Terahertz radiation induced ballistic electron transport in graphene

TL;DR

This study demonstrates that intense terahertz pulses can induce ballistic electron transport in graphene by promoting impact ionization, suppressing phonon emission, and enhancing carrier mobility, supported by experimental and theoretical analysis.

Contribution

It provides new insights into ultrafast carrier dynamics in graphene under terahertz excitation, highlighting impact ionization's role in enhancing transport.

Findings

Terahertz pulses induce large transparency in graphene.

Theoretical models match experimental results.

Impact ionization promotes efficient carrier transport.

Abstract

We investigated ultrafast carrier dynamics in graphene with near-infrared transient absorption measurement after intense half-cycle terahertz pulse excitation. The terahertz electric field efficiently drives the carriers, inducing large transparency in the near-infrared region. Theoretical calculations using the Boltzmann transport equation quantitatively reproduce the experimental findings. This good agreement suggests that the intense terahertz field should promote remarkable impact ioniza- tion process, which leads to suppression of optical phonon emission and results in efficient carrier transport in graphene.