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Proceedings Paper

Proposed two-color HgCdTe focal plane array
Author(s): Vikram Dhar; Vishnu Gopal
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Paper Abstract

Recently there has been considerable interest in two-color focal plane arrays (FPAs), particularly in mercury cadmium telluride. Single-color FPAs provide only the signal from the target, not its emissivity and temperature separately. The schemes that have been implemented for two-color FPAs involve two bumps per pixel, and two back-to-back diodes in four different layers, which are technologically challenging. We propose a simple scheme that requires only one bump per pixel, in a material that is not a heterostructure, and can be grown by liquid phase or molecular beam epitaxy. The two different cutoff wavelengths are obtained by implanting two different junction depths in a n+-on-p configuration. Since the n+ layer does not contribute, because of the Moss-Burstein shift, the different diodes correspond to different surface composition values, xs1 and xs2, in the graded p-type epilayer. The precise cutoff wavelengths can be chosen by appropriate slope s of the composition in the epilayer. For the purpose of radiometry it is not necessary that the two cutoff wavelengths should differ by large amounts: even 0.3 mm is sufficient - easily achievable, with reasonable junction depths. The two colors could form a checkerboard pattern across the FPA.

Paper Details

Date Published: 12 November 2001
PDF: 7 pages
Proc. SPIE 4454, Materials for Infrared Detectors, (12 November 2001); doi: 10.1117/12.448188
Show Author Affiliations
Vikram Dhar, Solid State Physics Lab. (India)
Vishnu Gopal, Solid State Physics Lab. (India)

Published in SPIE Proceedings Vol. 4454:
Materials for Infrared Detectors
Randolph E. Longshore, Editor(s)

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