Comparison of Nanobridge Lithography Techniques for Nanoscale SQUID Devices

NanoSQUIDS incorporating nanobridges as the Josephson element are desirable since their small dimensions mean they can be situated in close proximity to very small, highly localised magnetic moments for high spin sensitivity. Key to achieving the necessary dimensions are the lithographic technologies used to fabricate the nanobridges. Here we present characterisation of Nb nanoSQUIDs incorporating nanobridges fabricated by three different techniques: neon focused ion beam (FIB) lithography, gallium FIB lithography and e-beam lithography (EBL). We discuss the critical currents and voltage-current characteristics achieved by each technique at various temperatures for a range of nanobridge widths, and discuss the corresponding nanoSQUID voltage modulation and potential applications.