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Proceedings Paper

Gallium nitride photocathode development for imaging detectors
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Paper Abstract

Recent progress in Gallium Nitride (GaN, AlGaN, InGaN) photocathodes show great promise for future detector applications in Astrophysical instruments. Efforts with opaque GaN photocathodes have yielded quantum efficiencies up to 70% at 120 nm and cutoffs at ~380 nm, with low out of band response, and high stability. Previous work with semitransparent GaN photocathodes produced relatively low quantum efficiencies in transmission mode (4%). We now have preliminary data showing that quantum efficiency improvements of a factor of 5 can be achieved. We have also performed two dimensional photon counting imaging with 25mm diameter semitransparent GaN photocathodes in close proximity to a microchannel plate stack and a cross delay line readout. The imaging performance achieves spatial resolution of ~50μm with low intrinsic background (below 1 event sec-1 cm-2) and reasonable image uniformity. GaN photocathodes with significant quantum efficiency have been fabricated on ceramic MCP substrates. In addition GaN has been deposited at low temperature onto quartz substrates, also achieving substantial quantum efficiency.

Paper Details

Date Published: 22 July 2008
PDF: 9 pages
Proc. SPIE 7021, High Energy, Optical, and Infrared Detectors for Astronomy III, 70211B (22 July 2008); doi: 10.1117/12.790076
Show Author Affiliations
Oswald H. W. Siegmund, Univ. of California, Berkeley (United States)
Anton S. Tremsin, Univ. of California, Berkeley (United States)
John V. Vallerga, Univ. of California, Berkeley (United States)
Jason B. McPhate, Univ. of California, Berkeley (United States)
Jeffrey S. Hull, Univ. of California, Berkeley (United States)
James Malloy, Univ. of California, Berkeley (United States)
Amir M Dabiran, SVT Associates Inc. (United States)


Published in SPIE Proceedings Vol. 7021:
High Energy, Optical, and Infrared Detectors for Astronomy III
David A. Dorn; Andrew D. Holland, Editor(s)

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