From a study of 6H-type and 4H-type single crystals, grown under various conditions onto Si- and C-terminated seed surfaces, 3 types of defect with differing slit lengths were identified. Short slits with a length in the sub-mm range were spread between micropipes in an advanced stage of growth. Their generation was correlated with micropipe agglomeration. Long slits of up to some mm, which were associated with dislocation bundles in the basal plane, were correlated with polytype domain walls. In this region, slit formation seemed to be favorable; similar to the Frank mechanism of micropipe 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[2], 1187-91