Abstract
The III-V narrowgap semiconductor InSb has properties such as low effective mass, high mobility, and strong spin-orbit coupling which make it an ideal material for spintronics. Recently there have been numerous device schemes that have been proposed for generating spin polarised currents for spin injection in quantum technologies. At the heart of these schemes is the quantum point contact (QPC) which requires nanoscale lithography and gated structures. Here we present a complete fabrication toolkit that employs focused ion beam (FIB) lithography as a flexible direct-write technique for rapid prototyping of QPCs. Two approaches for fabricating QPCs have been explored. The first method involves defining QPCs using direct etch writing of InSb quantum wells. A FIB assisted XeF2 chemistry has been used to form side gates with air gaps. The second technique uses FIB assisted deposition to form a siloxane gate dielectric, as well as direct-write of metalization using platinum to form split top gates. Compatibility of InSb with these processes has been confirmed by post-fabrication measurements of the electronic properties using Shubnikov de Haas and quantum Hall. The versatility of this direct-write technique makes it ideal as a rapid device prototyping tool.