Drift velocity peak and negative differential mobility in high field transport in graphene nanoribbons explained by numerical simulations

TL;DR

This study uses numerical simulations to analyze high-field transport in graphene nanoribbons, revealing non-saturating drift velocity, negative differential mobility, and substrate effects on mobility.

Contribution

It provides new insights into high-field transport behavior in graphene nanoribbons, including the impact of substrates and edge conditions on drift velocity and mobility.

Findings

Drift velocity peaks and then decreases at high fields in suspended GNRs.

Deposition on HfO2 reduces mobility significantly at low fields.

High-field drift velocity approaches intrinsic values despite substrate effects.

Abstract

We present numerical simulations of high field transport in both suspended and deposited armchair graphene nanoribbon (A-GNR) on HfO2 substrate. Drift velocity in suspended GNR does not saturate at high electric field (F), but rather decreases, showing a maximum for F=10 kV/cm. Deposition on HfO2 strongly degrades the drift velocity by up to a factor of 10 with respect to suspended GNRs in the low-field regime, whereas at high fields drift velocity approaches the intrinsic value expected in suspended GNRs. Even in the assumption of perfect edges, the obtained mobility is far behind what expected in two-dimensional graphene, and is further reduced by surface optical phonons.