EFFECT OF VAPOR COMPOSITION ON POLYTYPE HOMOGENEITY OF EPITAXIAL SILICON-CARBIDE

The silicon to carbon precursor ratio is demonstrated as strongly affe cting the spontaneous nucleation of cubic SIC upon the growth of epita xial layers of 4H and 6H silicon carbide using the chemical vapor depo sition (CVD) technique. High C/Si ratios appear to promote the nucleat ion of cubic SIG. A model of CVD process chemistry that relates the ef fect to a decrease of SiC surface mobility with an increase of the C/S i ratio is proposed. The resulting increase of supersaturation at the surface terraces promotes the spontaneous nucleation of cubic SiC. (C) 1996 American Institute of Physics.