Phase transformation-induced superconducting aluminium-silicon alloy rings

TL;DR

This paper reports the formation of superconducting aluminium-silicon alloy nanowires via phase transformation, demonstrating their structural properties and observing quantum magnetoresistance oscillations in a mesoscopic ring.

Contribution

It introduces a novel phase transformation process to create smooth, conformal Al-Si alloy nanowires with superconducting properties on SOI platforms, advancing quantum device fabrication.

Findings

Formation of Al-Si alloy nanowires through phase transformation.

Observation of fluxoid quantization in superconducting rings.

Nanowires exhibit smooth walls and conformal geometry.

Abstract

The development of a materials platform that exhibits both superconducting and semiconducting properties is an important endeavour for a range of emerging quantum technologies. We investigate the formation of superconductivity in nanowires fabricated with silicon-on-insulator (SOI). Aluminium from deposited contact electrodes is found to interdiffuses with the Si nanowire structures to form an Al-Si alloy along the entire length of the predefined nanowire device over micron length scales at temperatures well below that of the Al-Si eutectic. The resultant transformed nanowire structures are layered in geometry with a continuous Al-Si alloy wire sitting on the buried oxide of the SOI and a residual Si cap sitting on top of the wire. The phase transformed material is conformal with any predefined device patterns and the resultant structures are exceptionally smooth-walled compared to similar nanowire devices formed by silicidation processes. The superconducting properties of a mesoscopic AlSi ring formed on a SOI platform are investigated. Low temperature magnetoresistance oscillations, quantized in units of the fluxoid, h/2e, are observed.