Artificial oxide barriers for NbN tunnel junctions

Journal Article · Sun Dec 15 04:00:00 EST 1985 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.336234· OSTI ID:5031994

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

Superconducting tunnel junctions have been prepared with NbN-base electrodes, oxidized Al or Mg tunnel barriers, and NbN or Pb counterelectrodes. The tunnel barriers were formed either by thermal oxidation at room temperature or by subjecting the thin overlayers of Al or Mg to a low-energy ion beam in an argon-5% oxygen background. High-quality junctions with Pb counterelectrodes were produced by either method. However, for junctions with NbN counterelectrodes deposited at room temperature, the thermal oxidation resulted in shorts and the ion-beam oxidation resulted in low-leakage junction. X-ray photoelectron spectroscopy measurements of the NbN artificial-oxide bilayers showed that the ion-beam treatment increased the aluminum oxide thickness by the minimum detectable increment, approximately 0.2 nm, and increased the MgO thickness by 1 nm. The superconducting energy gap inferred for NbN counterelectrodes was typically half as large as the gap of the NbN base. Limitations on the gap values of NbN counterelectrodes grown on these barriers were established by measuring the energy gap of films as thin as 7.5 nm.

• Research Organization: Westinghouse RandD Center, Pittsburgh, Pennsylvania 15235
• OSTI ID: 5031994
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 58:12; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALUMINIUM
BEAMS
CHEMICAL REACTIONS
COLLISIONS
CURRENTS
DIMENSIONS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION
ENERGY GAP
FABRICATION
ION BEAMS
ION COLLISIONS
IONIZING RADIATIONS
JUNCTIONS
LEAKAGE CURRENT
METALS
MOLYBDENUM
NIOBIUM COMPOUNDS
NIOBIUM NITRIDES
NITRIDES
NITROGEN COMPOUNDS
OXIDATION
PHOTOEMISSION
PHYSICAL PROPERTIES
PNICTIDES
RADIATIONS
REFRACTORY METAL COMPOUNDS
SECONDARY EMISSION
SUPERCONDUCTING JUNCTIONS
SUPERCONDUCTIVITY
THICKNESS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNNEL EFFECT
X RADIATION