Lattice mismatch measurement of epitaxial β-SiC on α-SiC substrates

Abstract

The lattice mismatch in chemically vapor deposited epitaxial β-SiC (3C-SiC) films on 6H- and 15R-SiC (0001) substrates was investigated using a high-resolution x-ray diffractometer. The misfit parallel and perpendicular to the growth plane was determined to be (Δc/c)∥=−9.3×10−4 and (Δa/a)⊥=1.9×10−4 for the 3C/6H system, and (Δc/c)∥=−10.0×10−4 and (Δa/a)⊥=2.3×10−4 for the 3C/15R system. Our analysis of the lattice parameters in these three SiC polytypes revealed that the Si-C pair spacings along the c direction increased with substrate hexagonality, while the lattice spacings along the a direction decreased with hexagonality. The extent of relaxation was greater in 3C films grown on 6H substrates, a phenomenon attributed to a higher density of double position boundaries.