Shadow lithography for <i>in-situ</i> growth of generic semiconductor/superconductor devices

Current progress in Majorana and Andreev qubits and devices using semiconductor/superconductor nanowires is built on the hard proximity-induced superconducting gap obtained from epitaxial indium arsenide/aluminium interfaces. Devices are conventionally obtained by selectively etching superconductor segments from the semiconductor. However, this is currently only possible for InAs/Al hybrids, excluding the use of potentially more desirable materials (e.g. Nb, InSb) in functional devices. Here, we present a crystal growth platform based on three-dimensional structuring of growth substrates for synthesising semiconductor nanowires with in-situ patterned superconductor shells. The shadow lithography platform enables independent choice of material since etching is no longer required, and is highly flexible with regard to device geometry. We grow and characterise tunnel probe devices, Josephson junctions and Majorana islands using aluminium, niobium, tantalum and vanadium. The devices exhibit increased yield and electrostatic stability compared to etched devices, which we attribute to the obviation of damaging etch processes. The shadow lithography platform promises high yield, stable, reproducible Majorana devices using the best possible materials.