Atomic Structure of Graphene on SiO2

TL;DR

This study uses advanced microscopy to uncover atomic-scale details of graphene on SiO2, revealing substrate effects and surface perturbations, with a new cleaning method enabling clearer imaging.

Contribution

First atomic-resolution imaging of graphene on SiO2 showing substrate-induced lattice perturbations and a novel cleaning process for pristine graphene surfaces.

Findings

Atomic resolution STM images show symmetry-breaking perturbations.

Structural corrugations partially follow the substrate.

Cleaning process improves imaging clarity.

Abstract

We employ scanning probe microscopy to reveal atomic structures and nanoscale morphology of graphene-based electronic devices (i.e. a graphene sheet supported by an insulating silicon dioxide substrate) for the first time. Atomic resolution STM images reveal the presence of a strong spatially dependent perturbation, which breaks the hexagonal lattice symmetry of the graphitic lattice. Structural corrugations of the graphene sheet partially conform to the underlying silicon oxide substrate. These effects are obscured or modified on graphene devices processed with normal lithographic methods, as they are covered with a layer of photoresist residue. We enable our experiments by a novel cleaning process to produce atomically-clean graphene sheets.