Uniformity of Epitaxial Graphene on On-axis and Off-axis SiC Probed by Raman Spectroscopy and Nanoscale Current Mapping

摘要

Epitaxial graphene was grown on the surface of on-axis and off-axis SiC (0001) by solid state graphitization at high temperatures (2000 °C) in Ar ambient. The effect of the miscut angle on the lateral uniformity of the few layers of graphene (FLG) was investigated by combined application of micro-Raman spectroscopy and Torsion Resonance Conductive Atomic Force Microscopy, the latter method enabling a quantification of the FLG coverage on SiC with submicrometer lateral resolution. While the on-axis samples result in uniform coverage by thin (～ 3 monolayers) FLG, the coverage for off-axis samples is much less uniform, following closely the step bunching morphology of the SiC surface.