Selective doping method for solar cell based on reverse diffusion

Abstract

The invention relates to a selective doping method for a solar cell based on reverse diffusion. The method includes the steps: diffusing a silicon slice in an aerobic environment at a high temperature to form a PN junction and oxidizing the upper surface of the silicon slice; removing an oxidation layer outside a top electrode area of the silicon slice; depositing an intrinsic amorphous silicon layer on the upper surface of the silicon slice; diffusing the silicon slice in a wet-oxygen environment at a high temperature, reversely diffusing doping elements in a non-top electrode area into the amorphous silicon layer, diffusing doping elements in an oxidation layer of the top electrode area to the top electrode area and oxidizing the amorphous silicon layer and the non-top electrode area of the surface of the silicon slice to form an oxidation layer; and removing the oxidation layer on the surface of the silicon slice to selectively dope the solar cell based on reverse diffusion. By means of reverse diffusion, impurities in the non-top electrode area are absorbed by amorphous silicon, the doping concentration of the non-top electrode area is reduced, the top electrode area is secondarily doped, the doping concentration difference between the top electrode area and the non-top electrode area is further increased, and selective doping effects are improved.

Description

technical field [0001] The invention relates to a method for selective doping of solar cells based on reverse diffusion, and belongs to the technical field of solar cell manufacturing. Background technique [0002] With the improvement of people's awareness of environmental protection, the demand for clean energy is increasing. Among the new clean energy researched by people, solar energy, as a clean energy that is not subject to geographical restrictions, has become the main direction of new energy development in the future. Solar cells are the main devices that people use the sun's light energy to convert into electrical energy. However, the conversion efficiency of solar cells cannot meet people's requirements at present. Improving the conversion efficiency of solar cells and reducing the manufacturing cost of solar cells has become a research hotspot. [0003] Selectively doped solar cells are an effective low-cost and high-efficiency solar cell. The structural featu...

AI Technical Summary

Problems solved by technology

Among them, the two-step diffusion method is to firstly diffuse the top electrode area, and then lightly diffuse the entire emission area. Control; the screen phosphate slurry method is to use a screen to print a high-concentration phosphate slurry locally. Through its diffusion and volatilization, one diffusion can make the top electrode area form a heavy doping, and other areas form a light doping. However, due to the use of local Phosphorus slurry as a diffusion source will inevitably lead to uneven surface diffusion, which will reduce the efficiency of the battery

The diffusion mask method is to lightly dope first, then perform laser or photolithography masking, and then carry out secondary heavy doping on the top electrode area. This method reduces the selectivity of the top electrode area due to light doping first. The difference between the impurity concentration of the substrate and the substrate during doping can better control the selective doping area of ​​the battery, but laser or photolithography methods are required, which increases the cost and reduces the production efficiency

[0004] In summary, there are certain defects in the current main selective doping methods. Therefore, it is necessary to find a new type of selective doping solar cell production process.

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