Thermally-Limited Current Carrying Ability of Graphene Nanoribbons

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.