Relativistic nature of carriers: Origin of electron-hole conduction asymmetry in m o n o l a ye r gr a p h e n e

TL;DR

This paper reveals that electron-hole conduction asymmetry in monolayer graphene arises from the relativistic nature of its charge carriers and impurity scattering, rather than contact effects, providing new insights into graphene's electronic behavior.

Contribution

It demonstrates that conduction asymmetry is due to intrinsic relativistic carrier properties and impurity scattering, challenging previous contact-based explanations.

Findings

Electron conduction is suppressed compared to hole conduction in graphene.

Metallic contacts have negligible impact on conduction asymmetry.

Relativistic quantum effects explain the sign-dependent scattering cross section.

Abstract

We report electron-hole conduction asymmetry in monolayer graphene. Previously, it has been claimed that electron-hole conduction asymmetry is due to imbalanced carrier injection from metallic electrodes. Here, we show that metallic contacts have negligible impact on asymmetric conduction and may be either sample or device-dependent phenomena. Electrical measurements show that monolayer graphene based devices exhibit suppressed electron conduction compared to hole conduction due to the presence of donor impurities which scatter electrons more efficiently. This can be explained by the relativistic nature of charge carriers in a graphene monolayer and can be reconciled with the fact that in a relativistic quantum system transport cross section does depend on the sign of scattering potential in contrast to a nonrelativistic quantum system.