Figure 2.
(a) and (b) Optical image of graphene on 300 nm SiO2/Si and 72 nm Al2O3/Si substrate. The dashed lines highlight the edge of the single layer graphene region. (c) and (d) the gray-scale optical image from (a) and (b). The arrows highlight the edge of the single layer graphene region. (e) Raman spectra of the single-layer graphene on 300 nm SiO2/Si and 72 nm Al2O3/Si substrates. (f) The contrast spectra of single-layer graphene 300 nm SiO2/Si and 72 nm Al2O3/Si substrates.