University of Illinois Urbana-Champaign

Growth, fabrication, and measurement of superconducting barium(1-x) potassium bismuth oxygen(3) thin films and devices

Schweinfurth, Ralph Alan

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Description

Title
Growth, fabrication, and measurement of superconducting barium(1-x) potassium bismuth oxygen(3) thin films and devices
Author(s)
Schweinfurth, Ralph Alan
Issue Date
1994
Doctoral Committee Chair(s)
Van Harlingen, Dale J.
Department of Study
Physics
Discipline
Physics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • Engineering, Electronics and Electrical
  • Physics, Condensed Matter
  • Engineering, Materials Science
Language
eng
Abstract
This thesis discusses growth, fabrication and measurement of $\rm Ba\sb{1-x}K\sb{x}BiO\sb3$ (BKBO) superconducting thin films and thin film devices. Interest in BKBO has been concerned with both fundamental questions concerning its mechanism of superconductivity and potential applications in superconductor devices. $\rm Ba\sb{1-x}K\sb{x}BiO\sb3$ is a superconducting compound at a small range of potassium concentration, with the highest transition temperature being about $32\sp\circ\rm K$ for 0.35 $<$ x $<$ 0.4 The in-situ growth of high quality superconducting thin films is described, using pulsed laser deposition. Film quality was analyzed with RBS, XRD, and SEM as well as transport. Fabrication of transport, microwave, and tunneling structures and devices is described, including dry etching techniques (ion milling and RIBM) as well as annealing and processing effects. Transport measurements yield $\rm T\sb{c0}$ = 25-29$\sp\circ\rm K,$ $\rm J\sb{c}$ $\ge$ 1 $\rm MA/cm\sp2$ $(4\sp\circ\rm K),$ and $\rm R\sb{s}$ $\approx$ 1 $\rm m\Omega$ (at $4\sp\circ\rm K$ and 10GHz) for the best films. Dissipation in fields up to 5 Tesla suggests that the superconducting coherence length $\xi\approx 38\rm\A$ and upper critical field $\rm H\sb{c2}(0)\approx$ 22T. Tunneling studies were also made using a BKBO electrode, a native oxide barrier, and the following counterelectrodes: Ag, Pb, Nb, and BKBO. Results were consistent with classical tunneling of a weak to moderately coupled superconductor where $\Delta$ = 4.5 meV and $2\Delta\rm /k\sb{B}T\sb{c}$ = 3.8. Prospects for practical BKBO superconducting devices are discussed.
Type of Resource
text
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http://hdl.handle.net/2142/23245
Copyright and License Information
Copyright 1994 Schweinfurth, Ralph Alan

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