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

Epitaxial graphene was grown on the surface of on-axis and off-axis SiC (0001) by solid state graphitization at high temperatures (2000 degrees 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 (similar to 3 monolayers) FLG, the coverage for off-axis samples is much less uniform, following closely the step bunching morphology of the SiC surface.