Development of a Nb-based semiconductor-superconductor hybrid platform

Abstract

Semiconductor-superconductor hybrid materials are used as a platform to realise Andreev bound states, which hold great promise for quantum applications. These states require transparent interfaces between the semiconductor and superconductor, which are typically realised by in-situ deposition of an Al superconducting layer. Here we present a hybrid material based on an InAs two-dimensional electron gas (2DEG) combined with in-situ deposited Nb and NbTi superconductors, which offer a larger operating range in temperature and magnetic field due to their larger superconducting gap. We overcome the inherent difficulty associated with the formation of an amorphous interface between III-V semiconductors and Nb-based superconductors by introducing a 7 nm Al interlayer. The Al interlayer provides an epitaxial connection between an in-situ magnetron sputtered Nb or NbTi thin film and a shallow InAs 2DEG. This metal-to-metal epitaxy is achieved by optimization of the material stack and results in an induced superconducting gap of approximately 1 meV, determined from transport measurements of superconductor-semiconductor Josephson junctions. This induced gap is approximately five times larger than the values reported for Al-based hybrid materials and indicates the formation of highly-transparent interfaces that are required in high-quality hybrid material platforms.

References in corpus (8)

• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Hard gap in epitaxial semiconductor-superconductor nanowires
• Transparent Semiconductor-Superconductor Interface and Induced Gap in an Epitaxial Heterostructure Josephson Junction
• Anomalous Fraunhofer Interference in Epitaxial Superconductor-Semiconductor Josephson Junctions
• Proximity Effect Transfer from NbTi into a Semiconductor Heterostructure via Epitaxial Aluminum
• Toward durable Al-InSb hybrid heterostructures via epitaxy of 2ML interfacial InAs screening layers
• Strained single-crystal Al2O3 grown layer-by-layer on Nb (110) thin films
• Observation of an Abrupt 3D-2D Morphological Transition in Thin Al Layers Grown by MBE on InGaAs surface

Cited by in corpus (4)

• Josephson Field Effect Transistors with InAs on Insulator and High Permittivity Gate Dielectrics
• Entangled Photon-Pair Emission in Waveguide Circuit QED from a Cooper Pair Splitter
• Impact of Layer Structure and Strain on Morphology and Electronic Properties of InAs Quantum Wells on InP (001)
• Hybrid superinductance with Al/InAs