Preparation method of submicron pyramid suede on surface of crystalline silicon
By adding indium oxide to the alkaline velvet making solution, the single crystal silicon wafer is directly etched in the alkali solution to prepare efficient submicron pyramid suede, which solves the problems of complex process, high cost and poor suede structure in the existing technology, and achieves an efficient and environmentally friendly velvet making process.
Patent Information
- Application Number
- CN202510058947.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-15
- Publication Date
- 2025-05-23
AI Technical Summary
In the prior art, when preparing submicron pyramid suede on crystalline silicon surface, the process is complex, the cost is high, the suede structure is poor, the waste liquid is not environmentally friendly, the process time is long, and organic pollution is easily introduced.
Indium oxide is added to conventional alkaline velvet making solution, and dense submicron pyramid suede is prepared by immersing a single crystal silicon wafer in an alkali solution containing sodium hydroxide, potassium hydroxide or tetramethylammonium hydroxide.
It achieves efficient light capture performance, is insensitive to incident light angles, reduces the cost of velvet making, simplifies process steps, reduces waste liquid treatment costs, and eliminates the need to use complex organic matter.
Smart Images
Figure CN120035257A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of crystalline silicon solar cell material preparation, in particular to a method for preparing a submicron pyramid velvet surface on the surface of crystalline silicon. Background Art
[0002] Crystalline silicon solar cells dominate the global photovoltaic market due to their high photoelectric conversion efficiency, good stability and low cost. A key point in achieving high-performance crystalline silicon solar cells is to texture the surface of crystalline silicon to improve the solar cell's absorption of light, reduce the reflection of incident light, and thus improve the efficiency of light utilization. The current mainstream texture structure is a 2-6 micron pyramid texture. Although this micron-scale pyramid texture can effectively reduce the reflectivity of the silicon wafer surface under vertical incident light, its reflectivity will increase significantly with the increase of the incident angle, that is, the anti-reflection performance is seriously dependent on the incident angle. This is not conducive to the practical application of solar cells. Studies have shown that when the size of the silicon pyramid is reduced to the submicron level, that is, when it is similar to the absorbable wavelength of light, its anti-reflection effect becomes insensitive to the incident angle of light, and can maintain a low reflectivity over a wide range of incident angles.
[0003] There are many methods reported to prepare silicon submicron pyramid velvet. For example, a thin film is deposited on the surface of crystalline silicon, and a mask pattern of appropriate size is defined by opening windows through photolithography, nanoimprinting, laser ablation or ion beam etching, and then a submicron pyramid velvet is prepared by etching with an alkaline solution, and finally the mask layer is removed. There are also reports that the silicon wafer is immersed in AgNO 3 CuNO 3 The method also involves etching in a high-concentration HF solution to prepare porous silicon, etching in an alkaline solution to prepare a submicron pyramid velvet, and finally removing the metal nanoparticles in a high-concentration nitric acid solution. The submicron pyramid velvet formed by this method has poor uniformity, a rough surface, and a large specific surface area, which causes serious carrier recombination. There are also reports on the preparation of submicron pyramid velvet by introducing a variety of complex organic substances into an alkaline solution.
[0004] It can be seen that the process of preparing silicon submicron pyramid velvet still faces various challenges, such as complex process, high cost, poor velvet structure, environmentally unfriendly waste liquid treatment, long process time or easy introduction of organic pollution. Therefore, a method for preparing submicron pyramid velvet on crystalline silicon surface is provided. Summary of the invention
[0005] The purpose of the present invention is to provide a method for preparing a submicron pyramid velvet surface on a crystalline silicon surface in view of the defects of the prior art, so as to solve the problems raised by the above-mentioned background technology.
[0006] To achieve the above object, the present invention provides the following technical solution: a method for preparing a submicron pyramid velvet surface on a crystalline silicon surface, the specific steps are as follows:
[0007] Step 1: prepare an alkaline solution of a certain concentration, and add a surfactant and indium oxide;
[0008] Step 2: At a certain solution temperature, the single crystal silicon wafer is placed in the alkaline solution prepared in step 1 and etched for a certain period of time, so that a dense submicron pyramid velvet surface can be obtained on the surface of the single crystal silicon.
[0009] As a preferred technical solution of the present invention, the alkaline solution is one or more mixed solutions containing sodium hydroxide, potassium hydroxide or tetramethylammonium hydroxide, and the concentration of the alkaline substance is 1%-5%.
[0010] As a preferred technical solution of the present invention, the surfactant is ethanol, isopropanol or sodium dodecylbenzene sulfonate, which can be used to reduce the surface tension of the solution and increase the wettability of the silicon wafer.
[0011] As a preferred technical solution of the present invention, the indium oxide is undoped indium oxide or doped indium oxide.
[0012] As a preferred technical solution of the present invention, the method of placing the single crystal silicon wafer into the alkaline solution prepared in step 1 in step 2 is: directly dissolving indium oxide into the alkaline solution or first depositing an indium oxide film on the silicon wafer and then immersing it in the alkaline solution to dissolve the indium oxide film in the alkaline solution.
[0013] As a preferred technical solution of the present invention, the single crystal silicon wafer is bare silicon or a single crystal silicon wafer covered with an indium oxide film.
[0014] As a preferred technical solution of the present invention, the indium oxide concentration is 0.016 g / L-0.2 g / L.
[0015] As a preferred technical solution of the present invention, the temperature of the alkaline solution is 60-80° C., and the etching time is 4-10 minutes.
[0016] Compared with the prior art, the present invention has the following beneficial effects:
[0017] 1. The present invention can prepare a submicron pyramid velvet surface by adding indium oxide to a conventional alkaline velvet solution, which has good light capture performance and is insensitive to the angle of incident light;
[0018] 2. No need to prepare a mask layer, no need to use processes such as photolithography, laser etching or ion beam etching to define the mask pattern, so no expensive equipment and process flow are required to achieve the preparation of sub-micron velvet, which can significantly reduce the velvet production cost;
[0019] 3. No need for multi-step acid solution pretreatment or post-treatment, reducing the cost of waste liquid treatment, simpler process steps, and denser and smoother suede;
[0020] 4. Using inorganic material indium oxide as nucleating agent, there is no need for complex and diverse organic substances as additives, thus reducing organic pollution.
[0021] 5. The solution temperature is low, which is beneficial to saving heat costs, shortening the process time, and improving productivity. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a SEM image of the submicron texture of a silicon wafer containing an ITO film after being etched at 80°C for 5 minutes in an alkaline solution;
[0023] Figure 2 This is a SEM image of the submicron texture of a silicon wafer etched at 80°C for 5 minutes in an alkaline solution containing indium oxide;
[0024] Figure 3 This is a SEM image of the submicron texture of a silicon wafer etched in an alkaline solution containing indium oxide at 65°C for 10 minutes;
[0025] Figure 4 This is a surface SEM image of a silicon wafer etched at 80°C for 8 minutes in an alkaline solution without indium oxide;
[0026] Figure 5 This is a SEM image of the micron texture of a silicon wafer after being etched at 80°C for 30 minutes in an alkaline solution without indium oxide. DETAILED DESCRIPTION
[0027] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.
[0028] Embodiment 1: A method for preparing a submicron pyramid velvet surface on a crystalline silicon surface.
[0029] In this embodiment, the following two steps are mainly included:
[0030] (1) Pretreatment of the indium oxide film on the surface of the silicon wafer, that is, depositing a layer of tin-doped indium oxide film (ITO) on the surface of the silicon wafer in a vacuum of 1.5x10 -4 When the pressure is below 1.0 Pa, a layer of ITO film with a thickness of about 30 nm is deposited on the surface of the silicon wafer by magnetron sputtering. A certain amount of argon gas (40 sccm) is passed into the sputtering chamber, and the sputtering power is adjusted to 50 W. After the glow of the target material is stabilized, the working pressure is adjusted to 0.3 Pa.
[0031] (2) Immerse the silicon wafer covered with ITO film in a conventional alkaline solution for texturing. The alkaline solution is composed of 2.5% (mass fraction) NaOH texturing solution and 5% isopropanol by volume. The solution temperature is 80°C and the etching time is 5 minutes. The prepared pyramid texture surface is a submicron structure. Figure 1 ; Obviously, in this embodiment, the indium oxide component is provided by the ITO film on the surface of the silicon wafer.
[0032] Example 2: A method for preparing a submicron pyramid velvet surface on a crystalline silicon surface.
[0033] First, an alkaline solution containing indium oxide and a surface additive is prepared; a silicon wafer containing an ITO film is immersed in a solution of 4% (mass fraction) NaOH and 5% isopropanol by volume, and the ITO film is fully dissolved in the alkaline solution at a solution temperature of 65-80°C, and the concentration of ITO dissolved is about 0.06g / L.
[0034] Then, a clean single crystal silicon wafer is immersed in the above solution and etched at a solution temperature of 80°C for 5 minutes to obtain a smooth and dense silicon submicron pyramid velvet surface. Figure 2 shown.
[0035] Embodiment 3:
[0036] The solution is prepared in the same manner as in Example 2; then, the clean surface of the single crystal silicon wafer is immersed in the above solution and etched at a solution temperature of 65°C for 10 minutes to obtain a smooth and dense silicon submicron pyramid velvet surface, such as Figure 3 shown.
[0037] Embodiment 4:
[0038] The solution is prepared in the same manner as in Example 2; then, a clean surface of a single crystal silicon wafer is immersed in the above solution and etched at a solution temperature of 65° C. for 5 minutes to obtain a smooth and dense silicon submicron pyramid velvet surface.
[0039] Embodiment 5:
[0040] Compared with Example 2, the main difference is the NaOH concentration; first, an alkaline solution containing indium oxide and a surface additive is prepared, and the silicon wafer containing the ITO film is immersed in a 2% (mass fraction) NaOH and 5% isopropanol solution by volume, and the ITO film is fully dissolved in the alkaline solution at a solution temperature of 65-80°C.
[0041] Then, a single crystal silicon wafer with a clean surface is immersed in the above solution and etched at a solution temperature of 78° C. for 5 minutes to obtain a smooth and dense silicon submicron pyramid velvet surface.
[0042] Embodiment 6:
[0043] Compared with Example 2, the amount of ITO incorporated is different; first, an alkaline solution containing indium oxide and a surface additive is prepared; the silicon wafer containing the ITO film is immersed in a 4% (mass fraction) NaOH and 5% isopropanol solution by volume, and the ITO film is fully dissolved in the alkaline solution at a solution temperature of 65-80°C, and the concentration of ITO incorporated is 0.1g / L.
[0044] Then, a single crystal silicon wafer with a clean surface is immersed in the above solution and etched at a solution temperature of 75°C for 7 minutes to obtain a smooth and dense silicon submicron pyramid velvet surface.
[0045] Comparative Example 1:
[0046] The solution composition is 2.5% (mass fraction) NaOH and 5% isopropanol solution by volume, that is, a texturing solution without indium oxide. The silicon wafer is immersed in the above solution and etched at a solution temperature of 80°C for 8 minutes. The surface of the silicon wafer is still shiny. Scanning electron microscopy shows that there are only sporadic quasi-pyramid structures on the silicon surface, and the scale is in the micron order, such as Figure 4 shown.
[0047] Comparative Example 2:
[0048] The solution composition is 1.5% (mass fraction) NaOH and 5% volume ratio isopropanol solution, that is, the texturing solution does not contain indium oxide. The silicon wafer is immersed in the above solution and etched at a solution temperature of 80°C for 30 minutes. Although the surface of the silicon wafer is black at this time, it can be found through scanning electron microscopy that the silicon surface is covered with pyramid structure velvet, but the average lateral size of the pyramid is 11 microns, such as Figure 5 shown.
[0049] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.
Claims
1. A method for preparing a submicron pyramid velvet surface on a crystalline silicon surface, characterized in that: The specific steps are as follows: Step 1: prepare an alkaline solution of a certain concentration, and add a surfactant and indium oxide; Step 2: At a certain solution temperature, the single crystal silicon wafer is placed in the alkaline solution prepared in step 1 and etched for a certain period of time, so that a dense submicron pyramid velvet surface can be obtained on the surface of the single crystal silicon.
2. The method for preparing a submicron pyramid velvet surface on a crystalline silicon surface according to claim 1, characterized in that: The alkaline solution is one or more mixed solutions containing sodium hydroxide, potassium hydroxide or tetramethylammonium hydroxide, and the concentration of the alkaline substance is 1%-5%.
3. The method for preparing submicron pyramid velvet on the surface of crystalline silicon according to claim 1, characterized in that: The surfactant is ethanol, isopropanol or sodium dodecylbenzene sulfonate, which is a substance used to reduce the surface tension of the solution and increase the wettability of the silicon wafer.
4. The method for preparing a submicron pyramid velvet surface on a crystalline silicon surface according to claim 1, characterized in that: The indium oxide is undoped indium oxide or doped indium oxide.
5. The method for preparing submicron pyramid velvet on the surface of crystalline silicon according to claim 1, characterized in that: In step 2, the single crystal silicon wafer is placed in the alkaline solution prepared in step 1. In the step 2, indium oxide is directly dissolved in the alkaline solution or an indium oxide film is first deposited on the silicon wafer and then immersed in the alkaline solution to dissolve the indium oxide film in the alkaline solution.
6. The method for preparing submicron pyramid velvet on the surface of crystalline silicon according to claim 1, characterized in that: The single crystal silicon wafer is bare silicon or a single crystal silicon wafer covered with an indium oxide film.
7. The method for preparing a submicron pyramid velvet surface on a crystalline silicon surface according to claim 1, characterized in that: The indium oxide concentration is 0.016 g / L-0.2 g / L.
8. The method for preparing submicron pyramid velvet on the surface of crystalline silicon according to claim 1, characterized in that: The temperature of the alkaline solution is 60-80° C., and the etching time is 4-10 minutes.