TERRACE GROWTH AND POLYTYPE DEVELOPMENT IN EPITAXIAL BETA-SIC FILMS ON ALPHA-SIC (6H AND 15R) SUBSTRATES

Epitaxial beta-SiC (3C) films were grown on (0001) 6H-SiC and 15R-SiC substrates by chemical vapor deposition (CVD). TEM characterization re vealed that films on both substrates exhibited large areas of atomical ly flat, coherent interfaces. However, when 3C-SiC films were grown on 6H substrates, double position boundaries (DPB's) were frequently obs erved, and islands of 6H were occasionally embedded in the predominant ly 3C film. In contrast, films of 3C-SiC grown on 15R substrates exhib ited relatively few DPB's and only occasional islands of 15R. A model of interlayer interactions in SiC was applied to predict the atomic st ructures at both 3C/6H and 3C/15R interfaces, and these predictions we re consistent with experimental observations of the interfaces by TEM. The observed interface structures and defect distributions were attri buted to a microscopic kinetic mechanism of terrace growth. Considerat ion of step energies and growth kinetics led to the prediction that DP B's can be avoided by growing 3C-SiC films on 15R-SiC substrates.