Josephson Junctions Via Anodization of Epitaxial Al on an InAs Heterostructure

TL;DR

This paper introduces a novel fabrication method for Josephson junctions using anodization of epitaxial aluminum on InAs heterostructures, which simplifies the process and produces high-quality junctions suitable for quantum computing applications.

Contribution

The paper presents a new anodization-based technique for defining Josephson junctions, avoiding wet-etching and enabling high-quality, selective oxidation in epitaxial Al-InAs heterostructures.

Findings

Observation of multiple Andreev reflections indicating high-quality junctions

Comparison showing differences in mobility and density between anodized and wet-etched Hall-bars

Potential for new fabrication approaches in junction-based qubit platforms

Abstract

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.