Epitaxial niobium nitride/insulator layered structures

Technical Report · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6422268

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

The properties of niobium nitride/insulator multilayers are reviewed. The NbN layers were polycrystalline or (100), (111), (110) or (135) single crystal films. The insulator was a 3 to 50 A thick epitaxial layer of A1/sub 2/O/sub 3/, MgO, or a metastable pseudo-binary compound, Mg1-xCaxO. The particular composition, x=0.27, was chosen to match the oxide lattice constant to that NbN. Superconductive tunneling measurements were used in conjunction with XPS, LEED, RHEED, and TEM to construct a model of oxide tunnel barrier microstructure and evaluate disorder in the layers of NbN adjacent to oxide interfaces. It was found that the chemistry of the native oxide of NbN can be modified during artificial oxide deposition to form a carboxide that effectively seals thin spots in the artificial oxide. A comparison of tri-layers made with MgO or with lattice-matched MgO-CaO showed little difference in the mode of epitaxial growth or in the superconducting properties of adjacent NbN layers. Niobium nitride films and tunnel junctions grown by single-crystal epitaxy had better superconducting properties than equivalent polycrystalline samples, particulary at temperatures less than 300 C.

• Research Organization: Westinghouse Electric Corp., Pittsburgh, PA (USA). Research and Development Center
• OSTI ID: 6422268
• Report Number(s): AD-A-201830/7/XAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360603* -- Materials-- Properties
420201 -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
CHEMISTRY
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DEPOSITION
DIMENSIONS
ELECTRIC CONDUCTIVITY
ELECTRICAL INSULATION
ELECTRICAL PROPERTIES
FILMS
INTERFACES
JUNCTIONS
LAYERS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MICROSTRUCTURE
NIOBIUM COMPOUNDS
NIOBIUM NITRIDES
NITRIDES
NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PNICTIDES
REFRACTORY METAL COMPOUNDS
SAMPLING
SUPERCONDUCTING FILMS
SUPERCONDUCTIVITY
THICKNESS
TRANSITION ELEMENT COMPOUNDS
TUNNELING