from the respective exhaust ports to form respective layers. In the deposition chamber 501, AlSi (9:
1), a ZnO thin film layer containing boron in the deposition chamber 502, and pi in the deposition chambers 503 to 508.
For the npin layer, a transparent electrode made of ITO is formed in the deposition chamber 509.

In each of the deposition chambers, a halogen lamp heater 518 for heating the substrate from behind is installed, and each deposition chamber is heated to a predetermined temperature. In the deposition chamber 501, a DC magnetron sputtering method is performed, Ar gas is introduced from a gas inlet 526, and AlSi (9: 1) is used as a target.
Is used. In the deposition chamber 502, RF magnetron sputtering is performed, an Ar gas is introduced, and ZnO containing no boron is used as a target. In the deposition chamber 509, R
F magnetron sputtering, O ₂ gas and A
r gas was introduced, and ITO (In ₂ O ₃ +
SnO ₂ (5 wt%) is used.

Reference numeral 550 denotes a top view of the deposition chambers 503 to 508. In the deposition chambers 504 and 507, an MWPCVD method to which RF power is applied is performed.
The PCVD method is performed, and the RFPCVD method is performed in the deposition chambers 503, 505, and 506. Each deposition chamber has a source gas inlet 514 and an exhaust port 515, an RF electrode 516 or a microwave applicator 517 is attached, and a source gas supply device (not shown) is connected to the source gas inlet 514. A vacuum exhaust pump (not shown) such as an oil diffusion pump or a mechanical booster pump is connected to an exhaust port of each deposition chamber, and an inlet 519 through which scavenging gas flows is provided in a separation passage 512 connected to the deposition chamber.
A scavenging gas as shown in the figure is introduced. A bias electrode 531 is arranged in the deposition chambers 504 and 507, which are the i-layer deposition chambers, and an RF power supply (not shown) is connected as a power supply.

540 is a side view of the deposition chamber 502.
In order to gradually change the boron content in the layer thickness direction, B ₂ H ₆ / H ₂ gas was used as a scavenging gas introduced into the separation passage between the deposition chamber 502 and the deposition chamber 503. By doing so, a part of the B ₂ H ₆ / H ₂ gas is removed from the deposition chamber 502.
, And partly flows into the deposition chamber 503. And pi
A lot of boron is contained in the vicinity 543 of the interface with the n-layer,
A change in the content is obtained such that the content gradually decreases toward the interface 541 with the Ag light reflection layer.

[0169] A delivery roll 520 is provided in the substrate delivery chamber.
And a guide roller 521 for applying an appropriate tension to the substrate and keeping the substrate horizontal at all times, and a winding roller 522 and a guide roller 523 in the substrate winding chamber.

First, the above stainless sheet is wound around a delivery roll (average radius of curvature: 30 cm), set in a substrate delivery chamber, passed through each deposition chamber, and then wound around a substrate take-up roll. The entire apparatus is evacuated by a vacuum pump, the lamp heaters in each deposition chamber are turned on, and the substrate temperature in each deposition chamber is set to a predetermined temperature. When the pressure of the entire apparatus becomes 1 mTorr or less, a scavenging gas as shown in FIG. 5 is introduced from a scavenging gas inlet 519, and the substrate is taken up by a take-up roll while moving in the direction of the arrow in the figure. Each source gas flows into each deposition chamber. At this time, the flow rate of the gas flowing into each separation passage or the pressure of each deposition chamber is adjusted so that the raw material gas flowing into each deposition chamber is not diffused into another deposition chamber. Next, RF power or MW power is introduced to generate plasma, and respective layers are formed.

An AlSi light reflecting layer (substrate temperature 350 ° C., layer thickness 300 nm) is formed on a substrate in a deposition chamber 501, and a ZnO thin film layer (substrate temperature 350 ° C., layer thickness 2) is formed in a deposition chamber 502.
000 nm), n1 layer (μc-Si: P
B, a layer thickness of 20 nm), an i1 layer (a-SiGe, a layer thickness of 180 nm) in the deposition chamber 504, and a p layer in the deposition chamber 505.
One layer (μc-Si: B, layer thickness 10 nm), deposition chamber 506
, N2 layer (μc-Si: P, layer thickness 20 nm), deposition chamber 5
07, i2 layer (a-Si, layer thickness 220 nm), deposition chamber 5
08, a p2 layer (μc-SiC: B, layer thickness 10 nm) and a transparent electrode (ITO, layer thickness 75 nm) were sequentially formed in the deposition chamber 509.

When the winding of the substrate was completed, all MW power, RF power, and sputtering power were turned off, the plasma was extinguished, and the inflow of the raw material gas and the scavenging gas was stopped. The entire device was leaked, and the take-up roll was taken out.

Next, a carbon space having a layer thickness of 5 μm and a line width of 0.5 mm was printed by a screen printing method, and a silver paste having a layer thickness of 10 μm and a line width of 0.5 mm was printed thereon to form a current collecting electrode. , Roll-shaped solar cell 250 mm x 10
It was cut to a size of 0 mm. Thus, the production of the pinpin type solar cell (SC Ex. 10) using the roll-to-roll method was completed.

(Comparative Example 10) The scavenging gas flowing in the separation passage between the deposition chambers 502 and 503 was changed to Ar gas,
A solar cell (SC ratio: 10) was manufactured under the same conditions as in Example 14 except that boron was not contained in the thin film layer.

When the same measurement as in Examples 1 and 2 was performed, it was found that the solar cell (SC Ex. 10) of the present invention had more excellent characteristics than the conventional solar cell (SC ratio: 10). Do you get it.

When the crystallinity was evaluated using an X-ray diffractometer in the same manner as in Example 1, (SC Ex. 10), (SC ratio 10)
Both were found to have c-axis orientation. Also (SC
In Example 10), the boron content in the ZnO thin film layer is
It was found by SIMS that it changed like b. Also, (SC ratio 10) did not contain boron.

Further, when (SC Ex 10) and (SC ratio 10) wound in a roll were stored in a dark place for 3 months,
In (SC Ex. 10), no delamination was observed, but in (SC ratio 10), delamination was slightly observed.

As described above, it was proved that the effect of the photovoltaic element of the present invention was exhibited irrespective of the element configuration and element material.

[0179]

The photovoltaic device of the present invention has a ZnO / pin
It is possible to suppress the recombination of photoexcited carriers near the layer interface and the ZnO / substrate interface, improve the open-circuit voltage and the short-circuit current, and improve the photoelectric conversion efficiency. In addition, light deterioration and vibration deterioration of the photovoltaic element in a high temperature and high humidity environment can be suppressed. Furthermore, it is possible to suppress light deterioration and vibration deterioration when a bias voltage is applied to the photovoltaic element in a high-temperature and high-humidity environment, and to prevent a short circuit. It does not delaminate even in a rolled state.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a layer configuration of a photovoltaic element of the present invention.

FIG. 2 is a schematic diagram illustrating an example of a deposition apparatus.

FIG. 3 is a graph showing a change in a boron content in a ZnO thin film layer in a layer thickness direction.

FIG. 4 is a schematic view showing another example of the layer configuration of the photovoltaic element of the present invention.

FIG. 5 is a schematic diagram showing an example of a roll-to-roll deposition apparatus.

[Explanation of symbols]

101, 411, 421 substrate, 102, 412, 422 ZnO thin film layer, 103 pin layer, 104, 414, 424 transparent electrode, 105, 415, 425 current collecting electrode, 106, 416, 426 crystal grain boundary, 107, 417, 427 crystal grain, 200 deposition apparatus, 201 deposition chamber, 202 vacuum gauge, 203 bias power supply, 204 substrate, 205 heater, 206 waveguide 207 conductance valve 208 valve, 209 target electrode, 210 bias electrode, 211 gas introduction pipe, 212 Applicator, 213 dielectric window, 214 sputtering power supply, 215 substrate shutter, 216 target, 217 target shutter, 219 microwave power supply, 220 exhaust port, 221 toroidal coil, 413 pinpin layer, 423 p npinpin layer, 501,502,503,504,505,506,5
07, 508, 509 deposition chamber, 510 substrate feeding chamber, 511 substrate winding chamber, 512 separation passage, 513 substrate, 514 gas inlet, 515 exhaust port, 516 RF electrode, 517 microwave applicator, 518 lamp heater, 519 scavenging gas Inlet, 520 delivery roll, 521 guide roller, 522 take-up roll, 523 guide roller, 526 gas inlet, 527 target electrode, 529 toroidal coil, 531 bias electrode, 541 interface, 543 interface vicinity.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-110125 (JP, A) JP-A-62-122011 (JP, A) JP-A-62-259480 (JP, A) JP-A 62-259480 295466 (JP, A) JP-A-4-369870 (JP, A) JP-A-1-161776 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 31/04-31 / 078

Claims (11)

(57) [Claims] 1. A zinc oxide thin film layer and a pin layer (p layer, i layer, n layer) made of a non-single-crystal silicon semiconductor material on a substrate.
Layer), the zinc oxide thin film layer is a c-axis oriented crystalline thin film having irregularities of 0.1 to 1.0 μm on the surface, and boron ( B)
Containing, taking the minimum value content of the boron at the interface with the substrate, it is increasing gradually towards the pin layer, before
High boron content near the grain boundaries of the zinc oxide thin film layer
A photovoltaic element, characterized in that it is provided. 2. The zinc oxide thin film layer contains silicon and / or germanium, and the content of the silicon and / or germanium has a minimum value at the interface with the substrate, and gradually increases toward the pin layer. The photovoltaic device according to claim 1, wherein: 3. A zinc oxide thin film layer and a pin layer (p layer, i layer, n layer) made of a non-single-crystal silicon semiconductor material on a substrate.
Layers), the zinc oxide thin film layer has a surface with irregularities of 0.1 to 1.0 μm,
a crystalline thin film having a c-axis orientation and containing boron (B), wherein the boron content has a minimum value at the interface with the substrate and gradually increases toward the pin layer ;
The zinc oxide thin film layer is made of silicon and / or germanium
Silicon and silicon near the grain boundaries of the zinc oxide thin film layer.
And / or germanium is contained in a large amount . Wherein said c-axis, the photovoltaic device according to any one of claims 1 to 3, characterized in that it is substantially perpendicular to the substrate surface. 5. The light according to claim 3, wherein the silicon and / or germanium content has a minimum value at the interface with the substrate and gradually increases toward the pin layer. Electromotive element. 6. The p-layer or the n-layer in contact with the zinc oxide thin film layer contains boron.
The photovoltaic device according to any one of claims 1 to 5. 7. The method according to claim 1, wherein the p-layer or the n-layer in contact with the zinc oxide thin-film layer is formed by a microwave plasma CVD method so that boron in the p-layer or the n-layer is diffused into the zinc oxide thin-film layer. The photovoltaic device according to claim 6, wherein: 8. After forming the p-layer or the n-layer in contact with the zinc oxide thin-film layer, the boron in the p-layer or the n-layer is subjected to plasma treatment by a microwave plasma CVD method. The photovoltaic device according to claim 6, wherein the photovoltaic device is diffused into the photovoltaic device. 9. A method in which the i-layer is formed by microwave plasma CVD to diffuse boron in the p-layer or the n-layer in contact with the zinc oxide thin film layer into the zinc oxide thin film layer. The photovoltaic device according to any one of claims 6 to 8, wherein: 10. The method according to claim 7, wherein silicon and / or germanium in the p layer or the n layer in contact with the zinc oxide thin film layer is diffused into the zinc oxide thin film layer together with boron. A photovoltaic device according to Item. 11. The photovoltaic device according to claim 1, wherein the substrate is a flexible band-shaped substrate and can be wound in a roll.