JP2012174759A - Compound semiconductor layer manufacturing method and photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a compound semiconductor layer such that band energy discontinuity between laminated layers can be moderated.SOLUTION: A compound semiconductor layer manufacturing method of forming a compound semiconductor surface layer 31 composed of a group Ib element, a group IIIb element and a group VIb element which have a composition different from that of a chalcopyrite compound semiconductor layer 30 on a surface of the chalcopyrite compound semiconductor layer 30 composed of a group Ib element, a group IIIb element and a group VIb element, comprises a first process of forming a semiconductor layer 31a composed of at least a group Ib element and a group VIb element, and a second process of immersing the semiconductor layer formed in the first process in a solution containing at least a compound containing a group IIIb element and a compound containing a group VIb element.

Description

  The present invention relates to a method for producing a compound semiconductor layer constituting a photoelectric conversion element and a photoelectric conversion element.

Conventionally, in the case of solar cells, Si-based solar cells using bulk single crystal Si or polycrystalline Si, or thin-film amorphous Si have been mainstream, but research and development of Si-independent compound semiconductor solar cells has been made. ing. As a compound semiconductor solar cell, a CIS or CIGS system composed of an Ib group element, an IIIb group element, and a VIb group element (CI (G) S represents a general formula Cu _1-z In _1-x Ga _x Se _2-y A compound semiconductor represented by S _y (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 2, 0 ≦ z ≦ 1), when x = 0, CIS system, and when x> 0, CIGS system Are known).

Although the CuInSe ₂ type solar cell is attracting attention as a highly efficient solar cell, there is a problem in that sunlight cannot be effectively used because of a small band gap. For this reason, the band gap is adjusted by adding an appropriate amount of Ga. From the viewpoint of the band gap, CuInS ₂ is larger, so that sunlight should be used effectively without adding Ga, but in reality, the power generation efficiency is lower with CuInS ₂ . This is because, in addition to effective use of sunlight, electronic characteristics such as carrier mobility, average lifetime, and diffusion distance have a great influence on power generation efficiency. Therefore, a CuInGaSe ₂ type material is preferable from the viewpoint of generating photoelectrons to separate charges.

  On the other hand, in order to take out the generated carrier out of the system, it is finally taken out from the translucent conductive layer via several layers, so that the band energy is smooth when the carrier moves between the laminated layers. It is preferable that it is connected to. Since the position of the band in each layer is determined by the material, a material having a high light absorption capability and a material having a high carrier transmission capability do not necessarily match. Therefore, it is theoretically possible to manufacture a solar cell with higher power generation efficiency if the continuity of the energy band can be improved by replacing only the vicinity of the surface of the light absorption layer (interface with the next layer) with a material having a different composition. Is possible.

  Each layer constituting the solar cell has a lattice constant specific to the material. In general, there is little disorder of crystallinity at the interface between materials with very close lattice constants, and conversely, low-crystalline regions are formed at the interfaces between greatly different materials to alleviate lattice distortion caused by the difference in lattice constants. . These states can be observed with a cross-sectional TEM of the film. A region with low crystallinity forms a local disturbance in the energy band, which causes an increase in resistance due to scattering of carriers passing through this region and a decrease in power generation characteristics due to recombination of electrons and holes. In this respect as well, it is theoretically possible to produce a solar cell with high power generation efficiency by replacing only the vicinity of the surface of the light absorption layer (interface with the next layer) with a material having a different composition and enhancing the fitting of the lattice constant. Is possible.

From the above viewpoint, the necessity of surface modification of the light absorption layer is increasing. Patent Document 1 discloses that a surface of CuInGaZnS is treated by treating the surface of a CuInGaSe ₂ semiconductor with a treatment liquid containing In, Zn and S. _The technology to change to ₂ is described. Patent Document 2 discloses a technique in which a metal portion is first formed, heat-treated in a Se atmosphere to form a Se compound once, and then the surface vicinity is changed to S by heat-treatment in the S atmosphere. Are listed.

Japanese Patent No. 3589380 Japanese Patent No. 3249408

Although Patent Document 1 does not describe the dynamics of thin film formation, the fact that the thin film formed on the surface contains Cu or Ga even though the treatment liquid is In—Zn—S means that the treatment liquid It is considered that Se is replaced by S with an overwhelmingly high concentration when it re-deposits while etching the CuInGaSe ₂ surface. In other words, the newly formed surface layer uses a semiconductor component serving as the underlying substrate. In such a case, the newly formed surface layer has a low variation in composition, and an optimal composition is not always obtained. Moreover, in patent document 2, only the substitution of Se in the vicinity of the surface with S cannot change the kind and concentration of the cation.

  The present invention has been made in view of the above circumstances, and a compound semiconductor capable of relaxing the band energy discontinuity between stacked layers by increasing the degree of freedom of the composition of the surface of the photoelectric conversion semiconductor layer. It is an object of the present invention to provide a method for producing a layer and to provide a semiconductor element provided with a compound semiconductor layer produced by the production method of the present invention.

  The method for producing a compound semiconductor layer according to the present invention comprises a group Ib element having a composition different from that of the chalcopyrite compound semiconductor layer on the surface of a chalcopyrite compound semiconductor layer comprising a group Ib element, a group IIIb element, and a group VIb element. A method for producing a compound semiconductor layer for forming a compound semiconductor surface layer composed of a group IIIb element and a group VIb element, the semiconductor layer comprising at least a group Ib element and a group VIb element on the surface of the chalcopyrite compound semiconductor layer And the second step of immersing the semiconductor layer formed in the first step in a solution containing at least a compound containing a group IIIb element and a compound containing a group VIb element. A surface layer is formed.

The solution in the second step may further contain a compound containing a group IIb element.
In the first step, the group Ib element is preferably Cu, and the group VIb element is preferably at least one of S and Se.
The group IIIb element in the second step is preferably at least one of In or Ga, and the group VIb element is preferably at least one of S or Se.
The group IIb element in the second step is preferably at least one of Zn and Cd.

  The photoelectric conversion element of the present invention is characterized in that a lower electrode, a compound semiconductor layer manufactured by the method for manufacturing a compound semiconductor layer, a buffer layer, and a translucent conductive layer are sequentially stacked on a substrate. It is what.

The substrate is an anodized substrate in which an anodized film mainly composed of Al ₂ O ₃ is formed on at least one surface side of an Al base material mainly composed of Al, and at least an Fe material mainly composed of Fe An anodized substrate in which an anodized film mainly composed of Al ₂ O ₃ is formed on at least one surface side of a composite base material in which an Al material composed mainly of Al is composited on one surface side, mainly Fe An anodized film mainly composed of Al ₂ O ₃ was formed on at least one surface side of the base material on which an Al film composed mainly of Al was formed on at least one surface side of the Fe material as a component It is preferably one of the anodized substrates.

  The method for producing a compound semiconductor layer according to the present invention includes a group Ib element having a composition different from that of the chalcopyrite compound semiconductor layer on the surface of a chalcopyrite compound semiconductor layer comprising a group Ib element, a group IIIb element, and a group VIb element. A compound semiconductor layer manufacturing method for forming a compound semiconductor surface layer comprising a group IIIb element and a group VIb element, wherein a semiconductor layer comprising at least a group Ib element and a group VIb element is formed on the surface of the chalcopyrite compound semiconductor layer A compound semiconductor surface layer is formed by a first step of forming and a second step of immersing the semiconductor layer formed in the first step in a solution containing at least a compound containing a group IIIb element and a compound containing a group VIb element. Since it is formed, it is possible to make the compound semiconductor surface layer have an optimum composition that has a high carrier transmission ability in terms of composition.

It is process drawing which shows the process of the manufacturing method of the compound semiconductor layer of this invention. It is a schematic sectional drawing of the photoelectric conversion element using the compound semiconductor layer manufactured by the manufacturing method of this invention. It is a schematic sectional drawing which shows the structure of an anodized substrate.

  The method for producing a compound semiconductor layer according to the present invention includes a group Ib having a composition different from that of the chalcopyrite compound semiconductor layer on the surface of a chalcopyrite compound semiconductor layer composed of a group Ib element, a group IIIb element, and a group VIb element. A method for producing a compound semiconductor layer for forming a compound semiconductor surface layer (hereinafter also simply referred to as a compound semiconductor surface layer) comprising an element, a group IIIb element, and a group VIb element, wherein at least a group Ib is formed on the surface of the chalcopyrite compound semiconductor layer A first step of forming a semiconductor layer comprising an element and a VIb group element; and immersing the semiconductor layer formed in the first step in a solution containing a compound containing at least a IIIb group element and a compound containing a VIb group element The second step is to form a compound semiconductor surface layer.

  The manufacturing method of the compound semiconductor layer of this invention is demonstrated in detail using the process drawing of FIG. In the first step, a semiconductor layer 31 a made of at least an Ib group element and a VIb group element is formed on the surface of the chalcopyrite compound semiconductor layer 30. The Ib group element is preferably Cu, and the VIb group element is preferably Se or S. Either one or both of the Ib group element and the VIb group element may be used. The method for forming the semiconductor layer 31a is not particularly limited. For example, a coating sintering method, an electrolytic method, a sputtering method, a liquid phase method, a chemical vapor deposition method, a metal organic thermal decomposition method, a vapor deposition method, a proximity sublimation method, What is necessary is just to form by conventionally well-known methods, such as a spray method. In order to remove the foreign substance layer deposited on the surface when forming the chalcopyrite layer 30 before the first step, for example, a step of immersing in a KCN aqueous solution or the like may be necessary. In such a case, in order to form a thin film by a vapor phase method or a film forming method that requires high temperature after processing in a solution system once, it is necessary to include a sufficient drying process, and the total process time It becomes a factor to postpone. Therefore, if the first step is also a liquid phase method like the second step, the manufacturing process can be reduced and the manufacturing process can have good continuity.

  In the second step, the semiconductor layer 31a formed in the first step is immersed in a solution containing a compound containing at least a IIIb group element and a compound containing a VIb group element. The solution in the second step may contain a compound containing a group IIb element in addition to a compound containing a group IIIb element and a compound containing a group VIb element. Either one or both of the compound containing a Group IIIb element and the compound containing a Group VIb element may be used. The group IIIb element in the second step is preferably In or Ga, the group VIb element is preferably S or Se, and the group IIb element is preferably Zn or Cd. By this second step, it is considered that the semiconductor layer 31 is formed by repeating a process in which a part of the surface of the semiconductor layer 31a is dissolved and group IIIb and IIb elements in the solution diffuse into the semiconductor layer 31a.

  The compound semiconductor surface layer 31 having a composition different from that of the chalcopyrite compound semiconductor composed of the original group Ib element, group IIIb element, and group VIb element can be formed by the first process and the subsequent second process. it can. In order to form a thin film having a preferred composition as in the present invention in one step only in a solution, it must be carried out in a high boiling point organic solvent or under high temperature and high pressure conditions such as autoclave. In an aqueous solution reaction system under normal pressure, the reaction temperature is limited, the reaction rates of the Ib group and VIb group and the reaction rates of the group IIIb and VIb group are greatly different, and separated into two layers of Ib-VIb compound and IIIb-VIb compound. In other words, it is very difficult to form a complex compound having a chalcopyrite structure as a hydroxide because each has a different stable pH range. Although it is possible to reduce the difference in the reaction rate and stability by selecting the pH of the reaction system and the starting compound, satisfactory results cannot be obtained within a limited temperature range.

When a film separated into two layers as described above or a film containing a hydroxide is formed, the power generation characteristics may be significantly reduced. For example, when one of the separation layers is copper sulfide, a leakage current is generated when defects such as pinholes exist in the buffer layer because of the high conductivity. Further, indium oxide and indium hydroxide may conversely become a high resistance layer, both of which are factors that reduce power generation efficiency. Although it is not a thin film system but a fine particle system, for example, in non-patent literature (Bonil Koo, Reken N. Patel, and Brian A Korgel, J. Am. Chem. Soc. 131 (2009) 3135), CuCl, In CuInSe ₂ fine particles are formed at 240 ° C. for 1 hour using InCl ₃ as a source and selenourea as a Se source in the presence of three elements in an oleylamine solution. Further, in non-patent literature (Yang Jiang, Yue Wu, Xiao Mo, Weichao Yu, Yi Xie, and Yitai Qian, 39 (2000) 2964), Cu powder as Cu source, In powder as In source and Se powder as Se source CuInSe ₂ fine particles are formed by autoclaving at 280 ° C. for 48 hours in a state where three elements coexist in an ethylenediamine solution. Thus, chalcopyrite can be formed under high temperature or high temperature and high pressure conditions in the presence of the three elements in the solution, but continuous film formation at high temperature and high pressure is impossible. In the case of forming in a high boiling point solvent, if the organic substance remains, it becomes a factor of deteriorating the solar cell characteristics, so that the cleaning process becomes very complicated and the cost is increased. Therefore, as in the present invention, a compound semiconductor surface layer having a preferred composition can be formed by forming the semiconductor layer 31a as a semiconductor layer 31a and then supplying the remaining composition from the solution side in two steps. Is optimal.

  The solution used in the second step preferably contains, as a solvent, at least one acid selected from hydrochloric acid, acetic acid, nitric acid and sulfuric acid, and the pH of this solution is preferably 1 to 4. By using an acidic solution, it is possible to form the layer stably and rapidly. The temperature of the solution is preferably 10 ° C to 100 ° C. Since it is possible to manufacture by such a low temperature process, the manufacturing cost can be reduced. The time of immersion in the solution varies depending on the concentration of the solution used and the type of compound, but is preferably about 1 to 30 minutes. The preparation of the layer thickness can be appropriately adjusted depending on the time of immersion in the solution.

  The compound containing a group IIIb element contained in the solution can be appropriately selected from a halide of a group IIIb element (chloride, iodide or bromide, hereinafter the same), acetate, nitrate, and sulfate. The compound containing a VIb group element is preferably a nitrogen organic compound of a VIb group element, and specifically, thioacetamide and thiourea are preferred. The compound containing a group IIb element can be appropriately selected from a halide, acetate, nitrate, and sulfate of a group IIb element. In addition, the same thing as the above can be utilized for the compound containing a VIb group element in the case of performing a 1st process by a liquid phase method. In addition, the compound containing a group Ib element can be appropriately selected from halides, acetates, nitrates, and sulfates of group Ib elements. The concentration of the solution used varies depending on the compound, but is preferably 0.005 mol / L to 0.1 mol / L.

  It is preferable to heat-treat the compound semiconductor surface layer after forming the compound semiconductor surface layer. By the heat treatment, the defect density in the compound semiconductor surface layer and at the interface between the compound semiconductor surface layer and the chalcopyrite compound semiconductor layer as the substrate can be further reduced, and the discontinuity can be further relaxed. The heat treatment is preferably performed in the range of 100 ° C to 400 ° C, and more preferably in the range of 200 ° C to 350 ° C.

  Next, with reference to FIG. 2 and FIG. 3, the photoelectric conversion element using the compound semiconductor layer manufactured by the manufacturing method of this invention as a photoelectric converting layer is demonstrated. FIG. 2 is a schematic cross-sectional view showing an embodiment of a photoelectric conversion element. In addition, in order to make it easy to visually recognize, the scale of each component in the drawing is appropriately different from the actual one. As shown in FIG. 2, the photoelectric conversion element 1 includes a lower electrode (back electrode) 20, a photoelectric conversion layer 30, a buffer layer 40, a window layer 50, a translucent conductive layer (transparent electrode) 60, and an upper portion on a substrate 10. An electrode (grid electrode) 70 is sequentially laminated.

  And the compound semiconductor surface layer 31 of the composition different from the composition of the photoelectric converting layer 30 manufactured by the manufacturing method of this invention is formed in the photoelectric converting layer 30 on the surface. The film thickness of the photoelectric conversion layer 30 is not particularly limited, and is preferably 1.0 to 3.0 μm, particularly preferably 1.5 to 2.0 μm. The thickness of the compound semiconductor surface layer 31 is preferably 10 nm or less (the thickness of the semiconductor layer 31a is preferably about 5 to 10 nm).

  The substrate 10 is a substrate obtained by anodizing at least one surface side of the base material 11. The base material 11 is an Al base material containing Al as a main component, a composite base material in which an Al material containing Al as a main component is combined on at least one surface side of an Fe material containing Fe as a main component, or Fe as a main component. A base material in which an Al film mainly composed of Al is formed on at least one surface side of the Fe material as a component is preferable.

The substrate 10 may be one in which an anodic oxide film 12 is formed on both surfaces of a base material 11 as shown in the left diagram of FIG. 3, or an anode on one surface of the base material 11 as shown in the right diagram of FIG. The oxide film 12 may be formed. The anodic oxide film 12 is a film mainly composed of Al ₂ O ₃ . In order to suppress the warpage of the substrate due to the difference in thermal expansion coefficient between Al and Al ₂ O ₃ and the film peeling due to this in the device manufacturing process, as shown in the left diagram of FIG. More preferably, the anodic oxide film 12 is formed on both surfaces.

  The main component of the lower electrode (back electrode) 20 is not particularly limited, and Mo, Cr, W, and combinations thereof are preferable, and Mo or the like is particularly preferable. The film thickness of the lower electrode (back electrode) 20 is not limited and is preferably about 200 to 1000 nm.

  The buffer layer 40 is a layer mainly composed of CdS, ZnS, Zn (S, O), and Zn (S, O, OH). The conductivity type of the buffer layer 40 is not particularly limited, and n-type or the like is preferable. The film thickness of the buffer layer 40 is not particularly limited, and is preferably 10 nm to 2 μm, more preferably 15 to 200 nm.

  The window layer 50 is an intermediate layer that captures light. The composition of the window layer 50 is not particularly limited, and i-ZnO or the like is preferable. The film thickness of the window layer 50 is not particularly limited, preferably 10 nm to 2 μm, and more preferably 15 to 200 nm. The window layer is an arbitrary layer and may be a photoelectric conversion element without the window layer 50.

  The translucent conductive layer (transparent electrode) 60 is a layer that takes in light and functions as an electrode through which a current generated in the photoelectric conversion layer 30 flows in a pair with the lower electrode 20. The composition of the translucent conductive layer 60 is not particularly limited, and n-ZnO such as ZnO: Al is preferable. The film thickness of the translucent conductive layer 60 is not particularly limited, and is preferably 50 nm to 2 μm.

  The main component of the upper electrode (grid electrode) 70 is not particularly limited, and examples thereof include Al. The film thickness of the upper electrode 70 is not particularly limited, and is preferably 0.1 to 3 μm.

The photoelectric conversion element using the compound semiconductor layer manufactured by the manufacturing method of the present invention can be preferably used for a solar cell or the like. If necessary, a cover glass, a protective film, or the like can be attached to the photoelectric conversion element 1 to form a solar cell.
EXAMPLES Hereinafter, the manufacturing method of the compound semiconductor layer of this invention is demonstrated in detail by an Example.

(Laminate A)
It is known as one of the methods for forming a CIGS layer on a Mo lower electrode by depositing a Mo lower electrode with a thickness of 0.8 μm on a 1 mm thick soda lime glass (SLG) substrate by sputtering. A laminate A was obtained by forming a Cu (In _0.7 Ga _0.3 ) Se ₂ layer having a thickness of 1.8 μm as a light absorption layer using a three-stage method.

(Laminated body B)
Using a stainless steel (SUS), an anodized substrate having an aluminum anodic oxide film (AAO) formed on the Al surface on an Al composite substrate, and a substrate having a soda lime glass (SLG) layer formed on the AAO surface was prepared. The thickness of each layer in the substrate was SUS: over 300 μm, Al: 300 μm, AAO: 20 μm, and SLG: 0.2 μm. A Mo lower electrode is formed on the SLG layer by sputtering to a thickness of 0.8 μm, and a three-stage method known as one of CIGS layer forming methods is formed on the Mo lower electrode as a light absorption layer. A layered product B was obtained by forming a Cu (In _0.7 Ga _0.3 ) Se ₂ layer having a thickness of 1.8 μm.

(Outline of the first process)
A predetermined amount of a compound containing an Ib group element and a compound containing a VIb group element was mixed with 50 ml of water and stirred well. After sufficiently stirring, the aqueous solution was heated to 80 ° C. to immerse the laminate for 1 to 30 minutes. After completion of the reaction, the laminate was sufficiently washed with pure water and then dried.

(Outline of the second process)
A predetermined amount of a compound containing a group IIIb element and a compound containing a group VI element was mixed with 50 ml of water and stirred well. When the IIb group element was included in addition to the IIIb group element and the VIb group element, a predetermined amount of the IIb group element was added. After sufficiently stirring, the aqueous solution was heated to 80 ° C. to immerse the laminate for 1 to 30 minutes. After completion of the reaction, the laminate was sufficiently washed with pure water and then dried.

(Composition analysis)
The composition in the depth direction of the light absorption layer was measured using secondary ion mass spectrometry (SIMS).

Example 1
Using the laminate A, the first step used 0.005 mol of cuprous chloride as a compound containing a group Ib element and 0.015 mol of sodium thiosulfate as a compound containing a group VIb element. In the second step, 0.005 mol of indium chloride was used as the compound containing the IIIb group element, and 0.05 mol of thioacetamide was used as the compound containing the VIb group element. The heating time was 3 minutes for the first step and 5 minutes for the second step. As a result of the composition analysis, the elements constituting the vicinity of the surface of the light absorption layer were Cu, In, and S, and Ga and Se were not detected.

(Example 2)
The first step was the same as in Example 1. In the second step, 0.005 mol of indium chloride was used as a compound containing a group IIIb element, 0.05 mol of thioacetamide was used as a compound containing a group VIb element, and 0.001 mol of cadmium sulfate was used as a compound containing a group IIb element. The heating time was 3 minutes for the first step and 5 minutes for the second step. As a result of the composition analysis, the elements constituting the surface vicinity of the light absorption layer were Cu, In, Cd, and S, and Ga and Se were not detected.

(Example 3)
The first step was the same as in Example 1. The second step is 0.005 mol of indium chloride as a compound containing a group IIIb element, 0.05 mol of thioacetamide as a compound containing a group VIb element, and 0.001 mol of zinc sulfate heptahydrate as a compound containing a group IIb element. Using. The heating time was 3 minutes for the first step and 5 minutes for the second step. As a result of the composition analysis, the elements constituting the surface vicinity of the light absorption layer were Cu, In, Zn and S, and Ga and Se were not detected.

Example 4
In the first step, 0.005 mol of cuprous chloride was used as a compound containing a group Ib element and 0.015 mol of sodium thiosulfate was used as a compound containing a group VI element. In the second step, 0.005 mol of indium chloride was used as the compound containing the IIIb group element, and 0.05 mol of thioacetamide was used as the compound containing the VIb group element. The heating time was 3 minutes 30 seconds in the first step and 6 minutes in the second step. As a result of the composition analysis, the elements constituting the vicinity of the surface of the light absorption layer were Cu, In, and S, and Ga and Se were not detected.

(Comparative Example 1)
Using Stack A, 0.005 mol of cuprous chloride as a compound containing a group Ib element, 0.015 mol of thioacetamide as a compound containing a group VIb element, and 0.005 mol of indium chloride as a compound containing a group IIIb element It was immersed in a solution containing the three elements simultaneously and heated for 5 minutes. As a result of the composition analysis, the elements constituting the surface vicinity of the light absorption layer were Cu, In, S and O, and Ga and Se were not detected.

(Comparative Example 2)
Using Stack B, 0.005 mol of cuprous chloride as a compound containing a group Ib element, 0.015 mol of thioacetamide as a compound containing a group VIb element, and 0.005 mol of indium chloride as a compound containing a group IIIb element It was immersed in a solution containing the three elements simultaneously and heated for 6 minutes. As a result of the composition analysis, the elements constituting the surface vicinity of the light absorption layer were Cu, In, S and O, and Ga and Se were not detected.

(Evaluation)
(Measurement of power generation efficiency)
An i-ZnO layer as a window layer and an n-ZnO layer doped with Al as a transparent conductive layer were formed by sputtering on the light absorption layers formed in Examples and Comparative Examples. Further, an Al upper electrode was formed thereon by vapor deposition to form a cell for evaluating solar cell characteristics. The energy conversion efficiency was measured using the artificial sunlight of Air Mass (AM) = 1.5 and 100 mW / cm ^{2 for} the produced cell.

Table 1 shows the details of the Ib group element, IIIb group element, and VIb group element used in the first and second steps of the examples, the composition of the inside and the surface of the formed light absorption layer, and the evaluation results. Table 2 shows the details of the semiconductor surface layer forming step, the composition of the inside and surface of the formed light absorption layer, and the evaluation results. The power generation efficiencies of Examples 1 to 3 and Comparative Example 1 are shown as relative values based on the laminate A, and the power generation efficiencies of Example 4 and Comparative Example 2 are shown as relative values based on the laminate B. Also, CIGSe in the table is Cu (In _0.7 Ga _0.3 ) Se ₂ , CIS is CuInS ₂ , and CISO is a complex compound that has an undefined structure but probably contains Cu or In hydroxide.

  As shown in Table 1 and Table 2, the light absorption layer of the example is formed of a CIGSe material having a high light absorption capability inside, and the surface thereof is formed of a material having a high carrier transmission capability. Since the carriers converted by efficiency can be taken out via the surface layer having improved energy band continuity, a solar cell with higher power generation efficiency could be obtained. On the other hand, since the light absorption layer of the comparative example has a single step of forming the compound semiconductor surface layer, the desired surface layer could not be formed, and the power generation efficiency was low. In addition, since the example and the comparative example are shown as relative values based on the power generation efficiency of the layered product A or the layered product B, the numerical values shown in the table seem to be slightly different from each other. The difference is larger than the difference shown.

DESCRIPTION OF SYMBOLS 1 Photoelectric conversion element 10 Anodized substrate 11 Al base material 12 Anodized film 20 Lower electrode (back surface electrode)
30 Chalcopyrite compound semiconductor layer (photoelectric conversion semiconductor layer)
31 Compound semiconductor surface layer 40 Buffer layer 50 Window layer 60 Translucent conductive layer (transparent electrode)
70 Upper electrode (grid electrode)

Claims (7)

  The surface of a chalcopyrite compound semiconductor layer comprising a group Ib element, a group IIIb element and a group VIb element comprises a group Ib element, a group IIIb element and a group VIb element having a composition different from that of the chalcopyrite compound semiconductor layer. A method for producing a compound semiconductor layer for forming a compound semiconductor surface layer, the method comprising: forming a semiconductor layer comprising at least a group Ib element and a group VIb element on the surface of the chalcopyrite compound semiconductor layer; The compound semiconductor surface layer is formed by a second step of immersing the semiconductor layer formed in one step in a solution containing at least a compound containing a group IIIb element and a compound containing a group VIb element. Layer manufacturing method.   The method for producing a compound semiconductor layer according to claim 1, wherein the solution in the second step further contains a compound containing a group IIb element.   The method for producing a compound semiconductor layer according to claim 1 or 2, wherein the Ib group element in the first step is Cu and the VIb group element is at least one of S and Se.   4. The compound semiconductor layer according to claim 1, wherein the group IIIb element in the second step is at least one of In or Ga, and the group VIb element is at least one of S or Se. Manufacturing method.   The method for producing a compound semiconductor layer according to claim 2, 3 or 4, wherein the group IIb element in the second step is at least one of Zn and Cd.   A lower electrode, a compound semiconductor layer manufactured by the method for manufacturing a compound semiconductor layer according to any one of claims 1 to 5, a buffer layer, and a light-transmitting conductive layer are sequentially stacked on the substrate. A photoelectric conversion element characterized by the above. The substrate is
An anodized substrate in which an anodized film mainly composed of Al ₂ O ₃ is formed on at least one surface side of an Al base material mainly composed of Al;
An anodized film mainly composed of Al ₂ O ₃ is formed on at least one surface side of a composite base material in which an Al material composed mainly of Al is combined on at least one surface side of an Fe material mainly composed of Fe. Formed anodized substrate,
An anodized film mainly composed of Al ₂ O ₃ is formed on at least one surface side of a base material on which an Al film mainly composed of Al is formed on at least one surface side of an Fe material mainly composed of Fe. Formed anodized substrate,
The photoelectric conversion element according to claim 6, wherein the photoelectric conversion element is any one of the following.

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