Intrinsic and Extrinsic Performance Limits of Graphene Devices on SiO2

TL;DR

This paper investigates the fundamental and extrinsic factors limiting graphene's electrical performance on SiO2, revealing intrinsic phonon scattering sets a high mobility limit, while substrate surface phonons significantly reduce mobility at room temperature.

Contribution

It quantifies intrinsic and extrinsic limits on graphene's resistivity and mobility, highlighting the dominant role of substrate surface phonons at room temperature.

Findings

Intrinsic resistivity limit of 30 Ohm at room temperature.

Intrinsic mobility exceeds 2x10^5 cm^2/Vs, surpassing other semiconductors.

Surface phonons of SiO2 reduce mobility to ~4x10^4 cm^2/Vs at RT.

Abstract

The linear dispersion relation in graphene[1,2] gives rise to a surprising prediction: the resistivity due to isotropic scatterers (e.g. white-noise disorder[3] or phonons[4-8]) is independent of carrier density n. Here we show that acoustic phonon scattering[4-6] is indeed independent of n, and places an intrinsic limit on the resistivity in graphene of only 30 Ohm at room temperature (RT). At a technologically-relevant carrier density of 10^12 cm^-2, the mean free path for electron-acoustic phonon scattering is >2 microns, and the intrinsic mobility limit is 2x10^5 cm^2/Vs, exceeding the highest known inorganic semiconductor (InSb, ~7.7x10^4 cm^2/Vs[9]) and semiconducting carbon nanotubes (~1x10^5 cm^2/Vs[10]). We also show that extrinsic scattering by surface phonons of the SiO2 substrate[11,12] adds a strong temperature dependent resistivity above ~200 K[8], limiting the RT mobility to ~4x10^4 cm^2/Vs, pointing out the importance of substrate choice for graphene devices[13].