A density functional theory study of epitaxial graphene on the (333)-reconstructed C-face of SiC

We study the electronic properties of epitaxial graphene on the (3 x 3)-reconstructed SiC(000 (1) over bar) plane within the density functional theory. Our results show that the interface interaction is inherently weak. The first graphene layer above the substrate is almost planar and sp(2)-hybridized. The substrate's contribution in the low-energy electronic spectrum is present through (a) interface states deriving from SiC surface atoms with bands that disperse around the Dirac point, (b) a mild n-type doping, and (c) a similar to 20 meV band-gap opening. Substrate interference is, therefore, an issue also in the case of graphene grown on the C-face of SiC.