We report electrical transport measurements between a metallic state induced on the surface of an insulating zinc oxide film by an electric double-layer transistor and superconducting niobium electrode. A superconductor/electric double-layer transistor channel/superconductor was created that can be a superconductor/metallic state/superconductor junction and is expected to function as a Josephson junction. The metallic state on the zinc oxide surface and a low contact resistance between niobium and zinc oxide were realized by high carrier doping arising from the electric field effect of the electric double-layer transistor. However, there was no supercurrent through the metallic state at the junction down to a temperature of 0.3 K. Nevertheless, temperature variations of the differential resistance of the junction below the superconducting transition temperature suggest the existence of a superconducting proximity effect between the superconducting Nb and the channel of the zinc oxide-based electric double-layer transistor.
展开▼
