Substrate induced nanoscale resistance variation in epitaxial graphene

TL;DR

This study uses scanning tunneling potentiometry to analyze nanoscale resistance variations in epitaxial graphene, revealing substrate interactions significantly influence local transport properties and resistance heterogeneity.

Contribution

It provides the first quantitative analysis linking substrate stacking sequence and graphene-substrate distance to local resistance variations in epitaxial graphene.

Findings

Resistance variation up to 270% at low temperatures

Correlation between resistance and substrate stacking sequence

Impact of graphene-substrate interaction on transport properties

Abstract

Graphene, the first true two-dimensional material still reveals the most remarkable transport properties among the growing class of two-dimensional materials. Although many studies have investigated fundamental scattering processes, the surprisingly large variation in the experimentally determined resistances associated with a localized defect is still an open issue. Here, we quantitatively investigate the local transport properties of graphene prepared by polymer assisted sublimation growth (PASG) using scanning tunneling potentiometry. PASG graphene is characterized by a spatially homogeneous current density, which allows to analyze variations in the local electrochemical potential with high precision. We utilize this possibility by examining the local sheet resistance finding a significant variation of up to 270% at low temperatures. We identify a correlation of the sheet resistance with the stacking sequence of the 6H-SiC substrate as well as with the distance between the graphene sheet and the substrate. Our results experimentally quantify the strong impact of the graphene-substrate interaction on the local transport properties of graphene.