JP2012151221A - Chalcogenide-based compound semiconductor and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel chalcogenide-based compound semiconductor having a relatively high conversion efficiency, and to provide a method of producing the same.SOLUTION: A chalcogenide-based compound semiconductor and a production method therefor are provided. (1) The chalcogenide-based compound semiconductor contains Cu, Zn, Sn, an element X(=S and/or Se), and O as essential elements. (2) The chalcogenide-based compound semiconductor is obtained by performing sulfidation and/or selenization of a precursor containing (a) Cu, Zn and Sn, and (b) one kind or more than one kind of non-crystalline oxide and/or hydroxide containing any one or more elements selected from Cu, Zn and Sn. Preferably, the precursor is formed by supplying a CVD material containing a Cu source, a Zn source and an Sn source to a CVD apparatus open to the atmosphere, and then gasifying the CVD material simultaneously.

Description

  The present invention relates to a chalcogenite-based compound semiconductor and a method for producing the same, and more specifically, to a novel chalcogenite-based compound semiconductor that is used in a light absorption layer of a photoelectric element and contains a predetermined amount of oxygen as an essential element, and a method for producing the same. .

  A photoelectric element refers to an element that can convert photon energy into an electrical signal (photoelectric conversion) through some physical phenomenon. A solar cell is a kind of photoelectric element, and can efficiently convert light energy of sunlight into electric energy.

The semiconductor used in solar cells, monocrystalline Si, polycrystalline Si, amorphous Si, GaAs, InP, CdTe, CuIn 1-x Ga x Se 2 (CIGS), Cu 2 ZnSnS 4 (CZTS) such as is known Yes.
Among these, chalcogenite-based compounds represented by CIGS and CZTS have a large light absorption coefficient, so that a thin film advantageous for cost reduction is possible. In particular, a solar cell using CIGS as a light absorption layer has high conversion efficiency in a thin film solar cell, and conversion efficiency exceeding that of a solar cell using polycrystalline Si is also obtained. However, CIGS has a problem that it contains an environmental load element and a rare element.
On the other hand, CZTS has a band gap energy (1.4 to 1.5 eV) suitable for a solar cell and is characterized by not containing an environmental load element or a rare element.

Various proposals have heretofore been made for a method for producing a light absorption layer of such a thin-film solar cell.
For example, in Non-Patent Document 1,
(A) Two or more metal powders are melted at about 900 ° C. under non-vacuum to form a molten metal, and the molten metal is sprayed, quenched, and pulverized to produce an alloy powder,
(B) An ink made of an alloy powder is applied on a substrate, dried, and fixed to produce a precursor made of an alloy;
(C) A method for producing a chalcopyrite compound semiconductor (CIS, CIGS, CIGSSe) by selenizing the precursor is disclosed.

Non-Patent Document 2 includes
(A) Under non-vacuum, two or more oxide powders are dissolved with an acid to form a hydroxide, and the hydroxide is dried, dispersed, and pulverized to produce oxide fine particles,
(B) An ink composed of oxide fine particles is applied on a substrate, dried, and fixed to produce a precursor composed of oxide;
(C) reducing the precursor at about 500 to 550 ° C. in an H ₂ + N ₂ atmosphere;
(D) A method for producing a chalcopyrite compound semiconductor by selenizing a reduced precursor is disclosed.

Patent Document 1 and Non-Patent Document 3 include
(A) Spin coating a solution of zinc acetate dihydrate, tin chloride dihydrate and copper acetate monohydrate on a soda lime glass substrate and drying at 300 ° C. for 5 minutes is repeated 5 times. ,
(B) holding the obtained membrane in air at 500 ° C. for 1 hour;
(C) Further, a method for producing a sulfide thin film is disclosed in which the film is held at 500 ° C. for 1 hour in an atmosphere of 5% hydrogen sulfide + 95% nitrogen.
In Non-Patent Document 3, when a CZTS compound semiconductor obtained by such a method is used for a light absorption layer, η = 2.3%, V _oc = 529 mV, J _sc = 10.2 mA / cm ² , F.R. It describes that a solar cell with F. = 41.6% is obtained.

In addition, in Patent Document 2,
(A) A Cu—Zn—Sn—S precursor film is formed by sputtering,
(B) A method for producing a sulfide-based compound semiconductor is disclosed in which a precursor film is subjected to sulfurization treatment at 550 to 580 ° C. for 3 hours in a 20% H ₂ S + N ₂ gas atmosphere.

Patent Document 3 discloses a method for producing partially oxidized titanium oxide in which crystalline titanium oxide is heated in a gas atmosphere containing a sulfur compound, although it is not a method for producing a light absorption layer.
Further, Patent Document 4 discloses a protective material for a light emitting material made of Cu ₂ Zn (Ge _{1 -x} Si _x ) S ₄ , although it is not a material used as a light absorption layer.

The method of forming a precursor film by applying an ink in which an alloy powder, oxide fine particles, salt, or the like is dispersed or dissolved on a substrate, has an advantage that a large-area thin film can be manufactured at low cost.
However, in this method, it is necessary to determine the composition of the precursor of the chalcogenite compound semiconductor at the time of producing the powder or the ink, and thus it is difficult to control the composition of the precursor. Also, since it is a wet process, a drying step is required to fix the ink on the substrate, and in order to obtain a thick film, it is necessary to repeat the application and drying of the ink a plurality of times. Furthermore, when a thin film (for example, the lower electrode) already formed on the substrate may be deteriorated by ink, it is necessary to form a deterioration preventing layer on the substrate surface before forming the precursor film.

On the other hand, in the method of forming the precursor film by the sputtering method, the composition control of the precursor film is relatively easy. Moreover, since it is a dry process, it is not necessary to perform a drying step, repeated application and drying, and formation of a deterioration preventing layer.
However, the sputtering method is
(1) Since it is a vacuum process, the manufacturing cost is high and it is difficult to increase the area.
(2) It is difficult to control the crystal form, crystallinity, orientation, etc. during the preparation of the precursor film of the chalcogenite compound semiconductor.
(3) ZnO, CuO, and, if co depositing SnO ₂ to form a precursor film of the oxide-based, since SnO ₂ sputtering rate is low, there is a limit to the composition control of the precursor film,
There are problems such as.
Furthermore, the CZTS semiconductor obtained by the conventional method has a problem that the conversion efficiency is relatively low.

JP 2007-269589 A JP 2009-026891 A JP 2004-277269 A JP 2009-021543 A

Thin Solid Films 361-362 (2000) p.514-519 Thin Solid Films 431-432 (2003) p.53-57 Proceedings of the 57th Joint Conference on Applied Physics 2010 Spring 20p-TE-2, p.14-249

The problem to be solved by the present invention is to provide a novel chalcogenite compound semiconductor having relatively high conversion efficiency and a method for producing the same.
In addition, another problem to be solved by the present invention is to provide a method for manufacturing a chalcogenite-based semiconductor that can be easily controlled in composition and can form a large-area thin film without increasing the manufacturing cost. There is to do.

In order to solve the above-described problems, the chalcogenite compound semiconductor according to the present invention is summarized as having the following configuration.
(1) The chalcogenite-based compound semiconductor contains Cu, Zn, Sn, element X ₃ (= S and / or Se), and O as essential elements.
(2) The chalcogenite compound semiconductor is:
(A) including Cu, Zn and Sn,
(B) Sulfurizing and / or selenizing a precursor containing one or more amorphous oxides and / or hydroxides containing any one or more elements selected from Cu, Zn and Sn. Can be obtained.

The method for producing a chalcogenite-based compound semiconductor according to the present invention includes:
(A) containing Cu, Zn and Sn, and
(B) a precursor preparation step of forming a precursor containing one or more amorphous oxides and / or hydroxides containing any one or more elements selected from Cu, Zn and Sn; ,
The gist of the present invention is to provide a chalcogenite-forming step of sulfiding and / or selenizing the precursor to obtain a chalcogenite-based compound semiconductor.
The precursor preparation step includes
A CVD raw material including a Cu source, a Zn source and a Sn source is supplied to an atmospheric open type CVD apparatus, and the CVD raw material is vaporized at the same time. In the atmosphere, an amorphous oxide containing Cu, Zn and Sn and / or Alternatively, it is preferable to provide an atmospheric open CVD process for forming the precursor containing hydroxide.

A chalcogenite compound semiconductor containing a predetermined amount of O exhibits a conversion efficiency equal to or higher than that of a chalcogenite compound semiconductor not containing O. Such a chalcogenite-based compound semiconductor is prepared by preparing a precursor containing one or more amorphous oxides or hydroxides including any one or more selected from Cu, Zn and Sn. It can be obtained by sulfurization and / or selenization.
In particular, when a precursor is prepared using an open-air CVD apparatus, composition control is easy, and a large-area thin film can be formed without increasing manufacturing costs.

SEM image (FIG. 1 (a): cross section, FIG. 1 (c): plane) of the film before sulfidation obtained in Example 1, and SEM image (FIG. 1 (b): cross section) of the film after sulfidation. FIG. 1 (d): a plane. 2 is an XRD pattern of a pre-sulfurized film obtained in Example 1. 2 is an XRD pattern of a film after sulfiding obtained in Example 1. FIG. 2 is an optical characteristic of a film before and after sulfiding obtained in Example 1. FIG. 2 is an EDS spectrum of the film after sulfiding obtained in Example 1. 2 is a SEM image of a cross section of the film after sulfiding obtained in Example 1. FIG. The number in the SEM image represents the EDS analysis position. It is an IV characteristic of the solar cell obtained in Example 2.

Hereinafter, an embodiment of the present invention will be described in detail.
[1. Chalcogenite compound semiconductor]
The chalcogenite compound semiconductor according to the present invention has the following configuration.
(1) The chalcogenite-based compound semiconductor contains Cu, Zn, Sn, element X ₃ (= S and / or Se), and O as essential elements.
(2) The chalcogenite compound semiconductor is:
(A) including Cu, Zn and Sn,
(B) Sulfurizing and / or selenizing a precursor containing one or more amorphous oxides and / or hydroxides containing any one or more elements selected from Cu, Zn and Sn. Can be obtained.

[1.1. Essential elements]
The chalcogenite-based compound semiconductor according to the present invention contains Cu, Zn, Sn, element X ₃ , and O as essential elements.
More specifically, in the present invention, the chalcogenite compound semiconductor is
(A) a compound in which part of S of the Cu ₂ ZnSnS ₄ (CZTS) -based compound is substituted with O (hereinafter also referred to as “CZTSO-based compound”), or
(B) a compound in which all or part of S in the CZTSO compound is substituted with Se;
Say.

[1.2. Element ratio of essential elements]
The element ratio of the essential elements of the chalcogenite compound semiconductor according to the present invention is not particularly limited, and an optimum element ratio can be selected according to the purpose.
In order to obtain high conversion efficiency, the ratio of Cu content (at%) to the sum of Zn and Sn contents (at%) (= Cu / (Zn + Sn) ratio) is 0.12 or more and 0.98. The following is preferred.
Similarly, the ratio of Zn content (at%) to Sn content (at%) (= Zn / Sn ratio) is preferably 0.50 or more and 3.91 or less.
Similarly, the ratio of the content of O (at%) to the sum of the contents of elements X ₃ and O (at%) (= O / (X ₃ + O) ratio) is 0.17 or more and 0.27 or less. preferable.

[1.3. Crystal structure]
The crystal structure of the chalcogenite compound semiconductor according to the present invention is not particularly limited, and various crystal structures can be adopted as long as the photoelectric effect is exhibited. Specific examples of the crystal structure of the chalcogenite compound semiconductor include a kesterite structure, a stannite structure, and a wurtz-stannite structure.

The chalcogenite-based compound semiconductor preferably includes only a phase having such a crystal structure (a phase exhibiting a photoelectric effect), but may include a different phase. However, when the heterogeneous phase content is excessive, high conversion efficiency cannot be obtained. In order to obtain high conversion efficiency, the content of the heterogeneous phase is preferably 50 vol% or less. The heterogeneous phase content is more preferably 30 vol% or less, and still more preferably 10 vol% or less.
Here, the “heterophase content” refers to a value obtained by a peak separation / fitting method of an X-ray diffraction pattern.

[1.4. precursor]
The chalcogenite compound semiconductor according to the present invention can be obtained by sulfiding and / or selenizing a precursor that satisfies the following conditions.
(A) First, the precursor needs to contain Cu, Zn, and Sn (essential metal element).
The precursor may be a single phase containing all essential metal elements, or may be a mixture of two or more phases containing one or more essential metal elements.

(B) Secondly, the precursor contains one or more amorphous oxides and / or hydroxides containing any one or more elements selected from Cu, Zn and Sn. There is a need.
Here, “non-crystal” refers to a solid substance having no spatially periodic arrangement. In the case where an amorphous film is formed on a glass substrate, “non-crystalline” refers to a state in which no peak other than a peak called halo that occurs in the vicinity of 10 to 30 ° appears in the XRD pattern. However, since the precursor is produced by controlling the composition ratio of each element, depending on the composition ratio, in addition to the halo, the precursor may include an oxide and / or hydroxide peak containing any of the constituent elements. There is also.

For example, the precursor may be composed of only an amorphous oxide and / or a hydroxide (noncrystalline phase). In this case, the precursor may consist of a single amorphous phase containing all essential metal elements, or a mixture of two or more amorphous phases containing one or more essential metal elements ( For example, it may be a laminate of a plurality of amorphous phases having different compositions.
Further, for example, the precursor may be a mixture of one or more amorphous phases and other phases (for example, crystalline oxide, hydroxide, sulfide, etc.).

Further, for example, the precursor may include an amorphous phase obtained using an atmospheric open type CVD apparatus. In this case, the precursor may be composed of only one or two or more amorphous phases obtained using an atmospheric open CVD apparatus, or one or two obtained using an atmospheric open CVD apparatus. It may be a mixture of an amorphous phase of at least a seed and an amorphous phase obtained by using another method or other phase (for example, a sulfide formed by sputtering).
Further, the precursor is supplied to a CVD source including a Cu source, a Zn source and a Sn source in an atmospheric open type CVD apparatus, and the CVD source is vaporized at the same time, and the amorphous material containing Cu, Zn and Sn on the substrate in the atmosphere. It may be obtained by forming an oxide and / or hydroxide.
Among these, the method of vaporizing and precipitating CVD raw materials containing all the essential metal elements at the same time using an open-air CVD apparatus is a material after sulfurization and / or selenization compared to the case of using other methods. Is particularly suitable as a precursor production method.

[2. Method for producing chalcogenite compound semiconductor]
The manufacturing method of the chalcogenite-based compound semiconductor according to the present invention includes a precursor manufacturing step and a chalcogenite forming step.

[2.1. Precursor manufacturing process]
The precursor production process is
(A) containing Cu, Zn and Sn, and
(B) A step of forming a precursor containing one or more amorphous oxides and / or hydroxides containing any one or more elements selected from Cu, Zn and Sn.

[2.1.1. Method for producing precursor]
The method for producing the precursor is not particularly limited as long as it is a method capable of producing a precursor containing an amorphous phase containing an essential metal element. Further, when the precursor is a mixture of an amorphous phase and other phases (for example, crystalline oxide, hydroxide, sulfide, etc.), a precursor is prepared by combining two or more methods. Also good.

The precursor is not necessarily a thin film, but a chalcogenite compound semiconductor is usually used in a thin film state, and therefore the precursor is also formed into a thin film.
When the precursor is a thin film, the method for forming the precursor film includes, specifically, a sputtering method, a vacuum evaporation method, a pulse laser deposition (PLD) method, a plating method, a chemical solution deposition (CBD) method, and electrophoresis. There are a film formation (EPD) method, a chemical vapor deposition (CVD) method, an atmospheric open CVD method, a spray pyrolysis film formation (SPD) method, a screen printing method, a spin coating method, a fine particle deposition method and the like.
Among these, the open air CVD method is suitable as a method for producing an amorphous phase containing one or more essential metal elements. When the precursor is a mixture of phases, it is preferred to form at least one amorphous phase using an open-air CVD method.

Furthermore, when producing a precursor film using the atmospheric open type CVD method, a CVD raw material including a Cu source, a Zn source and an Sn source is supplied to the atmospheric open type CVD apparatus, and the CVD raw material is vaporized at the same time. It is preferable to form a precursor containing an amorphous oxide and / or hydroxide containing Cu, Zn and Sn on the substrate.
Here, “atmospheric open type CVD method” means that a CVD raw material is vaporized in an inert gas atmosphere such as nitrogen, the vaporized raw material is transported with an inert gas, and a CVD raw material is deposited on the substrate placed in the air by a nozzle. Is a method of spraying. When the CVD raw material is sprayed on the substrate, the CVD raw material reacts with oxygen or water in the atmosphere, and an amorphous metal oxide or metal hydroxide can be directly formed on the substrate.
“At the same time vaporization”
(A) vaporizing a mixture of a plurality of raw materials with a single vaporizer, or
(B) vaporizing individual raw materials independently with individual vaporizers and mixing the obtained raw material gases;
Say.

[2.1.2. Precursor raw material]
As the precursor material, an optimum material is selected according to the method for producing the precursor.
For example, when an amorphous phase is produced using an atmospheric open type CVD apparatus, a metal complex such as bisacetylacetonate copper, bisacetylacetonate zinc, or bisacetylacetonate tin can be used as a CVD raw material.

[2.1.3. Precursor manufacturing conditions]
The optimum manufacturing conditions for the precursor are selected according to the composition of the precursor, the method for producing the precursor, the raw material used, and the like.
For example, when a precursor film is formed on a substrate using an atmospheric open type CVD apparatus, a predetermined amount of CVD raw material is sprayed onto the substrate heated to a predetermined temperature.
In this case, the temperature of the substrate may be a temperature at which an amorphous phase is formed. For example, when forming the precursor of a CZTSO-based compound, the temperature of the substrate is preferably 250 to 500 ° C.
The vaporization temperature of the CVD raw material is 90 to 200 ° C. although it depends on the type of the raw material. An appropriate flow rate (for example, 0.1 to 10 L / min) may be selected as the nitrogen gas flow rate for transporting the CVD raw material in accordance with the nozzle shape and dimensions of the open-air CVD apparatus. When a plurality of CVD raw materials are vaporized simultaneously using a plurality of vaporizers, each vaporizer may be independent for each CVD raw material, or may be connected in series and parallel.

The precursor is also at the time of sulfidation and / or selenization.
(A) The ratio of Cu content (at%) to the sum of Zn and Sn contents (at%) (= Cu / (Zn + Sn) ratio) is 0.12 or more and 0.98 or less,
(B) The ratio of Zn content (at%) to Sn content (at%) (= Zn / Sn ratio) is 0.50 or more and 3.91 or less,
It is preferable to produce it.
Therefore, for example, when a precursor is produced using an atmospheric open type CVD apparatus, when a deviation in element ratio occurs during production of the precursor or during sulfidation and / or selenization, the target composition is set. It is preferable to control the supply amount of each CVD raw material so that the chalcogenite-based compound is obtained.

[2.2. Chalcogenite conversion process]
The chalcogenitization step is a step of obtaining a chalcogenite-based compound semiconductor by sulfiding and / or selenizing the precursor.
Only one or both of sulfidation and selenization may be performed. Further, when both sulfurization and selenization are performed, sulfurization may be performed first, or selenization may be performed first.

As the conditions for sulfidation and selenization, optimum conditions are preferably selected according to the composition of the precursor and the crystal structure, respectively.
For example, sulfurization is performed by heating the precursor in the presence of a sulfur source at a predetermined temperature for a predetermined time. Examples of the sulfur source include hydrogen sulfide, sulfur, and carbon disulfide. The heating temperature and the heating time are usually about 500 to 600 ° C. × 1 to 4 hours, although depending on the composition of the precursor and the type of sulfur source.
Similarly, selenization is performed by heating the precursor at a predetermined temperature for a predetermined time in the presence of a selenium source. Examples of the selenium source include hydrogen selenide and selenium. The heating temperature and heating time are usually 500 to 600 ° C. × 1 to 4 hours, although depending on the composition of the precursor and the type of selenium source.

[3. Photoelectric element]
The chalcogenite compound semiconductor according to the present invention can be used as a light absorption layer of a photoelectric element. The film configuration other than the light absorption layer and the material thereof are not particularly limited, and an optimal one can be selected according to the purpose.
For example, a thin film solar cell which is a kind of photoelectric element has a structure in which a lower electrode, a light absorption layer, a buffer layer (interface layer), a window layer, and an upper electrode are formed in this order on a substrate. When the chalcogenite-based compound semiconductor according to the present invention is used for the light absorption layer, the materials of the other layers are not particularly limited, and various materials can be used. Further, the thickness of each layer is not particularly limited, and can be arbitrarily selected according to the purpose.

[4. Action of chalcogenite compound semiconductor and manufacturing method thereof]
As disclosed in Non-Patent Document 2, when a chalcogenite compound semiconductor is produced using an oxide as a precursor, a reduction treatment has been performed before selenization. This is because oxygen was considered harmful to the conversion efficiency.
On the other hand, a CZTSO compound semiconductor in which a part of S in the CZTS compound semiconductor is substituted with O exhibits a conversion efficiency equal to or higher than that of a CZTS compound semiconductor containing no O.
Since Se is in the same family as S, the same effect can be obtained even when all or part of S in the CZTSO-based compound semiconductor is replaced with Se.
In addition, the band gap can be controlled by introducing a predetermined amount of O into a predetermined site of the chalcogenite compound semiconductor.

In the case of manufacturing such a chalcogenite compound semiconductor, high conversion efficiency cannot be obtained even if a crystalline oxide film is used as a precursor and is sulfided and / or selenized.
On the other hand, a precursor containing one or two or more amorphous oxides or hydroxides containing any one or more selected from Cu, Zn, and Sn is produced, and this is sulfided and / or selenium. As a result, a chalcogenite compound semiconductor having relatively high conversion efficiency can be obtained. This is presumably because the amorphous oxide precursor is more easily reduced / sulfurized (selenized) and forms CZTSO more easily than crystalline. In addition, since CZTO which is a crystalline oxide has Cu: Zn: Sn: O = 1: 1: 1: 1, CZTSO (Cu: Zn: Sn: (S, O) = 2: 1: 1. : 4) It is considered that the composition range and sulfiding conditions for obtaining 4) are limited, and it is difficult to obtain high-quality CZTSO.

Furthermore, in the case of producing a precursor, if a method of vaporizing and precipitating CVD raw materials containing all the essential metal elements at the same time using an atmospheric open type CVD apparatus is used, the sulfurization is performed as compared with the case of using other methods. And / or the conversion efficiency of the material after selenization increases.
This is because each layer of the oxide precursor becomes a crystalline oxide or sulfide in the method of vaporizing and precipitating individually, whereas it becomes an amorphous oxide precursor in the method of vaporizing and precipitating simultaneously. This is probably because of this.

  Since the material obtained by the method according to the present invention is a chalcogenite-based compound semiconductor containing O, restrictions on the method and conditions for sulfidation and selenization are reduced. That is, options such as a sulfur source, a selenium source, a heating method, and temperature conditions are expanded. In addition, the method for producing the precursor using an open-air CVD apparatus is a non-vacuum dry process, and the composition can be determined simply by controlling the vaporization amount of the raw material in real time, so that the composition controllability is high. Since the number of processes is small, large area and low cost are easy.

Example 1
[1. Preparation of sample]
[1.1. Preparation of precursor]
An amorphous (Cu, Zn, Sn) -O film to be a precursor was produced using an atmospheric open type CVD apparatus. After bisacetylacetonate copper, bisacetylacetonate zinc and bisacetylacetonate tin serving as a Cu source, Zn source and Sn source were respectively arranged in the vaporizer, the inside of the vaporizer was made a nitrogen gas atmosphere. The Cu source, Zn source and Sn source were heated to 160 to 200 ° C., 90 to 130 ° C. and 100 to 160 ° C., respectively, and the Cu source, Zn source and Sn source were vaporized at the same time. The vaporized raw material is transported with nitrogen gas and sprayed onto a soda lime glass (SLG) substrate or Mo / SLG substrate heated to 250 to 500 ° C. arranged in the atmosphere, and directly on the substrate, amorphous (Cu , Zn, Sn) -O films were prepared. The film thickness of the amorphous (Cu, Zn, Sn) -O film was 800 nm.
[1.2. Sulfurization of precursor]
Next, the amorphous (Cu, Zn, Sn) -O film was sulfided to produce a CZTSO film. Sulfurization was performed by holding at 540 to 560 ° C. for 3 hours in a 5% H ₂ S—N ₂ atmosphere.

[2. Test method]
[2.1. X-ray fluorescence analysis (XRF)]
The composition of the film after sulfidation was measured by XRF.
[2.2. SEM observation]
SEM observation of the film before and after sulfidation was performed.
[2.3. X-ray diffraction]
The X-ray diffraction pattern of the film before and after sulfiding was measured.
[2.4. optical properties]
Using a spectrophotometer, the transmittance and light absorption coefficient of the film before and after sulfiding were measured.
[2.5. EDS analysis]
EDS analysis of the film after sulfidation was performed. In the EDS analysis, the acceleration voltage of the electron beam was set to 20 kV, and several point analyzes were performed in the film thickness direction and the film surface direction.

[3. result]
[3.1. XRF]
The Cu / (Zn + Sn) ratio of the film after sulfidation was 0.78. The Zn / Sn ratio of the film after sulfidation was 1.29.
[3.2. SEM observation]
FIG. 1 shows SEM images of the film before and after sulfidation. FIG. 1A and FIG. 1C are a cross section and a plane of the film before sulfidation, respectively. Moreover, FIG.1 (b) and FIG.1 (d) are the cross sections and planes of a film | membrane after sulfidation, respectively. FIG. 1 shows that the crystal grains are coarsened by the sulfidation treatment.

[3.3. X-ray diffraction]
FIG. 2 shows the XRD pattern of the film before sulfidation. FIG. 3 shows the XRD pattern of the film after sulfidation. From the sample before sulfidation, only a 10-30 ° halo indicating an SLG substrate could be confirmed. On the other hand, each peak indicating CZTS could be confirmed from the sample after sulfidation.

[3.4. optical properties]
FIG. 4 shows the optical characteristics of the film before and after sulfidation. As a result of extrapolating the optical characteristics and estimating the optical band gap, it was confirmed that the film before sulfidation had an optical band gap of about 2.52 eV, and the film after sulfidation had an optical band gap of about 1.57 eV. The optical band gap of CZTS within the generally reported power generation composition range is about 1.45 to 1.50 eV. Therefore, from these results, it was confirmed that a CZTS film (Cu ₂ ZnSn (S, O) ₄ film) containing O can be obtained by sulfiding the amorphous (Cu, Zn, Sn) -O film. .

[3.4. EDS analysis]
An EDS analysis of the film after sulfidation was performed. FIG. 5 shows an example of the EDS spectrum. FIG. 6 shows an SEM image of the cross section of the film after sulfidation. The number in the SEM image represents the EDS analysis position.
Of the EDS spectra, O-Ka around 0.5 keV and S-Ka around 2.3 keV were used to calculate the composition values (at%) of O and S. Furthermore, the composition values (at%) of O and S at each analysis position shown in FIG. 6 were averaged in the film thickness direction and the film surface direction, and the O / (S + O) ratio was calculated.

The average O / (S + O) ratio calculated in the film thickness direction is 0.27 at the measurement position (1, 2, 3) in FIG. 6, 0.19 at (4, 5, 6), and (7, 8). 9) was 0.22. The average O / (S + O) ratio calculated for the film surface direction is 0.27 for the measurement position (1, 4, 7) in FIG. 6, 0.17 for (2, 5, 8), (3 , 6, 9) was 0.24. Furthermore, the average O / (S + O) ratio of all measurement points was 0.23.
From the above results, it was confirmed that the CZTSO film produced by the method according to the present invention contained oxygen of about 0.17 to 0.27 at an O / (S + O) ratio.

(Example 2, Comparative Example 1)
[1. Preparation of sample]
A solar cell having a structure of upper electrode / window layer / buffer layer / light absorption layer / lower electrode / substrate was produced. Al was used for the upper electrode. ZnO: Al was used for the window layer. CdS was used for the buffer layer. Mo was used for the lower electrode. SLG was used for the substrate.
In the light absorption layer,
(A) CZTSO film obtained in Example 1 (Example 1), or
(B) Cu ₂ ZnSn (S, O) ₄ film (Comparative Example 1) obtained by sulfiding a crystalline oxide film (ZnCuSnO ₄ film)
Was used.
The crystalline oxide film is controlled in composition by using an open-air CVD apparatus so that the substrate heating temperature is about 400 to 600 ° C. and Cu: Zn: Sn = 1: 1: 1 (vaporization temperature and raw material). The amount was adjusted).

[2. Test method]
Using the produced solar cell, the short-circuit current density (J _SC ), the open-circuit voltage (V _OC ), the form factor (FF), and the conversion efficiency (E _ff ) were evaluated. A solar simulator was used for the measurement. In the measurement, artificial solar light of air mass 1.5 (AM1.5) was applied to the solar cell, the measurement was started without taking time, and the measurement was completed in about 20 seconds.
Conversion efficiency (E _ff ), open-circuit voltage (V _OC ), short-circuit current density (J _SC ), form factor (F.F.), and pseudo-sunlight energy per unit area of the irradiated surface (E The relationship of the following formula (1) is established in _sun ).
E _ff = V _OC × J _SC × F.F. ÷ E _sun (1)

[3. result]
In FIG. 7, the IV characteristic of the solar cell obtained in Example 2 is shown. In the case of the solar cell obtained in Example 2, the generation of V _oc = 654 mV, J _sc = 15.5 mA, FF = 52.1%, η = 5.26% was confirmed from the IV characteristics. did.
On the other hand, the solar cell obtained in Comparative Example 1 could not confirm power generation.

From the above, when an amorphous (Cu, Zn, Sn) -O film prepared by simultaneously vaporizing a plurality of raw materials using an atmospheric open type CVD apparatus is used as a precursor, a precursor prepared by another non-vacuum method It was confirmed that the conversion efficiency of the membrane after sulfidation was higher than when using the body.
Unlike the conventional CZTS film, the CZTSO film obtained by the method according to the present invention does not need to positively remove oxygen in the precursor film, so that the restriction of the sulfidation method and conditions is reduced (that is, It can be said that the options such as the sulfur source, the heating method, and the temperature condition can be expanded. Furthermore, the open-air CVD method is a non-vacuum dry process, has high composition controllability, and has a small number of steps, so that it is easy to increase the area and cost of the CZTSO film.

(Examples 3 to 5)
[1. Preparation of sample]
[1.1. Preparation of precursor]
A precursor composed of a laminate of a plurality of films was produced using an atmospheric open type CVD apparatus. Among the films constituting the precursor, an amorphous oxide film containing a part of Cu, Zn, and Sn is obtained by vaporizing the Cu source, the Zn source, and the Sn source individually using an atmospheric open type CVD apparatus. Produced. Other manufacturing conditions were the same as in Example 1. Of the films constituting the precursor, the sulfide film was produced by sputtering.
The film configuration of the precursor is in order from the film surface,
(A) Amorphous ZnO / Amorphous CuO / Amorphous SnO ₂ (Example 3),
(B) Amorphous (Zn, Cu) -O / Amorphous SnO ₂ (Example 4) or
(C) Amorphous (Zn, Cu) -O / SnS (Example 5)
It was.
Of each film constituting the laminated film, the film thickness of amorphous ZnO, amorphous CuO, amorphous SnO ₂ , and SnS is 300 nm, respectively, and the film thickness of amorphous (Zn, Cu) -O is It was 700 nm.
[1.2. Sulfurization of precursor]
Under the same conditions as in Example 1, the precursor was sulfided.

[2. Test method]
In the same manner as in Example 1, the X-ray diffraction measurement and optical characteristics of the film after sulfidation were evaluated. In addition, the solar cell characteristics were evaluated in the same manner as in Example 2.
[3. result]
All the samples after sulfidation exhibited an XRD pattern of CZTS. In addition, it was confirmed that all the samples after sulfurization had an optical band gap of about 1.52 to 1.55 eV. Moreover, as a result of evaluating the solar cell characteristics, η = 1.7% (Example 5) was confirmed.
From the above, when producing a precursor using an atmospheric open type CVD apparatus, using a method of vaporizing and precipitating a plurality of raw materials at the same time, compared with a method of vaporizing and precipitating a plurality of raw materials individually, It was confirmed that the conversion efficiency of the membrane was increased.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

  The chalcogenite-based compound semiconductor element and the manufacturing method thereof according to the present invention can be used for light absorption layers such as thin film solar cells, photoconductive cells, photodiodes, phototransistors, sensitized solar cells, and the manufacture thereof.

Claims (6)

A chalcogenite compound semiconductor having the following configuration.
(1) The chalcogenite-based compound semiconductor contains Cu, Zn, Sn, element X ₃ (= S and / or Se), and O as essential elements.
(2) The chalcogenite compound semiconductor is:
(A) including Cu, Zn and Sn,
(B) Sulfurizing and / or selenizing a precursor containing one or more amorphous oxides and / or hydroxides containing any one or more elements selected from Cu, Zn and Sn. Can be obtained. The precursor is
A CVD source including a Cu source, a Zn source and a Sn source is supplied to an atmospheric open type CVD apparatus, the CVD source is vaporized at the same time, and the amorphous oxide containing Cu, Zn and Sn on the substrate in the atmosphere and The chalcogenite-based compound semiconductor according to claim 1, wherein the chalcogenite-based compound semiconductor is obtained by forming a hydroxide. (A) The ratio of Cu content (at%) to the sum of Zn and Sn contents (at%) (= Cu / (Zn + Sn) ratio) is 0.12 or more and 0.98 or less,
(B) The ratio of Zn content (at%) to Sn content (at%) (= Zn / Sn ratio) is 0.50 or more and 3.91 or less,
(C) The ratio of the content of O (at%) to the sum of the contents of elements X ₃ and O (at%) (= O / (X ₃ + O) ratio) is 0.17 or more and 0.27 The chalcogenite-based compound semiconductor according to claim 1 or 2, which is: (A) containing Cu, Zn and Sn, and
(B) a precursor preparation step of forming a precursor containing one or more amorphous oxides and / or hydroxides containing any one or more elements selected from Cu, Zn and Sn; ,
A method for producing a chalcogenite-based compound semiconductor comprising: a chalcogenite-forming step for obtaining a chalcogenite-based compound semiconductor by sulfiding and / or selenizing the precursor. The precursor preparation step includes
A CVD raw material including a Cu source, a Zn source and a Sn source is supplied to an atmospheric open type CVD apparatus, and the CVD raw material is vaporized at the same time. In the atmosphere, an amorphous oxide containing Cu, Zn and Sn and / or Or the manufacturing method of the chalcogenite type compound semiconductor of Claim 4 provided with the air release CVD process which forms the said precursor containing a hydroxide. In the precursor preparation step, at the time of sulfurization and / or selenization,
(A) The ratio of Cu content (at%) to the sum of Zn and Sn contents (at%) (= Cu / (Zn + Sn) ratio) is 0.12 or more and 0.98 or less,
(B) The ratio of Zn content (at%) to Sn content (at%) (= Zn / Sn ratio) is 0.50 or more and 3.91 or less,
To produce the precursor,
The chalcogenite conversion step includes
(C) The ratio of the content of O (at%) to the sum of the contents of elements X ₃ and O (at%) (= O / (X ₃ + O) ratio) is 0.17 or more and 0.27 The method for producing a chalcogenite-based compound semiconductor according to claim 4 or 5, wherein sulfidation and / or selenization is performed so as to satisfy the following conditions.

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