Fabrication of Nb/AlOx/Nb Josephson Tunnel Junctions by Sputtering Apparatus with Load-Lock System

Akiyoshi NAKAYAMA  Naoki INABA  Shigenori SAWACHI  Kazunari ISHIZU  Yoichi OKABE  

IEICE TRANSACTIONS on Electronics   Vol.E77-C   No.8   pp.1164-1168
Publication Date: 1994/08/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Superconducting Devices)
Category: LTS
Josephson junctions,  tunnel barrier,  Nb,  load-lock system,  substrate temperature,  

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We have fabricated Nb/AlOx/Nb Josephson tunnel junctions by a sputtering apparatus with a load-lock system. This sputtering apparatus had the sub chamber for preparation and the main chamber for sputtering. The substrate temperature was confirmed to be kept less than 85 during Nb sputtering at the deposition rate of 1.18 nm/s for 7 minutes. The junctions that had 50µm50 µm area successfully showed the Vm value (the product of the critical current and the subgap resistance at 2 mV) as high as 50 mV at the current density of 100 A/cm2.