Fabrication of high-quality topological insulator nanodevices from bulk-insulating air-sensitive Sb-Bi$_2$Se$_3$

Abstract

High-quality topological insulator (TI) materials are essential for the realization and detection of Majorana bound states (MBSs) in TI-superconductor hybrid platforms. Widely used compensated TIs exhibit substantial disorder and charge inhomogeneity, which may be detrimental for Majorana devices. In this regard, Sb-substituted Bi$_2$Se$_3$ (SBS) is promising, because it is non-compensated and yet achieves very low bulk carrier density. We systematically investigate the impact of thermal processing during microfabrication on the transport properties of SBS. We developed a room-temperature fabrication protocol that preserves the low carrier density of exfoliated SBS upon fabrication of Hall bar and nanowire devices as evidenced from the observation of quantum interference oscillations in nanowires, a large gate tunability, and clear signatures of weak antilocalization (WAL).