InAs nanowire superconducting tunnel junctions： Quasiparticle spectroscopy, thermometry, and nanorefrigeration

• Published in: Nano research 2017-10, Vol.10 (10), p.3468-3475
• Main Authors: Mastomäki, Jaakko, Roddaro, Stefano, Rocci, Mirko, Zannier, Valentina, Ercolani, Daniele, Sorba, Lucia, Maasilta, Ilari J., Ligato, Nadia, Fornieri, Antonio, Strambini, Elia, Giazotto, Francesco
• Format: Article
• Language: English
• Subjects: Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Chemistry and Materials Science; Condensed Matter Physics; Electron distribution; InAs; Indium arsenides; Materials Science; Nanotechnology; Nanowires; Oxidation; Refrigeration; Research Article; Spectroscopy; Superconductivity; Thermometers; Thermometry; Tunnel junctions; 光谱测温; 准粒子; 半导体纳米线; 半导体纳米结构; 实验数据; 控制氧化; 超导隧道结
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-017-1558-7

We demonstrate an original method based on controlled oxidation for creating high-quality tunnel junctions between superconducting A1 reservoirs and InAs semiconductor nanowires （NWs）. We show clean tunnel characteristics with a current suppression by 〉4 orders of magnitude for a junction bias well below the A1 gap of △0≈ 200 μeV. The experimental data agree well with the Bardeen- Cooper-Schrieffer theoretical expectations for a superconducting tunnel junction. The studied devices employ small-scale tunnel contacts functioning as thermometers as well as larger electrodes that provide proof-of-principle active cooling of the electron distribution in the NWs. A peak refrigeration of approximately δT = 10 mK is achieved at a bath temperature of Tbath≈ 250-350 mK for our prototype devices. This method introduces important perspectives for the investigation of the thermoelectric effects in semiconductor nanostructures and for nanoscale refrigeration.