Thermally-Limited Current Carrying Ability of Graphene Nanoribbons

TL;DR

This study explores the high-current transport limits of graphene nanoribbons, revealing that their maximum current density is constrained by self-heating and is influenced by heat dissipation mechanisms, with implications for nanoscale device design.

Contribution

It provides the first detailed analysis of thermal effects on current carrying capacity in graphene nanoribbons, highlighting the role of heat spreading and edge scattering.

Findings

GNRs can carry >3 mA/um current density before breakdown.

Thermal conductivity of GNRs is ~80 W/m/K, much lower than micron-sized graphene.

Heat dissipation mechanisms significantly influence GNR current limits.

Abstract

We investigate high-field transport in graphene nanoribbons (GNRs) on SiO2, up to breakdown. The maximum current density is limited by self-heating, but can reach >3 mA/um for GNRs ~15 nm wide. Comparison with larger, micron-sized graphene devices reveals that narrow GNRs benefit from 3D heat spreading into the SiO2, which enables their higher current density. GNRs also benefit from lateral heat flow to the contacts in short devices (< ~0.3 um), which allows extraction of a median GNR thermal conductivity (TC), ~80 W/m/K at 20 C across our samples, dominated by phonons. The TC of GNRs is an order of magnitude lower than that of micron-sized graphene on SiO2, suggesting strong roles of edge and defect scattering, and the importance of thermal dissipation in small GNR devices.