Emergent Cavity Junction around Metal-on-Graphene Contacts

Abstract

Harnessing graphene’s electronic properties for practical applications requires a comprehensive understanding of its interfaces with metal contacts, which are essential for device integration. Traditionally, the metal–graphene (MG) interface has been considered straightforward, primarily affecting graphene’s work function through doping mechanisms. However, as device dimensions shrink to the sub-micrometer scale, subtle interfacial phenomena become increasingly significant. Here, we investigate transport phenomena occurring at high-quality, sub-micrometer metal contacts on graphene. Through transport measurements, electrostatic simulations, and first-principles calculations, we demonstrate that the metal contact induces a localized n-doped radial cavity, defined cooperatively by the metal-induced electrostatic potential and Klein tunneling. This mechanism leads to quantized energy states and secondary resistance peaks as a function of graphene doping that decrease with increasing contact size. In the presence of a perpendicular magnetic field, the cavity hosts a distinct set of Landau levels, resulting in the formation of a secondary bulk interacting with the intrinsic graphene bulk. This interplay enables the direct observation of topological edge states arising from bulk-boundary correspondence. Our results provide an improved understanding of metal–graphene interfaces, highlighting fundamental properties of graphene relevant for graphene-based nanoelectronic devices.