Superconductor/semiconductor-nanowire hybrid structures can serve as versatile building blocks to realize Majorana circuits or superconducting qubits based on quantized levels such as Andreev qubits. For all these applications it is essential that the superconductor-semiconductor interface is as clean as possible. Furthermore, the shape and dimensions of the superconducting electrodes needs to be precisely controlled. We fabricated self-defined InAs/Al core/shell nanowire junctions by a fully in-situ approach, which meet all these criteria. Transmission electron microscopy measurements confirm the sharp and clean interface between the nanowire and the in-situ deposited Al electrodes which were formed by means of shadow evaporation. Furthermore, we report on tunnel spectroscopy, gate and magnetic field-dependent transport measurements. The achievable short junction lengths,the observed hard-gap and the magnetic field robustness make this new hybrid structure very attractive for applications which rely on a precise control of the number of sub-gap states, like Andreev qubits or topological systems.
@article{arxiv.2004.09839,
title = {Hard-gap spectroscopy in a self-defined mesoscopic InAs/Al nanowire Josephson junction},
author = {Patrick Zellekens and Russell Deacon and Pujitha Perla and H. Aruni Fonseka and Timm Moerstedt and Steven A. Hindmarsh and Benjamin Bennemann and Florian Lentz and Mihail Ion Lepsa and Ana M. Sanchez and Detlev Grützmacher and Koji Ishibashi and Thomas Schäpers},
journal= {arXiv preprint arXiv:2004.09839},
year = {2020}
}
Comments
9 pages, 6 figures. Inclusion of additional TEM and EDX data