  We combine electron beam lithography and masked anodization of epitaxial
aluminium 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 new fabrication
approaches to junction-based qubit platforms.
