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Pb-alloy film preparation technique for Josephson junctions

Journal Article · · J. Appl. Phys.; (United States)
DOI:https://doi.org/10.1063/1.335449· OSTI ID:6101892
A Pb-alloy film preparation technique is proposed and applied to high-reliability Josephson junctions with small threshold current spreads. Fine-grained films with the average grain sizes as small as 30 nm are obtained. This is accomplished by condensing Pb, In, and Au molecular beams onto liquid-nitrogen-cooled substrates. Fine grains result from AuIn/sub 2/ particles being dispersed finely and uniformly in alloy films. Josephson junctions are fabricated using these fine-grained films as base electrodes. The threshold current standard deviation is reduced to 2.4%. This is due to the fine grain size and surface passivation treatment for the base electrodes. The cumulative failure is found to be less than 0.13% after 8400 thermal cycles between 4.2 K and room temperature. This is the best value reported thus far. This technique achieves fine-grained metal alloy films providing new properties. These properties promise to aid development of high-performance Josephson IC's.
Research Organization:
Atsugi Electrical Communication Laboratory, Nippon Telegraph and Telephone Public Corporation, Ono, Atsugi, Kanagawa 243-01, Japan
OSTI ID:
6101892
Journal Information:
J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 57:7; ISSN JAPIA
Country of Publication:
United States
Language:
English