Early stage formation of graphene on the C-face of 6H-SiC

摘要

An investigation of the early stage formation of graphene on the C-face of6H-SiC is presented. We show that the sublimation of few atomic layers of Siout of the SiC substrate is not homogeneous. In good agreement with the resultsof theoretical calculations it starts from defective sites, mainly dislocationsthat define nearly circular flakes, which have a pyramidal, volcano-like, shapewith a center chimney where the original defect was located. At highertemperatures, complete conversion occurs but, again, it is not homogeneous.Within the sample surface the intensity of the Raman G and 2D bands, evidencesnon-homogeneous thickness.