An equivalent circuit model for the long-wavelength quantum well infrared photodetectors
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An equivalent circuit model for the long-wavelength quantum well infrared photodetectors L. Li · D. Y. Xiong · J. Wen · Q. C. Weng
Received: 27 September 2012 / Accepted: 31 December 2012 / Published online: 9 January 2013 © Springer Science+Business Media New York 2013
Abstract We present an equivalent circuit model for AlGaAs/GaAs long wavelength quantum well infrared photodetectors (LW-QWIPs). Bias dependence of the dark current and photoresponse is described with the aid of analogue circuit modeling technique in the TINA software. This model can be integrated with the readout circuit for the whole device circuit simulation and optimization further. The designed parameters of the LW-QWIPs can be fed into this model as user-defined circuit parameters to simulate the detector performance. The obtained results are consistent with the experimental measurements. Keywords Quantum well infrared photodetectors · Analogue circuit modeling · Dark current · Photoresponse
1 Introduction There has been considerable interest in electronic phenomena in quantum well infrared photodectors (QWIPs) especially long-wavelength QWIPs (LW-QWIPs) based on intersubband transitions over past two decades. Large, highly uniform imaging arrays exhibiting promising performances have already been demonstrated (Levine 1993; Shen 1994; Lu et al. 1994; Lu and Fu 2004; Costard et al. 1998). Despite an important amount of experimental and the theoretical work, reliable circuit models that one could use as simulation tools for the performances of LW-QWIPs are very lacking. The practical applications of the LW-QWIPs require the integration of readout circuits with the photodetectors. For the optimization of the whole detector circuit system, it is necessary to simulate the LWQWIPs along with the readout circuit, Therefore, effective equivalent circuit models for the LW-QWIPs are quite needed. Traditionally, the operation of a LW-QWIP is described by a set of equations based on semiconductor device physics (Levine 1993). However, these
L. Li · D. Y. Xiong (B)· J. Wen · Q. C. Weng Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai200241, People’s Republic of China e-mail: [email protected]
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650 Fig. 1 I p is photocurrent and Id is dark current. Va is bias voltage
L. Li et al.
Ip
Id Va
equations cannot be directly utilized when the photodetector is connected to its readout electronics for the whole device circuit simulation and optimization. In a previous article, Costard et al. (1998) presented an equivalent circuit model of QWIPs using a few current sources in parallel with the detector resistance of the dark current, but this model didn’t provide the specific circuit structures, nor provide the bias and temperature dependence of the dark current, hence it is not applicable for a wide range. The TINA Design Suite is a powerful yet affordable circuit simulation and PCB design software package (TINA simulation package (http://www.tina.com/English/tina/). With its help we have bu
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