An x‐ray topographic study of β‐SiC films on Si substrates

Defects in β‐SiC films grown on Si substrates by chemical‐vapor deposition have been investigated using x‐ray double‐crystal topography. Varying levels of dislocations are often observed in the form of channels, originating at the SiC/Si interface, which can be detected topographically regardless of the visible roughness in the film surface. It is found that rough surfaces are crystallographically more ‘‘flat,’’ on a macroscopic scale, compared to smooth surfaces which are often curved. Films in the latter group also contain fewer defects than the former, and are characterized mostly by misfit striations along [110] directions. A model for defect propagation is proposed connecting the observed topographic detail to the lattice mismatch, differences in thermal expansion, and the relative thickness of film and substrate.