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Proceedings Paper

Improved HgCdTe detectors with novel antireflection coating
Author(s): R. Sachidananda Babu; Kelley Hu; Sridhar Manthripragada; Robert J. Martineau; Carl A. Kotecki; F. A. Peters; Andre S. Burgess; Danny J. Krebs; David Brent Mott; Audrey J. Ewin; Avery I. Miles; Trang L. Nguyen; Peter K. Shu
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Paper Abstract

The composite infrared spctrometer (CIRS) is an important instrument for the upcoming Cassini mission for sensing infrared (IR) radiation from the Saturanian planetary system. We have delivered a linear, ten element, mercury cadmium telluride (HgCdTe) photoconductive detector array for use on focal plane 3 (FP3), which is responsible for detecting radiation from the 9.1 micrometer to 16.6 micrometer wavelength range. Reliable HgCdTe detectors require robust passivation, a low-stress zinc sulfide (ZnS) anti-reflection (AR) coating with good adhesion, and a proper optical cavity design to smooth out the resonance in the detector spectral response. During the development of CIRS flight array, we have demonstrated the potential of using an in-situ interfacial layer, such as SiNx, between ZnS and the anodic oxide. Such an interfacial layer drastically improves the adhesion between the ZnS and oxide, without degrading the minority carrier lifetime. We have also demonstrated the feasibility of applying a SiNx 'rain coat' layer over the ZnS to prevent moisture and other chemicals from attacking the AR coating, thus improving the long term reliability. This also enables device operation in a hazardous environment. The alumina/epoxy/HgCdTe/oxide/ZnS structure is a complicated multi-cavity optical system. We have developed an extensive device simulation, which enables us to make the optimal choice of individual cavity thickness for minimizing the resonance and maximizing the quantum efficiency. We have also used 0.05 micrometer alumina powder loaded epoxy to minimize the reflections at the epoxy/HgCdTe interface, thus minimizing the resonance.

Paper Details

Date Published: 22 October 1996
PDF: 6 pages
Proc. SPIE 2816, Infrared Detectors for Remote Sensing: Physics, Materials, and Devices, (22 October 1996); doi: 10.1117/12.255155
Show Author Affiliations
R. Sachidananda Babu, Ball Aerospace and Technology Corp. (United States)
Kelley Hu, Hughes STX Corp. (United States)
Sridhar Manthripragada, NASA Goddard Space Flight Ctr. (United States)
Robert J. Martineau, NASA Goddard Space Flight Ctr. (United States)
Carl A. Kotecki, NASA Goddard Space Flight Ctr. (United States)
F. A. Peters, NASA Goddard Space Flight Ctr. (United States)
Andre S. Burgess, NASA Goddard Space Flight Ctr. (United States)
Danny J. Krebs, NASA Goddard Space Flight Ctr. (United States)
David Brent Mott, NASA Goddard Space Flight Ctr. (United States)
Audrey J. Ewin, NASA Goddard Space Flight Ctr. (United States)
Avery I. Miles, NASA Goddard Space Flight Ctr. (United States)
Trang L. Nguyen, NASA Goddard Space Flight Ctr. (United States)
Peter K. Shu, NASA Goddard Space Flight Ctr. (United States)


Published in SPIE Proceedings Vol. 2816:
Infrared Detectors for Remote Sensing: Physics, Materials, and Devices
Randolph E. Longshore; Jan W. Baars, Editor(s)

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