Intrinsic anisotropy of thermal conductance in graphene nanoribbons

TL;DR

This study systematically investigates the intrinsic anisotropy in thermal conductance of graphene nanoribbons, revealing that zigzag GNRs conduct heat up to 30% better than armchair GNRs at small widths, with implications for nanoelectronics.

Contribution

It uncovers the origin of anisotropic thermal conductance in GNRs due to boundary conditions and quantifies its dependence on ribbon width.

Findings

Zigzag GNRs have up to 30% higher thermal conductance than armchair GNRs at room temperature.

Anisotropy diminishes and disappears for widths larger than 100 nm.

Boundary conditions at edges cause the intrinsic anisotropy in thermal conductance.

Abstract

Thermal conductance of graphene nanoribbons (GNRs) with the width varying from 0.5 to 35 nm is systematically investigated using nonequilibrium Green's function method. Anisotropic thermal conductance is observed with the room temperature thermal conductance of zigzag GNRs up to ~ 30% larger than that of armchair GNRs. At room temperature, the anisotropy is found to disappear until the width is larger than 100 nm. This intrinsic anisotropy originate from different boundary condition at ribbon edges, and can be used to tune thermal conductance, which have important implications for the applications of GNRs in nanoelectronics and thermoelectricity.