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Proceedings Paper

Negative response of HgCdTe photodiode induced by nanosecond laser pulse
Author(s): Zuodong Xu; Jianmin Zhang; Xinwei Lin; Bibo Shao; Pengling Yang
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Paper Abstract

Photodetectors’ behavior and mechanism of transient response are still not understood very well, especially under high photon injection. Most of the researches on this topic were carried out with ultra-short laser pulse, whose pulse width ranged from femtosecond scale to picosecond scale. However, in many applications the durations of incident light are in nanosecond order and the light intensities are strong. To investigate the transient response characteristics and mechanisms of narrow-bandgap photovoltaic detectors under short laser irradiation, we performed an experiment on HgCdTe photodiodes. The n+-on-p type HgCdTe photodiodes in the experiment were designed to work in spectrum from 1.0μm to 3.0μm, with conditions of zero bias and room temperature. They were exposed to in-band short laser pulses with dwell time of 20 nanosecond. When the intensity of incident laser beam rose to 0.1J/cm2 order, the photodiodes’ response characteristics turned to be bipolar from unipolar. A much longer negative response with duration of about 10μs to 100μs followed the positive light response. The amplitude of the negative response increased with the laser intensity, while the dwell time of positive response decreased with the laser intensity. Considering the response characteristics and the device structure, it is proposed that the negative response was caused by space charge effect at the electrodes. Under intense laser irradiation, a temperature gradient formed in the HgCdTe material. Due to the temperature gradient, the majority carriers diffused away from upper surface and left space charge at the electrodes. Then negative response voltage could be measured in the external circuit. With higher incident laser intensity, the degree of the space charge effect would become higher, and then the negative response would come earlier and show larger amplitude.

Paper Details

Date Published: 12 May 2017
PDF: 6 pages
Proc. SPIE 10173, Fourth International Symposium on Laser Interaction with Matter, 1017308 (12 May 2017); doi: 10.1117/12.2268345
Show Author Affiliations
Zuodong Xu, Northwest Institute of Nuclear Technology (China)
Jianmin Zhang, Northwest Institute of Nuclear Technology (China)
Xinwei Lin, Northwest Institute of Nuclear Technology (China)
Bibo Shao, Northwest Institute of Nuclear Technology (China)
Pengling Yang, Northwest Institute of Nuclear Technology (China)

Published in SPIE Proceedings Vol. 10173:
Fourth International Symposium on Laser Interaction with Matter
Yongkun Ding; Guobin Feng; Dieter H. H. Hoffmann; Jianlin Cao; Yongfeng Lu, Editor(s)

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