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Title: Study of fabrication problems with Nb/sub 3/Sn films used for Josephson tunnel junctions

Abstract

The fabrication of superconductive Nb/sub 3/Sn thin films was done by two different techniques, composite target sputtering and the reaction of elemental films. Both techniques deposited films onto cooled substrates and then used annealing to form the high T/sub c/, A15 phase of the films. Transition temperature of 17.9 to 18.0K measured resistively were routinely achieved. Composite target films needed a surface-modification procedure before tunnel junctions showing large energy gap could be made. A range of fabrication parameters were tried. Reaction method films were mace by varying the Nb/Sn ratio, annealing temperature, sputter etch depth in sputter cleaning and cathode bias while sputter cleaning. Optimum values were 3:1; 850/sup 0/C, 5-10 nm, and 250-500 V, respectively. All junctions made on these films exhibited leakage currents that showed a definite increase at the Pb energy gap indicating normal material in the film and x-ray diffraction showed very small amounts of Nb/sub 6//Sn/sub 5/. An in-situ surface analysis system was built to study the surface of the Nb/sub 3/Sn films after processing and to correlate these measurements with junctions fabricated directly on the characterized surfaces. Auger spectroscopy, ellipsometry, sputter cleaning and film annealing were some of the techniques and processes studied inmore » this system. The Sn-poor surface created by sputter cleaning could be improved by an in-situ anneal.« less

Authors:
Publication Date:
Research Org.:
Wisconsin Univ., Madison (USA)
OSTI Identifier:
5583796
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 36 MATERIALS SCIENCE; JOSEPHSON JUNCTIONS; FABRICATION; NIOBIUM ALLOYS; SUPERCONDUCTIVITY; THIN FILMS; TIN ALLOYS; ENERGY GAP; LEAKAGE CURRENT; TRANSITION TEMPERATURE; TUNNEL EFFECT; ALLOYS; CURRENTS; ELECTRIC CONDUCTIVITY; ELECTRIC CURRENTS; ELECTRICAL PROPERTIES; FILMS; JUNCTIONS; PHYSICAL PROPERTIES; SUPERCONDUCTING JUNCTIONS; THERMODYNAMIC PROPERTIES; 420201* - Engineering- Cryogenic Equipment & Devices; 360101 - Metals & Alloys- Preparation & Fabrication

Citation Formats

Houck, L L. Study of fabrication problems with Nb/sub 3/Sn films used for Josephson tunnel junctions. United States: N. p., 1985. Web.
Houck, L L. Study of fabrication problems with Nb/sub 3/Sn films used for Josephson tunnel junctions. United States.
Houck, L L. Tue . "Study of fabrication problems with Nb/sub 3/Sn films used for Josephson tunnel junctions". United States.
@article{osti_5583796,
title = {Study of fabrication problems with Nb/sub 3/Sn films used for Josephson tunnel junctions},
author = {Houck, L L},
abstractNote = {The fabrication of superconductive Nb/sub 3/Sn thin films was done by two different techniques, composite target sputtering and the reaction of elemental films. Both techniques deposited films onto cooled substrates and then used annealing to form the high T/sub c/, A15 phase of the films. Transition temperature of 17.9 to 18.0K measured resistively were routinely achieved. Composite target films needed a surface-modification procedure before tunnel junctions showing large energy gap could be made. A range of fabrication parameters were tried. Reaction method films were mace by varying the Nb/Sn ratio, annealing temperature, sputter etch depth in sputter cleaning and cathode bias while sputter cleaning. Optimum values were 3:1; 850/sup 0/C, 5-10 nm, and 250-500 V, respectively. All junctions made on these films exhibited leakage currents that showed a definite increase at the Pb energy gap indicating normal material in the film and x-ray diffraction showed very small amounts of Nb/sub 6//Sn/sub 5/. An in-situ surface analysis system was built to study the surface of the Nb/sub 3/Sn films after processing and to correlate these measurements with junctions fabricated directly on the characterized surfaces. Auger spectroscopy, ellipsometry, sputter cleaning and film annealing were some of the techniques and processes studied in this system. The Sn-poor surface created by sputter cleaning could be improved by an in-situ anneal.},
doi = {},
url = {https://www.osti.gov/biblio/5583796}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1985},
month = {1}
}

Thesis/Dissertation:
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