Intrinsic carrier mobility of Dirac cones: The limitations of deformation potential theory

An analytic formula for the intrinsic carrier mobility of Dirac cones under acoustic phonon scattering conditions was obtained for 2D systems such as graphene and graphyne. The influences of both the transverse acoustic (TA) and longitudinal acoustic phonon modes and that of the anisotropy were considered. Some extraordinary characteristics unlike those predicted by the deformation potential theory were revealed: the mobility at the neutrality point is proportional to 1/T-3, where T is the temperature; also, carrier scattering by the TA phonons dominates the mobility of graphene, which explains the overestimation of the measured deformation potential of graphene in previous experiments. The theory was combined with first-principles calculations to determine the mobility of graphene and five graphynes with Dirac cones. It was predicted that most graphynes will have much higher mobility than graphene because of the suppression of the scattering by the TA phonons. (C) 2014 AIP Publishing LLC.