Perspectives of miniaturization of β-Ga2O3 devices with graphene electrodes

Micrometer-scale circular graphene/β-Ga2O3 structures are fabricated by transferring graphene layers to (2‾01) and (010) bulk gallium oxide substrates. Focused ion beam etching is used to downscale the area of the graphene/β-Ga2O3 junctions, and a nanoprobe-based approach is employed for their electrical characterization in the chamber of the scanning electron microscope. Using this approach, the impact of defects in graphene on the electrical characteristics of the junctions is suppressed. A significant difference between the structures fabricated on (2‾01) and (010) gallium oxide surfaces is further demonstrated. By numerical fitting of the measured data, several electric charge transport mechanisms are distinguished depending on the applied bias and orientation of the gallium oxide surface.