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Proceedings Paper

Improvement of low-temperature sensing realized with a superlattice infrared photodetector
Author(s): Chun-Chi Chen; Mao-Chieh Hsu; Wen-Hsing Hsieh; Chieh-Hsiung Kuan
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Paper Abstract

It is found that the temperature accuracy (dT), measured by the photocurrent ratio of two linearly independent spectral responses, depends on two factors. One is the dissimilarity of the spectral responses determined primarily by the separation of the long and short wavelength peaks, and is not related with their responsivity magnitude. The other is dominated between the smaller S/N for the two measured photocurrents. The dissimilarity can be improved by moving the short wavelength peak to an even shorter one. However, this decreases the signal magnitude measured by the shorter wavelength peak at low target temperature, and results in the degradation of the S/N and (Delta) T. Therefore, a superlattice structure with absorption peaks at 6.7 micrometers and 9.7 micrometers was designed, and the wavelength separation is less than the conventional two-color QWIP. The spectral response of the detector is voltage-tunable through a current blocking layer that acts as an energy filter for the photo-excited carriers. The measured peak detectivity of this detector is 3.7 X 109 cmHz0.5/W (9.7 micrometers ) at -0.5 V and 2.2 X 1010 cmHz0.5/W (6.7 micrometers ) at -0.1 V at 45K. Our detector is capable of measuring target temperatures ranging from 300K to 1200K and higher. The estimated (Delta) T is 0.8K for 300K target, and 0.17K for 1200K target.

Paper Details

Date Published: 12 June 2001
PDF: 10 pages
Proc. SPIE 4288, Photodetectors: Materials and Devices VI, (12 June 2001); doi: 10.1117/12.429425
Show Author Affiliations
Chun-Chi Chen, National Taiwan Univ. (Taiwan)
Mao-Chieh Hsu, National Taiwan Univ. (Taiwan)
Wen-Hsing Hsieh, National Taiwan Univ. (Taiwan)
Chieh-Hsiung Kuan, National Taiwan Univ. (Taiwan)

Published in SPIE Proceedings Vol. 4288:
Photodetectors: Materials and Devices VI
Gail J. Brown; Manijeh Razeghi, Editor(s)

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