Crystalline oxide tunnel barriers formed by thermal oxidation of aluminum overlayers on superconductor surfaces

Journal Article · Mon Sep 15 04:00:00 EDT 1986 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.337209· OSTI ID:5393289

Braginski, A I; Talvacchio, J; Janocko, M A; Gavaler, J R

Crystalline oxide tunnel barriers were formed by thermal oxidation of thin Al overlayers on single-crystal and polycrystalline films of four refractory superconductors: Nb, Mo-Re, Nb/sub 3/Sn, and NbN. Tunnel junctions were fabricated mostly with Pb-Bi and also with Nb, Mo-Re, and NbN counterelectrodes. Differences in the base electrode crystallinity, surface roughness, oxygen affinity, and native oxide properties influenced the average barrier height, the subgap and normal (above-gap) conductance and the occurrence of microshorts. An effect of the overlayer deposition method (evaporation versus sputtering) was also noticed. The comparison of properties of barriers obtained on different base electrodes and of those amorphized by ion milling lead to the observation that amorphous barriers are more uniform and representative of Al/sub 2/O/sub 3/ than the crystalline and epitaxial barriers. The properties of the latter are defined, in part, by the shunting native oxide channels which result from a nonuniform coverage of the base electrode.

• Research Organization: Westinghouse RandD Center, Pittsburgh, Pennsylvania 15235
• OSTI ID: 5393289
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 60:6; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
420201 -- Engineering-- Cryogenic Equipment & Devices
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ALUMINIUM
BISMUTH ALLOYS
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
ELECTRODES
ELEMENTS
FABRICATION
INTERFACES
JUNCTIONS
LAYERS
METALS
NIOBIUM
NIOBIUM COMPOUNDS
NIOBIUM NITRIDES
NITRIDES
NITROGEN COMPOUNDS
OXIDATION
PNICTIDES
POTENTIALS
REFRACTORY METAL COMPOUNDS
RHENIUM
SPUTTERING
SUPERCONDUCTING JUNCTIONS
TIN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNNEL EFFECT