An investigation of superconductor/semiconductor/superconductor Josephson junctions with separations between the Nb superconducting electrodes down to 20 nm is presented. To achieve such short distances, a preparation technique employing an anodic Nb oxide film as a spacer has been developed. The Nb electrodes are coupled through the quasi two-dimensional electron gas in the native inversion layer at the surface of p-type InAs. High characteristic voltages up to 1.35 mV at T=2 K are observed. A sensitive dependence of the magnitude of the characteristic voltage on interface quality is demonstrated. Good agreement is found between the experimental temperature dependence of the critical current and a theoretical model valid for short weak links.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.