Shadow mask platform for in-situ patterning of superconductor on InAs nanowires

I present a shadow mask method for patterning the superconductor layer during deposition directly after VLS InAs nanowire growth. This allowed us to fabricate functional devices without need to develop specific etches and/or lithography techniques for each material. The method thus streamlines growth and fabrication while minimizing the risk of materials degradation during post-processing. We have demonstrated several key architectures including tunnel probes, Josephson Junctions and Majorana islands. These devices facilitated characterization of induced superconductivity properties in InAs nanowires, and provide insights into the requirements for obtaining a hard superconducting gap. Also of interest was the nanoscale superconducting properties of each material since the critical temperatures and critical magnetic fields differ strongly from bulk values. In particular, the materials we studied show dramatically increased out-of-plane critical field compared to aluminium, which is highly desirable for many proposed applications in topological superconductivity. The ability to fabricate devices based on a wide variety of interfaces broadens the scope for future applications of superconductor/semiconductor hybrid devices.

Elia Strambini - elia.strambini@nano.cnr.it