The Carbon's solubility into copper is extremely reduced and so mostly surface area diffusion and nucleation of carbon atoms are involved. For that reason and the 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/Innovative-Applications-of-Silicon-Carbide-in-Sensor-Technology-Silicon-carbide-SiC-a-versatile-semiconductor-materi