paper

Phonon-limited resistivity of graphene by first-principle calculations: electron-phonon interactions, strain-induced gauge field and Boltzmann equation

arXiv:1407.0830 · doi:10.1103/PhysRevB.90.125414

Abstract

Electron-phonon coupling in graphene is extensively modeled and simulated from first principles. We find that using an accurate model for the polarizations of the acoustic phonon modes is crucial to obtain correct numerical results. The interactions between electrons and acoustic phonon modes, the gauge field and deformation potential, are calculated at the DFT level in the framework of linear response. The zero-momentum limit of acoustic phonons is interpreted as a strain pattern, allowing the calculation of the acoustic gauge field parameter in the GW approximation. The role of electronic screening on the electron-phonon matrix elements is investigated. We then solve the Boltzmann equation semi-analytically in graphene, including both acoustic and optical phonon scattering. We show that, in the Bloch-Grüneisen and equipartition regimes, the electronic transport is mainly ruled by the unscreened acoustic gauge field, while the contribution due to the deformation potential is negligible and strongly screened. By comparing with experimental data, we show that the contribution of acoustic phonons to resistivity is doping- and substrate-independent. The DFT+GW approach underestimates this contribution to resistivity by about 30 %. Above 270K, the calculated resistivity underestimates the experimental one more severely, the underestimation being larger at lower doping. We show that, beside remote phonon scattering, a possible explanation for this disagreement is the electron-electron interaction that strongly renormalizes the coupling to intrinsic optical-phonon modes. Finally, after discussing the validity of the Matthiessen rule in graphene, we derive simplified analytical solutions of the Boltzmann equation to extract the coupling to acoustic phonons, related to the strain-induced gauge field, directly from experimental data.

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