Description

Graphene, the first true two-dimensional material, still reveals the most remarkable transport properties among the growing class of two-dimensional materials. We here study the local transport properties of graphene using the method of scanning tunneling potentiometry. This allows us to image the voltage drop in the sample down to nanoscale. Our Graphene samples were prepared by a new method using polymer assisted sublimation growth. These samples show a very high homogeneity of the resistance on the nanoscale, but we find that the resistance can change by up to 270% at low temperatures for different stacking sequences of the 6H silicon carbide substrate. We show that this variation in resistance is caused by the distance between the graphene and the substrate. Our results experimentally quantify the impact of the graphene-substrate interaction on the local transport properties of graphene.