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Phonon-limited transport coefficients in extrinsic graphene

The effect of electron-phonon scattering processes over the thermoelectric properties of extrinsic graphene was studied. Electrical and thermal resistivity, as well as the thermopower, were calculated within the Bloch theory approximations. Analytical expressions for the different transport coefficients were obtained from a variational solution of the Boltzmann equation. The phonon-limited electrical resistivity ρ_{e-ph} shows a linear dependence at high temperatures, and follows ρ_{e-ph} \sim T^{4} at low temperatures, in agreement with experiments and theory previously reported in the literature. The phonon-limited thermal resistivity at low temperatures exhibits a \sim T dependence, and achieves a nearly constant value at high temperatures. The predicted Seebeck coefficient at verylow temperatures is Q(T) \sim -π2 k_B T /(3 e E_F), which shows a n^{-1/2} dependence with the density of carriers, in agreement with experimental evidence. Our results suggest that thermoelectric properties can be controlled by adjusting the Bloch-Gruneisen temperature through its dependence on the extrinsic carrier density in graphene.