Clustered impurities and carrier transport in supported graphene

TL;DR

This paper models how charged impurity clusters and carrier interactions affect electronic transport in supported graphene, revealing how impurity distributions influence conductivity and how carrier interactions cause sublinear behavior at high densities.

Contribution

It introduces a self-consistent simulation approach to analyze impurity effects and carrier interactions in graphene, linking impurity clustering to observed transport phenomena.

Findings

Impurity clusters of 40-50 nm produce electron-hole puddles matching experiments.

Residual conductivity and slope depend on impurity distribution, enabling impurity density estimation.

Carrier-carrier interactions cause sublinear conductivity at high carrier densities.

Abstract

We investigate the effects of charged impurity distributions and carrier-carrier interactions on electronic transport in graphene on SiO$_2$ by employing a self-consistent coupled simulation of carrier transport and electrodynamics. We show that impurity clusters of characteristic width 40--50 nm generate electron--hole puddles of experimentally observed sizes. In the conductivity versus carrier density dependence, the residual conductivity and the linear-region slope are determined by the impurity distribution, and the measured slope can be used to estimate the impurity density in experiment. Furthermore, we show that the high-density sublinearity in the conductivity stems from carrier-carrier interactions.