Buffer layer limited conductivity in epitaxial graphene on the Si face of SiC

We describe a mechanism in which low-energy phonons of the SiC/graphene interface modify the separation between the buffer layer and the graphene overlayer, resulting in a deformation potential and hence charge carrier scattering. We determine this deformation potential ab initio, and then calculate transport properties within the Boltzmann formalism. Our results show (i) a remarkable decrease in the resistivity (rho) near the Dirac point with increasing temperature (T), (ii) a linear increase of rho with T away from the Dirac point, and (iii) good agreement with experiment for low temperature to room temperature change in resistivity for epitaxial graphene on the SiC Si face.