Investigating inter-subband photocurrent in CdS/ZnSe quantum well photodetector for infrared applications
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TECHNICAL PAPER
Investigating inter-subband photocurrent in CdS/ZnSe quantum well photodetector for infrared applications Md Aref Billaha1
•
Biplab Bhowmick1 • Santosh K. Choudhary2
Received: 6 November 2020 / Accepted: 13 November 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The current work presents a theoretical investigation of a CdS/ZnSe quantum well infrared photodetector (QWIP). Many body effects are incorporated for the accurate estimation of confined subband energies in the conduction band. Results show that optical transition energy is obtained from short to mid-wavelengths (2–5.85 lm) by tailoring CdS well layer. Rate equation is solved for the photocurrent calculation of the CdS/ZnSe QWIP. Photocurrents of 0.084, 0.11 and 0.14 A/cm2 are observed at 4.3, 5 and 5.85 lm respectively for 20 QW periods. An improved responsivity of 160 mA/W at 5 lm is obtained for high value of doping concentration.
1 Introduction Quantum Wells, Quantum dot and Type-II strained layer superlattice infrared photodetectors are becoming a standard technology for infrared detection (Tian et al. 2015; Besikci 2018). The progress of quantum well infrared photodetector (QWIP) technology has been significant due to the progress in crystal growth and semiconductor etching (Zeiri et al. 2014). The use of different semiconductor material systems such as InGaAs/AlGaAs, InGaAs/InAlAs and GaAs/AlGaAs allow us to access a huge range of wavelengths starting from short-wavelength (2 lm) to long-wavelength (14 lm) infrared (IR) region (Fiore et al. 1994; Lenchyshyn et al. 1995; Vardi et al. 2008; Gadir et al. 2002; Alves et al. 2008). The commercially available mid-infrared QWIPs are made from InGaAs/InAlAs material system (Georgiev et al. 2003). InGaAs/InAlAs material system has a conduction band offset of 0.52 eV when lattice is being matched and it is not enough to attain the 3–5 lm range (Georgiev et al. 2003). Larger band offset can be achieved by introducing strained layer and those structures can operate up to 4 lm wavelengths due to & Md Aref Billaha [email protected] 1
Department of Electronics and Communication Engineering, Asansol Engineering College, Asansol 713305, India
2
Department of Electronics and Communication Engineering, VNR Vignana Jyothi Institute of Engineering and Technology, Hyderabad, India
intervalley scattering (Bandyopadhyay et al. 2012; Marko et al. 2009). Other mid-infrared detectors are made from InGaAs/AlGaAs QWs where absorption quantum efficiency is limited due to the incorporation of strained layer (since lattice mismatch between InGaAs and GaAs material) (Shen 2018). Absorption quantum efficiency can be increased by increasing doping concentration and the number of quantum wells (QWs). However, the dark current also increases with the doping (Shen 2018). In recent time, wide bandgap II-VI low-dimension semiconductors are becoming the focus of current research work among researchers for their better performance (Kaya et
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