Ultra-high quality Nb/AlO sub x Nb tunnel junctions with epitaxial base layers

Conference · Fri Mar 01 04:00:00 EST 1991 · IEEE Transactions on Magnetics (Institute of Electrical and Electronics Engineers); (United States)

OSTI ID:6045519

Kirk, E C.G.; Blamire, M G; Somekh, R E; Evetts, J E ^[1]; Van Vechten, D; Lovellette, N N ^[2]

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1. Dept. of Materials Science and Metallurgy, Univ. of Cambridge, Pembroke Street, Cambridge CB2 3QZ (GB)
2. Naval Research Lab., Washington, DC (United States)

In this paper using an ultra-high vacuum DC sputtering system the authors have fabricated NB/AlO{sub x}/Nb tunnel junction devices with epitaxial Nb base layers. We have been investigating the improvements in device quality which can be achieved by heating the substrates during the growth of the tunnel barrier. By measuring the subgap characteristic under magnetic field at temperatures down to 0.4K, we show that for V {lt} {Delta}Nb the currents in devices with critical current densities in the range 10{sub 5}--10{sup 6} Am{sup {minus}2} follow closely the BCS prediction and show no extrinstic leakage current. The divergence of the curve for higher current densities and at higher voltages is discussed.

• OSTI ID: 6045519
• Report Number(s): CONF-900944--
• Conference Information: Journal Name: IEEE Transactions on Magnetics (Institute of Electrical and Electronics Engineers); (United States) Journal Volume: 27:2
• Country of Publication: United States
• Language: English

Related Subjects

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75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCS THEORY
CONTROL
CURRENT DENSITY
CURRENTS
DIFFUSION BARRIERS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ELEMENTS
FABRICATION
JUNCTIONS
LAYERS
LEAKAGE CURRENT
MAGNETIC FIELDS
METALS
NIOBIUM
PHYSICAL PROPERTIES
QUALITY CONTROL
SPUTTERING
SUPERCONDUCTING JUNCTIONS
SUPERCONDUCTIVITY
TRANSITION ELEMENTS
TUNNEL EFFECT
ULTRAHIGH VACUUM