Density functional simulations of physisorbed and chemisorbed single graphene layers on 4H-SiC (0001), (0001̅) and 4H-SiC:H surface

The nature of the interaction between the substrate and the graphene is critical in terms of impact upon the graphene electron dispersion relation, and in terms of charge transfer. We present here the results of density functional simulations of 4H-SiC-graphene heterostructures using large, periodic simulation supercells. We show that covalent bonding between the substrate and graphene leads both to changes in the electronic structure, and extensive charge transfer, but that the larger simulation system yields qualitatively different electronic structure to that from the more usual √3×√3 R30° cell.