Single crystals of 6H-type material were grown by using the physical vapor transport method. The crystal was cut into several (00•1) wafers, and 2 of the wafers were selected for analysis: a wafer close to the surface of the boule (wafer A), and a wafer close to the substrate (wafer B). The wafers were characterized by double-crystal X-ray diffraction rocking curves. The rocking curve of wafer A showed a single symmetrical peak, with full-widths at half-maximum of 40arcsec, while that of wafer B showed split peaks which indicated the existence of sub-grains. Defects such as dislocations, micropipes and sub-grains, in the 2 wafers, were studied by KOH etching combined with optical micrography and X-ray topography. Possible relationships between the observed defects and their formation mechanisms during growth were deduced.

Defect Analysis in Single Crystalline 6H-SiC at Different PVT Growth Stages. S.Wang, J.He: Materials Science and Engineering B, 2001, 83[1-3], 8-12