A kind of polycrystalline silicon ingot and preparation method thereof

Abstract

The invention provides a method for preparing a polycrystalline silicon ingot, which is characterized in that it comprises the following steps: a) laying a seed crystal on the bottom of a crucible, and then covering the polycrystalline silicon material to obtain a packed silicon material; the seed crystal is a oriented monocrystalline silicon; b) performing directional solidification growth, annealing and cooling in turn on the loaded silicon material obtained in step a) to obtain polycrystalline silicon ingots. Compared with the prior art, the present invention uses monocrystalline silicon with a single crystal orientation as the seed crystal, adopts a specific preparation process to achieve better interaction, and the prepared polycrystalline silicon ingot has a consistent crystal orientation, which can reduce the dislocation density , especially the dislocation density in the upper part of the silicon ingot, thereby improving the crystal quality and photoelectric conversion efficiency. Experimental results show that the polycrystalline silicon ingot prepared by the preparation method provided by the invention has a single crystal orientation consistent with that of the seed crystal; the crystal quality is good, and polycrystalline silicon blocks and polycrystalline silicon wafers can be further obtained; and the photoelectric conversion efficiency can reach more than 19.8%.

Description

technical field [0001] The invention relates to the technical field of polysilicon, and more specifically, relates to a polysilicon ingot and a preparation method thereof. Background technique [0002] In the solar photovoltaic industry, crystalline silicon is the most widely used solar cell material. There are two main types of substrates used in crystalline silicon cells: monocrystalline silicon wafers and polycrystalline silicon wafers. Among them, there is only one crystal grain on the surface of a monocrystalline silicon wafer, and the crystal orientation of the grain is fixed. The single wafer rod is mainly prepared by the pulling method, and then obtained through truncation, squaring, multi-wire cutting and other processes; the surface distribution of polycrystalline silicon wafers has There are multiple crystal grains, and the grains have different sizes, irregular shapes, and inconsistent crystal orientations. They are mainly obtained by preparing polycrystalline s...

AI Technical Summary

Problems solved by technology

However, this kind of crystalline silicon cannot solve dislocation problems such as dislocations and subgrain boundaries, especially in the upper and middle parts of the silicon ingot. The rapid proliferation of dislocation defects leads to low and scattered photoelectric conversion efficiency of the battery, many battery stalls, and difficulty in industrialization.

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