In(Ga)As/GaAs Quantum Dot Infrared Photodetectors (QDIPs) with Quaternary Capping
Mid-wavelength infrared (MWIR) ~3–5 μm and long-wavelength infrared (LWIR) ~8–14 μm detectors and FPAs are important in a variety of commercial, military and space applications, e.g., night vision, thermal imaging, chemical analysis, non-destructive detec
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In(Ga)As/GaAs Quantum Dot Infrared Photodetectors (QDIPs) with Quaternary Capping Abstract Mid-wavelength infrared (MWIR) ~3–5 μm and long-wavelength infrared (LWIR) ~8–14 μm detectors and FPAs are important in a variety of commercial, military and space applications, e.g., night vision, thermal imaging, chemical analysis, non-destructive detecting, remote sensing and missile guidance and defence applications. In this chapter we have reported two different types of QDIP capped with quaternary InAlGaAs and GaAs layers. By using In(Ga)As/GaAs QDs, we have obtained two-colour infrared detector of responsivity ~2.16 A/W at 77 K and detectivity 1.01 × 1011 cm Hz1/2/W at 77 K. Subsequently by using InAs/GaAs QDs, we have obtained multi-colour, broadband infrared detector with ultra-narrow spectral width. Keywords QDIP • Responsivity • Two-colour • Multicolour • Spectral width
4.1 Introduction Mid-wavelength infrared (MWIR) ~3–5 μm and long-wavelength infrared (LWIR) ~8–14 μm detectors and FPAs are important in a variety of commercial, military and space applications, e.g. night vision, thermal imaging, chemical analysis, non- destructive detecting, remote sensing, and missile guidance and defence applications. QDIPs have evolved from the quantum-well infrared photodetector (QWIP) technology and can detect infrared (IR) wavelengths across a broad range. Due to their long carrier capture and relaxation times, QDIPs with self-organized InAs/ GaAs QDs in their active regions have the potential for lower dark current and higher photoresponse levels than QWIPs. These advantages are believed to arise from the three-dimensional confinement of carriers within the dot. Thus, the bound Portion of this chapter [Reprinted with permission from S. Chakrabarti, S. Adhikary, N. Halder, Y. Aytac and A. G. U. Perera, “High-performance, long-wave (~10.2 μm) InGaAs/GaAs quantum dot infrared photodetector with quaternary In0.21Al0.21Ga0.58As capping” Applied Physics Letters, Vol. 99, No. 18, pp. 181102, 2011, AIP Publishing LLC] and [Reprinted with permission from S. Adhikary et al “A multicolor, broadband (5–20 μm), quaternary-capped InAs/GaAs quantum dot infrared photodetector,” Applied Physics Letters, Vol. 101, pp. 261114, 2012, AIP Publishing LLC] © Springer Nature Singapore Pte Ltd. 2018 S. Adhikary, S. Chakrabarti, Quaternary Capped In(Ga)As/GaAs Quantum Dot Infrared Photodetectors, DOI 10.1007/978-981-10-5290-3_4
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4 In(Ga)As/GaAs Quantum Dot Infrared Photodetectors (QDIPs) with Quaternary…
carriers are sensitive to normal incident light, making QDIPs particularly attractive for FPA implementation. Several studies have attempted to realize high performance QDIPs using bandgap engineering. These structures were discussed in Chap. 1; however, the device performance levels of the available IR photodetectors are inadequate. Design and implementation of QDIP devices with large responsivity and detectivity that work within a broad spectral range (8–14 μm) proves challenging.
4.2 G rowth, Fabrication and Characterization
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