Inelastic carrier lifetime in a coupled graphene electron-phonon system: Role of plasmon-phonon coupling

TL;DR

This paper investigates how strong plasmon-phonon coupling in graphene systems causes abrupt increases in inelastic scattering rates, revealing new decay channels that could enhance hot electron device functionalities.

Contribution

It introduces a comprehensive calculation of quasiparticle self-energy considering electron-electron and electron-phonon interactions with dynamic screening, highlighting the impact of plasmon-phonon coupling on scattering rates in graphene.

Findings

Abrupt increase in scattering rate due to coupled plasmon-phonon modes

Single jump in monolayer graphene scattering rate

Two jumps in bilayer graphene scattering rate

Abstract

We calculate the inelastic scattering rates and the hot electron inelastic mean free paths for both monolayer and bilayer graphene on a polar substrate. We study the quasiparticle self-energy by taking into account both electron-electron and electron-surface optical (SO) phonon interactions. In this calculation the leading order dynamic screening approximation (G$_0$W approximation) is used to obtain the quasiparticle self-energy by treating electrons and phonons on an equal footing. We find that the strong coupling between the SO phonon and plasmon leads to a new decay channel for the quasiparticle through the emission of the coupled mode, and gives rise to an abrupt increase in the scattering rate, which is absent in the uncoupled system. In monolayer graphene a single jump in the scattering rate occurs, arising from the emission of the low energy branch of the coupled plasmon-phonon modes. In bilayer graphene the emission of both low and high energy branches of the coupled modes contributes to the scattering rate and gives rise to two abrupt changes in the scattering rate. The jumps in the scattering rate can be potentially used in the hot electron device such as switching devices and oscillators.