Temperature dependent transport in suspended graphene

TL;DR

This study investigates the temperature-dependent electrical transport properties of ultra-clean suspended graphene, revealing near-ballistic transport at low temperatures and phonon scattering effects at higher temperatures, with record-high mobility values.

Contribution

It provides detailed measurements of resistivity and mobility in suspended graphene across a wide temperature range, highlighting phonon scattering and non-universal conductivity behaviors.

Findings

Resistivity increases with temperature above 50K, linearly suggesting acoustic phonon scattering.

Mobility remains exceptionally high (~120,000 cm^2/Vs at 240K), surpassing known semiconductors.

Near-ballistic transport observed at 5K in a 2μm device.

Abstract

The resistivity of ultra-clean suspended graphene is strongly temperature dependent for 5K<T<240K. At T~5K transport is near-ballistic in a device of ~2um dimension and a mobility ~170,000 cm^2/Vs. At large carrier density, n>0.5*10^11 cm^-2, the resistivity increases with increasing T and is linear above 50K, suggesting carrier scattering from acoustic phonons. At T=240K the mobility is ~120,000 cm^2/Vs, higher than in any known semiconductor. At the charge neutral point we observe a non-universal conductivity that decreases with decreasing T, consistent with a density inhomogeneity <10^8 cm^-2.