Low-cost metal substrate thin film gallium arsenide solar cell and preparation method thereof

Abstract

The invention relates to a low-cost metal substrate thin film gallium arsenide solar cell and a preparation method thereof. The solar cell sequentially comprises an antireflection film and an upper metal electrode from top to bottom, the gallium arsenide epitaxial layer grows in an inverted mode; evaporating a metal titanium layer; evaporating a metal chromium layer; evaporating a metal nickel layer; and electroplating a metal nickel or nickel alloy layer. The preparation method comprises the steps of flip epitaxial growth, stress balance metal transition layer evaporation, metal substrate electroplating, temporary substrate bonding, original GaAs substrate removal and thin film solar cell device technology. The metal substrate thin film gallium arsenide solar cell prepared by the invention adopts cheap titanium, chromium, nickel and other metal materials and an electroplating method, and has the advantages of stress matching, low cost, light weight and the like compared with the existing thin film gallium arsenide solar cell.

Description

Low-cost thin-film gallium arsenide solar cells on metal substrates and their fabrication methods Technical Field

[0001] This invention relates to the field of solar cells, specifically to a low-cost metal substrate thin-film gallium arsenide solar cell and its preparation method. Background Technology

[0002] Gallium arsenide (GaAs) solar cells, as representatives of III-V compound semiconductor devices, have high conversion efficiency and stability due to their direct bandgap, high absorption coefficient and excellent radiation resistance. Therefore, they are widely used in space, near space, special equipment and defense fields.

[0003] In recent years, to further improve the power-to-weight ratio of thin-film gallium arsenide (GaAs) and expand its application range, some researchers have replaced the GaAs substrates originally used for epitaxial growth of the GaAs light-absorbing layer with polyimide substrates and metal thin-film substrates using substrate transfer processes. Patent CN206003783U discloses a germanium-based GaAs multi-junction flexible thin-film solar cell. After growing a light-absorbing layer on a germanium substrate, the P-type germanium substrate is thinned using mechanical and chemical solutions. Then, the epitaxially grown GaInP / InGaAs / Ge cell is bonded to a flexible polyimide substrate using a metal bonding process to form a flexible thin-film solar cell, thereby reducing the cell weight and making it bendable. However, this method requires additional substrate thinning and polyimide substrate bonding processes, and the bonding process requires a large amount of precious metal materials, increasing the manufacturing cost of the thin-film GaAs solar cell.

[0004] To reduce the fabrication cost of thin-film gallium arsenide (GaAs) solar cells, patent CN202411888558.8 discloses a space-use reverse quadruple junction thin-film GaAs solar cell and its fabrication method. This method involves first depositing an Au-Zn-Au-Ag seed layer on the surface of a flip-chip grown epitaxial layer, followed by electroplating a Cu / Ni composite metal substrate. Compared to the metal evaporation and bonding process, the electroplating process reduces fabrication costs. However, the cost of the 1000-1500nm noble metal seed layer remains high, and compared to GaAs (5.8×10⁻⁶), the cost is still relatively high. -6 The coefficient of thermal expansion of Cu (at 15.8 × 10⁻⁶ °C) is given by the following formula: -6 / ℃)\Ag(19×10 -6 / ℃)\Ni (13.4×10 -6 The coefficient of thermal expansion (°C) is still relatively high, which means that the prepared thin-film gallium arsenide solar cells cannot be adapted to a wide temperature range.

[0005] Patent CN201510291455 discloses a high-efficiency flexible gallium arsenide solar cell and its fabrication method. It uses a copper-molybdenum-copper three-layer composite metal as the substrate metal material for the thin-film gallium arsenide solar cell. Due to the low coefficient of thermal expansion of molybdenum, the overall coefficient of thermal expansion of the composite metal substrate material is reduced to (6~7)×10⁻⁶. -6 / ℃, which is similar to GaAs material, but the composite metal substrate material is too thick (70~110 micrometers) to be obtained by electroplating process, and this results in a high surface density of thin-film gallium arsenide solar cells. Summary of the Invention

[0006] The purpose of this invention is to provide a low-cost metal substrate thin-film gallium arsenide solar cell and its preparation method. By rationally designing the multilayer metal substrate of the solar cell, the cost of the thin-film gallium arsenide solar cell can be reduced.

[0007] To achieve the above objectives, the present invention provides a low-cost metal substrate thin-film gallium arsenide solar cell, which, from top to bottom, comprises: an anti-reflection film and an upper metal electrode; a flip-chip grown gallium arsenide epitaxial layer; a vapor-deposited titanium layer; a vapor-deposited chromium layer; a vapor-deposited nickel layer; and an electroplated nickel or nickel alloy layer.

[0008] In the aforementioned low-cost metal substrate thin-film gallium arsenide solar cell, the thickness of the vapor-deposited titanium layer is 20nm~200nm; the thickness of the vapor-deposited chromium layer is 20nm~200nm; the thickness of the vapor-deposited nickel layer is 50nm~300nm; and the thickness of the electroplated nickel or nickel alloy layer is 15μm~30μm.

[0009] In the aforementioned low-cost metal substrate thin-film gallium arsenide solar cell, the flip-grown gallium arsenide epitaxial layer is a flip-chip single-junction, flip-chip double-junction, or flip-chip triple-junction epitaxial structure.

[0010] The aforementioned low-cost metal substrate thin-film gallium arsenide solar cell uses a group III-V semiconductor substrate instead of a GaAs substrate.

[0011] The present invention also provides a method for fabricating the above-mentioned low-cost metal substrate thin-film gallium arsenide solar cell, comprising: 1) growing a GaAs epitaxial layer on a GaAs substrate by flip-chip growth using a metal-organic chemical vapor deposition method; 2) sequentially depositing a titanium layer, a chromium layer, and a nickel layer on the flip-chip grown GaAs epitaxial layer using a vacuum evaporation process; 3) electroplating a nickel or nickel alloy layer on the chromium layer; 4) attaching a temporary bonding material to one side of the nickel or nickel alloy layer and temporarily bonding the temporary bonding material to a temporary rigid substrate using a vacuum bonding device; 5) removing the GaAs substrate used to grow the flip-chip epitaxial layer by mechanical grinding or chemical etching; and 6) fabricating the thin-film solar cell device.

[0012] The above-mentioned method for fabricating low-cost metal substrate thin-film gallium arsenide solar cells includes an epitaxial layer comprising a contact layer, a window layer, an emitter region, a base region, a back field layer, a buffer layer, a sacrificial layer, and a tunnel junction; if it is a multi-junction epitaxial structure, the epitaxial layer includes multiple window layers, emitter regions, base regions, and back field layers.

[0013] The above-mentioned method for preparing low-cost metal substrate thin-film gallium arsenide solar cells, wherein, in step 3), the main salt solution used in the electroplating process is nickel sulfate or nickel aminosulfonate, except for nickel.

[0014] In the above-mentioned method for preparing low-cost metal substrate thin-film gallium arsenide solar cells, in step 3), the nickel alloy further includes at least one of iron, chromium, copper, molybdenum, and titanium, and the mass content of nickel is between 10% and 90%.

[0015] In the above-mentioned method for preparing low-cost metal substrate thin-film gallium arsenide solar cells, in step 4), the temporary bonding material is double-sided adhesive; the temporary bonding material is a thermally degradable film, an ultraviolet light degradable film, or a temporary bonding adhesive.

[0016] The above-mentioned method for preparing low-cost metal substrate thin-film gallium arsenide solar cells includes, in step 6), the following steps: on the side after removing the GaAs substrate, performing top electrode photolithography, isolation trench overlay etching, antireflection film overlay etching, antireflection film evaporation, thin-film solar cell dicing, and thin-film solar cell cell release to complete the preparation of the thin-film solar cell cell device; corresponding to the release conditions of the temporary bonding material used, the release of the thin-film solar cell cell is heating release, light irradiation release, or solution immersion release, and after release, the temporary bonding material is completely desorbed from the electroplated metal.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are:

[0018] (1) In this invention, 20nm~200nm metallic titanium is directly connected to GaAs to form an ohmic contact, while ensuring the bonding force between the metal layer and the semiconductor layer.

[0019] (2) The coefficients of thermal expansion of the titanium (20nm~200nm), chromium (20nm~200nm), and nickel (50nm~300nm) vapor-deposited in this invention are 8.6×10⁻⁶. -6 / ℃, 6.2×10 -6 / ℃, 13.4×10 -6 / ℃, the thermal expansion coefficients of titanium and chromium are close to those of GaAs material, which can both enhance the bonding force and play a mechanical transition role, preventing the stress caused by the strain of nickel or nickel alloy substrate from being directly transmitted to the GaAs epitaxial layer and causing damage to the epitaxial layer when the temperature range changes.

[0020] (3) The total thickness of the metal substrate of the thin-film gallium arsenide solar cell of the present invention is between 15 μm and 20 μm, and titanium, chromium and nickel are all common metal materials, with low material and process costs; the areal density of the metal substrate is 120 g / m³. 2 ~180g / m 2 In this process, gallium arsenide serves as both a battery support material and a back electrode material, resulting in thin-film gallium arsenide solar cells that are lightweight, thin, and flexible. Attached Figure Description

[0021] The low-cost metal substrate thin-film gallium arsenide solar cell and its preparation method of the present invention are given by the following embodiments and figures.

[0022] Figure 1 shows a schematic diagram of the low-cost metal substrate thin-film gallium arsenide solar cell structure of the present invention.

[0023] Figure 2 is a flowchart of the low-cost metal substrate thin-film gallium arsenide solar cell fabrication process of the present invention.

[0024] Figure 3 is a flowchart of the fabrication process of a thin-film gallium arsenide solar cell in this invention.

[0025] Figure 4 is a comparison of the IV characteristic curves of the low-cost metal substrate thin-film gallium arsenide solar cell before and after the temperature shock test under the AM0 spectrum in an embodiment of the present invention. Detailed Implementation

[0026] The low-cost metal substrate thin-film gallium arsenide solar cell and its preparation method of the present invention will be further described in detail below with reference to Figures 1 to 4.

[0027] Figure 1 shows a schematic diagram of the low-cost metal substrate thin-film gallium arsenide solar cell structure of the present invention.

[0028] As shown in Figure 1, the low-cost metal substrate thin-film gallium arsenide solar cell of the present invention comprises, from top to bottom:

[0029] Antireflective coating and upper metal electrode;

[0030] The flip-grown gallium arsenide epitaxial layer 1 can be a flip-chip single junction, flip-chip double junction, or flip-chip triple junction epitaxial structure.

[0031] A vapor-deposited titanium layer 2, with a thickness of 20nm~200nm;

[0032] A vapor-deposited chromium layer 3, with a thickness of 20nm~200nm;

[0033] A nickel layer 4 is deposited by vapor deposition, with a thickness of 50nm~300nm;

[0034] Electroplated nickel or nickel alloy layer 5, with a thickness of 15μm ~30μm.

[0035] Figure 2 shows a flowchart of the low-cost metal substrate thin-film gallium arsenide solar cell fabrication process of the present invention; Figure 3 shows a flowchart of the fabrication process of a single thin-film gallium arsenide solar cell device in the present invention.

[0036] As shown in Figure 2, the method for preparing the low-cost metal substrate thin-film gallium arsenide solar cell of the present invention includes:

[0037] 1) Epitaxial layer growth: GaAs epitaxial layers are grown on GaAs substrates by flip-chip method using metal-organic chemical vapor deposition (MOCVD);

[0038] The epitaxial layer includes a contact layer, a window layer, an emitter region, a base region, a back field layer, a buffer layer, a sacrificial layer, and a tunneling junction; if it is a multi-junction epitaxial structure, the epitaxial layer includes multiple window layers, emitter regions, base regions, and back field layers.

[0039] The flip-chip growth of epitaxial layers can be achieved using existing technologies, which will not be described in detail here;

[0040] Indium phosphide or other group III-V semiconductor substrates can be used to replace GaAs substrates;

[0041] 2) Stress-balanced seed layer evaporation: A 20nm~200nm thick titanium layer 2, a 20nm~200nm thick chromium layer 3, and a 50nm~300nm thick nickel layer 4 are sequentially deposited on the flip-chip grown GaAs epitaxial layer using a vacuum evaporation process.

[0042] 3) Electroplating on a metal substrate: Electroplating a nickel or nickel alloy layer 5 on the chromium layer 3, wherein the thickness of the nickel or nickel alloy layer 5 is 15~30μm;

[0043] The main salt solution used in the electroplating process is nickel sulfate or nickel aminosulfonate;

[0044] In addition to nickel, nickel alloys also contain at least one of iron, chromium, copper, molybdenum, and titanium, and the nickel content is between 10% and 90% by mass.

[0045] 4) Temporary substrate bonding: Temporary bonding material is pasted on one side of the nickel 4 or nickel alloy layer 5, and the temporary bonding material is temporarily bonded to the temporary rigid substrate using a vacuum bonding device;

[0046] The temporary bonding material is double-sided adhesive and can be a pyrolytic film, a UV-dissolving film, or a temporary bonding adhesive.

[0047] 5) GaAs substrate removal: The GaAs substrate used to grow the flip-chip epitaxial layer is removed by mechanical polishing or chemical etching, while the grown GaAs epitaxial layer is retained;

[0048] 6) Fabrication of thin-film solar cell devices;

[0049] As shown in Figure 3, on the side after the GaAs substrate is removed, the following steps are performed in sequence: top electrode photolithography, isolation trench overlay, antireflection film overlay, antireflection film evaporation, thin-film solar cell dicing, and thin-film solar cell cell release, to complete the fabrication of thin-film solar cell cell device.

[0050] Depending on the release conditions of the temporary bonding material used, the release of a single thin-film solar cell can be heating release (pyrolysis film), light release (ultraviolet light film), or solution immersion release (temporary bonding adhesive). After release, the temporary bonding material is completely desorbed from the electroplated metal.

[0051] Example 1

[0052] The low-cost metal substrate thin-film gallium arsenide solar cell fabrication method of this embodiment includes the following steps:

[0053] 1) Single-junction or multi-junction cell epitaxial layers are grown on GaAs substrates using MOCVD equipment; the epitaxial layer includes a contact layer, window layer, emitter region, base region, back field layer, buffer layer, sacrificial layer and tunnel junction; if it is a multi-junction cell, the epitaxial layer includes multiple window layers, emitter regions, base regions and back field layers.

[0054] 2) A metal evaporation process is used to sequentially deposit 100nm titanium, 100nm chromium, and 200nm nickel onto the surface of the epitaxial layer. The vacuum level of the three metals must be maintained at 1×10⁻⁶ in the evaporation chamber. -3 The following Pa values ​​are successively vapor-deposited;

[0055] 3) Place the GaAs wafer with the metal vapor-deposited coating in a 20% (w / w) dilute sulfuric acid solution for activation for 10-20 seconds, then remove and rinse thoroughly with deionized water. Prepare the nickel plating solution: 300 g / L nickel sulfate, 90 g / L nickel chloride, and 40 g / L boric acid. Use a nickel sheet as the anode and the GaAs wafer with the metal vapor-deposited coating as the cathode. Ensure the pH of the plating solution is between 3.4 and 4.5, the solution temperature is set to 50℃, and the current density of the GaAs wafer is 4 A / dm³. 2 ~6A / dm 2 Electroplating for 40 to 60 minutes continuously can yield an electroplated nickel layer with a thickness of about 20 μm.

[0056] 4) Clean the electroplated GaAs wafer with deionized water and dry it; attach a heat-release film to a quartz temporary rigid substrate, attach the quartz temporary rigid substrate to the side of the GaAs wafer with electroplated metal, and use a vacuum hot press to perform temporary bonding. The temporary bonding temperature is ≤100℃ and the bonding pressure is 100mbar~500mbar.

[0057] 5) Prepare the GaAs substrate etching solution: ammonia, hydrogen peroxide, and water in a volume ratio of 1:2:4; place the temporarily bonded GaAs wafer in the etching solution for etching, ensuring the solution temperature is 25±3℃ and the etching solution is in a circulating state during the etching process; after etching for 40 minutes, remove the GaAs wafer and clean it with deionized water, then immerse it in concentrated hydrochloric acid solution for 10 to 20 seconds to remove the etching barrier layer;

[0058] 6) Processing of thin-film gallium arsenide solar cell devices: First, spin-coat photoresist on the side where the GaAs substrate has been removed, perform photolithography, development, and evaporation of the electrode metal. After stripping, the metal pattern of the upper electrode is completed. Second, spin-coat a 5μm–6μm thick positive resist on the surface where the upper electrode has been formed, perform photolithography and development to complete the patterning of the isolation trench. Subsequently, use hydrogen peroxide and hydrochloric acid solutions to alternately etch the GaAs wafer with the patterned isolation trench until the GaAs semiconductor material is etched through to expose the metal material. Use acetone alcohol to remove the patterned positive resist, completing the etching of the isolation trench. Third, spin-coat photoresist on the GaAs wafer, and then... The first step involves etching and developing a patterned photoresist to cover the electrode areas. The second step involves vacuum evaporation to deposit aluminum oxide and titanium oxide on the GaAs wafer surface to form an antireflective film. Then, citric acid solution is used to remove the GaAs contact layer, and acetone alcohol is used to remove the photoresist on the electrode surface to complete the antireflective film deposition. The third step involves using a dicing machine to cut along the isolation groove, adjusting the dicing machine blade height to the height of the pyrolysis film to ensure that the blade cuts through the cell. The fourth step involves using a hot plate to bake the GaAs wafer after cutting, heating the hot plate to 200°C to detach the pyrolysis film. At this point, the thin-film GaAs solar cell device will be detached from the temporary quartz substrate.

[0059] Example 2

[0060] The low-cost metal substrate thin-film gallium arsenide solar cell fabrication method of this embodiment includes the following steps:

[0061] 1) Single-junction or multi-junction cell epitaxial layers are grown on GaAs substrates using MOCVD equipment. The epitaxial layer includes a contact layer, window layer, emitter region, base region, back field layer, buffer layer, sacrificial layer and tunnel junction. If it is a multi-junction cell, the epitaxial layer includes multiple window layers, emitter regions, base regions and back field layers.

[0062] 2) A metal evaporation process is used to sequentially deposit 100nm titanium, 100nm chromium, and 200nm nickel onto the surface of the epitaxial layer. The three metals must be kept under a vacuum of 1×10⁻⁶ in the evaporation chamber. -3 The following Pa values ​​are successively vapor-deposited;

[0063] 3) Place the GaAs wafer with the metal vapor deposited above into a 20% (w / w) dilute hydrochloric acid solution for activation for 10-20 seconds, then remove and rinse thoroughly with deionized water; prepare the nickel plating solution: 400 g / L nickel sulfamate, 20 g / L nickel chloride, and 30 g / L boric acid. Use a nickel sheet as the anode and the GaAs wafer with the metal vapor deposited as the cathode. Ensure the pH of the plating solution is between 3.4 and 4.5, the solution temperature is set to 50℃, and the current density of the GaAs wafer is 5 A / dm³. 2 ~10A / dm 2 Electroplating for 40 to 60 minutes continuously can yield an electroplated nickel layer with a thickness of about 20 μm.

[0064] 4) Clean the electroplated GaAs wafer with deionized water and dry it; attach a heat-release film to a quartz temporary rigid substrate, attach the quartz temporary rigid substrate to the side of the GaAs wafer with electroplated metal, and use a vacuum hot press to perform temporary bonding. The temporary bonding temperature is ≤100℃ and the bonding pressure is 100mbar~500mbar.

[0065] 5) Fix the GaAs wafer onto a ceramic substrate with paraffin wax. First, use a diamond abrasive with a larger grit (e.g., #320-#500 mesh) to thin the original 400μm GaAs wafer to about 50μm. Then, use a diamond abrasive with a finer grit (e.g., #2000-#3000 mesh) to perform low-speed, low-pressure grinding until the GaAs wafer is thinned to about 10μm. Heat the substrate to melt the paraffin wax and remove the thinned wafer. Thoroughly clean the wafer with acetone, alcohol, and deionized water. Then, use hydrogen peroxide solution and hydrochloric acid solution to remove residual gallium arsenide substrate material and gallium indium phosphide corrosion barrier material from the surface of the GaAs wafer.

[0066] 6) Processing of thin-film gallium arsenide solar cell devices: First, spin-coat photoresist on the side where the GaAs substrate has been removed, perform photolithography, development, and evaporation of the electrode metal. After stripping, the metal pattern of the upper electrode is completed. Second, spin-coat a 5μm–6μm thick positive resist on the surface where the upper electrode has been formed, perform photolithography and development to complete the patterning of the isolation trench. Subsequently, use hydrogen peroxide and hydrochloric acid solutions to alternately etch the GaAs wafer with the patterned isolation trench until the GaAs semiconductor material is etched through to expose the metal material. Use acetone alcohol to remove the patterned positive resist, completing the etching of the isolation trench. Third, spin-coat photoresist on the GaAs wafer, perform photolithography... The process involves six steps: 1) developing and patterning photoresist to cover the electrode areas; 2) vacuum evaporation to deposit aluminum oxide and titanium oxide on the GaAs wafer surface to form an antireflective film, followed by removing the GaAs contact layer with citric acid solution and then removing the photoresist on the electrode surface with acetone alcohol to complete the antireflective film deposition; 3) dicing along the isolation groove using a dicing machine, adjusting the dicing machine blade height to the height of the pyrolysis film to ensure the blade cuts through the cell; 4) after dicing, baking the GaAs wafer with a hot plate to 200°C to detach the pyrolysis film, thus allowing the thin-film GaAs solar cell to detach from the temporary rigid quartz substrate.

[0067] The low-cost metal substrate thin-film gallium arsenide solar cell prepared by the above method undergoes a temperature shock test from -180℃ to 150℃. The changes in its IV characteristic curve under the AM0 spectrum are shown in Figure 4. It can be seen that the changes in its open-circuit voltage, short-circuit current and fill factor are all less than 1%.

[0068] The metal substrate thin-film gallium arsenide solar cell prepared by this invention uses inexpensive metal materials such as titanium, chromium, and nickel, as well as electroplating methods, and has advantages such as stress matching, low cost, and light weight compared with existing thin-film gallium arsenide solar cells.

[0069] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A low-cost metal substrate thin-film gallium arsenide solar cell, characterized in that, From top to bottom, it includes: an anti-reflective coating and an upper metal electrode; a flip-chip grown gallium arsenide epitaxial layer; a vapor-deposited titanium layer; a vapor-deposited chromium layer; a vapor-deposited nickel layer; and an electroplated nickel or nickel alloy layer.

2. The low-cost metal substrate thin-film gallium arsenide solar cell as described in claim 1, characterized in that, The thickness of the vapor-deposited titanium layer is 20nm~200nm; the thickness of the vapor-deposited chromium layer is 20nm~200nm; the thickness of the vapor-deposited nickel layer is 50nm~300nm; and the thickness of the electroplated nickel or nickel alloy layer is 15μm~30μm.

3. The low-cost metal substrate thin-film gallium arsenide solar cell as described in claim 1, characterized in that, The flip-grown gallium arsenide epitaxial layer is a flip-chip single junction, flip-chip double junction, or flip-chip triple junction epitaxial structure.

4. The low-cost metal substrate thin-film gallium arsenide solar cell as described in claim 1, characterized in that, The GaAs substrate was replaced with a III-V semiconductor substrate.

5. A method for preparing a low-cost metal substrate thin-film gallium arsenide solar cell according to any one of claims 1 to 4, characterized in that, include: 1) Flip-chip growth of GaAs epitaxial layer on GaAs substrate using metal-organic chemical vapor deposition; 2) Sequential deposition of titanium, chromium, and nickel layers on flip-chip grown GaAs epitaxial layer using vacuum evaporation process; 3) Electroplating of nickel or nickel alloy layer on chromium layer; 4) Attaching temporary bonding material to one side of nickel or nickel alloy layer and temporarily bonding the temporary bonding material to temporary rigid substrate using vacuum bonding equipment; 5) Removal of GaAs substrate used for growing flip-chip epitaxial layer by mechanical polishing or chemical etching; 6) Fabrication of thin-film solar cell device.

6. The method for preparing a low-cost metal substrate thin-film gallium arsenide solar cell as described in claim 5, characterized in that, The epitaxial layer includes a contact layer, a window layer, a emitter region, a base region, a back field layer, a buffer layer, a sacrificial layer, and a tunneling junction; if it is a multi-junction epitaxial structure, the epitaxial layer includes multiple window layers, emitter regions, base regions, and back field layers.

7. The method for preparing a low-cost metal substrate thin-film gallium arsenide solar cell as described in claim 5, characterized in that, In step 3), the main salt solution used in the electroplating process is nickel sulfate or nickel aminosulfonate, except for nickel.

8. The method for preparing a low-cost metal substrate thin-film gallium arsenide solar cell as described in claim 5, characterized in that, In step 3), the nickel alloy also contains at least one of iron, chromium, copper, molybdenum, and titanium, and the mass content of nickel is between 10% and 90%.

9. The method for preparing a low-cost metal substrate thin-film gallium arsenide solar cell as described in claim 5, characterized in that, In step 4), the temporary bonding material is double-sided adhesive; the temporary bonding material is a pyrolytic film, a UV pyrolytic film, or a temporary bonding adhesive.

10. The method for preparing a low-cost metal substrate thin-film gallium arsenide solar cell as described in claim 5, characterized in that, Step 6) includes: sequentially performing top electrode photolithography, isolation trench overlay etching, antireflection film overlay etching, antireflection film evaporation, thin-film solar cell dicing, and thin-film solar cell cell release on the side after removing the GaAs substrate, to complete the fabrication of the thin-film solar cell cell device; corresponding to the release conditions of the temporary bonding material used, the release of the thin-film solar cell cell is heating release, light release, or solution immersion release, and after the release is completed, the temporary bonding material is completely desorbed from the electroplated metal.

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