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arXiv · 1611.10166

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

A. C. C. Drachmann·H. J. Suominen·M. Kjaergaard·B. Shojaei·C. J. Palmstrøm·C. M. Marcus·F. Nichele
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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 $Δ^*=0.50~\mathrm{meV}$ and a critical temperature of $7.8~\mathrm{K}$. Tunneling spectroscopy yields a hard induced gap in the InAs adjacent to the superconductor of $Δ^*=0.43~\mathrm{meV}$ with substructure characteristic of both Al and NbTi.

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A. C. C. Drachmann, H. J. Suominen, M. Kjaergaard, B. Shojaei, C. J. Palmstrøm, C. M. Marcus, F. Nichele. 2016-11-30. Proximity Effect Transfer from NbTi into a Semiconductor Heterostructure via Epitaxial Aluminum. https://doi.org/10.1021/acs.nanolett.6b04964

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