MBE Growth of Al/InAs and Nb/InAs Superconducting Hybrid Nanowire Structures

Abstract

We report on \textit{in situ} growth of crystalline Al and Nb shells on InAs nanowires. The nanowires are grown on Si(111) substrates by molecular beam epitaxy (MBE) without foreign catalysts in the vapor-solid mode. The metal shells are deposited by electron-beam evaporation in a metal MBE. High quality supercondonductor/semiconductor hybrid structures such as Al/InAs and Nb/InAs are of interest for ongoing research in the fields of gateable Josephson junctions and quantum information related research. Systematic investigations of the deposition parameters suitable for metal shell growth are conducted. In case of Al, the substrate temperature, the growth rate and the shell thickness are considered. The substrate temperature as well as the angle of the impinging deposition flux are explored for Nb shells. The core-shell hybrid structures are characterized by electron microscopy and x-ray spectroscopy. Our results show that the substrate temperature is a crucial parameter in order to enable the deposition of smooth Al layers. Contrary, Nb films are less dependent on substrate temperature but strongly affected by the deposition angle. At a temperature of 200°C Nb reacts with InAs, dissolving the nanowire crystal. Our investigations result in smooth metal shells exhibiting an impurity and defect free, crystalline superconductor/InAs interface. Additionally, we find that the superconductor crystal structure is not affected by stacking faults present in the InAs nanowires.

8 pages, 10 figures, 1 table

References in corpus (7)

• Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
• Evidence of Majorana fermions in an Al - InAs nanowire topological superconductor
• Epitaxy of Semiconductor-Superconductor nanowires
• Tunable Supercurrent Through Semiconductor Nanowires
• Strong tuning of Rashba spin orbit interaction in single InAs nanowires
• Tunable effective g-factor in InAs nanowire quantum dots
• Fermi surface topology and negative longitudinal magnetoresistance observed in centrosymmetric NbAs2 semimetal

Cited by in corpus (14)

• Realizing Majorana zero modes in superconductor-semiconductor heterostructures
• Engineering Hybrid Epitaxial InAsSb/Al Nanowire Materials for Stronger Topological Protection
• Epitaxial Pb on InAs nanowires
• Shadow epitaxy for in-situ growth of generic semiconductor/superconductor devices
• In Situ Epitaxy of Pure Phase Ultra-Thin InAs-Al Nanowires for Quantum Devices
• Dependence of the electronic structure of the EuS/InAs interface on the bonding configuration
• Fully in-situ InAs nanowire Josephson junctions by selective-area growth and shadow evaporation
• Structure Prediction of Epitaxial Inorganic Interfaces by Lattice and Surface Matching with Ogre
• Superconductivity and parity preservation in as-grown In islands on InAs nanowires
• Hard-gap spectroscopy in a self-defined mesoscopic InAs/Al nanowire Josephson junction
• Nonlinearity of transparent SNS weak links decreases sharply with length
• InP/GaSb core-shell nanowires: a novel hole-based platform with strong spin-orbit coupling for full-shell hybrid devices
• Development of a Nb-based semiconductor-superconductor hybrid platform
• Phase-controlled minimal Kitaev chain in multiterminal Josephson junctions