Theoretical investigation of the band alignment of graphene on a polar SrTiO3 (111) surface

Doping graphene layers presents a difficult practical and fundamental problem. We consider theoretically, the possibility of electrostatic doping of graphene by the intrinsic field of a polar substrate. By way of example, we perform density functional theory calculations for a graphene sheet placed on the (111)-oriented perovskite $\mathrm{SrTi}{\mathrm{O}}₃$ surface. We find that the Fermi surface moves well below the Dirac point of graphene, resulting simultaneously in a fast conducting channel in graphene, and a slow (large-effective-mass) channel at the oxide surface. Additionally, electrostatic gating may open a way to explore peculiar states that, through the ``no crossing,'' represent a hybrid carrier that exists simultaneously in both materials.