Defects analysis in single crystalline 6H-SiC at different PVT growth stages

6H-SiC single crystal was grown by the physical vapor transport (PVT) metho d. The crystal was cut into several (0001) wafers and two of the wafers wer e selected for analysis: the wafer close to the surface of the boule (wafer A), and the wafer close to the substrate (wafer B). The wafers were charac terized by a double crystal X-ray diffraction rocking curve. The rocking cu rve of wafer A shows a single symmetrical peak with full widths at half max imum (FWHM) of 40 arcsec, while that of wafer B shows split peaks. which in dicate the existence of subgrains. Defects. such as dislocations. micropipe s, subgrains etc., in the two wafers were studied by KOH etching combined w ith optical micrography and X-ray topography. Possible relationships betwee n the observed defects and their formation mechanisms in the growth process are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.