Synchrotron white-beam topography was used to study defects in 6H-type platelets which had been grown by means of the Lely method. High-resolution X-ray diffraction, chemical etching, capacitance-voltage and photoluminescence measurements were used to complement the topographic results. The post-growth defects consisted of curved dislocations and precipitates. The distorted regions acted as Frank-Read dislocation sources from which dislocation loops or half-loops emerged. In the best samples, no dislocations were found in synchrotron topographs which covered areas of up to 80mm2. The etch-pit densities were as low as 100/cm2. In the worst samples, the etch-pit densities were of the order of 104/cm2.

Nature and Occurrence of Defects in 6H-SiC Lely Crystals. M.Tuominen, A.Ellison, T.Tuomi, R.Yakimova, S.Milita, E.Janzén: Journal of Crystal Growth, 2001, 225[1], 23-33