Restraint of nucleation of SiC polycrystals surrounding the seed during SiC single crystal growth

The nucleation and growth of SiC polycrystals around seed crystals restrain the growth of SiC single crystals in the radial direction fabricated by physical vapor transport method in which the ordinary graphite is used as the crucible lid. Therefore, it is necessary to reduce the nucleation and growth of SiC polycrystals around the seed crystals. In order to effectively enlarge SiC single crystals, the authors propose the use of a graphite paper instead of graphite as the lid to restrain the nucleation of SiC polycrystals on the lid. The micrographs of SiC polycrystals on the graphite paper and graphite at the different growth stages show that the nucleation of SiC polycrystals on the graphite paper is more difficult than that on graphite. X-ray diffraction and scanning electron microscope investigations show that the graphite paper possesses high-macroscopic anisotropy, which induced that polycrystals can only grow on the surface of graphite paper and be easily removed.