CN111312855B - Preparation method of photoelectric detector - Google Patents

Preparation method of photoelectric detector Download PDF

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CN111312855B
CN111312855B CN202010113650.2A CN202010113650A CN111312855B CN 111312855 B CN111312855 B CN 111312855B CN 202010113650 A CN202010113650 A CN 202010113650A CN 111312855 B CN111312855 B CN 111312855B
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light absorption
layer
etching
electrode layer
block
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CN111312855A (en
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杜建华
关峰
高宇鹏
袁广才
曲峰
王政焱
王恒
何可
陈明
杨春雷
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BOE Technology Group Co Ltd
Shenzhen Institute of Advanced Technology of CAS
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BOE Technology Group Co Ltd
Shenzhen Institute of Advanced Technology of CAS
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0256—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
    • H01L31/0264—Inorganic materials
    • H01L31/032—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
    • H01L31/0322—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312 comprising only AIBIIICVI chalcopyrite compounds, e.g. Cu In Se2, Cu Ga Se2, Cu In Ga Se2
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0352—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
    • H01L31/035272—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions characterised by at least one potential jump barrier or surface barrier
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/541—CuInSe2 material PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract

The application provides a preparation method of a photoelectric detector. The preparation method comprises the following steps: providing a substrate; forming a first electrode layer on the substrate; forming a light absorption layer covering the first electrode layer on the first electrode, wherein the light absorption layer is made of copper indium gallium selenide; etching the light absorption layer to obtain a plurality of light absorption blocks arranged in an array; etching the side wall of the light absorption block by using a mixed solution of bromine water and liquid organic matters as an etching liquid so as to remove impurities on the side wall of the light absorption block; and the compound generated by the reaction of the impurities and bromine is dissolved in the liquid organic matter.

Description

Preparation method of photoelectric detector
Technical Field
The application relates to the technical field of semiconductors, in particular to a preparation method of a photoelectric detector.
Background
Copper Indium Gallium Selenide (CIGS) materials are widely used in thin film solar cells because of their near-optimal optical bandgap, excellent radiation resistance, and stability. Meanwhile, researchers try to apply the photoelectric detector to achieve a better photoelectric conversion effect due to the fact that the photoelectric detector has excellent absorptivity and high quantum efficiency. How to prepare the photoelectric detector with excellent performance by utilizing the copper indium gallium selenide material is a key point of the technology.
Disclosure of Invention
The embodiment of the application provides a preparation method of a photoelectric detector, which comprises the following steps:
providing a substrate;
forming a first electrode layer on the substrate;
forming a light absorption layer covering the first electrode layer on the first electrode layer, wherein the light absorption layer is made of copper indium gallium selenide;
etching the light absorption layer to obtain a plurality of light absorption blocks arranged in an array;
etching the side wall of the light absorption block by using a mixed solution of bromine water and liquid organic matters as an etching liquid so as to remove impurities on the side wall of the light absorption block; and the compound generated by the reaction of the impurities and bromine is dissolved in the liquid organic matter.
In one embodiment of the present application, the liquid organic includes at least one of propylene glycol, glycerol, and butylene glycol.
In an embodiment of the application, in the mixed solution of bromine water and liquid organic matter, the volume fraction of bromine water is 5% to 10%, and the mass fraction of bromine in the bromine water is 3%.
In an embodiment of the present application, the etching the light absorption layer includes:
forming a shielding layer covering the light absorption layer on the light absorption layer, and carrying out patterning treatment on the shielding layer to obtain shielding blocks arranged in an array;
and etching the part of the light absorption layer which is not shielded by the shielding blocks by using etching liquid so as to pattern the light absorption layer and obtain a plurality of light absorption blocks which are arranged in an array.
In an embodiment of the application, the etching the portion of the light absorption layer that is not shielded by the shielding block with an etching solution includes:
and etching the part of the light absorption layer which is not shielded by the shielding block by using bromine water as an etching liquid, wherein the mass fraction of a bromine substance in the bromine water is 0.5-10%.
In an embodiment of the application, the first electrode layer is made of a simple metal substance, and after the mixed solution of bromine water and liquid organic matter is used as an etching liquid to etch the side wall of the light absorption block, the preparation method further includes:
and processing the first electrode layer by adopting an aqueous solution of hydrogen peroxide to obtain electrode blocks which correspond to the light absorption blocks one to one.
In one embodiment of the present application, the mass fraction of hydrogen peroxide in the aqueous hydrogen peroxide solution is between 20% and 50%.
In one embodiment of the present application, after the treating the first electrode layer with the aqueous solution of hydrogen peroxide, the preparation method further includes:
and removing the blocking blocks on the light absorption blocks.
In an embodiment of the present application, the material of the blocking layer is photoresist, and the etching solution used for removing the blocking piece is acetone.
In an embodiment of the application, after the mixed solution of bromine water and liquid organic matter is used as an etching liquid to etch the side wall of the light absorption block, the preparation method further includes:
a buffer layer formed on the light absorbing layer;
forming an n-type semiconductor layer on the buffer layer;
and forming a transparent second electrode layer on the n-type semiconductor layer.
The embodiment of the application achieves the main technical effects that:
according to the preparation method of the photoelectric detector, the material of the light absorption layer is copper indium gallium selenide, so that the photoelectric detector can achieve a better photoelectric conversion effect, and the sensitivity of the photoelectric detector can be improved; after the light absorption layer is etched to obtain the light absorption block, the mixed solution of bromine water and liquid organic matters is used as etching liquid to etch the side wall of the light absorption block, so that impurities on the side wall of the light absorption block can be effectively removed, the roughness of the side wall of the light absorption block is reduced, the dark current and the leakage current of the photoelectric detector are further reduced, and the performance of the photoelectric detector is improved; the impurities on the side wall of the light absorption block are removed by adopting a wet etching process, so that the requirements on equipment are low, the repeatability is good, and the mass production is easy; the mixed solution of bromine water and liquid organic matters is used as the etching liquid to etch the side wall of the light absorption block, so that no harmful substances are generated, and the method is environment-friendly.
Drawings
FIG. 1 is a flow chart of a method of fabricating a photodetector provided by an exemplary embodiment of the present application;
FIG. 2 is a schematic diagram of a photodetector structure provided in an exemplary embodiment of the present application;
FIG. 3 is a schematic diagram of a first intermediate structure of a photodetector provided in accordance with an exemplary embodiment of the present application;
FIG. 4 is a schematic diagram illustrating etching of a light absorbing layer of a photodetector according to an exemplary embodiment of the present disclosure;
FIG. 5 is a schematic diagram of a second intermediate structure of a photodetector provided in accordance with an exemplary embodiment of the present application;
FIG. 6 is a schematic illustration of a light absorbing block as sidewalls are etched as provided by an exemplary embodiment of the present application;
FIG. 7 is a schematic diagram of a fourth intermediate structure of a photodetector provided by an exemplary embodiment of the present application.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.
It is to be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present application. The word "if" as used herein may be interpreted as "at … …" or "when … …" or "in response to a determination", depending on the context.
The following describes in detail a method for manufacturing a photodetector provided in an embodiment of the present application with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.
In the embodiments of the present application, for convenience of description, the up-down direction is defined by defining the direction from the substrate to the first electrode layer as up and the direction from the first electrode layer to the substrate as down. It is easy to understand that the different direction definitions do not affect the actual operation of the process and the actual shape of the product.
The embodiment of the present application provides a method for manufacturing a photodetector, and the photodetector 100 shown in fig. 2 can be manufactured by the method provided by the embodiment of the present application. Referring to fig. 1, the method for manufacturing the photodetector includes the following steps 110 to 150. The steps will be described in detail below.
In step 110, a substrate is provided.
In one embodiment, the substrate 10 may be a glass substrate, and the material of the substrate 10 may be soda-lime glass, for example. Of course, in other embodiments, other materials may be used for the substrate 10, such as sapphire, etc.
In one embodiment, the surface of the substrate 10 may be cleaned to remove stains from the surface of the substrate 10, thereby improving adhesion between a subsequently formed film layer and the substrate 10. In one exemplary embodiment, the surface of the substrate 10 may be sequentially cleaned with an aqueous solution of a detergent, an aqueous solution of NaOH, and a deionized water solution, and then evaporated to dryness under a high temperature vacuum after the cleaning is completed.
In step 120, a first electrode layer is formed on the substrate.
In one embodiment, the material of the first electrode layer 20 may be a simple metal with better conductivity, such as molybdenum. In other embodiments, other materials with better conductivity can be used for the first electrode layer 20.
In one embodiment, the thickness of the first electrode layer 20 is 500nm to 2000 nm. When the thickness of the first electrode layer 20 is within the range, the phenomenon that the normal operation of the photodetector is affected due to the fact that the resistance of the first electrode layer 20 is too large because the thickness of the first electrode layer 20 is too small can be avoided; too large a thickness of the first electrode layer 20 to cause excessive stress of the first electrode layer 20 on the substrate 10, which may result in bending of the substrate 10, can also be avoided. The thickness of the first electrode layer 20 may be, for example, 500nm, 700nm, 800nm, 1000nm, 1200nm, 1400nm, 1600nm, 1800nm, 2000nm, or the like.
In one embodiment, the first electrode layer 20 may be prepared using a direct current magnetron sputtering method. Specifically, firstly, the cleaned soda-lime glass substrate is put into a vacuum degree of less than 3X 10-4And introducing high-purity inert gas such as argon into the film coating cavity under Pa to make the pressure in the film coating cavity reach 2.8 Pa. Then, turning on a sputtering power supply to adjust the sputtering power to 1000W, and starting to deposit the film layer to obtain a first electrode with the thickness of 500nm to 2000nmAnd a pole layer 20. The inert gas is then turned off and sputtering is stopped. And taking out the second electrode layer 20 after cooling for 10-15 min.
In step 130, a light absorption layer covering the first electrode layer is formed on the first electrode layer, and the material of the light absorption layer is copper indium gallium selenide.
The copper indium gallium selenide material is a direct band gap semiconductor material, the forbidden band width of the copper indium gallium selenide material can be continuously adjusted within 1.04 eV-1.67 eV, and the copper indium gallium selenide material has higher light absorption rate and higher quantum efficiency. The copper indium gallium selenide material is applied to the photoelectric detector 100 as the light absorption layer, so that the photoelectric detector can achieve a good photoelectric conversion effect, and the sensitivity of the photoelectric detector 100 can be improved.
In one embodiment, the light absorption layer has a thickness of 0.5 μm to 3.0 μm. When the thickness of the light absorption layer is within the range, the poor light absorption effect caused by too small thickness of the light absorption layer can be avoided; and the phenomenon that the detection efficiency of the photoelectric detector is reduced due to carrier recombination caused by too large thickness of the light absorption layer can also be avoided. The thickness of the light-absorbing layer may be, for example, 0.5. mu.m, 0.8. mu.m, 1.0. mu.m, 1.2. mu.m, 1.4. mu.m, 1.6. mu.m, 1.8. mu.m, 2.0. mu.m, 2.2. mu.m, 2.5. mu.m, 2.8. mu.m, 3.0. mu.m, or the like.
In one embodiment, the light absorbing layer may be prepared by magnetron sputtering followed by selenization, or by co-evaporation three-step, or by Molecular Beam Epitaxy (MBE).
In one exemplary embodiment, when the light absorbing layer is prepared by the molecular beam epitaxy method, the substrate 10 having the second electrode layer 20 formed on the surface thereof is first placed in a molecular beam epitaxy vacuum deposition apparatus. When the light absorption layer is evaporated, four targets can be adopted for simultaneous evaporation, and the materials of the four targets are Cu, In, Ga and Se respectively. At vacuum degree lower than 4x10-5Evaporating in the coating cavity of Pa for about 1h to form a light absorption layer with the thickness of 1.05-2.0 μm. And finally, taking out the light absorption layer, the second electrode layer 20 and the substrate 10 from the vacuum coating equipment after the temperature of the light absorption layer, the second electrode layer and the substrate is reduced.
In step 140, the light absorption layer is etched to obtain a plurality of light absorption blocks arranged in an array.
The light absorption layer is etched to obtain a plurality of light absorption blocks 31 which are arranged in an array, so that the photoelectric detector is facilitated to acquire more optical signals, and the optical signals are converted by the conversion circuit and then output more electric signals, so that the purpose of detecting optical information is achieved.
In the semiconductor manufacturing process, the etching process includes a wet etching process and a dry etching process. However, dry etching has high requirements for equipment and high cost, and is not suitable for mass production. The wet etching process is relatively simple, and meanwhile, the etching conditions can be accurately controlled, so that the method is favorable for large-scale application. Thus, the light absorbing layer may be etched using a wet etching process.
In an embodiment, the step 140 of etching the portion of the light absorption layer that is not covered by the photoresist layer by using an etching solution may include the following steps 141 and 142.
In step 141, a shielding layer is formed on the light absorbing layer to cover the light absorbing layer, and the shielding layer is patterned to obtain shielding blocks arranged in an array.
A first intermediate structure as shown in fig. 3 is obtained by step 141.
In one embodiment, the light absorption layer 30 is made of photoresist, and after a masking layer covering the light absorption layer is formed on the light absorption layer 30, the photoresist may be patterned by an exposure and development process.
In an exemplary embodiment, the material of the blocking layer is a positive photoresist, a portion of the photoresist that needs to be removed is exposed, and then a developing process is performed, the exposed portion of the photoresist is washed away, and a portion that is not exposed is remained, and the remained portion is the blocking block 41. In another exemplary embodiment, the material of the blocking layer is a negative photoresist, and the photoresist is exposed to the remaining portions, and then developed, so that the unexposed portions of the photoresist are washed away, the exposed portions are retained, and the retained portions are the blocking blocks 41.
In other embodiments, other materials can be used for the material of the shielding layer as long as the material can be easily removed in the subsequent step.
In step 142, etching the portion of the light absorption layer that is not shielded by the shielding blocks with an etching solution to pattern the light absorption layer, so as to obtain a plurality of light absorption blocks arranged in an array.
In an embodiment, the step 142 of etching the portion of the light absorbing layer that is not shielded by the shielding block with an etching solution may be completed by the following steps:
and etching the part of the light absorption layer which is not shielded by the shielding block by using bromine water as an etching liquid, wherein the mass fraction of a bromine substance in the bromine water is 0.5-10%. Bromine water is used as etching liquid to etch the light absorption layer 30, and the mass fraction of bromine in the bromine water is 0.5% -10%, so that the etching speed of the etching liquid to the light absorption layer 30 is high, the light absorption layer 30 can be etched in the longitudinal direction, and the side wall of the light absorption block 31 can be prevented from being excessively etched. The mass fraction of bromine in the bromine water may be, for example, 0.5%, 1%, 3%, 5%, 7%, 9%, 10%, or the like.
In one embodiment, when the etching solution is bromine water, the etching solution can be prepared from 3% by mass of bromine water and deionized water according to a certain ratio. In other embodiments, other components, such as ammonia, can be used in the etching solution.
In one embodiment, referring to fig. 4, when etching the portion of the light absorption layer 30 that is not blocked by the blocking piece 41 with an etching solution, 150ml to 200ml of the etching solution may be first added into a container 201; then, the first intermediate structure (including the substrate 10, the first conductive layer 20 formed on the substrate 10, the light absorption layer 30 formed on the first conductive layer 20, and the stopper 41 formed on the light absorption layer 30) obtained in step 141 is placed on the sample holder 202, and the sample holder 202 and the first intermediate structure are placed into the container 201, wherein the first intermediate structure is completely submerged by the etching solution. The portion of the light absorbing layer 30 of the first intermediate structure that is not blocked by the blocking block is in contact with the etching solution and reacts with the etching solution. After the first intermediate structure is immersed in the etching solution for 10min to 15min, the light absorption layer 30 is etched to obtain a plurality of light absorption blocks 31 arranged in an array, and a second intermediate structure as shown in fig. 5 can be obtained. Thereafter, the sample holder 202 and the second intermediate structure are taken out, the surface of the second intermediate structure is rinsed with deionized water, and the surface of the second intermediate structure is blow-dried with dry nitrogen gas. Wherein the sample holder 202 is configured to support the first intermediate structure and the second intermediate structure, thereby facilitating the placement of the first intermediate structure into the container 201 and facilitating the removal of the second intermediate structure from the container 201.
In the process of etching the light absorption layer 30 by using the etching solution, the portion blocked by the blocking block 41 is not etched, so that the finally formed light absorption blocks 31 correspond to the blocking blocks 41 one by one, and the orthographic projection of the light absorption blocks 31 on the substrate 10 is approximately overlapped with the orthographic projection of the blocking blocks 41 on the substrate 10.
In step 150, a mixed solution of bromine water and liquid organic matter is used as an etching solution to etch the side wall of the light absorption block, so as to remove impurities on the side wall of the light absorption block; and the compound generated by the reaction of the impurities and bromine is dissolved in the liquid organic matter.
In the process of preparing the light absorbing layer 30, some impurities may be formed in the light absorbing layer regardless of the method of preparation. Wherein the impurities refer to components except copper indium gallium selenide, and mainly refer to selenium-containing compounds such as Cu2Se and selenium. After the light absorption layer 30 is etched to obtain the light absorption block 31, impurities on the sidewall of the light absorption block 31 are exposed, so that the roughness of the sidewall of the light absorption block 31 is large, and further, the dark current and the leakage current of the photodetector 100 are large, which affects the performance of the photodetector 100.
When the mixed solution of bromine water and liquid organic matter is used as etching liquid to etch the side wall of the light absorption block 31, the bromine in the bromine water reacts with impurities on the side wall of the light absorption block 31, and the generated compound is dissolved in the liquid organic matter. Meanwhile, the liquid organic matter can dilute the concentration of bromine in the bromine water, slow down the etching rate of bromine to the light absorption block 31, and prevent the side wall of the light absorption block 31 from being excessively etched.
Further, the liquid organic matter is soluble in water, so that the liquid organic matter on the side wall of the light absorption block 31 can be removed by washing with deionized water subsequently, and new impurities cannot be generated by the reaction of bromine water and the impurities. It can be seen that, in step 150, impurities on the sidewall of the light absorption block 31 can be removed, and the roughness of the sidewall of the light absorption block 31 is reduced, so as to reduce the dark current and the leakage current of the photo detector 100, thereby improving the performance of the photo detector 100.
In the process of etching the side wall of the light absorption block by using a mixed solution of bromine water and liquid organic matters as an etching solution, the formula of the chemical reaction mainly generated is as follows:
Br2+Cu2Se→CuBr2+Se；
Se+2Br2→SeBr4。
compound CuBr produced by reaction2With SeBr4Can be dissolved in liquid organic matter.
In one embodiment, the liquid organic includes at least one of propylene glycol, glycerol, and butylene glycol. Glycerol, propylene glycol, butanediol to CuBr2And SeBr4The solubility of the compound is better, and the glycerol, the propylene glycol and the butanediol are soluble in water.
In one embodiment, in the mixed solution of bromine water and liquid organic matter, the volume fraction of the bromine water is 5% -10%, and the mass fraction of bromine in the bromine water is 3%. Therefore, the problem that impurities on the side wall of the light absorption block 31 cannot be effectively removed due to too low bromine concentration in the etching liquid, and the dark current and the leakage current of the photoelectric detector are large can be avoided; and the phenomenon that the performance of the photoelectric detector is influenced by the reduction of the light absorption surface of the light absorption block 31 due to the fact that the side wall of the light absorption block 31 is excessively etched due to the fact that the bromine concentration in the etching liquid is too high can also be avoided. The volume fraction of the bromine water in the mixed solution of the bromine water and the liquid organic substance may be, for example, 5%, 6%, 7%, 8%, 9%, 10%, or the like.
In one embodiment, referring to fig. 6, when etching the side wall of the light absorption block by using the mixed solution of bromine water and liquid organic substance as the etching solution, the mixed solution of bromine water and liquid organic substance is first added into the container 201, and then the second intermediate structure obtained in step 141 is placed on the sample holder 202, and the sample holder 202 is placed into the container 201 together with the second intermediate structure, wherein the second intermediate structure is completely submerged by the mixed solution of bromine water and liquid organic substance. And after the second intermediate structure is soaked in the etching solution for 3-5 min, taking out the sample frame 202 and the second intermediate structure, flushing the surface of the second intermediate structure with deionized water, and drying the surface of the second intermediate structure with dry nitrogen to obtain a third intermediate structure.
In an embodiment, the material of the first electrode layer 20 is a metal simple substance, and after the step 150 of etching the side wall of the light absorption block by using the mixed solution of bromine water and liquid organic matter as an etching solution, the preparation method further includes the following step 160.
In step 160, the first electrode layer is treated with an aqueous solution of hydrogen peroxide to obtain electrode blocks corresponding to the light absorption blocks one to one.
The first electrode layer can be etched by the aqueous solution of hydrogen peroxide and the first electrode layer. In the process of etching the first electrode layer 20 with the aqueous solution of hydrogen peroxide, the portion blocked by the light absorbing block 31 is not etched, so that the finally formed electrode blocks 21 correspond to the light absorbing blocks 31 one by one, and the orthographic projection of the light absorbing blocks 31 on the substrate 10 is approximately overlapped with the orthographic projection of the electrode blocks 21 on the substrate 10.
In one embodiment, the mass fraction of hydrogen peroxide in the aqueous solution of hydrogen peroxide is 20% to 50%. Therefore, the first electrode layer 20 can be prevented from being over-etched due to too large mass fraction of the hydrogen peroxide, and the first electrode layer 20 can be prevented from being not etched through due to too small mass fraction of the hydrogen peroxide. The mass fraction of hydrogen peroxide in the aqueous solution of hydrogen peroxide may be, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or the like.
In one embodiment, the first electrode layer is treated with an aqueous solution of hydrogen peroxide by first adding the aqueous solution of hydrogen peroxide to the container 201, then placing the third intermediate structure on the sample holder 202, and placing the sample holder 202 together with the third intermediate structure into the container 201, wherein the third intermediate structure is completely submerged in the aqueous solution of hydrogen peroxide. After the third intermediate structure is soaked in the aqueous solution of hydrogen peroxide for about 30min, a fourth intermediate structure as shown in fig. 7 can be obtained. The sample holder 202 and the fourth intermediate structure are removed, and the surface of the fourth intermediate structure is rinsed with deionized water and then dried with dry nitrogen.
In one embodiment, after the step 160 after the step of treating the first electrode layer with the aqueous solution of hydrogen peroxide, the preparation method further comprises the following step 170.
In step 170, the blocking blocks on the light absorbing block are removed.
The blocking piece 41 on the light absorption block 31 is removed, so that the performance of the photoelectric detector can be prevented from being influenced by the existence of the blocking piece 41.
In one embodiment, the material of the blocking layer 41 is photoresist, and the blocking piece 41 can be removed by a wet etching process. In an exemplary embodiment, the etching solution used for removing the blocking piece 41 is acetone. The acetone solution can completely remove the shielding block 41, and the acetone does not react with the light absorption block 31 and damage the surface of the light absorption block 31. After the blocking pieces 41 on the light absorption layer 30 are removed by using the acetone solution, the acetone solution remained on the surface of the light absorption piece 31 may be washed by using deionized water and dried by using nitrogen.
In one embodiment, after the step 170 of removing the blocking blocks on the light absorption block, the preparation method further includes the following steps 180 to 200.
In step 180, a buffer layer is formed on the light absorbing layer.
The buffer layer 50 may include a plurality of block structures arranged in an array, and the plurality of block structures corresponds to the plurality of light absorption blocks one to one. The buffer layer 50 can protect the light absorption block 31, and prevent the surface of the light absorption block 31 from being damaged when other film layers are formed in the subsequent steps, so that defects are generated on the surface of the light absorption block 31. The buffer layer 50 may be a highly dense film layer, which provides better protection for the light absorbing block 31.
In one embodiment, the material of buffer layer 50 is cadmium sulfide. In other embodiments, the buffer layer 50 may be made of zinc sulfide.
In one embodiment, the buffer layer 50 may be prepared using a chemical water bath method. Compared with the scheme of forming the buffer layer 50 by adopting the magnetron sputtering method, the buffer layer 50 is prepared by adopting the chemical water bath method, so that the environment is protected, and the environmental pollution can be avoided.
In step 190, an n-type semiconductor layer is formed on the buffer layer.
The conductivity type of the light absorption block 31 is p-type, and the light absorption block 31 forms a PN junction with the n-type semiconductor layer 60.
The n-type semiconductor layer 60 may include a plurality of block structures arranged in an array, and the plurality of block structures correspond one-to-one to the plurality of light absorption blocks 31.
In one embodiment, the material of the n-type semiconductor layer 60 may be zinc oxide.
In one embodiment, the n-type semiconductor layer 60 may be formed using a magnetron sputtering method.
In one embodiment, the n-type semiconductor layer 60 has a thickness of 30nm to 100 nm. When the thickness of the n-type semiconductor layer 60 is within the range, the phenomenon that the film distribution of the n-type semiconductor layer 60 is uneven to influence the formation of a PN junction due to too small thickness of the n-type semiconductor layer 60 can be avoided; it is also avoided that the thickness of the n-type semiconductor layer 60 is too large to affect the carrier transmission efficiency and thus the sensitivity of the photodetector 100. The thickness of the n-type semiconductor layer 60 may be, for example, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, or 100 nm.
In step 200, a transparent second electrode layer is formed overlying the n-type semiconductor layer.
The second electrode layer 70 may include a plurality of block structures arranged in an array, and the plurality of block structures correspond to the plurality of light absorption blocks 31 one to one.
In one embodiment, the material of the second electrode layer 70 is a mixture of metallic aluminum and zinc oxide. Thus, the second electrode layer 70 has good conductivity, and the second electrode layer 70 has high light transmittance. In other embodiments, other transparent conductive materials, such as indium tin oxide, indium zinc oxide, etc., can be used for the second electrode layer 70.
In one embodiment, magnetron sputtering may be used to form the transparent second electrode layer 70.
In one embodiment, the thickness of the second electrode layer 70 is 200nm to 700 nm. The thickness of the second electrode layer 70 is within the range, so that the problem that the normal operation of the photoelectric detector is influenced due to the fact that the resistance of the second electrode layer 70 is large and a large enough electric field cannot be generated due to the fact that the thickness of the second electrode layer 70 is too small can be avoided; it can also be avoided that the thickness of the second electrode layer 70 is too large, which results in the light transmittance of the second electrode layer 70 being reduced, and further affects the light absorption effect of the photodetector.
When the photodetector 100 operates, one of the first electrode layer 20 and the second electrode layer 70 is connected to the positive pole of an applied voltage, and the other is connected to the negative pole of the applied voltage, so as to generate an electric field. Light is incident from the second electrode layer 70 of the photodetector 100, absorbed by the light absorbing block 31, and photo-generated carriers (electrons and holes) are generated, and the carriers are transported by the reverse electric field, so that the reverse current is increased. The greater the intensity of the light, the greater the reverse current.
After step 200, the preparation method may further include: and cutting the substrate to obtain a plurality of photodetectors. Each photodetector comprises a light absorbing block 31.
According to the preparation method of the photoelectric detector, the material of the light absorption layer is copper indium gallium selenide, so that the photoelectric detector can achieve a better photoelectric conversion effect, and the sensitivity of the photoelectric detector can be improved; after the light absorption layer is etched to obtain the light absorption block, the mixed solution of bromine water and liquid organic matters is used as etching liquid to etch the side wall of the light absorption block, so that impurities on the side wall of the light absorption block can be removed, the roughness of the side wall of the light absorption block is reduced, the dark current and the leakage current of the photoelectric detector are reduced, and the performance of the photoelectric detector is improved; impurities on the side wall of the light absorption block are removed by adopting a wet etching process, so that the requirements on equipment are low, the repeatability is good, and the large-scale production is easy; the mixed solution of bromine water and liquid organic matters is used as the etching liquid to etch the side wall of the light absorption block, so that no harmful substances are generated, and the method is environment-friendly.
It is noted that in the drawings, the sizes of layers and regions may be exaggerated for clarity of illustration. Also, it will be understood that when an element or layer is referred to as being "on" another element or layer, it can be directly on the other element or layer or intervening layers may also be present. In addition, it will be understood that when an element or layer is referred to as being "under" another element or layer, it can be directly under the other element or intervening layers or elements may also be present. In addition, it will also be understood that when a layer or element is referred to as being "between" two layers or elements, it can be the only layer between the two layers or elements, or more than one intermediate layer or element may also be present. Like reference numerals refer to like elements throughout.
Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.
It will be understood that the present application is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims (10)

1. A method of fabricating a photodetector, the method comprising:
providing a substrate;
forming a first electrode layer on the substrate;
forming a light absorption layer covering the first electrode layer on the first electrode layer, wherein the light absorption layer is made of copper indium gallium selenide;
etching the light absorption layer to penetrate the light absorption layer to obtain a plurality of light absorption blocks arranged in an array;
etching the side wall of the light absorption block by using a mixed solution of bromine water and liquid organic matters as an etching liquid so as to remove impurities on the side wall of the light absorption block; and a compound generated by the reaction of the impurities and the bromine water is dissolved in the liquid organic matter.
2. The method of claim 1, wherein the liquid organic substance comprises at least one of propylene glycol, glycerol, and butylene glycol.
3. The method for preparing the photoelectric detector according to claim 2, wherein in the mixed solution of bromine water and liquid organic matter, the volume fraction of the bromine water is 5-10%, and the mass fraction of bromine in the bromine water is 3%.
4. The method of claim 1, wherein the etching the light absorption layer comprises:
forming a shielding layer covering the light absorption layer on the light absorption layer, and carrying out patterning treatment on the shielding layer to obtain shielding blocks arranged in an array;
and etching the part of the light absorption layer which is not shielded by the shielding blocks by using etching liquid so as to pattern the light absorption layer and obtain a plurality of light absorption blocks which are arranged in an array.
5. The method for manufacturing a photodetector according to claim 4, wherein the etching the portion of the light absorption layer that is not covered by the blocking block with the etching solution comprises:
and etching the part of the light absorption layer which is not shielded by the shielding block by using bromine water as an etching liquid, wherein the mass fraction of a bromine substance in the bromine water is 0.5-10%.
6. The method according to claim 4, wherein the first electrode layer is made of a metal simple substance, and after the mixed solution of bromine water and liquid organic matter is used as an etching solution to etch the side wall of the light absorption block, the method further comprises:
and processing the first electrode layer by adopting an aqueous solution of hydrogen peroxide to obtain electrode blocks which correspond to the light absorption blocks one to one.
7. The method of claim 6, wherein the aqueous solution of hydrogen peroxide contains 20 to 50% by weight of hydrogen peroxide.
8. The method of manufacturing a photodetector according to claim 6, wherein after the treating the first electrode layer with the aqueous solution of hydrogen peroxide, the method further comprises:
and removing the blocking blocks on the light absorption blocks.
9. The method of claim 8, wherein the blocking layer is made of photoresist, and the etching solution for removing the blocking piece is acetone.
10. The method for manufacturing a photodetector according to any one of claims 1 to 9, wherein after the etching of the sidewall of the light absorbing block is performed by using a mixed solution of bromine water and a liquid organic substance as an etching solution, the method further comprises:
a buffer layer formed on the light absorbing layer;
forming an n-type semiconductor layer on the buffer layer;
and forming a transparent second electrode layer on the n-type semiconductor layer.
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