Thermally Limited Current Carrying Ability of Graphene Nanoribbons

Abstract

We investigate high-field transport in graphene nanoribbons (GNRs) on ${\mathrm{SiO}}_{2}$, up to breakdown. The maximum current density is limited by self-heating, but can reach $>3\text{ }\text{ }\mathrm{mA}/\ensuremath{\mu}\mathrm{m}$ for GNRs $\ensuremath{\sim}15\text{ }\text{ }\mathrm{nm}$ wide. Comparison with larger, micron-sized graphene devices reveals that narrow GNRs benefit from 3D heat spreading into the ${\mathrm{SiO}}_{2}$, which enables their higher current density. GNRs also benefit from lateral heat flow to the contacts in short devices ($<\ensuremath{\sim}0.3\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$), which allows extraction of a median GNR thermal conductivity (TC), $\ensuremath{\sim}80\text{ }\text{ }\mathrm{W}\text{ }{\mathrm{m}}^{\ensuremath{-}1}{\mathrm{K}}^{\ensuremath{-}1}$ at $20\text{ }\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ across our samples, dominated by phonons. The TC of GNRs is an order of magnitude lower than that of micron-sized graphene on ${\mathrm{SiO}}_{2}$, suggesting strong roles of edge and defect scattering, and the importance of thermal dissipation in small GNR devices.