Browsing by Subject "MWIR"
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Item Open Access High performance 15-μm pitch 640 × 512 MWIR InAs/GaSb type-II superlattice sensors(IEEE, 2021-11-18) Oğuz, Fikri; Ülker, E.; Arslan, Y.; Nuzumlali, Ö. L.; Bek, Alpan; Özbay, EkmelWe report the high performance of Mid-wave Infrared Region (MWIR) InAs/GaSb Type-II Superlattice (T2SL) sensors with $640\times512$ format and 15- $\mu \text{m}$ pixel pitch at both Focal Plane Array (FPA) and pixel level. The p-intrinsic-Barrier-n epilayer structure is adopted for this study, which is grown on 620 ± $30~ \mu \text{m}$ thick GaSb substrate and highly-doped GaSb cap layer at the top structure. The mesa type pixels with sizes of $220\,\,\mu \text{m}\,\,\times 220\,\,\mu \text{m}$ have dark currents $7.8\times10$ −12 A at 77 K both of which are equivalent to state-of-the-art values for Type-II Superlattice sensors. The various passivation techniques to lower the dark current are applied and the results are given in terms of dark current. Electro-optical measurements yielded comparable results to literature. After gathering data and optimizing the fabrication conditions, the FPA of 15- $\mu \text{m}$ pitch having $4.92~ \mu \text{m}$ cut-off wavelength ( $\lambda _{\mathrm {c}}$ ) shows 1.6 A/W peak responsivity, Noise Equivalent Temperature Difference (NETD) of 22.6 mK with optics of f/2.3, quantum efficiency larger than 65% and 99.75% operability. The acquired images by using aforementioned FPA device is presented in this paper. With the reduction of dark current, an encouraging imaging performance is obtained which shows the potential of the Type-II Superlattice detectors in 3 rd generation infrared sensors.Item Open Access Mid-infrared quantum cascade laser(Bilkent University, 2017-05) Bozok, BerkayMid-infrared quantum cascade laser technology has been developed rapidly since it was demonstrated in 1994. Since quantum cascade laser technology is small, robust and efficient, they have become commonly used mid-infrared laser source for various applications. The particular application fields of quantum cascade lasers are free space communication, chemical spectroscopy, environmental monitoring and infrared countermeasure. This work presents a comprehensive study over mid-infrared quantum cascade laser including review of theoretical background, theoretical analyses, active layer design, quantum mechanical, thermal and optical simulations, device fabrication, optimization and experimental characterization. As a result of this work mid-infrared quantum cascade laser have been successfully demonstrated.Item Open Access N-structure based on InAs/AlSb/GaSb superlattice photodetectors(Academic Press, 2015) Hostut, M.; Alyoruk, M.; Tansel, T.; Kilic, A.; Turan, R.; Aydınlı, Atilla; Ergun, Y.We have studied the theoretical and experimental properties of InAs/AlSb/GaSb based type-II superlattice (T2SL) pin photodetector called N-structure. Electronic properties of the superlattice such as HH-LH splitting energies was investigated using first principles calculations taking into account InSb and AlAs as possible interface transition alloys between AlSb/InAs layers and individual layer thicknesses of GaSb and InAs. T2SL N-structure was optimized to operate as a MWIR detector based on these theoretical approaches tailoring the band gap and HH-LH splitting energies with InSb transition layers between InAs/AlSb interfaces. Experimental results show that AlSb layers in the structure act as carrier blocking barriers reducing the dark current. Dark current density and R0A product at 125 K were obtained as 1.8 × 10-6 A cm-2 and 800ωcm2 at zero bias, respectively. The specific detectivity was measured as 3 × 1012 Jones with cut-off wavelengths of 4.3 μm at 79 K reaching to 2 × 109 Jones and 4.5 μm at 255 K. ©2014 Elsevier Ltd. All rights reserved.