The crystalline quality of commercial wafers of 4H material was studied. Various structure-sensitive techniques were used to reveal specific macro-defects. Microscopic examination, together with preferential chemical etching, revealed dislocation networks, micro-pipes, basal-plane defects and cracks. Synchrotron X-ray topographs revealed the presence of defect-associated strains and lattice misorientations which arose in the vicinity of some micro-pipes. High-resolution X-ray diffractometry and Bragg-angle topography were used to provide evidence of existing domains, and their misorientation. The results were considered with regard to defect formation mechanisms.

M.Tuominen, R.Yakimova, R.C.Glass, T.Tuomi, E.Janzén: Journal of Crystal Growth, 1994, 144[3-4], 267-76