HTS Surface-Modified Junctions with Integrated Ground-Planes for SFQ Circuits

Yoshihisa SOUTOME  Tokuumi FUKAZAWA  Kazuo SAITOH  Akira TSUKAMOTO  Kazumasa TAKAGI  

IEICE TRANSACTIONS on Electronics   Vol.E85-C   No.3   pp.759-763
Publication Date: 2002/03/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Issue on Superconductive Electronics)
Category: Junctions and Processing
high-temperature-superconductor,  Josephson junction,  SFQ circuit,  ramp-edge junction,  groundplane,  

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We fabricated ramp-edge junctions with barriers by modifying surface and integrating ground-planes. The fabricated junctions had current-voltage characteristics consistent with the resistive shunted-junction model. We also obtained a 1-sigma spread in the critical current of 7.9% for 100 junctions at 4.2 K. The ground-plane reduced the sheet inductance of a stripline by a factor of 3. The quality of the ground-plane was improved by using an anneal in oxygen atmosphere after fabrication. The sheet inductance of a counter-electrode with a ground-plane was 1.0 pH per square at 4.2 K.