Unraveling the acoustic electron-phonon interaction in graphene

TL;DR

This paper uses first-principles calculations to analyze acoustic electron-phonon interactions in graphene, deriving analytic coupling forms, and examining their impact on carrier mobility and deformation potential, revealing discrepancies with experimental data.

Contribution

It provides analytic expressions for electron-phonon couplings in graphene and assesses their effects on mobility, highlighting differences with experimental deformation potentials.

Findings

Analytic coupling forms accurately describe first-principles data.

Intrinsic deformation potential of graphene is 6.8 eV.

Mobility decreases faster than T^{-4} at higher temperatures.

Abstract

Using a first-principles approach we calculate the acoustic electron-phonon couplings in graphene for the transverse (TA) and longitudinal (LA) acoustic phonons. Analytic forms of the coupling matrix elements valid in the long-wavelength limit are found to give an almost quantitative description of the first-principles based matrix elements even at shorter wavelengths. Using the analytic forms of the coupling matrix elements, we study the acoustic phonon-limited carrier mobility for temperatures 0-200 K and high carrier densities of 10^{12}-10^{13} cm^{-2}. We find that the intrinsic effective acoustic deformation potential of graphene is \Xi_eff = 6.8 eV and that the temperature dependence of the mobility \mu ~ T^{-\alpha} increases beyond an \alpha = 4 dependence even in the absence of screening when the full coupling matrix elements are considered. The large disagreement between our calculated deformation potential and those extracted from experimental measurements (18-29 eV) indicates that additional or modified acoustic phonon-scattering mechanisms are at play in experimental situations.