KPFM distinguishes between graphene and boron nitride on a copper substrate

KPFM surface potential overlaid on topography for flakes of boron nitride (triangles) and graphene (circles) grown on a copper foil substrate. At a single atom thick, the flakes cannot be resolved in the topography images due to the roughness of the copper substrate. However, they are readily identified by variations in the SKPM tip-sample potential. The surface potential also distinguishes between the graphene and boron nitride and reveals boron nitride regions growing epitaxially out from the graphene islands. Scan size 60 ?m. Imaged on the MFP-3D AFM. Sample courtesy N. Wilson (University of Warwick).