A kind of preparation method of high-purity semi-insulating silicon carbide single crystal

Abstract

Disclosed is a method for preparing a highly pure semi-insulating silicon carbide single crystal, belonging to the technical field of growing crystals, wherein by introducing a Group IVA element with a greater atomic size into a raw material while reducing the electrically active impurities therein, by using a doped SiC raw material for growing a crystal during the process of the growth of the crystal, and by introducing an appropriate amount of a Group IV element into a SiC crystal, the concentration of intrinsic point defects in the crystal is increased, full compensation for shallow energy level impurities is achieved, and the semi-insulating properties of the SiC crystal are achieved. The growth of the highly pure semi-insulating SiC crystal is achieved without rapid cooling, thereby decreasing stresses in the crystal, and improving the quality of the crystal; furthermore, by controlling the doping concentration, the concentration of intrinsic point defects introduced into the crystal can be well controlled, thereby realizing the adjustment of the electrical resistivity of the crystal.

Description

technical field [0001] The invention belongs to the technical field of crystal growth, and in particular relates to a method for preparing a high-purity semi-insulating silicon carbide single crystal. Background technique [0002] The high-purity semi-insulating SiC single crystal substrate has excellent properties such as high resistivity and high thermal conductivity, especially the low lattice mismatch between SiC and GaN, which makes the high-purity semi-insulating SiC single crystal substrate It becomes the preferred substrate material for high-frequency transistors such as AlGaN / GaN. In order to prepare high-purity semi-insulating SiC single crystal substrates, it is necessary to control the purity of SiC raw materials used to grow SiC single crystals, so that the concentration of electrically active impurities in SiC single crystals can reach a lower content, thereby realizing its semi-insulating properties. However, the electrical properties of SiC single crystals n...

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Problems solved by technology

However, in the process of rapid cooling, the crystal will suffer a large thermal shock, which will introduce a large internal stress into the crystal, resulting in an increase in the cracking rate of the crystal during processing and post-processing, and the curvature and warpage of the substrate due to the large internal stress. The quality of isosurface is poor, which affects the quality of subsequent GaN epitaxial layers and devices