Hot Electron Terahertz Oscillations in Graphene: Crater and Terraces in the Carrier Distribution Function

TL;DR

This paper predicts terahertz oscillations in graphene's carrier dynamics caused by ballistic acceleration and phonon interactions, leading to unique distribution features like terraces and momentum-free areas.

Contribution

It introduces a novel dynamical phenomenon of terahertz oscillations and distribution function features in graphene under electric fields, linking phonon interactions to transient carrier behavior.

Findings

Terahertz oscillations in carrier velocity and energy are predicted.

Distinct terraces and momentum-free regions form in the distribution function.

The effect depends on voltage and sample length, influenced by phonon interactions.

Abstract

In graphene, after the electric field is turned-on, the ballistic acceleration of charge carriers up to the monochromatic optic phonon energy generates a back-and-forth motion of the whole distribution function between the zero point energy and the phonon energy. This effect is predicted to manifest in damped terahertz oscillations of the carrier drift velocity and average energy. The most dramatic feature of this transient phenomenon is the onset of momentum-free areas surrounded by high momentum probability in phase space, and smooth steps or terraces in the distribution function. This dynamical effect that only takes place within a voltage and sample length window, is the direct consequence of the interplay between the electric force and the randomizing nature of deformation potential optic phonons in the linear band structure of graphene.