abstract: A series of Molybdenum-Copper bilayers were studied for use in 120mK superconducting transition edge sensors for spectrometer applications. The Transition temperature (T<sub>C</sub>) was tuned to the desired temperature using the proximity effect, by adjusting the thickness of a normal copper layer in direct contact with the superconducting molybdenum layer in a proximitized bilayer structure. The bilayers have a fixed normal metal thickness d<sub>Cu</sub>=1250 Å, on top of a variable superconductor thickness 650 Å ≤ d<sub>Mo</sub> ≤ 1000 Å. Material characterization techniques including X-ray Diffraction (XRD), Rutherford Backscattering Spectroscopy (RBS), Atomic Force Microscopy (AFM), and 4-point electrical characterization are used to characterize the films. Film TC are compared with the results of the Usadel proximity theory. The results of RBS analysis demonstrated that some Argon-contamination is observed at the Mo film-substrate interface, which correlates with bilayer surface roughness (as observed with AFM), reduced crystalline quality (via XRD Rocking Curve), and a deviation from the theoretical expected TC for a bilayer. The Argon contamination is presumably the cause of interface roughness, reducing the interface transmission coefficient in the Usadel model, and producing the discrepancy from the expected TC. / Dissertation/Thesis / Masters Thesis Materials Science and Engineering 2014
| Identifer | oai:union.ndltd.org:asu.edu/item:25826 |
| Date | January 2014 |
| Contributors | Kopas, Cameron J (Author), Newman, Nathan (Advisor), Singh, Rakesh (Committee member), Chamberlin, Ralph (Committee member), Arizona State University (Publisher) |
| Source Sets | Arizona State University |
| Language | English |
| Detected Language | English |
| Type | Masters Thesis |
| Format | 38 pages |
| Rights | http://rightsstatements.org/vocab/InC/1.0/, All Rights Reserved |
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