Ballistic Hot Electron Transport in Graphene

TL;DR

This paper provides a theoretical analysis of hot electron inelastic scattering and mean free paths in graphene, highlighting the effects of electron-electron and electron-phonon interactions on ballistic transport.

Contribution

It introduces a detailed theoretical model accounting for optical phonon emission and electron-electron scattering in graphene's hot electron transport.

Findings

Inelastic scattering time is approximately 10^{-2} to 10^{-1} ps.

Mean free path ranges from 10 to 100 nm.

A finite jump in mean free path occurs at the phonon energy of 200 meV.

Abstract

We theoretically study the inelastic scattering rate and the carrier mean free path for energetic hot electrons in graphene, including both electron-electron and electron-phonon interactions. Taking account of optical phonon emission and electron-electron scattering, we find that the inelastic scattering time $\tau \sim 10^{-2}-10^{-1} \mathrm{ps}$ and the mean free path $l \sim 10-10^2 \mathrm{nm}$ for electron densities $n = 10^{12}-10^{13} \mathrm{cm}^{-2}$. In particular, we find that the mean free path exhibits a finite jump at the phonon energy $200 \mathrm{meV}$ due to electron-phonon interaction. Our results are directly applicable to device structures where ballistic transport is relevant with inelastic scattering dominating over elastic scattering.