JPH088450A - Manufacture of solar cell - Google Patents

Abstract

PURPOSE:To manufacture a semiconductor thin film of a chalcopyrite structure consisting of elements of groups I, III and VI, which have an even compositional ratio in a large area, in a simple process and to provide a solar cell, which can be simplified its protective layer, is superior in productivity and is capable of obtaining a high energy conversion efficiency. CONSTITUTION:An oxide thin film (for example, a Cu2In2O5 film) 2 containing elements of groups I and III is deposited on a transparent base body 1 and is heat-treated in a group VI element-containing atmosphere (for example, H2Se- containing Ar gas), whereby a semiconductor thin film (a CuInSe2 film) 3 of chalcopyrite structure consisting of elements of groups I, III and VI is manufactured. An electrode film (for example, an Au film) 4 is deposited on this thin film 3 of the chalcopyrite structure and a solar cell is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a solar cell having high energy conversion efficiency.

[0002]

2. Description of the Related Art In recent years, thin film solar cells using CuInSe ₂ as a light absorbing layer as a chalcopyrite structure semiconductor thin film composed of group I, group III and group VI elements have shown high energy conversion efficiency, It has been reported to have the advantage of no degradation.

As one of CuInSe ₂ thin film solar cells, a transparent conductive film is formed on a transparent insulating substrate such as glass, an n-type window layer and a CuInSe ₂ film are sequentially formed on the transparent conductive film, and then a metal electrode is formed. There is a configuration (hereinafter, referred to as a super straight configuration). In the superstrate structure, since the light incident side is the substrate, the protective layer can be simplified, the package to the solar cell module is easy, the adhesion to the substrate is good, and the manufacturing process can be simplified. It has been pointed out that the structure has advantages such as large area, mass production, and cost reduction of solar cells.

However, CuInSe ₂ in this configuration
As a method of manufacturing the film, a ternary vapor deposition method is mainly used. Three
The former vapor deposition method has an advantage that a film having a small area and a precisely controlled and uniform composition can be obtained, but has problems such as high manufacturing cost and difficulty in forming a large area thin film. is there.

On the other hand, although not used in the superstrate structure, as a manufacturing method for obtaining a CuInSe ₂ thin film having a large area and relatively uniform, a laminated thin film of Cu and In formed on a metal film is formed into H ₂ Se or A method called selenization, which is produced by firing in an atmosphere containing Se vapor, has been reported.

This method is a simple process, and Cu
Although it has an advantage that the manufacturing cost of the InSe ₂ thin film can be reduced, the weak adhesion between CuInSe ₂ and the metal film, the variation in the composition ratio in a minute region due to the condensation of In, and the formation of a heterophase compound other than CuInSe ₂ However, there are problems such as a decrease in conversion efficiency due to the above.

As a method for solving the problem of the selenization method, an oxide (Cu-In-O) thin film containing Cu and In is formed and baked in an atmosphere containing H2S gas to form CuIn.
A method for producing an S ₂ film is described in "Applied Physics Letters", Vol. 62, No. 16, pp. 1943 to 1945, "Preparation of Materials".
CuInS ₂ Films Bisulfurization of Cu-In-O Films (Preparatio
n of CuInS ₂ films by sulfurization of Cu-In-Ofilm
s) ”. In this report, the sulfide CuIn
Although S ₂ is described, a selenide CuInSe ₂ film can be obtained by using H ₂ Se gas.

Since this method uses an oxide of Cu and In, a CuInS ₂ or CuInSe ₂ film having a large area and a uniform composition can be obtained without causing In aggregation. Further, the CuInS ₂ and CuInSe ₂ films produced by the sulfurization or selenization method using this oxide thin film as a precursor also have excellent adhesion to the underlying metal film. However, there is no manufacturing method suitable for the superstrate structure.

[0009]

From the above, it can be seen that a solar cell having a superstrate structure in which a chalcopyrite structure semiconductor thin film produced by the selenization method is used as a light absorption layer is most excellent in productivity. However, as described above, most of the preparation methods of the chalcopyrite structure semiconductor thin film used for the solar cell of the superstrate structure are the ternary co-evaporation method, and there are few reports of the superstrate type solar cell using the selenization method. (Reference: 11th EC Ph
tovoltaic Solar Energy Conference, T. Yoshida, FAB
RICATION OF CuInSe ₂ SOLAR CELLS IN A SUPERSTRATE C
ONFIGURATION). In this report, a CuInSe2 film is formed on the CdS film by the selenization method. However, it has been observed that in the obtained film, interdiffusion of Cd or Cu or In occurs between CdS and CuInSe ₂ , and that a heterogeneous compound such as Cu ₃ Se ₂ exists.

This indicates that an inhomogeneous element distribution occurs in the film surface or in the film. As a result, only a low conversion efficiency of 1.5% is obtained. Further, weak adhesion between the CdS film and the CuInSe ₂ film is pointed out.

Therefore, in order to produce a solar cell having a superstrate structure suitable for industrialization, a calco compound having excellent adhesiveness to a substrate or a thin film coated on the substrate and having a uniform composition distribution free of heterophasic compounds. It is important to prepare a pyrite structure semiconductor thin film by the selenization method.

[0012]

In order to solve the above-mentioned problems, according to the present invention, an oxide thin film containing a group I element and a group III element is formed on a transparent substrate and then heat-treated in an atmosphere containing a group VI element. This is a method for manufacturing a solar cell including a step of forming a chalcopyrite structure semiconductor thin film composed of a group I element, a group III element and a group VI element.

In the present invention, there are three methods for forming the oxide thin film which is the precursor before the heat treatment in the atmosphere of the group VI element.

The first is a method of using as a precursor an oxide thin film containing a group I element and a group III element on a transparent substrate and in which the element is uniformly distributed in the film.

The second method is to use an oxide thin film formed by stacking an oxide thin film containing a group III element and an oxide thin film containing a group I element on a transparent substrate as a precursor.

A third method is to use as a precursor an oxide thin film formed by alternately depositing at least two layers of an oxide thin film containing a group I element and an oxide thin film containing a group III on a transparent substrate.

Further, in the third method, a transparent substrate is formed.
When alternately depositing an oxide thin film containing a group I element and an oxide thin film containing a group III element, including the group I element deposited on the thin film with respect to the thickness of the oxide thin film containing a group III element It is preferable to form the oxide thin film by gradually increasing the film thickness ratio from the base.

The present invention also presents two methods for forming an atmosphere containing a Group VI element.

The first method is a method using at least one of hydrogenated gas and carbonized gas of Group VI element.

The second method is a method using an organic substance containing a Group VI element. The heat treatment temperature is 200 ° C
Is preferably set as a lower limit and 1000 ° C. as an upper limit.

Further, it is preferable to use, as the transparent substrate, a transparent insulator substrate coated with at least one of a transparent conductive film and a transparent insulator film. As the transparent conductive film, it is preferable to use a thin film composed of at least one of the group consisting of tin oxide, indium tin oxide, and zinc oxide containing at least one of Group III elements and hydrogen. As the insulator film, it is preferable to use a thin film composed of at least one selected from the group consisting of zinc oxide, aluminum oxide, silicon oxide, yttrium oxide, and titanium oxide.

[0022]

[Function] When an oxide thin film containing a group I element and a group III element is heat-treated in an atmosphere containing a group VI element, for example, in a gas containing H2S, a chalcopyrite structure semiconductor thin film having a uniform composition distribution (hereinafter referred to as I-III -VI2 thin film) is formed as described in the above prior art.

Using the method for producing a chalcopyrite structure semiconductor thin film by selenizing this oxide, an oxide containing a group I and a group III element is formed on a transparent substrate and heat-treated in a group VI atmosphere to obtain p. A type I-III-VI2 thin film is formed. A pn junction is formed by the p-type film and the n-type semiconductor film coated on the transparent substrate. Alternatively, a Schottky junction (possible even if an insulating layer is sandwiched) is formed with a transparent conductive film coated on a transparent substrate. From the surface of the transparent substrate not covered with the n-type semiconductor film or the conductive film, the pn
Alternatively, when light is incident on the Schottky junction region, carriers are excited and extracted as a current to the outside. As described above, a solar cell having a superstrate structure can be manufactured by a simple process.

Furthermore, selenization method of oxides, oxide layer containing VI group elements and unreacted III group element at the boundary between the heat treatment temperature or time of a transparent substrate (e.g., Ga ₂ O _3,
In ₂ O ₃ ) can remain. This oxide layer is transparent to visible and near-infrared light and has n-type conduction and high resistance. Therefore, it is used as an n-type semiconductor layer or a transparent insulating layer on the above-mentioned transparent substrate as a solar cell. Can be used for window layer. Therefore, since the pn or Schottky junction can be formed only by controlling the heat treatment temperature and time, the manufacturing process of the solar cell can be simplified, the productivity can be improved, and the cost can be reduced. Further, since the oxide containing the group III element and the transparent conductive film or the transparent insulator film covering the transparent substrate are excellent in adhesion, the I-III-VI2 thin film and the transparent substrate are not peeled off. Therefore, it is possible to form a uniform thin film having no pinhole (hole) even in a large area.

As described above, it is possible to provide a solar cell having a high energy conversion efficiency and excellent productivity.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a part of a manufacturing process of a solar cell showing one embodiment of the present invention. Here, as the translucent substrate 1, a substrate in which a transparent conductive film indium tin oxide (ITO) is coated on a glass substrate and zinc oxide (ZnO) which is a transparent insulating film is sequentially deposited thereon is used. The respective film thicknesses are 0.2 and 0.1 μm.

On the transparent substrate (substrate) 1, a group I and a group III
Cu, which is an oxide containing a group element₂In₂O_FiveThin film 2 spa
It was formed by vapor deposition. The degree of vacuum for sputter deposition is 8 ×
10 ^-3Cu in Ar atmosphere of Torr₂In₂O_FiveGrilled
High-frequency magnetron sputtering method with a target as a target
Went by. Cu made₂In₂O_FiveHas a film thickness of 0.8μ
m. A substrate coated with this oxide thin film is placed in a quartz tube.
2% H diluted in Ar₂In an atmosphere containing Se
And heat treated at 450 ℃ for 1 hour.
C, which is a chalcopyrite-type structural semiconductor thin film composed of a single element
uInSe₂The thin film 3 was formed. CuInSe formed₂
The film thickness is 1.5 μm. This CuInSe₂On membrane 3
The Au film 4 to be the electrode is formed by electron beam evaporation to a film thickness of 0.
2 μm was formed.

The composition distributions of the Cu ₂ In ₂ O ₅ thin film and the CuInSe ₂ thin film formed after heat treatment with H ₂ Se were measured by energy dispersive X-ray fluorescence analysis (EDX). In the Cu ₂ In ₂ O ₅ thin film, the composition of only Cu and In was analyzed. Ten points were measured within an area of 5 cm ² . Typical composition ratio is Cu: In = 49.5: 50.5
Met. Also, the error of the composition ratio at each measurement point is 0.
It was 5% or less.

Similarly, a 10-point composition ratio was measured in a CuInSe ₂ film having an area of 5 cm ² , and a typical value was C.
u: In: Se = 24.2: 25.2: 50.6 was obtained. The error at each measurement point was 0.5% or less, as in the case of the Cu ₂ In ₂ O ₅ film. Therefore, it can be seen that both Cu ₂ In ₂ O ₅ and CuInSe ₂ films have a uniform composition distribution in the film plane.

Next, a Cu ₂ In ₂ O ₅ thin film and CuInSe ₂
The element distribution of the thin film is measured by secondary ion mass spectrometry (SIMS), and the results are shown in FIGS. 2 (a) and 2 (b). The horizontal axis represents the film thickness, and the film thickness of 0 represents the surface of the manufactured film. It can be seen from FIG. 2A that the constituent elements Cu, In, and O of the oxide thin film Cu ₂ In ₂ O ₅ are distributed almost uniformly in the film thickness direction. As shown in FIG. 2B, CuIn
It can be seen that in the Se ₂ thin film, Cu, In, and Se are uniformly distributed from the film surface to a film thickness of 1.4 μm in the vicinity of the boundary with the ZnO film serving as the substrate. However, in the vicinity of the boundary, the amounts of In and O increase and the amounts of Cu and Se decrease. This is due to the In-O system III near the boundary with ZnO.
It indicates that an oxide layer of a group element is present. Also,
Almost no diffusion of Zn into the CuInSe ₂ film occurs.

From the above, the Cu ₂ In ₂ O ₅ film and CuInS
It can be seen that in the e ₂ film, each element is uniformly distributed both in the film plane and in the film thickness direction. The composition ratio of the group I and group III elements of the CuInSe ₂ film is almost the same as that of the Cu ₂ In ₂ O ₅ film. It was also confirmed that an In-O-based oxide film existed between the CuInSe ₂ and ZnO films.

AM1.5, 100 was added to the manufactured solar cell.
As a result of irradiating with mW / cm ² light and measuring the current-voltage characteristics, a conversion efficiency of 10% or more was obtained. This is a value higher than that of a conventional solar cell having a superstrate structure (conversion efficiency 6 to 7%).

In this example, Se which is a VI group element is used.
Although H ₂ Se gas is used as the supply method of Cs, the same CuIn gas can be obtained by using CSe ₂ gas or N ₂ or Ar gas containing organic (CH ₃ ) ₂ Se or (C ₂ H ₅ ) ₂ Se.
Se ₂ film can be produced.

(Embodiment 2) FIG. 3 is a part of a process of manufacturing a solar cell showing another embodiment of the present invention.

Here, as the translucent substrate 1, a glass substrate on which a transparent conductive film ZnO: Al was deposited by 1.5 μm was used. On this transparent conductive film, an oxide thin film In ₂ O ₃ film 5 containing a group III element and an oxide thin film CuO film 6 containing a group I element were sequentially deposited by sputter deposition in the same Ar gas atmosphere as in Example 1. . The film thickness of each is 0.30 and 0.50 μm
Is. This oxide thin film was diluted with Ar gas to produce H2S.
After heat-treating at 400 ° C. for 30 minutes in an atmosphere containing e, the temperature is raised to 550 ° C. and heat-treating for 10 minutes to form Cu.
InSe ₂ film 3 was prepared. An Au film 4 serving as an electrode was vapor-deposited on the CuInSe ₂ film to manufacture a solar cell.

As a result of measuring the composition ratio of the CuInSe ₂ film by EDX, almost the same value is shown in the film plane, and the ratio is C
u: In: Se = 24.2: 25.9: 49.9. Next, FIGS. 4 (a) and 4 (b) show the results of examining the element distribution in the film thickness direction of the film just heat-treated at 400 ° C. for 30 minutes and the film further heat-treated at 550 ° C. for 10 minutes. From FIG. 4A, it can be seen that in the film heat-treated at 400 ° C. for 30 minutes, O in the CuO film escapes and Se is mixed. However, in the In2O3 film, although Se is mixed in the vicinity of the interface with the CuO film, almost no O escapes. Further, the distributions of Cu and In are separated, and there is almost no change from the distribution of the metal elements in the deposited two-layer oxide film.

On the other hand, as shown in FIG.
It can be seen that by adding the heat treatment at 0 ° C. for 10 minutes, most of the O _{2 in} the In ₂ O ₃ film is removed and selenized. Further, it can be seen that Cu and In are distributed almost uniformly. Therefore, by heat treatment at 550 ° C., Cu-
It can be seen that Se reacts with In ₂ O ₃ and H ₂ Se to form a CuInSe ₂ film having a uniform composition distribution. Further, an In—O-based oxide layer is present in an amount of about 0.2 μm near the interface with the ZnO: Al film. The thickness of this oxide layer can be controlled by the time of heat treatment at 550 ° C. Therefore, it is shown that the width of the depletion layer, which is important for improving the efficiency of the solar cell, can be optimized by the heat treatment time.

Further, with a scanning electron microscope (SEM),
When the film surface of the CuInSe ₂ film produced in Example 1 and this example was observed, the average particle size of the film of Example 1 was about 1 μm.
On the other hand, the average grain size of the film of this example was about 2 μm, and it was confirmed that grains were growing. This is 400
It is considered that the Cu—Se based layer formed by heat treatment at 30 ° C. for 30 minutes contributes to grain growth.

AM1.5, 100 was added to the manufactured solar cell.
As a result of irradiating light of mW / cm2 and measuring current-voltage characteristics, a conversion efficiency of 10% or more was obtained.

In the method of this embodiment, the composition ratio of the I-III-VI2 film to be produced can be easily controlled by the film thicknesses of the group I oxide film and the group III oxide film to be deposited. Furthermore, it is possible to form an oxide layer consisting of a pure Group III element at the interface with the transparent conductive film or the insulator film on the substrate depending on the heat treatment temperature or time, which is a factor that affects the performance of the solar cell. It is possible to easily optimize a certain depletion layer width and the like.

(Embodiment 3) FIG. 5 is a part of a manufacturing process of a solar cell showing another embodiment of the present invention.

Here, as the transparent substrate 1, a transparent conductive film ZnO: Al and a transparent insulating film ZnO are formed in order of 1.
A glass substrate having a thickness of 5 μm and a thickness of 0.1 μm was used. On this substrate, an In ₂ O ₃ film 5 was first deposited to a thickness of 25 nm by the same sputtering method as in Example 1, and a CuO film 6 was formed thereon.
Was deposited to a thickness of 10 nm.

Then, a thin film 7 of oxide Ga ₂ O _{3 made} of a group III element is deposited to a thickness of 5 nm on the CuO film, and CuO is formed thereon.
Film 6 was deposited to 10 nm. Further, an In ₂ O ₃ film having the same thickness as described above is deposited on this CuO film. In this way, the oxide thin film was repeatedly deposited 15 times in the order of In ₂ O ₃ —CuO—Ga ₂ O ₃ —CuO, and In ₂ O ₃ , Ga ₂ O ₃ and C were deposited.
The total film thickness of uO is 0.30, 0.375, and 0.075μ, respectively.
A multilayer oxide thin film 8 having a thickness of m was formed. This multi-layered oxide thin film is heat-treated at 450 ° C. for 1 hour in an atmosphere containing 2% H 2 Se diluted with Ar to obtain a chalcopyrite structure semiconductor thin film C composed of a group I, group III and group VI element.
A u (In, Ga) Se ₂ thin film 9 was formed. This Cu
A Au cell 4 serving as an electrode was vapor-deposited on the (In, Ga) Se ₂ film to manufacture a solar cell.

As a result of analyzing the composition ratio of the Cu (In, Ga) Se ₂ film from EDX, Cu: In: Ga: Se = 2.
The ratio was 4.3: 19.5: 5.2: 51.0, indicating a substantially uniform composition ratio with an error of 0.5% or less within the film surface. Here, the composition ratio of the group III oxide film before heat treatment is In: Ga.
= 3.76: 1, and it was confirmed that the composition ratio (In: Ga = 3.75: 1) was preserved even after the heat treatment.

Next, FIG. 6 shows the result of SIMS analysis of the element distribution in the film thickness direction. It can be seen that Cu, In, Ga and Se are uniformly distributed. Also, as in Example 1, it was found that an In—Ga—O-based oxide layer was present in the vicinity of the interface with the ZnO film by about 0.1 μm. Thus, a chalcopyrite structure semiconductor thin film having a uniform composition distribution can be formed even by using a multi-layer oxide film.

AM1.5, 100 was added to the manufactured solar cell.
As a result of irradiating light of mW / cm ² and measuring current-voltage characteristics, a conversion efficiency of about 11% was obtained.

In the method of this embodiment, In ₂ O ₃ and Ga ₂ O _{3 are used.}
I by making the film thickness ratio of the group III thin film such as
-It is possible to control the group III element ratio of the III-VI2 film. Since the band gap of the I-III-VI2 film changes when the group III ratio changes, the method of this example can be used to easily form an I-III-VI2 film having a desired band gap. It becomes possible. Therefore, for example, it becomes possible to manufacture a tandem-type solar cell configured by stacking solar cells having different light absorption wavelengths.

(Example 4) A method for producing an I-III-VI2 thin film using an oxide thin film as a precursor, which is different from the above examples, will be described. SnO ₂ film on a glass substrate, Al ₂ O ₃ film of each in order 2 [mu] m, 0.1 [mu] m using each deposited translucent substrate, the embodiment similarly to In ₂ O ₃ film and the C thereon
uO films are stacked alternately. At this time, the film thickness of CuO of one layer is kept constant at 20 nm, and the film thickness of the In ₂ O ₃ film is set to 200 nm on the substrate as shown in FIG. An object thin film was formed. This multilayer oxide thin film was heat-treated at 500 ° C. for 1 hour in an Ar atmosphere containing 10% H ₂ S to prepare CuInS ₂ .
The film thickness was 1.5 μm. Au on this CuInS ₂ film
An electrode film was formed to produce a solar cell. The composition ratio measured from EDX is Cu: In: S = 23.5: 26.4: 50.
It was 1, indicating a uniform composition ratio in the film plane. SIM
The element distribution in the film thickness direction due to S showed a uniform distribution in all of Cu, In, and S, although the oxide film had a distribution of In.

Further, from the SEM observation, the grain size on the film surface is about 2 μm, which is larger than the grain size of 1 μm of the CuInS ₂ film of the same thickness produced by the vapor deposition method and the grains are grown. Was confirmed. The manufacturing method of this embodiment is an effective method for growing crystal grains.

AM1.5, 100 was added to the manufactured solar cell.
As a result of irradiating with mW / cm ² light and measuring the current-voltage characteristics, a conversion efficiency of 10% or more was obtained.

(Example 5) FIG. 8 shows an example of a method for producing an I-III-VI2 film having a forbidden band width.

Transparent conductor ZnO on the transparent conductor ITO film
The oxide Cu ₂ In ₂ O ₅ is formed on the transparent substrate 1 on which the film is deposited.
The thin film 2 is sputter-deposited, and further Cu ₂ containing Ga is mixed.
The (In, Ga) ₂ O ₅ film 10 was deposited. The film thickness of each is 0.6 and 0.2 μm. Here, the second oxide film
The group III element ratio is In: Ga = 1: 3. This laminated oxide thin film was heat-treated at 500 ° C. for 45 minutes in an atmosphere containing 2% H ₂ Se diluted with Ar to Cu (In, Ga) Se ₂
Membrane 9 was prepared. An Au electrode film 4 was formed on this I-III-VI2 film to prepare a solar cell.

FIG. 9 shows Cu, In, Ga, by SIMS.
The distribution of Se is shown. Cu and Se are uniformly distributed in the film, but the amounts of In and Ga change. In is Cu
Less on the surface of (In, Ga) Se2 film, film thickness 0.5 μm
It is observed that it is increasing from the vicinity. On the contrary, Ga is present in a large amount on the film surface and decreases in the vicinity of the film thickness of 0.5 μm. Since the forbidden band width widens when the amount of Ga is large, the forbidden band width of the obtained Cu (In, Ga) Se 2 film is wide on the film surface and gradually narrows near the film thickness of 0.5 μm, and becomes CuInSe ₂ . It is expected to have changed to a close value. Thus, by changing the forbidden band width, it becomes possible to generate an internal electric field in the entire film except the pn junction region. Therefore, it becomes possible to efficiently collect the photo-excited carriers, and the efficiency of the solar cell is improved.

AM1.5, 100 was added to the manufactured solar cell.
As a result of irradiating light of mW / cm2 and measuring current-voltage characteristics, a conversion efficiency of about 11% was obtained.

According to the method of this embodiment, it is possible to easily produce a multi-element I-III-VI2 film in which elements are distributed in various ways, and to improve the efficiency of the solar cell by changing the forbidden band width. be able to.

In Examples 1, 3, 4, and 5, Y ₂ O ₃ , TiO ₂ or SiO ₂ was used as the transparent insulator film.
Similar results are obtained with a membrane. Furthermore, similar results can be obtained by using ZnO: H or ZnO: Al, H film instead of ZnO: Al as the transparent conductive film in Examples 2 and 3.

In Examples 2, 3, and 4, the ratio of Group I to O of CuO as the oxide of Group I element was 1: 1.
Of In ₂ as an oxide containing a Group III element
A compound having a ratio of Group III to O such as O ₃ or Ga ₂ O ₃ and O is 2: 3 is used, but it is not always necessary to use a thin film having the above composition ratio in the production method of the present invention. For example, a Cu ₂ O thin film having a composition ratio of group I and O of 2: 1 or an I ₂ film having a composition ratio of group III and O of 1: 1.
The I-III-VI2 thin film can be produced by using a thin film of nO or the like.

[0059]

According to the present invention, it is possible to form a chalcopyrite structure semiconductor thin film consisting of a group I, a group III and a group VI having a large area and a uniform composition. Furthermore, it is possible to easily form a pn junction or a Schottky junction depending on the heat treatment temperature and time. Therefore, a highly efficient solar cell with excellent productivity can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a part of a manufacturing process of a solar cell according to an embodiment of the present invention.

FIG. 2 (a) is Cu ₂ In ₂ O measured by SIMS.
₅ Diagram showing element distribution in the film thickness direction (b) is a diagram showing element distribution in the film thickness direction of the CuInSe ₂ film measured by SIMS

FIG. 3 is a diagram showing a part of a manufacturing process of a solar cell according to an embodiment of the present invention.

FIG. 4 (a) is 400 ° C./3 measured by SIMS.
The diagram (b) showing the distribution of elements in the thickness direction of the oxide film after heat treatment for 0 minute is 400 ° C. for 30 minutes and 5 measured by SIMS.
Diagram showing element distribution in the film thickness direction of the oxide film after heat treatment at 50 ° C. for 10 minutes

FIG. 5 is a diagram showing a part of the manufacturing process of the solar cell according to the embodiment of the present invention.

FIG. 6 Cu (In, Ga) S measured by SIMS
Diagram showing the distribution of elements in the film thickness direction of the e ₂ film

FIG. 7 is a diagram showing a change in group III oxide film thickness with respect to the total film thickness of a multilayer oxide thin film.

FIG. 8 is a diagram showing a part of the manufacturing process of the solar cell according to the embodiment of the present invention.

FIG. 9: Cu (In, Ga) S measured by SIMS
Diagram showing the distribution of elements in the film thickness direction of the e ₂ film

[Explanation of symbols]

1 Transparent Substrate 2 Oxide Thin Film Containing Group I and Group III Elements (Cu ₂ In
₂ O ₅ ) 3 chalcopyrite structure semiconductor thin film (CuInSe ₂ ) 4 electrode film (Au) 3 group III and VI group element oxide (In ₂ O ₃ ) 6 I group element -Containing oxide thin film (CuO) 7 Oxide thin film containing group III element (Ga ₂ O ₃ ) 8 Multi-layer oxide thin film containing group I and group III elements (CuO-I
_{n 2 O 3 -Ga 2 O 3} ) 9 I , Group chalcopyrite structure made of a group III and VI elements semiconductor thin film (Cu (In, Ga) Se 2) oxide thin film containing 10 I Group and Group III element ( Cu2 (I
n, Ga) ₂ O ₅ )

Front page continuation (72) Inventor Mikihiko Nishitani 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (11)

[Claims] 1. A chalcopyrite composed of a group I, a group III and a group VI element by heat treatment in an atmosphere containing a group VI element after forming an oxide thin film containing a group I and group III element on a transparent substrate. A method for manufacturing a solar cell, which comprises the step of forming a structural semiconductor thin film. 2. After forming an oxide thin film in which group I and group III elements are uniformly distributed in the film on a transparent substrate, heat treatment is performed in an atmosphere containing a group VI element, and group I, group III and group VI A method for manufacturing a solar cell, which includes a step of forming a chalcopyrite structure semiconductor thin film made of a group element. 3. An oxide thin film formed by stacking an oxide thin film containing a group III element and an oxide thin film containing a group I element on a transparent substrate, followed by heat treatment in an atmosphere containing a group VI element. A method for manufacturing a solar cell, which comprises a step of forming a chalcopyrite structure semiconductor thin film composed of a group I element, a group III element, and a group VI element. 4. An oxide thin film containing a group I element on a transparent substrate and I
After forming an oxide thin film by alternately depositing at least two layers of group II-containing oxide thin films, heat treatment is performed in an atmosphere containing group VI elements to obtain a chalcone composed of group I, group III and group VI elements. A method for manufacturing a solar cell, which comprises the step of forming a pyrite structure semiconductor thin film. 5. An oxide thin film containing a group I element on a transparent substrate and I
When alternately depositing an oxide thin film containing a group II, the ratio of the thickness of the oxide thin film containing a group I element deposited on the thin film to the thickness of the oxide thin film containing a group III element The method of manufacturing a solar cell according to claim 4, wherein an oxide thin film is formed by gradually increasing the thickness from the base. 6. The production of a solar cell according to claim 1, further comprising the step of forming an atmosphere containing a group VI element using at least one of hydrogenated gas or carbonized gas of the group VI element. Method. 7. The method for manufacturing a solar cell according to claim 1, further comprising the step of forming an atmosphere containing a Group VI element using an organic substance containing a Group VI element. 8. The lower limit of the heat treatment temperature is 200.degree.
The method for producing a solar cell according to any one of claims 1 to 4, wherein the upper limit is set to 00 ° C. 9. The method for producing a solar cell according to claim 1, wherein a transparent insulator substrate coated with at least one of a transparent conductive film and a transparent insulator film is used as the transparent substrate. 10. A thin film made of at least one of the group consisting of tin oxide, indium tin oxide, and zinc oxide containing at least one of Group III elements and hydrogen is used as the transparent conductive film. The method for manufacturing a solar cell according to. 11. The method for producing a solar cell according to claim 8, wherein the transparent insulator film is a thin film made of at least one selected from the group consisting of zinc oxide, aluminum oxide, silicon oxide, yttrium oxide, and titanium oxide. Method.