Heat treatment method of solar-grade silicon crystal

Abstract

The invention discloses a heat treatment method of a solar-grade silicon crystal, which comprises the steps of placing the silicon crystal into a vacuum heating furnace, introducing protective gas into the vacuum heating furnace and leading the protective gas to flow through the surface of the silicon crystal during the heat treatment process of the silicon crystal, wherein the protective gas is a) gas containing hydrogen atoms; or b) mixture of the gas containing the hydrogen atoms and inert gas. The adoption of the method for carrying out heat treatment on the silicon crystal can significantly prolong the minority carrier lifetime of the silicon crystal, simultaneously regulate the distribution uniformity of radial resistivity of the silicon crystal and lead the resistivity of the silicon crystal to be more uniform on the radius direction of the crystal due to the roles of passivation, impurity absorption and the like of H to impurities and defects in the silicon crystal. The method is simple to operate and easy to carry out industrial production, and can significantly improve the quality of a product.

Description

technical field [0001] The invention relates to a heat treatment method for silicon crystals, in particular to a heat treatment method for silicon crystals used in solar cells with high conversion efficiency. Background technique [0002] The raw silicon crystals used in the preparation of crystalline silicon solar cells are divided into silicon single crystals or silicon polycrystals. In the process of silicon crystal preparation, due to the different raw materials or processing processes, there are metal impurities, oxygen and carbon impurities, grain boundaries, dislocations, voids (point defects) and other defects inside the silicon material, and these impurities and defects often form many unidentified Saturated dangling bonds form electroactive centers and become traps and recombination centers for minority carriers (minority carriers). These traps and recombination centers reduce the minority carrier diffusion length and affect the performance of photovoltaic devices...

AI Technical Summary

Problems solved by technology

These traps and recombination centers reduce the minority carrier diffusion length, affecting the performance of photovoltaic devices

It is specifically manifested in the fact that the minority carrier life of silicon wafers made of the above-mentioned silicon single crystal and silicon polycrystalline is relatively low, and ultimately affects the photoelectric conversion efficiency and life of the manufactured crystalline silicon solar cells.

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