IBC structure gallium antimonide thermal photovoltaic cell and preparation method thereof

Abstract

The present invention relates to a preparation method of an IBC structure gallium antimonide thermophotovoltaic cell, belonging to the technical field of thermophotovoltaic cells. The preparation method of the present invention comprises the following steps: S1, cleaning and drying a P-type GaSb wafer; S2, texture etching on the front of the P-type GaSb wafer, and preparing a Si3N4 or Ta2O5 antireflection film; S3, preparing a SiO2 or TiO2 passivation layer after polishing the back of the P-type GaSb wafer, then defining an N+ type region, removing the passivation layer, and forming an N+ type diffusion layer by thermal diffusion of selenium; S4, supplementary deposition of a passivation layer on the back of the P-type GaSb wafer, then defining a P+ type region, removing the passivation layer, and forming a P+ type diffusion layer by thermal diffusion of zinc; S5, supplementary deposition of a passivation layer on the back of the P-type GaSb wafer again, then defining a negative electrode region and a positive electrode region, removing the passivation layer, and preparing a negative electrode and a positive electrode. The present invention combines an IBC structure with a GaSb thermophotovoltaic cell, and the preparation process is reliable and effective, which significantly improves the internal and external quantum efficiency and output power density of the GaSb thermophotovoltaic cell.

Description

Technical Field

[0001] The invention belongs to the technical field of near-infrared thermal photovoltaic cells and relates to an IBC structure gallium antimonide thermal photovoltaic cell and a preparation method thereof. Background Art

[0002] Thermophotovoltaic power generation is a technology that directly converts the energy of high-temperature thermal radiators into electrical energy through semiconductor PN junction cells. Compared with general solar photovoltaic cells, thermophotovoltaic cells are not affected by day and night, seasons or weather because they can use heat sources. They have simple structures, are not prone to failure, and have high theoretical efficiency. They can obtain more power per unit area and have higher efficiency. Thermophotovoltaic power generation systems can be used in many aspects. For example, thermophotovoltaic devices with special structures can be used to design them into photoelectric components in infrared detectors, night vision devices, and infrared digital cameras. Thermophotovoltaic cells have stable performance, are noiseless, and are easy to carry, making them suitable for use in various occasions.

[0003] As early as the 1960s, researchers at MIT gave the complete principles and concepts of thermophotovoltaic systems, but due to the technical conditions at the time, it was always in the theoretical research stage. It was not until the 1990s that low-bandgap gallium antimonide (GaSb) cells were developed, and some advantages of thermophotovoltaic systems were initially verified. The bandgap width of gallium antimonide is 0.72eV, which enables it to absorb radiation in near-infrared wavelengths and has a large power output. GaSb thermophotovoltaic cells made of gallium antimonide wafers can use PN junctions to produce photovoltaic effects under the irradiation of near-infrared light, and can directly convert near-infrared radiation generated by fuel combustion into electrical energy; when the heat source temperature is 1200°C, the maximum output power per unit area of ​​the battery can reach 1.5~2W / cm 2 The conversion system using gallium antimonide batteries as the original power output element is also quiet and portable, and has good development prospects in various fields.

[0004] Since the actual system is limited by the PN junction theory of thermal photovoltaic cells, the calculated expected efficiency can only reach 20%~30%, so improving efficiency is an important issue faced by the research of thermal photovoltaic systems. Currently, research work on thermal photovoltaic systems mainly focuses on the optimal design of individual components.

[0005] The IBC (interdigitated back contact) cell was proposed by Schwartz and Lammert in 1975. This cell structure is a special structure in which both the emitter and base regions are on the back of the cell. This structure has a relatively excellent output in ordinary solar photovoltaics. Summary of the invention

[0006] The purpose of the present invention is to address the technical problem of low output efficiency of existing GaSb thermal photovoltaic cells, and propose an IBC structure GaSb thermal photovoltaic cell, which combines the IBC structure with a GaSb thermal photovoltaic cell to significantly improve the internal and external quantum efficiency and output power density of the GaSb thermal photovoltaic cell.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A gallium antimonide thermophotovoltaic cell with an IBC structure, characterized in that the gallium antimonide thermophotovoltaic cell with an IBC structure comprises a P-type GaSb substrate and positive and negative electrodes in contact with the back side of the P-type GaSb substrate, the front side of the P-type GaSb substrate has a suede structure and is covered with a Si3N4 anti-reflection film, and the back side of the P-type GaSb substrate is formed with a P+ type diffusion layer and an N+ type diffusion layer by thermal diffusion.

[0009] Preferably, the thickness of the P-type GaSb substrate is 15 μm to 20 μm.

[0010] Preferably, a passivation layer is provided between the P-type GaSb substrate and the positive and negative electrodes, and the positive and negative electrodes penetrate the passivation layer and contact the P+ type diffusion layer and the N+ type diffusion layer on the back of the P-type GaSb substrate.

[0011] Preferably, the anti-reflection film is a Si3N4 film or a Ta2O5 film with a thickness of 0.17 μm to 0.20 μm.

[0012] Preferably, the thickness of the P+ type diffusion layer is 0.07 μm to 0.14 μm, and the thickness of the N+ type diffusion layer is 0.1 μm to 0.2 μm.

[0013] Preferably, the passivation layer is a SiO2 layer or a TiO2 layer with a thickness of 0.08 μm to 0.15 μm.

[0014] Preferably, the P+ type diffusion layer and the N+ type diffusion layer are in contact with each other in an interdigitated arrangement.

[0015] Another object of the present invention is to provide a reliable and effective method for preparing an IBC structure gallium antimonide thermophotovoltaic cell, the preparation method comprising the following steps:

[0016] S1, cleaning and drying the undoped P-type GaSb wafer;

[0017] S2, performing texture etching on the front side of the cleaned and dried P-type GaSb wafer, and then preparing an anti-reflection film on the front side of the P-type GaSb wafer, wherein the anti-reflection film is made of Si3N4 or Ta2O5;

[0018] S3, polishing the back side of the cleaned and dried P-type GaSb wafer, and then preparing a passivation layer, and then defining an N+ type area to be diffused, removing the passivation layer in this area, and forming an N+ type diffusion layer in the N+ type area by thermally diffusing selenium, wherein the material of the passivation layer is SiO2 or TiO2;

[0019] S4, depositing a passivation layer on the back of the P-type GaSb wafer, so that the N+ type region where the N+ type diffusion layer is located has a passivation layer flush with other regions, and then defining the P+ type region to be diffused, removing the passivation layer in this region, and forming a P+ type diffusion layer by thermally diffusing zinc;

[0020] S5. A passivation layer is deposited again on the back of the P-type GaSb wafer so that the P+ type region where the P+ type diffusion layer is located has a passivation layer flush with other regions, and then a negative electrode region and a positive electrode region are defined in the N+ type region and the P+ type region respectively, and the passivation layers of the negative electrode region and the positive electrode region are removed to form a negative electrode and a positive electrode in the negative electrode region and the positive electrode region.

[0021] Preferably, the thickness of the P-type GaSb wafer in step S1 is 15 μm to 20 μm, and the carrier concentration is 3×10 18 cm -3 ~5×10 18 cm -3 .

[0022] Preferably, the cleaning and drying method in step S1 is to clean and degrease the P-type GaSb wafer with hot xylene, acetone and methanol in sequence, then clean the P-type GaSb wafer with 8wt%~13wt% hot dilute hydrochloric acid for 40s~80s, and then dry it.

[0023] Preferably, the texture etching in step S2 is performed using an etching solution, which is a mixture of a sulfuric acid solution and a hydrogen peroxide solution in a volume ratio of (1.3-2.5):1, the mass fraction of the sulfuric acid solution is 60%-70%, and the mass fraction of the hydrogen peroxide solution is 2%-5%.

[0024] Preferably, the anti-reflection film in step S2 is prepared by PECVD deposition method and has a thickness of 0.17 μm to 0.20 μm.

[0025] Preferably, the passivation layer in steps S3, S4 and S5 is prepared by plasma chemical vapor deposition and has a thickness of 0.08 μm to 0.15 μm.

[0026] Preferably, the method for removing the SiO2 passivation layer in steps S3, S4 and S5 is to remove it by immersion in a corrosive solution, wherein the corrosive solution is a mixture of hydrofluoric acid, ammonium fluoride and deionized water, wherein the ratio of hydrofluoric acid, ammonium fluoride and deionized water is (4~6) ml: (5~7) g: 10 ml.

[0027] Preferably, the N+ type region, P+ type region, negative electrode region and positive electrode region in steps S3, S4 and S5 are defined by photolithography.

[0028] Preferably, the polishing in step S4 is performed using a 16wt% to 25wt% NaOCl solution at a temperature of 15°C to 30°C, and the polishing reaction time is 10min to 20min.

[0029] Preferably, the thermally diffused selenium in step S4 is placed in a quartz tube of a diffusion furnace with pure Se as the diffusion source, and heated and diffused at a heating temperature of 500°C to 550°C for 4h to 6h. The diffusion depth of the N+ type diffusion layer is 0.1μm to 0.2μm, and the doping concentration is 3×10 18 cm -3 ~5×10 18 cm -3 The thermal diffusion zinc in step S5 is placed in a quartz tube of a diffusion furnace with pure Zn as the diffusion source, and heated and diffused at a heating temperature of 450°C to 550°C for 1.5h to 2.5h. The diffusion depth of the P+ type diffusion layer is 0.07μm to 0.14μm, and the doping concentration is 1×10 19 cm -3 ~3×10 19 cm -3 And it is gradient doping.

[0030] Preferably, the negative electrode and the positive electrode in step S5 are formed by vacuum evaporation, the negative electrode is Ti50nm / Pt50nm / Ag250nm, and the positive electrode is Pt50nm / Ag250nm.

[0031] The N+ type region, P+ type region, negative electrode region and positive electrode region in steps S3, S4 and S5 of the present invention refer to the positions corresponding to the N+ type diffusion layer, P+ type diffusion layer, negative electrode and positive electrode on the back side of the P-type GaSb wafer. The N+ type diffusion layer and the P+ type diffusion layer adopt the contact form of interdigitated back.

[0032] For GaSb thermophotovoltaic cells, a good structure can bring higher output efficiency. The emitter region and base region of the IBC cell structure are both on the back of the cell. It has relatively excellent output when applied to ordinary solar photovoltaics, but it has not been applied to thermophotovoltaic cells. The present invention combines the IBC cell structure with the GaSb thermophotovoltaic cell, and optimizes its preparation method and specific cell hierarchy, as well as the materials of each cell structure, including anti-reflection film, suede structure, doping on the back of the cell, preparation method of positive and negative electrodes and their materials, so that the prepared IBC structure gallium antimonide thermophotovoltaic cell has excellent internal and external quantum efficiency and output power density.

[0033] The present invention forms a velvet structure on the front of a P-type GaSb wafer by texture etching, and can provide the GaSb wafer with a good anti-reflection effect by cooperating with a Si3N4 or Ta2O5 anti-reflection film, and increase the light absorption rate on the front surface. The present invention controls the thickness of the anti-reflection film between 0.13 μm and 0.26 μm. The anti-reflection film in this thickness range has a good anti-reflection effect on the GaSb wafer, and increases the light absorption rate on the front surface. Too thick or too thin film cannot achieve the ideal anti-reflection effect; SiO2 or TiO2 passivation layer can reduce the surface recombination rate, improve the minority carrier lifetime and the internal quantum efficiency of the battery; polishing before preparing the passivation layer can remove the damaged layer caused by slicing and grinding, thereby improving the bonding tightness between the passivation layer and the GaSb wafer and the quality of the passivation layer itself. The present invention controls the diffusion conditions so that the N+ type diffusion layer and the P+ type diffusion layer have a specific diffusion depth and diffusion gradient, so that the prepared IBC structure gallium antimonide thermal photovoltaic cell has a higher quantum efficiency and battery output power.

[0034] Compared with the prior art, the present invention has the following beneficial effects: the IBC structure gallium antimonide thermophotovoltaic cell prepared by the method of the present invention has high quantum efficiency, can absorb solar radiation in the wavelength range of 0.3μm~2μm, and can also be used as a thermophotovoltaic device with a conversion heat source temperature of 1000℃~3000℃. Compared with IBC cells made of general Si materials, the IBC structure cell of GaSb is thinner and has low material cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of the IBC structure gallium antimonide thermophotovoltaic cell prepared by the present invention.

[0036] Figure 2 It is a diagram of the internal and external quantum efficiency of the IBC structure gallium antimonide thermophotovoltaic cell prepared by the present invention.

[0037] Figure 3 It is a preparation flow chart of the IBC structure gallium antimonide thermal photovoltaic cell of the present invention.

[0038] Figure 4The external quantum efficiency of the IBC structure gallium antimonide thermophotovoltaic cell prepared by the present invention is compared with the GaSb cell produced by JX Crystals Company of the United States. DETAILED DESCRIPTION

[0039] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments. Example

[0040] like Figure 1 As shown, the IBC structure GaSb thermophotovoltaic cell of this embodiment includes Si3N4 anti-reflection film 1, P-type GaSb substrate 2, diffusion layer, SiO2 passivation layer 4 and positive and negative electrodes 6 from top to bottom, and the diffusion layer includes P+ type diffusion layer 3 and N+ type diffusion layer 5. Among them, the thickness of P-type GaSb substrate 2 is 17μm, and its front side has a velvet structure and is covered with a layer of Si3N4 anti-reflection film 1 with a thickness of 0.19μm; the P+ type diffusion layer 3 and the N+ type diffusion layer 5 are formed on the back of the P-type GaSb substrate 2 by thermal diffusion, forming a part of the P-type GaSb substrate 2, and the two are in contact in the form of a cross-finger back arrangement, the thickness of the P+ type diffusion layer 3, that is, the diffusion depth, is 0.1μm, and the concentration is 2×10 19 cm -3 The thickness of the N+ type diffusion layer 5, i.e. the diffusion depth, is 0.16 μm, and the doping concentration is 4×10 18 cm -3 And it is gradient doping; the SiO2 passivation layer 4 is located between the P-type GaSb substrate 2 and the positive and negative electrodes 6, and the thickness is 0.11μm; the positive and negative electrodes 6 penetrate the SiO2 passivation layer 4 and contact the diffusion layer on the back of the P-type GaSb substrate 2, the P+ type diffusion layer 3 corresponds to the positive electrode in the positive and negative electrodes 6, and the N+ type diffusion layer 5 corresponds to the negative electrode in the positive and negative electrodes 6.

[0041] like Figure 3 As shown, the preparation method of the IBC structure gallium antimonide thermophotovoltaic cell in this embodiment includes the following steps:

[0042] (1) The undoped P-type GaSb wafer was cleaned and degreased with xylene, acetone and methanol, and then cleaned with 11wt% dilute hydrochloric acid for 60s and then dried. The thickness of the P-type GaSb wafer was 17μm and the carrier concentration was 4×10 18 cm -3 ;

[0043] (2) Texture etching is performed on the front side of the cleaned and dried P-type GaSb wafer. The etching solution used for texture etching is a mixture of sulfuric acid solution and hydrogen peroxide solution in a volume ratio of 2:1, the mass fraction of sulfuric acid solution is 65%, and the mass fraction of hydrogen peroxide solution is 3%. Then, a Si3N4 anti-reflection film 1 with a thickness of 0.19 μm is deposited on the front side by a PECVD deposition method;

[0044] (3) The back side of the cleaned and dried P-type GaSb wafer was polished by using a 20wt% NaOCl solution at 23°C for 15 min. After polishing, a SiO2 passivation layer 4 with a thickness of 0.11 μm was prepared on the back side of the P-type GaSb wafer by using a plasma chemical vapor deposition method. Then, a photolithography process was used to define the N+ type area to be diffused. The SiO2 passivation layer 4 in this area was removed. Then, pure Se was used as the diffusion source in the quartz tube of the diffusion furnace and heated for diffusion at a heating temperature of 530°C for 4.0 h. A diffusion depth of 0.16 μm and a doping concentration of 4×10 18 cm -3 And it is a gradient doped N+ type diffusion layer 5;

[0045] (4) Then, a SiO2 passivation layer 4 is deposited on the back of the P-type GaSb wafer, so that the N+ type region where the N+ type diffusion layer 5 is located has a SiO2 passivation layer 4 flush with other regions. Then, a photolithography process is used to define the P+ type region to be diffused. The SiO2 passivation layer 4 in this region is removed, and pure Zn is placed in a quartz tube of a diffusion furnace as a diffusion source. It is heated at a heating temperature of 500°C for 2.0 h to form a diffusion depth of 0.1 μm and a doping concentration of 2×10 19 cm -3 The P+ type diffusion layer 3 is gradient doped; the P-type GaSb wafer with the diffusion layer formed by thermal diffusion is the P-type GaSb substrate 2 of the battery structure;

[0046] (5) A SiO2 passivation layer 4 is deposited again on the back of the P-type GaSb wafer so that the P+ type region where the P+ type diffusion layer 3 is located has a SiO2 passivation layer 4 flush with other regions. Then, a negative electrode region and a positive electrode region are defined in the N+ type region and the P+ type region by photolithography, respectively. The SiO2 passivation layer 4 in the negative electrode region and the positive electrode region are removed, and a negative electrode and a positive electrode are formed in the negative electrode region and the positive electrode region by vacuum evaporation. The negative electrode material is Ti50nm / Pt50nm / Ag250nm, and the positive electrode material is Pt50nm / Ag250nm.

[0047] The method for removing the SiO2 passivation layer 4 in steps (3), (4) and (5) is to remove it by immersion in a corrosive solution, wherein the corrosive solution is a mixture of hydrofluoric acid, ammonium fluoride and deionized water, wherein the ratio of hydrofluoric acid, ammonium fluoride and deionized water is 3ml:6g:10ml. Example

[0048] like Figure 1 As shown, the IBC structure GaSb thermophotovoltaic cell of this embodiment includes Si3N4 antireflection film 1, P-type GaSb substrate 2, diffusion layer, SiO2 passivation layer 4 and positive and negative electrodes 6 from top to bottom, and the diffusion layer includes P+ type diffusion layer 3 and N+ type diffusion layer 5. Among them, the thickness of P-type GaSb substrate 2 is 15μm, and its front side has a velvet structure and is covered with a layer of Si3N4 antireflection film 1 with a thickness of 0.17μm; P+ type diffusion layer 3 and N+ type diffusion layer 5 are formed on the back of P-type GaSb substrate 2 by thermal diffusion, forming a part of P-type GaSb substrate 2, and the two are in contact in the form of interdigitated back arrangement, the thickness of P+ type diffusion layer 3, i.e., diffusion depth, is 0.11μm, and the doping concentration is 1.2×10 19 cm -3 The thickness of the N+ type diffusion layer 5, i.e. the diffusion depth, is 0.2 μm, and the doping concentration is 3×10 18 cm -3 And it is gradient doping; the SiO2 passivation layer 4 is located between the P-type GaSb substrate 2 and the positive and negative electrodes 6, and the thickness is 0.13μm; the positive and negative electrodes penetrate the SiO2 passivation layer 4 and contact the diffusion layer on the back of the P-type GaSb substrate 2, the P+ type diffusion layer 3 corresponds to the positive electrode in the positive and negative electrodes 6, and the N+ type diffusion layer 5 corresponds to the negative electrode in the positive and negative electrodes 6.

[0049] like Figure 3 As shown, the preparation method of the IBC structure gallium antimonide thermophotovoltaic cell in this embodiment includes the following steps:

[0050] (1) The undoped P-type GaSb wafer was cleaned and degreased with xylene, acetone and methanol successively. The P-type GaSb wafer was then cleaned with 9wt% dilute hydrochloric acid for 80s and then dried. The thickness of the P-type GaSb wafer was 15μm and the carrier concentration was 5×10 18 cm -3 ;

[0051] (2) Texture etching is performed on the front side of the cleaned and dried P-type GaSb wafer. The etching solution used for texture etching is a mixture of sulfuric acid solution and hydrogen peroxide solution with a volume ratio of 1.5:1, the mass fraction of sulfuric acid solution is 60%, and the mass fraction of hydrogen peroxide solution is 3%. Then, a Si3N4 anti-reflection film 1 with a thickness of 0.17 μm is deposited on the front side by a PECVD deposition method;

[0052] (3) The back side of the cleaned and dried P-type GaSb wafer was polished by using 18wt% NaOCl solution at 30°C for 13 min. After polishing, a SiO2 passivation layer 4 with a thickness of 0.13 μm was prepared on the back side of the P-type GaSb wafer by plasma chemical vapor deposition. Then, a photolithography process was used to define the N+ type area to be diffused. The SiO2 passivation layer 4 in this area was removed. Then, pure Se was used as the diffusion source in the quartz tube of the diffusion furnace. The diffusion was heated at 500°C for 6 h, forming a diffusion depth of 0.2 μm and a doping concentration of 3×10 18 cm -3 And it is a gradient doped N+ type diffusion layer 5;

[0053] (4) Then, a SiO2 passivation layer 4 is deposited on the back of the P-type GaSb wafer, so that the N+ type region where the N+ type diffusion layer 5 is located has a SiO2 passivation layer 4 flush with other regions. Then, a photolithography process is used to define the P+ type region to be diffused. The SiO2 passivation layer 4 in this region is removed, and pure Zn is placed in a quartz tube of a diffusion furnace as a diffusion source. It is heated at a heating temperature of 450°C for 2.5 hours to form a diffusion depth of 0.11 μm and a doping concentration of 1.2×10 19 cm -3 The P+ type diffusion layer 3 is gradient doped; the P-type GaSb wafer with the diffusion layer formed by thermal diffusion is the P-type GaSb substrate 2 of the battery structure;

[0054] (5) A SiO2 passivation layer 4 is deposited again on the back of the P-type GaSb wafer so that the P+ type region where the P+ type diffusion layer 3 is located has a SiO2 passivation layer 4 flush with other regions. Then, a negative electrode region and a positive electrode region are defined in the N+ type region and the P+ type region by photolithography, respectively. The SiO2 passivation layer 4 in the negative electrode region and the positive electrode region are removed, and a negative electrode and a positive electrode are formed in the negative electrode region and the positive electrode region by vacuum evaporation. The negative electrode material is Ti50nm / Pt50nm / Ag250nm, and the positive electrode material is Pt50nm / Ag250nm.

[0055] The method for removing the SiO2 passivation layer 4 in steps (3), (4) and (5) is to remove it by immersion in a corrosive solution, wherein the corrosive solution is a mixture of hydrofluoric acid, ammonium fluoride and deionized water, wherein the ratio of hydrofluoric acid, ammonium fluoride and deionized water is 3ml:6g:10ml. Example

[0056] like Figure 1As shown, the IBC structure GaSb thermophotovoltaic cell of this embodiment includes Ta2O5 anti-reflection film 1, P-type GaSb substrate 2, diffusion layer, TiO2 passivation layer 4 and positive and negative electrodes 6 from top to bottom, and the diffusion layer includes P+ type diffusion layer 3 and N+ type diffusion layer 5. Among them, the thickness of P-type GaSb substrate 2 is 20μm, and its front side has a velvet structure and is covered with a layer of Ta2O5 anti-reflection film 1 with a thickness of 0.20μm; P+ type diffusion layer 3 and N+ type diffusion layer 5 are formed on the back of P-type GaSb substrate 2 by thermal diffusion, forming a part of P-type GaSb substrate 2, and the two are in contact in the form of a cross-finger back arrangement, the thickness of P+ type diffusion layer 3, i.e., the diffusion depth, is 0.09μm, and the doping concentration is 3×10 19 cm -3 The thickness of the N+ type diffusion layer 5, i.e. the diffusion depth, is 0.13 μm, and the doping concentration is 5×10 18 cm -3 And it is gradient doping; the TiO2 passivation layer 4 is located between the P-type GaSb substrate 2 and the positive and negative electrodes 6, with a thickness of 0.10μm; the positive and negative electrodes penetrate the TiO2 passivation layer 4 and contact the diffusion layer on the back of the P-type GaSb substrate 2, the P+ type diffusion layer 3 corresponds to the positive electrode in the positive and negative electrodes 6, and the N+ type diffusion layer 5 corresponds to the negative electrode in the positive and negative electrodes 6.

[0057] like Figure 3 As shown, the preparation method of the IBC structure gallium antimonide thermophotovoltaic cell in this embodiment includes the following steps:

[0058] (1) The undoped P-type GaSb wafer was cleaned and degreased with xylene, acetone and methanol, and then cleaned with 13wt% dilute hydrochloric acid for 40s and then dried. The thickness of the P-type GaSb wafer was 20μm and the carrier concentration was 3×10 18 cm -3 ;

[0059] (2) Texture etching is performed on the front side of the cleaned and dried P-type GaSb wafer. The etching solution used for texture etching is a mixture of sulfuric acid solution and hydrogen peroxide solution with a volume ratio of 1.2:1, the mass fraction of sulfuric acid solution is 70%, and the mass fraction of hydrogen peroxide solution is 4%. Then, a Ta2O5 anti-reflection film 1 with a thickness of 0.20 μm is deposited on the front side by a PECVD deposition method;

[0060] (3) The back side of the cleaned and dried P-type GaSb wafer was polished by using a 21wt% NaOCl solution at 18°C ​​for 20 min. After polishing, a TiO2 passivation layer 4 with a thickness of 0.10 μm was prepared on the back side of the P-type GaSb wafer by using a plasma chemical vapor deposition method. Then, a photolithography process was used to define the N+ type area to be diffused. The TiO2 passivation layer 4 in this area was removed. Then, pure Se was used as the diffusion source in a quartz tube of a diffusion furnace. The diffusion was heated at 550°C for 4 h, forming a diffusion depth of 0.13 μm and a doping concentration of 5×10 18 cm -3 And it is a gradient doped N+ type diffusion layer 5;

[0061] (4) A TiO2 passivation layer 4 is then deposited on the back of the P-type GaSb wafer so that the N+ type region where the N+ type diffusion layer 5 is located has a TiO2 passivation layer 4 flush with other regions. Then, a photolithography process is used to define the P+ type region to be diffused. The TiO2 passivation layer 4 in this region is removed, and pure Zn is placed in a quartz tube of a diffusion furnace as a diffusion source. The wafer is heated at 550°C for 1.5 hours to form a diffusion depth of 0.09 μm and a doping concentration of 3×10 19 cm -3 The P+ type diffusion layer 3 is gradient doped; the P-type GaSb wafer with the diffusion layer formed by thermal diffusion is the P-type GaSb substrate 2 of the battery structure;

[0062] (5) A TiO2 passivation layer 4 is deposited on the back of the P-type GaSb wafer again, so that the P+ type region where the P+ type diffusion layer 3 is located has a TiO2 passivation layer 4 flush with other regions, and then a negative electrode region and a positive electrode region are defined in the N+ type region and the P+ type region by photolithography, and the TiO2 passivation layer 4 in the negative electrode region and the positive electrode region are removed. A negative electrode and a positive electrode are formed in the negative electrode region and the positive electrode region by vacuum evaporation, and the negative electrode material is Ti50nm / Pt50nm / Ag250nm, and the positive electrode material is Pt50nm / Ag250nm.

[0063] The method for removing the TiO2 passivation layer in steps (3), (4) and (5) is to remove it by immersion in a corrosive solution, wherein the corrosive solution is a mixture of hydrofluoric acid, ammonium fluoride and deionized water, wherein the ratio of hydrofluoric acid, ammonium fluoride and deionized water is 6ml:5g:10ml.

[0064] The N+ type region, P+ type region, negative electrode region and positive electrode region in steps (3), (4) and (5) of the above embodiment refer to the positions corresponding to the N+ type diffusion layer 5, the P+ type diffusion layer 3, the negative electrode and the positive electrode on the back side of the P-type GaSb wafer.

[0065] like Figure 2 As shown, the IBC structure GaSb thermophotovoltaic cell prepared in this embodiment has higher internal and external quantum efficiency and greater output power density.

[0066] Comparative Example 1

[0067] Commercially available ordinary PN junction GaSb battery produced by JX Crystals of the United States.

[0068] like Figure 4 As shown, by comparing the IBC structure GaSb thermal photovoltaic cell prepared in Example 1 of the present invention and the GaSb cell produced by JX Crystals of the United States, it can be known that the IBC structure GaSb thermal photovoltaic cell prepared by the present invention has an external quantum efficiency that is better than that of the GaSb cell of JX Crystals of the United States as a whole, and is specifically manifested in that it has an external quantum efficiency that is better than that of the GaSb cell of JX Crystals of the United States in most wavelength bands of 0~2000nm.

[0069] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. An IBC structure gallium antimonide thermophotovoltaic cell, characterized in that: The IBC structure gallium antimonide thermal photovoltaic cell includes a P-type GaSb substrate and positive and negative electrodes in contact with the back side of the P-type GaSb substrate. The front side of the P-type GaSb substrate has a suede structure and is covered with an anti-reflection film. The back side of the P-type GaSb substrate is formed with a P+ type diffusion layer and an N+ type diffusion layer by thermal diffusion. The thickness of the P-type GaSb substrate is 15 μm to 20 μm, the thickness of the anti-reflection film is 0.17 μm to 0.20 μm, the thickness of the P+ type diffusion layer is 0.07 μm to 0.14 μm, and the thickness of the N+ type diffusion layer is 0.1 μm to 0.2 μm.

2. The IBC structured GaSb thermophotovoltaic cell according to claim 1, characterized in that: A SiO2 passivation layer is arranged between the P-type GaSb substrate and the positive and negative electrodes. The positive and negative electrodes penetrate the SiO2 passivation layer and contact the P+ type diffusion layer and the N+ type diffusion layer on the back of the P-type GaSb substrate.

3. A method for preparing an IBC structure gallium antimonide thermophotovoltaic cell according to any one of claims 1 to 2, characterized in that: The preparation method comprises the following steps: S1, cleaning and drying the undoped P-type GaSb wafer; S2, performing texture etching on the front side of the cleaned and dried P-type GaSb wafer, and then preparing an anti-reflection film on the front side of the P-type GaSb wafer, wherein the anti-reflection film is made of Si3N4 or Ta2O5; S3, polishing the back side of the cleaned and dried P-type GaSb wafer, and then preparing a passivation layer, and then defining an N+ type area to be diffused, removing the passivation layer in this area, and forming an N+ type diffusion layer in the N+ type area by thermally diffusing selenium, wherein the material of the passivation layer is SiO2 or TiO2; S4, depositing a passivation layer on the back of the P-type GaSb wafer, so that the N+ type region where the N+ type diffusion layer is located has a passivation layer flush with other regions, and then defining the P+ type region to be diffused, removing the passivation layer in this region, and forming a P+ type diffusion layer by thermally diffusing zinc; S5. A passivation layer is deposited again on the back of the P-type GaSb wafer so that the P+ type region where the P+ type diffusion layer is located has a passivation layer flush with other regions, and then a negative electrode region and a positive electrode region are defined in the N+ type region and the P+ type region respectively, and the passivation layers of the negative electrode region and the positive electrode region are removed to form a negative electrode and a positive electrode in the negative electrode region and the positive electrode region.

4. The method for preparing the IBC structure gallium antimonide thermophotovoltaic cell according to claim 3, characterized in that: The thickness of the P-type GaSb wafer in step S1 is 15 μm to 20 μm, and the carrier concentration is 3×10 18 cm -3 ~5×10 18 cm -3 .

5. The method for preparing the IBC structure gallium antimonide thermophotovoltaic cell according to claim 3, characterized in that: The anti-reflection film in step S2 is prepared by PECVD deposition method, and has a thickness of 0.17 μm to 0.20 μm.

6. The method for preparing the IBC structure gallium antimonide thermophotovoltaic cell according to claim 3, characterized in that: The passivation layer in steps S3, S4 and S5 is prepared by plasma chemical vapor deposition and has a thickness of 0.08 μm to 0.15 μm.

7. The method for preparing the IBC structure gallium antimonide thermophotovoltaic cell according to claim 3, characterized in that: The thermal diffusion of selenium in step S4 is to place pure Se as the diffusion source in a quartz tube of a diffusion furnace, and heat and diffuse it at a heating temperature of 500°C to 550°C for 4h to 6h. The diffusion depth of the N+ type diffusion layer is 0.1μm to 0.2μm, and the doping concentration is 3×10 18 cm -3 ~5×10 18 cm -3 The thermally diffused zinc in step S5 is placed in a quartz tube of a diffusion furnace with pure Zn as the diffusion source, and heated and diffused at a heating temperature of 450°C to 550°C for 1.5h to 2.5h. The diffusion depth of the P+ type diffusion layer is 0.07μm to 0.14μm, and the doping concentration is 1×10 19 cm -3 ~3×10 19 cm -3 .

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