Fabrication of deep-sub-micrometer NbN/AlN/NbN epitaxial junctions on a Si-substrate. (5th November 2020)

• Record Type: Journal Article
• Authors: Qiu, Wei; Terai, Hirotaka
• Is Part Of: Applied physics express. Volume 13:Number 12(2020)
• Publication Date: 2020-11-05
• Subjects: NbN -- Epitaxial -- Tunnel junction -- qubit; Physics -- Periodicals; Technology -- Periodicals; 621.05
• DOI: 10.35848/1882-0786/abbfde
• Languages: English
• ISSNs: 1882-0778

Abstract

Abstract: We have developed a novel fabrication process for ultra-small, full-epitaxial NbN Josephson junctions on a TiN buffered silicon (Si) substrate. We use an electron beam lithography for junction definition followed by a reactive-ion-etch (RIE). A chemical mechanical polishing process and an RIE by using CHF3 gas formed reliable electrical contacts for the junction electrodes. All junctions, with a junction size down to 0.27 μ m in diameter, showed excellent current–voltage characteristics with a clear gap and small sub-gap leakage current. We have confirmed that the quality of the junctions was maintained after the removal of the SiO2 dielectric interlayer.