Effect of anisotropic band curvature on carrier multiplication in graphene

TL;DR

This paper investigates how anisotropic band curvature in graphene influences electron relaxation and carrier multiplication, revealing direction-dependent suppression and critical thresholds for relaxation due to trigonal warping effects.

Contribution

It demonstrates that anisotropic band curvature can suppress or enable electron relaxation in graphene, introducing a directional and curvature-dependent mechanism affecting carrier dynamics.

Findings

Anisotropic band curvature suppresses relaxation in certain directions.

Relaxation occurs only if curvature exceeds a critical value.

Non-decaying quasiparticle states can exist depending on direction.

Abstract

We study relaxation of an excited electron in the conduction band of intrinsic graphene at zero temperature due to production of interband electron-hole pairs. The electronic band curvature, being anisotropic because of trigonal warping, is shown to suppress relaxation for a range of directions of the initial electron momentum. For other directions, relaxation is allowed only if the curvature exceeds a finite critical value; otherwise, a non-decaying quasiparticle state is found to exist.