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

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Schweinfurth, Ralph Alan

Contributors dc:contributor

• Van Harlingen, Dale J.

• Engineering, Electronics and Electrical
• Physics, Condensed Matter
• Engineering, Materials Science

Statement dc:rights

• Copyright 1994 Schweinfurth, Ralph Alan

Language dc:language

eng

Identifier

AAI9503312
(UMI)AAI9503312

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/23245