Gain and transient photoresponse of quantum well infrared photodetectors: a detailed ensemble Monte Carlo study

被引:18
作者
Cellek, OO
Memis, S
Bostanci, U
Ozer, S
Besikci, C [1 ]
机构
[1] Middle E Tech Univ, Dept Elect Engn, TR-06531 Ankara, Turkey
[2] Middle E Tech Univ, Dept Phys, TR-06531 Ankara, Turkey
关键词
quantum well infrared photodetector; capture; gain; photoresponse;
D O I
10.1016/j.physe.2004.06.043
中图分类号
TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
We investigate different gain characteristics observed on quantum well infrared photodetectors (QWIPs) fabricated with various material systems, and the effects of barrier material properties on the device characteristics through detailed ensemble Monte Carlo simulations. When the energy spacing between the central and satellite valleys is increased, the improvement in the excited electron lifetime is found to be much stronger than that in the average electron velocity in the device. According to our results, relatively high gain observed in lnP/In0.53Ga0.47As QWIPs under large bias is not due to the higher mobility in InP as suggested earlier; it can mainly be attributed to higher excited electron lifetime as a result of relatively large Gamma-L energy spacing. We discuss the details of the fast part of the Al0.3Ga0.7As/GaAs QWIP transient photoresponse, which exhibits three regions with different decay characteristics under a short pulse of radiation. The duration of the final region, during which the electrons excited near the emitter are extracted from the collector, is observed to be considerably long due to the dispersion of the photoelectrons. The photoresponse time rapidly decreases with increasing bias under low bias, and nearly saturates at similar to10 ps under large bias being similar to40% larger than the average transit time estimated by dividing the device length to the average steady-state electron velocity in device. We also investigate the effects of the interface reflections on the photoresponse time. (C) 2004 Elsevier B.V. All rights reserved.
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页码:318 / 327
页数:10
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