Epitaxy of Semiconductor-Superconductor nanowires

TL;DR

This paper demonstrates epitaxial growth of semiconductor-superconductor nanowires with atomically uniform interfaces, enabling improved device performance for superconducting electronics and topological applications.

Contribution

It introduces a molecular beam epitaxy method for growing InAs/Al nanowires with epitaxially matched interfaces, advancing controlled nanostructure fabrication.

Findings

Achieved atomically uniform semiconductor-superconductor interfaces.

Provided a theoretical model for metal grain growth kinetics.

Potentially solved the soft-gap problem in hybrid structures.

Abstract

Controlling the properties of semiconductor/metal interfaces is a powerful method for designing functionality and improving the performance of electrical devices. Recently semiconductor/superconductor hybrids have appeared as an important example where the atomic scale uniformity of the interface plays a key role for the quality of the induced superconducting gap. Here we present epitaxial growth of semiconductor-metal core-shell nanowires by molecular beam epitaxy, a method that provides a conceptually new route to controlled electrical contacting of nanostructures and for designing devices for specialized applications such as topological and gate-controlled superconducting electronics. Our materials of choice, InAs/Al, are grown with epitaxially matched single plane interfaces, and alternative semiconductor/metal combinations allowing epitaxial interface matching in nanowires are discussed. We formulate the grain growth kinetics of the metal phase in general terms of continuum parameters and bicrystal symmetries. The method realizes the ultimate limit of uniform interfaces and appears to solve the soft-gap problem in superconducting hybrid structures.