Comparative characteristics of the Raman scattering spectra of graphene films on conductive and semi-insulating 6H-SiC substrates

The raman scattering (RS) spectra of graphene on semi-insulating and conductive 6H-SiC substrates formed by preliminary and additional annealing of silicon carbide at various temperatures are studied. The degree of perfection of the graphene films and sizes of its clusters are estimated. It is shown that the temperature of additional annealing in the case of conductive substrates should be higher than that for semi-insulating substrates to obtain graphene layers with the same structural perfection.