Fig. 2

False colour optical image of the same graphene-coated Si MRR (r = 10-μm device) (scale bar = 10 μm) showing the different mapped regions (white dashed squares) for the a G and b 2D peaks, respectively. The graphene is revealed by the slightly darker contrast (with its bottom left hand corner indicated by the arrows). c and d show the corresponding peak positon and e and f the Fermi level maps, determined from Eqs. (1) and (2), respectively