High quality Nb/Al-AlOx/Nb Josephson junction

Journal Article · Sat Jun 15 04:00:00 EDT 1985 · Appl. Phys. Lett.; (United States)

DOI:https://doi.org/10.1063/1.95696· OSTI ID:5670145

Morohashi, S; Shinoki, F; Shoji, A; Aoyagi, M; Hayakawa, H

We have improved the quality of Nb/Al-AlOx/Nb Josephson junctions and obtained the most excellent junction characteristics ever obtained for all refractory Josephson junctions. The V/sub m/ values (the product of the critical current and the subgap resistance measured at 2 mV) are 88 mV at the critical current density I/sub j/ = 500 A/cm/sup 2/ and 72 mV at I/sub j/ = 1000 A/cm/sup 2/. The V/sub m/ values are larger than 40 mV up to I/sub j/ of 2400 A/cm/sup 2/. The high V/sub m/ values are important to obtain the low subgap leakage current and not to reduce the transfer current to the load in Josephson circuit. These characteristics have been achieved by improving the quality of the Nb film and optimizing the Al thickness. We have also confirmed that I/sub j/ can be controlled by both the oxidation pressure and time in the range of 40--4600 A/cm/sup 2/.

• Research Organization: Electrotechnical Laboratory, 1-1-4 Umezono, Sakura-mura, Niihari-gun, Ibaraki 305, Japan
• OSTI ID: 5670145
• Journal Information: Appl. Phys. Lett.; (United States), Journal Name: Appl. Phys. Lett.; (United States) Vol. 46:12; ISSN APPLA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CRITICAL CURRENT
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
FABRICATION
JOSEPHSON JUNCTIONS
JUNCTIONS
LEAKAGE CURRENT
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
OPTIMIZATION
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PERFORMANCE
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
SUPERCONDUCTING JUNCTIONS
TRANSITION ELEMENT COMPOUNDS
TUNNEL EFFECT