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Proceedings Paper

Multilayered superconducting tunnel junctions for use as high-energy-resolution x-ray detectors
Author(s): Edward D. Rippert; Shenian N. Song; John B. Ketterson; Melville P. Ulmer
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Paper Abstract

X-ray detectors based on superconducting tunnel junction technology are desirable due to their potential for higher energy resolution and greater charge carrier production than conventional semiconductor devices. Single junction devices fabricated by thermal or plasma oxidation of elemental, soft metal, superconductors have shown some promise, but tend to suffer from poor opacity, performance degradation upon thermal recycling, and unequal total charge collected for absorption of x rays in different layers due to differing tunneling characteristics of each layer. More complex designs, such as quasi-particle trapping systems and all refractory materials, can help with the unequal charge and thermal cycling problems, respectively. However, new problems in complexity of fabrication and short quasi-particle lifetimes arise. Other potential difficulties include resolution degradation due to trapping of quasi-particles at the photoabsorption site or near defects and tolerance of the devices to faults induced by their environment. The use of multilayers of superconducting tunnel junctions, consisting of tens to hundreds of identical tunnel junctions stacked on top of one another, as a design can address these problems. The multilayer can, in principle, be made as thick as desired in order to increase opacity, while the individual superconducting layers can be made very thin in order that the tunneling time of the quasi-particles be short compared with the quasi-particle lifetime for even refractory superconductors. In addition, the layer thinness helps to alleviate undesirable quasi-particle trapping. The inherent redundancy of junctions in a multilayered device allows for continued operation even after multiple single layer failures. The unique physical and technological possibilities of multilayered devices, such as resonant tunneling and built in preamplification, make them structures worthy of study even without the more pragmatic inducements described above.

Paper Details

Date Published: 1 October 1991
PDF: 6 pages
Proc. SPIE 1549, EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy II, (1 October 1991); doi: 10.1117/12.48346
Show Author Affiliations
Edward D. Rippert, Northwestern Univ. (United States)
Shenian N. Song, Northwestern Univ. (United States)
John B. Ketterson, Northwestern Univ. (United States)
Melville P. Ulmer, Northwestern Univ. (United States)

Published in SPIE Proceedings Vol. 1549:
EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy II
Oswald H. W. Siegmund; Richard E. Rothschild, Editor(s)

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