Optimizing electronic structure and quantum transport at the graphene-Si(111) interface: An ab-initio density-functional study

TL;DR

This study uses ab initio density functional calculations to explore how a graphene monolayer interacts with the Si(111) surface, revealing a wavy structure that impacts electronic and transport properties.

Contribution

It provides new insights into the atomic-scale interaction and structural adaptation of graphene on Si(111), including the formation of a wavy structure and its effects on transport.

Findings

Graphene forms covalent bonds with Si(111) surface.

Wavy graphene structure accommodates lattice mismatch.

High mobility along ridges with efficient carrier injection.

Abstract

We use ab initio density functional calculations to determine the interaction of a graphene monolayer with the Si(111) surface. We found that graphene forms strong bonds to the bare substrate and accommodates the 12% lattice mismatch by forming a wavy structure consisting of free-standing conductive ridges that are connected by ribbon-shaped regions of graphene, which bond covalently to the substrate. We perform quantum transport calculations for different geometries to study changes in the transport properties of graphene introduced by the wavy structure and bonding to the Si substrate. Our results suggest that wavy graphene combines high mobility along the ridges with efficient carrier injection into Si in the contact regions.