From the study of 6H and 4H single crystals, grown under various conditions on Si- and C- terminated seed surfaces, two types of defects with different slit length were detected. Short slits with a length in the sub-mm range were spread between micro-pipes in an advanced growth stage. Their generation was correlated to micro-pipe agglomeration. Long slits, of up to some mm, which were associated with dislocation bundles in the basal plane, were correlated to polytype domain walls. In this region, the slit formation seems to be favourable similar to the Frank mechanism of micro-pipe generation.

Evolution of Domain Walls in 6H- and 4H-SiC Single Crystals. D.Siche, H.J.Rost, J.Doerschel, D.Schulz, J.Wollweber: Journal of Crystal Growth, 2002, 237-239, 1187-91