Electron-Phonon Interactions in Bilayer Graphene: A First Principles Approach

TL;DR

This study uses first principles calculations to analyze electron-phonon interactions in bilayer graphene, revealing similarities with bulk graphite and providing insights into scattering mechanisms affecting mobility.

Contribution

It offers a detailed first-principles analysis of electron-phonon interactions in bilayer graphene, highlighting differences from monolayer graphene and modeling scattering rates.

Findings

Phonon scattering in bilayer graphene resembles bulk graphite more than monolayer.

Low-energy electron-phonon scattering is dominated by six acoustic and acoustic-like phonon branches.

Predicted low-field mobility in bilayer graphene is lower than in monolayer graphene due to enhanced acoustic phonon scattering.

Abstract

Density functional perturbation theory is used to analyze electron-phonon interaction in bilayer graphene. The results show that phonon scattering in bilayer graphene bears more resemblance with bulk graphite than monolayer graphene. In particular, electron-phonon scattering in the lowest conduction band is dominated by six lowest (acoustic and acoustic-like) phonon branches with only minor contributions from optical modes. The total scattering rate at low/moderate electron energies can be described by a simple two-phonon model in the deformation potential approximation with effective constants Dac $\approx$ 15 eV and Dop $\approx 2.8 \times 108$ eV/cm for acoustic and optical phonons, respectively. With much enhanced acoustic phonon scattering, the low field mobility of bilayer graphene is expected to be significantly smaller than that of monolayer graphene.