By Topic

Characterization of Nanometer Step Structure Formation During the Fabrication of Large-Scale Superconducting-Tunnel-Junction Array Detectors

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$33 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

3 Author(s)
Masahiro Ukibe ; Nat. Inst. of Adv. Ind. Sci. & Technol., Tsukuba, Japan ; Akira Kurokawa ; Masataka Ohkubo

Superconducting-tunnel-junction (STJ) array detectors with an effective sensitive area of 4 mm2 were fabricated for mass spectrometry. An array detector has one hundred Nb/Al/AlOx/Al/Nb junctions with a 200 mum-square sensitive area. The junctions are quasi-horizontally arranged on a 10 mm-square chip. In the course of fabrication processes, we have found that an anomalous nanometer-step structure appears within the junctions located in the outer region of the array detectors at a specific stage of the fabrication processes. The anomalous steps cause an increase of the leakage current from ~5 nA to a few 100 nA. In order to characterize and prevent the step structure formation, we performed structural analyses with atomic force microscopy, interference microscopy, differential interference contrast microscopy, and transmission electron microscopy. Vertical fault and blister formations were identified in the junctions around the periphery of the array arrangement even on a low stress sputtering condition of 40 MPa. In addition, it is reasonable that a horizontal slip in the AlOx barrier layer is induced by a nanoscale plastic deformation, which causes the large increase of the leakage current.

Published in:

IEEE Transactions on Applied Superconductivity  (Volume:19 ,  Issue: 3 )