Universal mobility characteristics of graphene originating from electron/hole scattering by ionised impurities

TL;DR

This paper presents a universal model linking graphene's carrier mobility to its conductance variation, enabling accurate predictions of transport properties across diverse samples and informing device engineering.

Contribution

It introduces a convolution-based conductivity model that predicts the full conductance curve from a single measurement, validated by Boltzmann transport equation analysis.

Findings

Universal conductance variation with carrier density in graphene.

Model accurately predicts conductance curves from single data points.

Includes effects of charged impurities and optical phonons.

Abstract

Pristine graphene and graphene-based heterostructures exhibit exceptionally high electron mobility and conductance if their surface contains few electron-scattering impurities. Here, we reveal a universal connection between graphene's carrier mobility and the variation of its electrical conductance with carrier density. Our model of graphene conductivity is based on a convolution of carrier density and its uncertainty, which reproduces the observed universality. Taking a single conductance measurement as input, this model accurately predicts the full shape of the conductance versus carrier density curves for a wide range of reported graphene samples. We verify the convolution model by numerically solving the Boltzmann transport equation to analyse in detail the effects of charged impurity scattering on carrier mobility. In this model, we also include optical phonons, which relax high-energy charge carriers for small impurity densities. Our numerical and analytical results both capture the universality observed in experiment and provide a way to estimate all key transport parameters of graphene devices. Our results demonstrate how the carrier mobility can be predicted and controlled, thereby providing insights for engineering the properties of 2D materials and heterostructures.