Thermoelectric imaging of structural disorder in epitaxial graphene

TL;DR

This paper demonstrates that local thermoelectric measurements can be used as a high-resolution imaging technique to detect atomic-scale structural disorder in epitaxial graphene, revealing defects and domain wall patterns.

Contribution

It introduces a novel thermoelectric imaging method for atomic-scale structural disorder detection in epitaxial graphene, enhancing understanding of defect-induced electronic variations.

Findings

Identified point defects in epitaxial graphene's first layer.

Uncovered soliton-like domain wall patterns between stacking regions.

Demonstrated high sensitivity of thermoelectric signals to local density of states.

Abstract

Heat is a familiar form of energy transported from a hot side to a colder side of an object, but not a notion associated with microscopic measurements of electronic properties. A temperature difference within a material causes charge carriers, electrons or holes, to diffuse along the temperature gradient inducing a thermoelectric voltage. Here we show that local thermoelectric measurements can yield high sensitivity imaging of structural disorder on the atomic and nanometre scales. The thermopower measurement acts to amplify the variations in the local density of states at the Fermi-level, giving high differential contrast in thermoelectric signals. Using this imaging technique, we uncovered point defects in the first layer of epitaxial graphene, which generate soliton-like domain wall line patterns separating regions of the different interlayer stacking of the second graphene layer.