Thermoelectric Imaging of Epitaxial Graphene

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. Using this imaging technique, we discovered a defect-mediated dimensional evolution of strain-response patterns in epitaxial graphene with increasing thickness.