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Proceedings Paper

High-performance ferroelectric and magnetoresistive materials for next-generation thermal detector arrays
Author(s): Michael A. Todd; Paul P. Donohue; Rex Watton; Dennis J. Williams; Carl J. Anthony; Mark G. Blamire
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Paper Abstract

This paper discusses the potential thermal imaging performance achievable from thermal detector arrays and concludes that the current generation of thin-film ferroelectric and resistance bolometer based detector arrays are limited by the detector materials used. It is proposed that the next generation of large uncooled focal plane arrays will need to look towards higher performance detector materials - particularly if they aim to approach the fundamental performance limits and compete with cooled photon detector arrays. Two examples of bolometer thin-film materials are described that achieve high performance from operating around phase transitions. The material Lead Scandium Tantalate (PST) has a paraelectric-to-ferroelectric phase transition around room temperature and is used with an applied field in the dielectric bolometer mode for thermal imaging. PST films grown by sputtering and liquid-source CVD have shown merit figures for thermal imaging a factor of 2 to 3 times higher than PZT-based pyroelectric thin films. The material Lanthanum Calcium Manganite (LCMO) has a paramagnetic to ferromagnetic phase transition around -20oC. This paper describes recent measurements of TCR and 1/f noise in pulsed laser-deposited LCMO films on Neodymium Gallate substrates. These results show that LCMO not only has high TCR's - up to 30%/K - but also low 1/f excess noise, with bolometer merit figures at least an order of magnitude higher than Vanadium Oxide, making it ideal for the next generation of microbolometer arrays. These high performance properties come at the expense of processing complexities and novel device designs will need to be introduced to realize the potential of these materials in the next generation of thermal detectors.

Paper Details

Date Published: 5 December 2002
PDF: 12 pages
Proc. SPIE 4795, Materials for Infrared Detectors II, (5 December 2002); doi: 10.1117/12.452244
Show Author Affiliations
Michael A. Todd, QinetiQ Ltd. (United Kingdom)
Paul P. Donohue, QinetiQ Ltd. (United Kingdom)
Rex Watton, Rex Watton Infrared Ltd. (United Kingdom)
Dennis J. Williams, QinetiQ Ltd. (United Kingdom)
Carl J. Anthony, QinetiQ Ltd. (United Kingdom)
Mark G. Blamire, Univ. of Cambridge (United Kingdom)


Published in SPIE Proceedings Vol. 4795:
Materials for Infrared Detectors II
Randolph E. Longshore; Sivalingam Sivananthan, Editor(s)

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