Carbon inclusions in silicon carbide single crystals grown by physical vapor transport method

4H-SiC single crystal with a diameter of 3 inch was grown by physical vapor transport (PVT) method. Particular distribution of weakly connected carbon particles on the surface of source powder was intentionally created during the growth process by mounting a graphite plate with multiple perforative round holes on the surface of the source powder. One-to-one correspondence between distribution of carbon inclusions in the as-grown 4H-SiC single crystal and the pattern of graphite plate was observed. The formation mechanism of carbon inclusion was proposed. It was believed that the generation of carbon particles in growth cavity is a source of carbon inclusions. The methods for reducing carbon inclusions in SiC single crystal are further proposed.