Electron-hole puddles in the absence of charged impurities

TL;DR

This paper shows that physical corrugations in graphene can cause electron-hole puddles, challenging the common belief that charged impurities are the main cause, using advanced density-functional calculations.

Contribution

It introduces a density-functional approach demonstrating that surface corrugations alone can induce electron-hole puddles in graphene.

Findings

Corrugations can account for puddles on larger length scales.

Charged impurities are not the sole cause of inhomogeneities.

Surface morphology influences local electronic properties.

Abstract

It is widely believed that carrier-density inhomogeneities ("electron-hole puddles") in single-layer graphene on a substrate like quartz are due to charged impurities located close to the graphene sheet. Here we demonstrate by using a Kohn-Sham-Dirac density-functional scheme that corrugations in a real sample are sufficient to determine electron-hole puddles on length scales that are larger than the spatial resolution of state-of-the-art scanning tunneling microscopy.