Defect analysis in Lely-grown 6H SiC

Two Lely-grown 6H polytype SiC platelets were investigated in terms of their crystalline quality and defect characteristics, Synchrotron X-ray topography, along with optical microscopy and high-resolution X-ray diffractometry were used as characterization techniques. In the first platelet a distorted area where the nucleation has started was observed. It consists of micropipes and a complex network of the Frank-Read dislocation loops. Their Burgers vectors were completely determined by X-ray topographic analysis. Outside the distorted area the only large defects observed were dislocations with a low density (in the order of 10(2) cm(-2)) and few stacking faults. The quality of this platelet has improved during the growth. The second platelet was found to be of an excellent crystalline quality. It does not contain micropipes or stacking faults and its dislocation density is very low (about 30 cm(-2)). The rocking curve widths (FWHM) of both samples were very narrow (from 5.8 '' to 8.3 ''). Possible relationships between the observed defects and their formation mechanisms in the growth processes are discussed.