Fully in-situ InAs nanowire Josephson junctions by selective-area growth and shadow evaporation

Abstract

Josephson junctions based on InAs semiconducting nanowires and Nb superconducting electrodes are fabricated in-situ by a special shadow evaporation scheme for the superconductor electrode. Compared to other metallic superconductors such as Al, Nb has the advantage of a larger superconducting gap which allows operation at higher temperatures and magnetic fields. Our junctions are fabricated by shadow evaporation of Nb on pairs of InAs nanowires grown selectively on two adjacent tilted Si (111) facets and crossing each other at a small distance. The upper wire relative to the deposition source acts as a shadow mask determining the gap of the superconducting electrodes on the lower nanowire. Electron microscopy measurements show that the fully in-situ fabrication method gives a clean InAs/Nb interface. A clear Josephson supercurrent is observed in the current-voltage characteristics, which can be controlled by a bottom gate. The excess current of 0.68 indicates a high junction transparency. Under microwave radiation, pronounced integer Shapiro steps are observed suggesting a sinusoidal current-phase relation. Owing to the large critical field of Nb, the Josephson supercurrent can be maintained to magnetic fields exceeding 1 T. Our results show that in-situ prepared Nb/InAs nanowire contacts are very interesting candidates for superconducting quantum circuits requiring large magnetic fields.

9 pages, 6 figures, supplementary information

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Cited by in corpus (12)

• Selective area epitaxy of PbTe-Pb hybrid nanowires on a lattice-matched substrate
• Epitaxial Superconductor-Semiconductor Two-Dimensional Systems for Superconducting Quantum Circuits
• Measurements of Phase Dynamics in Planar Josephson Junctions and SQUIDs
• Progress in superconductor-semiconductor topological Josephson junctions
• Microwave spectroscopy of Andreev states in InAs nanowire-based hybrid junctions using a flip-chip layout
• InAs/MoRe hybrid semiconductor/superconductor nanowire devices
• Microscopic theory of the current-voltage characteristics of Josephson tunnel junctions
• Nonlinearity of transparent SNS weak links decreases sharply with length
• Photon assisted tunneling of high order multiple Andreev reflections in epitaxial nanowire Josephson junctions
• Development of a Nb-based semiconductor-superconductor hybrid platform
• Fate of the superconducting state in floating islands of hybrid nanowire devices
• Superconducting bistability in floating Al islands of hybrid Al/InAs nanowires