The Carbon's solubility into copper is amazingly low and therefore primarily surface diffusion and nucleation of carbon atoms are involved. For that reason as well as growth kinetics, the graphene thickness is restricted to predominantly a monolayer. The large benefit is that the graphene may be developed on Cu foil https://www.quora.com/profile/Trevor-Flatcher-2/Prospects-for-Silicon-Carbide-in-Solar-Cells-Silicon-Carbide-SiC-has-emerged-as-a-promising-material-for-enhancing-th