Effect of vapor composition on polytype homogeneity of epitaxial silicon carbide

The silicon to carbon precursor ratio is demonstrated as strongly affecting the spontaneous nucleation of cubic SiC upon the growth of epitaxial layers of 4H and 6H silicon carbide using the chemical vapor deposition (CVD) technique. High C/Si ratios appear to promote the nucleation of cubic SiC. A model of CVD process chemistry that relates the effect to a decrease of SiC surface mobility with an increase of the C/Si ratio is proposed. The resulting increase of supersaturation at the surface terraces promotes the spontaneous nucleation of cubic SiC.