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

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• 作者：A. C. C. Drachmann ; H. J. Suominen ; M. Kjaergaard ; B. Shojaei ; C. J. Palmstrøm ; C. M. Marcus ; F. Nichele
• 刊名：Nano Letters
• 出版年：2017
• 出版时间：February 8, 2017
• 年：2017
• 卷：17
• 期：2
• 页码：1200-1203
• 全文大小：359K
• ISSN：1530-6992

文摘

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 reflections reveal near-unity transparency with an induced gap Δ* = 0.50 meV and a critical temperature of 7.8 K. Tunneling spectroscopy yields a hard induced gap in the InAs adjacent to the superconductor of Δ* = 0.43 meV with substructure characteristic of both Al and NbTi.