The relation between the macroscopic charge transport properties and the microscopic carrier distribution inside conducting channels is one of the central issues in physics and future applications of graphene devices (GDs). With scanning gate microscopy (SGM) a powerful experimental tool to probe the transport properties of a device through local gating, we find strong local charge accumulation at the edges of a GD. At high carrier densities, SGM signals are an order of magnitude larger at the edges of GDs than inside the bulk channel. We developed a theoretical model relating the conductance enhancement observed at the edges of GDs to the opening of an additional conduction channel. The channel is induced by the band bending of graphene edge states caused and controlled by the edge-charge accumulation and the local tip-gating effect.
Citation: Nano Letters
Pub Type: Journals
graphene, scanning gate microscopy, atomic force microscopy