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Fabrication of X-ray Microcalorimeter Focal Planes Composed of Two Distinct Pixel TypesWe develop superconducting transition-edge sensor (TES) microcalorimeter focal planes for versatility in meeting the specifications of X-ray imaging spectrometers, including high count rate, high energy resolution, and large field of view. In particular, a focal plane composed of two subarrays: one of fine pitch, high count-rate devices and the other of slower, larger pixels with similar energy resolution, offers promise for the next generation of astrophysics instruments, such as the X-ray Integral Field Unit Instrument on the European Space Agencys ATHENA mission. We have based the subarrays of our current design on successful pixel designs that have been demonstrated separately. Pixels with an all-gold X-ray absorber on 50 and 75 micron pitch, where the Mo/Au TES sits atop a thick metal heatsinking layer, have shown high resolution and can accommodate high count rates. The demonstrated larger pixels use a silicon nitride membrane for thermal isolation, thinner Au, and an added bismuth layer in a 250-sq micron absorber. To tune the parameters of each subarray requires merging the fabrication processes of the two detector types. We present the fabrication process for dual production of different X-ray absorbers on the same substrate, thick Au on the small pixels and thinner Au with a Bi capping layer on the larger pixels to tune their heat capacities. The process requires multiple electroplating and etching steps, but the absorbers are defined in a single-ion milling step. We demonstrate methods for integrating the heatsinking of the two types of pixel into the same focal plane consistent with the requirements for each subarray, including the limiting of thermal crosstalk. We also discuss fabrication process modifications for tuning the intrinsic transition temperature (T(sub c)) of the bilayers for the different device types through variation of the bilayer thicknesses. The latest results on these 'hybrid' arrays will be presented.
Document ID
20170003465
Document Type
Reprint (Version printed in journal)
Authors
Wassell, Edward J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Adams, Joseph S. (Maryland Univ. Baltimore County Baltimore, MD, United States)
Bandler, Simon R. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Betancour-Martinez, Gabriele L (Maryland Univ. College Park, MD, United States)
Chiao, Meng P. (Alcyon Technical Services-JV, Inc. Huntsville, AL, United States)
Chang, Meng Ping (SGT, Inc. Greenbelt, MD, United States)
Chervenak, James A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Datesman, Aaron M. (SGT, Inc. Greenbelt, MD, United States)
Eckart, Megan E. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Ewin, Audrey J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kelley, Richard (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kilbourne, Caroline A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Porter, Frederick Scott (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Sadleir, John E. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
April 14, 2017
Publication Date
December 1, 2016
Publication Information
Publication: IEEE Transactions on Applied Superconductivity
Volume: 27
Issue: 4
ISSN: 1051-8223
Subject Category
Astrophysics
Instrumentation and Photography
Report/Patent Number
GSFC-E-DAA-TN41300
Funding Number(s)
CONTRACT_GRANT: NNG17PT01A
Distribution Limits
Public
Copyright
Other
Keywords
Terms—Arrays
X-ray spectroscopy. I
microcalorimeters
transition-edge sensors (TES)
low temperature detectors