INTERFACE STRUCTURES OF EPITAXIAL BETA-SIC ON ALPHA-SIC SUBSTRATES

Epitaxial beta-SiC (3C) films were grown on (0001) 6H-SiC and 15R-SiC substrates by chemical vapor deposition (CVD). Transmission electron microscopy (TEM) characterization revealed that both films exhibited large areas of atomically flat, coherent interfaces. These areas were sometimes separated by structural ledges that were integral numbers of alpha-SiC unit cells in height. When 3C-SiC films were grown on 6H substrates, the primary defects were double position boundaries (DPBs), and islands of 6H were occasionally embedded in the predominantly 3C film. Films of 3C-SiC grown on 15R substrates exhibited relatively few grain boundaries, although islands of 15R were sometimes observed. The effect of substrate surface terraces on the observed interfacial microstructures and on defect formation mechanisms is discussed.