Top-Down Fabrication of Bulk-Insulating Topological Insulator Nanowires for Quantum Devices
Matthias Rößler, Dingxun Fan, Felix Münning, Henry F. Legg, Andrea Bliesener, Gertjan Lippertz, Anjana Uday, Roozbeh Yazdanpanah, Junya Feng, A. A. Taskin, Yoichi Ando
Abstract
In a nanowire (NW) of a three-dimensional topological insulator (TI), the quantum confinement of topological surface states leads to a peculiar sub-band structure that is useful for generating Majorana bound states. Top-down fabrication of TINWs from a high-quality thin film would be a scalable technology with great design flexibility, but there has been no report on top-down-fabricated TINWs where the chemical potential can be tuned to the charge neutrality point (CNP). Here we present a top-down fabrication process for bulk-insulating TINWs etched from high-quality (Bi 1– x Sb x ) 2 Te 3 thin films without degradation. We show that the chemical potential can be gate-tuned to the CNP, and the resistance of the NW presents characteristic oscillations as functions of the gate voltage and the parallel magnetic field, manifesting the TI-sub-band physics. We further demonstrate the superconducting proximity effect in these TINWs, preparing the groundwork for future devices to investigate Majorana bound states.