Ripples in epitaxial graphene

TL;DR

This paper investigates how the SiC substrate influences the structure of epitaxial graphene, revealing that substrate interactions induce nanostructuring and ripples in the graphene lattice, affecting its electronic properties.

Contribution

It provides combined ab initio calculations and STM experiments showing substrate-induced nanostructuration and ripples in epitaxial graphene's lattice.

Findings

Substrate induces strong nanostructuration of the interface carbon layer.

Ripples in the honeycomb lattice are generated by substrate interactions.

Nanostructuration propagates to the graphene layer, causing incommensurate ripples.

Abstract

Graphene outstanding properties directly come from its pecular electronic structure and thus from the honeycomb lattice symmetry. The way interaction with the substrate impact this lattice is of primary importance. This is peculiarly true for epitaxial graphene because of the SiC substrate. The advantage of this system that produces macroscopic samples in registry with a substrate could turn to a major drawback if the graphene lattice reveals to be strongly distorted. Extensive ab initio calculations supported by Scanning Tunneling Microscopy experiments, demonstrate here that the substrate indeed induces a strong nanostructuration of the interface carbon layer. It propagates to the above C layer where it generates incommensurate ripples in the honeycomb lattice.