Proximity Effect Transfer from NbTi into a Semiconductor Heterostructure via Epitaxial Aluminum

Abstract

We demonstrate the transfer of the superconducting properties of NbTi---a large-gap high-critical-field superconductor---into an InAs heterostructure via a thin intermediate layer of epitaxial Al. Two device geometries, a Josephson junction and a gate-defined quantum point contact, are used to characterize interface transparency and the two-step proximity effect. In the Josephson junction, multiple Andreev reflection reveal near-unity transparency, with an induced gap ${\Delta }^{\ast }=0.50\mathrm{meV}$ and a critical temperature of $7.8\mathrm{K}$. Tunneling spectroscopy yields a hard induced gap in the InAs adjacent to the superconductor of ${\Delta }^{\ast }=0.43\mathrm{meV}$ with substructure characteristic of both Al and NbTi.

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• Spin-orbit coupling effects in zinc-blende InSb and wurtzite InAs nanowires: Realistic calculations with multiband $\vec{k}\cdot \vec{p}$ method
• Coherent Josephson thermodynamic cycles
• Full electrostatic control of quantum interference in an extended trenched Josephson junction
• Progress in superconductor-semiconductor topological Josephson junctions
• Supercurrent parity-meter in a nanowire Cooper-pair transistor
• Mobility exceeding 100,000 cm${}^2$/Vs in modulation-doped shallow InAs quantum wells coupled to epitaxial aluminum
• Anodic Oxidation of Epitaxial Superconductor-Semiconductor Hybrids
• InAs on Insulator: A New Platform for Cryogenic Hybrid Superconducting Electronics
• Development of a Nb-based semiconductor-superconductor hybrid platform
• Josephson Field Effect Transistors with InAs on Insulator and High Permittivity Gate Dielectrics
• Planar Josephson junction devices with narrow superconducting strips: Topological properties and optimization
• Gate-controlled Supercurrent in Ballistic InSb Nanoflag Josephson Junctions