Josephson junctions via anodization of epitaxial Al on an InAs heterostructure

Abstract

We combine electron beam lithography and masked anodization of epitaxial aluminum to define tunnel junctions via selective oxidation, alleviating the need for wet-etch processing or direct deposition of dielectric materials. Applying this technique to define Josephson junctions in proximity-induced superconducting Al-InAs heterostructures, we observe multiple Andreev reflections in transport experiments, indicative of a high quality junction. We further compare the mobility and density of Hall-bars defined via wet etching and anodization. These results may find utility in uncovering better fabrication approaches to junction-based qubit platforms.