InAs nanowire with epitaxial aluminium as a single-electron transistor with fixed tunnel barriers

TL;DR

This paper presents a novel fabrication method for InAs nanowire single-electron transistors with epitaxial aluminium and fixed tunnel barriers, demonstrating superconducting gaps and stable device behavior.

Contribution

It introduces a new approach to create multichannel contacts with fixed tunnel barriers and shows how to prevent unwanted quantum dots in InAs nanowire devices.

Findings

Devices exhibit a hard superconducting gap.

Multichannel contacts provide a new platform for studies.

Unwanted quantum dots can be effectively prevented.

Abstract

We report on fabrication of single-electron transistors using InAs nanowires with epitaxial aluminium with fixed tunnel barriers made of aluminium oxide. The devices exhibit a hard superconducting gap induced by the proximized aluminium cover shell and they behave as metallic single-electron transistors. In contrast to the typical few channel contacts in semiconducting devices, our approach forms opaque multichannel contacts to a semiconducting wire and thus provides a complementary way to study them. In addition, we confirm that unwanted extra quantum dots can appear at the surface of the nanowire. Their presence is prevented in our devices, and also by inserting a protective layer of GaAs between the InAs and Al, the latter being suitable for standard measurement methods.