Preparation method of PVT method silicon carbide crystal growth raw material

Abstract

The invention belongs to the field of silicon carbide crystals, and discloses a preparation method of a PVT method silicon carbide crystal growth raw material. The method comprises the following steps of: (1) adding starch and PVA into silicon carbide powder, and fully mixing and stirring to form a silicon carbide colloid; (2) pressing the silicon carbide colloid into a compact body; (3) calcining the compact body to obtain a silicon carbide porous ceramic body; (4) treating natural crystalline flake graphite, and drying and puffing to obtain sulfur-free expanded graphite; (5) adding Si powder and PVA into the sulfur-free expanded graphite to form sulfur-free expanded graphite colloid; (6) soaking the silicon carbide porous ceramic body in the sulfur-free expanded graphite colloid to form a porous graphite body filled with expanded graphite and silicon; and (7) drying the formed porous graphite body filled with expanded graphite and silicon, and performing high-temperature treatment to obtain the silicon carbide crystal growth raw material. The problem that crystals are polymorphic and carbon inclusions are generated due to non-uniform proportion of Si and C in a silicon carbide crystal raw material is solved.

Description

technical field [0001] The invention belongs to the field of silicon carbide crystal preparation, and more specifically relates to a method for preparing silicon carbide crystal growth raw materials by a PVT method. Background technique [0002] At present, during the PVT silicon carbide crystal growth process, the silicon in the heated raw material at the edge of the crucible is sublimated and easily graphitized, and the silicon element enters the growth chamber and forms Si at the edge of the growth chamber. 2 C and SiC 2 The intermediates are further sublimated to the surface of the seed crystal to complete the crystal growth, but because the edge is hotter than the middle, the Si sublimation at the edge is more severe than that in the middle. As the crystal growth progresses, the ratio of Si and C elements in the later stage is not uniform. , it will lead to crystal polymorphism, defects such as carbon inclusions, which seriously affect the quality of crystal growth in ...

AI Technical Summary

Problems solved by technology

[0003] In order to solve the PVT silicon carbide crystal growth process in the prior art, due to the uneven ratio of Si and C elements in the growth raw materials, the crystals are polymorphic, and the defects of carbon inclusions seriously affect the quality of the crystal growth in the later stage. The invention provides a method for preparing silicon carbide crystal growth raw materials by PVT method

Images