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1.  
nBn extended short-wavelength infrared focal plane array
nBn extended short-wavelength infrared focal plane array
ARASH DEHZANGI, ABBAS HADDADI, ROMAIN CHEVALLIER, YIYUN ZHANG, AND MANIJEH RAZEGHI
Optics Letters-- February 1, 2018
An extended short-wavelength nBn InAs/GaSb/AlSb type-II superlattice-based infrared focal plane array imager was demonstrated. A newly developed InAs0.10Sb0.90∕GaSb superlattice design was used as the large-bandgap electron barrier in this photodetector. The large band gap electron-barrier design in this nBn photodetector architecture leads to the device having lower dark current densities. A new bi-layer etch-stop scheme using a combination of InAs0.91Sb0.09 bulk and AlAs0.1Sb0.9∕GaSb superlattice layers was introduced to allow complete substrate removal and a shorter wavelength cut-on. Test pixels exhibit 100% cutoff wavelengths of ∼2.30 and ∼2.48 μm at 150 and 300 K, respectively. The devices achieve saturated quantum efficiency values of 59.7% and 63.8% at 150 and 300 K, respectively, under backside illumination and without any antireflection coating.At 150 K, photodetectors exhibit dark current density of 8.75 × 10−8 A∕cm2 under −400 mV applied bias, providing specific detectivity of 2.82 × 1012 cm · Hz1∕2∕W at 1.78 μm. At 300 K, the dark current density reaches 4.75 × 10−2 A∕cm2 under −200 mV bias, providing a specific detectivity of 8.55 × 109 cm · Hz1∕2∕W 1.78 μm. reprint
 
2.  
Type-II InAs/GaSb/AlSb superlatticebased heterojunction phototransistors: back to the future
Type-II InAs/GaSb/AlSb superlatticebased heterojunction phototransistors: back to the future
Abbas Haddadi, Arash Dehzangi, Romain Chevallier, Thomas Yang, Manijeh Razeghi
Proc. SPIE 10540, Quantum Sensing and Nano Electronics and Photonics XV- Page-1054004-1-- January 26, 2018
Most of reported HPTs in literatures are based on InGaAs compounds that cover NIR spectral region. However, InGaAs compounds provide limited cut-off wavelength tunability. In contrast, type-II superlattices (T2SLs) are a developing new material system with intrinsic advantages such as great flexibility in bandgap engineering, low growth and manufacturing cost, high-uniformity, auger recombination suppression, and high carrier effective mass that are becoming an attractive candidate for infrared detection and imaging from short-wavelength infrared to very long wavelength infrared regime. We present the recent advancements in T2SL-based heterojunction phototransistors in e– SWIR, MWIR and LWIR spectral ranges. A mid-wavelength infrared heterojunction phototransistor based on type-II InAs/AlSb/GaSb superlattices on GaSb substrate has been demonstrated. Then, we present the effect of vertical scaling on the optical and electrical performance of heterojunction phototransistors, where the performance of devices with different base width was compared as the base was scaled from 60 down to 40 nm. reprint
 
3.  
Dark current reduction in microjunction-based compound electron barrier type-II InAs/InAs1-xSbx superlattice-based long-wavelength infrared photodetectors
Dark current reduction in microjunction-based compound electron barrier type-II InAs/InAs1-xSbx superlattice-based long-wavelength infrared photodetectors
Romain Chevallier, Abbas Haddadi, Manijeh Razeghi
Proc. SPIE 10540, Quantum Sensing and Nano Electronics and Photonics XV Page. 1054007-1-- January 26, 2018
Reduction of dark current density in microjunction-based InAs/InAs1-xSbx type-II superlattice long-wavelength infrared photodetectors was demonstrated. A double electron barrier design was used to suppress both generation-recombination and surface dark currents. The photodetectors exhibited high surface resistivity after passivation with SiO2, which permits the use of small size features without having strong surface leakage current degrading the electrical performance. Fabricating a microjunction structure (25×25 μm2 mesas with 10×10 μm2 microjunctions) with this photodetector double barrier design results in a dark current density of 6.3×10-6 A/cm2 at 77 K. The device has an 8 μm cut-off wavelength at 77 K and exhibits a quantum efficiency of 31% for a 2 μm-thick absorption region, which results in a specific detectivity value of 1.2×1012 cm·Hz1/2/W at 77 K. reprint
 
4.  
Type-II superlattice-based extended short-wavelength infrared focal plane array with an AlAsSb/GaSb superlattice etch-stop layer to allow near-visible light detection
Type-II superlattice-based extended short-wavelength infrared focal plane array with an AlAsSb/GaSb superlattice etch-stop layer to allow near-visible light detection
Romain Chevallier, Arash Dehzangi, Abbas Haddadi, and Manijeh Razeghi
Optics Letters Vol. 42, Iss. 21, pp. 4299-4302 (2017)-- October 17, 2017
A versatile infrared imager capable of imaging the near-visible to the extended short-wavelength infrared (e-SWIR) is demonstrated using e-SWIR InAs/GaSb/AlSb type-II superlattice-based photodiodes. A bi-layer etch-stop scheme consisting of bulk InAs0.91Sb0.09 and AlAs0.1Sb0.9/GaSb superlattice layers is introduced for substrate removal from the hybridized back-side illuminated photodetectors. The implementation of this new technique on an e-SWIR focal plane array results in a significant enhancement in the external quantum efficiency (QE) in the 1.8–0.8μm spectral region, while maintaining a high QE at wavelengths longer than 1.8μm. Test pixels exhibit 100% cutoff wavelengths of ∼2.1 and ∼2.25μm at 150 and 300K, respectively. They achieve saturated QE values of 56% and 68% at 150 and 300K, respectively, under back-side illumination and without any anti-reflection coating. At 150K, the photodetectors (27μm×27μm area) exhibit a dark current density of 4.7×10−7  A/cm2 under a −50  mV applied bias providing a specific detectivity of 1.77×1012  cm·Hz1/2/W. At 300K, the dark current density reaches 6.6×10−2  A/cm2 under −50 mV bias, providing a specific detectivity of 5.17×109  cm·Hz1/2/W. reprint
 
5.  
Bias-selectable three-color short-, extended-short-, and mid-wavelength infrared photodetectors based on type-II InAs/GaSb/AlSb superlattices
Bias-selectable three-color short-, extended-short-, and mid-wavelength infrared photodetectors based on type-II InAs/GaSb/AlSb superlattices
Abbas Haddadi, and Manijeh Razeghi
Optics Letters Vol. 42, Iss. 21, pp. 4275-4278 (2017)-- October 16, 2017
A bias-selectable, high operating temperature, three-color short-, extended-short-, and mid-wavelength infrared photodetector based on InAs/GaSb/AlSb type-II superlattices on GaSb substrate has been demonstrated. The short-, extended-short-, and mid-wavelength channels’ 50% cutoff wavelengths were 2.3, 2.9, and 4.4μm, respectively, at 150K. The mid-wavelength channel exhibited a saturated quantum efficiency of 34% at 4μm under +200 mV bias voltage in a front-side illumination configuration and without any antireflection coating. At 200mV, the device exhibited a dark current density of 8.7×10−5  A/cm2 providing a specific detectivity of ∼2×1011  cm·Hz1/2/W at 150K. The short-wavelength channel achieved a saturated quantum efficiency of 20% at 1.8μm. At −10  mV, the device’s dark current density was 5.5×10−8  A/cm2. At zero bias, its specific detectivity was 1×1011  cm·Hz1/2/W at 150K. The extended short-wavelength channel achieved a saturated quantum efficiency of 22% at 2.75 μm. Under −2  V bias voltage, the device exhibited a dark current density of 1.8×10−6  A/cm2 providing a specific detectivity of 6.3×1011  cm·Hz1/2/W at 150K. reprint
 
6.  
Dark current reduction in microjunction-based double electron barrier type-II InAs/InAsSb superlattice long-wavelength infrared photodetectors
Dark current reduction in microjunction-based double electron barrier type-II InAs/InAsSb superlattice long-wavelength infrared photodetectors
Romain Chevallier, Abbas Haddadi, & Manijeh Razeghi
Scientific Reports 7, Article number: 12617 (2017)-- October 3, 2017
Microjunction InAs/InAsSb type-II superlattice-based long-wavelength infrared photodetectors with reduced dark current density were demonstrated. A double electron barrier design was employed to reduce both bulk and surface dark currents. The photodetectors exhibited low surface leakage after passivation with SiO2, allowing the use of very small size features without degradation of the dark current. Fabricating microjunction photodetectors (25 × 25 µm² diodes with 10 × 10 µm² microjunctions) in combination with the double electron barrier design results in a dark current density of 6.3 × 10−6 A/cm² at 77 K. The device has an 8 µm cut-off wavelength at 77 K and exhibits a quantum efficiency of 31% for a 2 µm-thick absorption region, which results in a specific detectivity value of 1.2 × 1012 cm·Hz½/W. reprint
 
7.  
Toward realization of small-size dual-band long-wavelength infrared photodetectors based on InAs/GaSb/AlSb type-II superlattices
Toward realization of small-size dual-band long-wavelength infrared photodetectors based on InAs/GaSb/AlSb type-II superlattices
Romain Chevallier, Abbas Haddadi, Manijeh Razeghi
Solid-State Electronics-- June 20, 2017
In this study, we demonstrate 12 × 12 µm² high-performance, dual-band, long-wavelength infrared (LWIR) photodetectors based on InAs/GaSb/AlSb type-II superlattices. The structure consists of two back-to-back heterojunction photodiodes with 2 µm-thick p-doped absorption regions. High quality dry etching combined with SiO2 passivation results in a surface resistivity value of 7.9 × 105 Ω·cm for the longer (red) channel and little degradation of the electrical performance. The device reaches dark current density values of 4.5 × 10−4 A/cm² for the longer (red) and 1.3 × 10−4 A/cm² for the shorter (blue) LWIR channels at quantum efficiency saturation. It has 50% cut-off wavelengths of 8.3 and 11.2 µm for the blue and red channel, respectively, at 77 K in back-side illumination configuration and exhibits quantum efficiencies of 37% and 29%, respectively. This results in specific detectivity values of 2.5 × 1011 cm·Hz½/W and 1.3 × 1011 cm·Hz½/W at 77 K. reprint
 
8.  
Bias–selectable nBn dual–band long–/very long–wavelength infrared photodetectors based on InAs/InAsSb/AlAsSb type–II superlattices
Bias–selectable nBn dual–band long–/very long–wavelength infrared photodetectors based on InAs/InAsSb/AlAsSb type–II superlattices
Abbas Haddadi, Arash Dehzangi, Romain Chevallier, Sourav Adhikary, & Manijeh Razeghi
Scientific Reports 7, Article number: 3379 (2017) -- June 13, 2017
Type–II superlattices (T2SLs) are a class of artificial semiconductors that have demonstrated themselves as a viable candidate to compete with the state–of–the–art mercury–cadmium–telluride material system in the field of infrared detection and imaging. Within type–II superlattices, InAs/InAs1−xSbx T2SLs have been shown to have a significantly longer minority carrier lifetime. However, demonstration of high–performance dual–band photodetectors based on InAs/InAs1−xSbx T2SLs in the long and very long wavelength infrared (LWIR & VLWIR) regimes remains challenging. We report the demonstration of high–performance bias–selectable dual–band long–wavelength infrared photodetectors based on new InAs/InAsSb/AlAsSb type–II superlattice design. Our design uses two different bandgap absorption regions separated by an electron barrier that blocks the transport of majority carriers to reduce the dark current density of the device. As the applied bias is varied, the device exhibits well–defined cut–off wavelengths of either ∼8.7 or ∼12.5 μm at 77 K. This bias–selectable dual–band photodetector is compact, with no moving parts, and will open new opportunities for multi–spectral LWIR and VLWIR imaging and detection. reprint
 
9.  
Recent advances in antimonide-based gap-engineered Type-II superlattices material system for 2 and 3 colors infrared imagers
Recent advances in antimonide-based gap-engineered Type-II superlattices material system for 2 and 3 colors infrared imagers
Manijeh. Razeghi, Abbas Haddadi, Arash Dehzangi, Romain Chevallier, and Thomas Yang
Proceedings of SPIE 10177, Infrared Technology and Applications XLIII, 1017705-- May 9, 2017
InAs/InAs1-xSbx/AlAs1-xSbx type-II superlattices (T2SLs) is a system of multi-interacting quantum wells. Since its introduction, this material system has drawn a lot of attention especially for infrared detection. In recent years, InAs/InAs1- xSbx/AlAs1-xSbx T2SL material system has experienced incredible improvements in material quality, device structure designs and device fabrication process which elevated the performances of T2SL-based photodetectors to a comparable level to the state-of-the-art material systems for infrared detection such as Mercury Cadmium Telluride (MCT). In this paper, we will present the current status of InAs/InAs1-xSbx/AlAs1-xSbx T2SL-based photodetectors for detection in different infrared regions, from short-wavelength (SWIR) to long-wavelength (LWIR) infrared, and the future outlook of this material system. reprint
 
10.  
Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices with an AlAsSb/GaSb superlattice barrier
Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices with an AlAsSb/GaSb superlattice barrier
A. Haddadi, R. Chevallier, A. Dehzangi, and M. Razeghi
Applied Physics Letters 110, 101104 (2017)-- March 8, 2017
Extended short-wavelength infrared nBn photodetectors based on type-II InAs/AlSb/GaSb superlattices on GaSb substrate have been demonstrated. An AlAsSb/GaSb H-structure superlattice design was used as the large-bandgap electron-barrier in these photodetectors. The photodetector is designed to have a 100% cut-off wavelength of ∼2.8 μm at 300 K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.65 A/W at 1.9 μm, corresponding to a quantum efficiency of 41% at zero bias under front-side illumination, without any anti-reflection coating. With an R × A of 78 Ω·cm² and a dark current density of 8 × 10−3 A/cm² under −400 mV applied bias at 300 K, the nBn photodetector exhibited a specific detectivity of 1.51 × 1010 Jones. At 150 K, the photodetector exhibited a dark current density of 9.5 × 10−9 A/cm² and a quantum efficiency of 50%, resulting in a detectivity of 1.12 × 1013 Jones. reprint
 
11.  
Background–limited long wavelength infrared InAs/InAsSb type-II superlattice-based photodetectors operating at 110 K
Background–limited long wavelength infrared InAs/InAsSb type-II superlattice-based photodetectors operating at 110 K
Abbas Haddadi, Arash Dehzangi, Sourav Adhikary, Romain Chevallier, and Manijeh Razeghi
APL Materials 5, 035502 (2016)-- February 13, 2017
We report the demonstration of high-performance long-wavelength infrared (LWIR) nBn photodetectors based on InAs/InAsSb type-II superlattices. A new saw-tooth superlattice design was used to implement the electron barrier of the photodetectors. The device exhibited a cut-off wavelength of ∼10 μm at 77 K. The photodetector exhibited a peak responsivity of 2.65 A/W, corresponding to a quantum efficiency of 43%. With an R × A of 664 Ω·cm² and a dark current density of 8 × 10−5 A/cm², under −80 mV bias voltage at 77 K, the photodetector exhibited a specific detectivity of 4.72 × 1011 Jones and a background–limited operating temperature of 110 K. reprint
 
12.  
Impact of scaling base thickness on the performance of heterojunction phototransistors
Impact of scaling base thickness on the performance of heterojunction phototransistors
Arash Dehzangi, Abbas Haddadi, Sourav Adhikary, and Manijeh Razeghi
Nanotechnology 28, 10LT01 (2017)-- February 2, 2017
In this letter we report the effect of vertical scaling on the optical and electrical performance of mid-wavelength infrared heterojunction phototransistors based on type-II InAs/GaSb/AlSb superlattices. The performance of devices with different base thickness was compared as the base was scaled from 60 down to 40 nm. The overall optical performance shows enhancement in responsively, optical gain, and specific detectivity upon scaling the base width. The saturated responsivity for devices with 40 nm bases reaches 8,845 and 9,528 A/W at 77 and 150 K, respectively, which is almost five times greater than devices with 60 nm bases. The saturated optical gain for devices with 40 nm bases is measured as 2,760 at 77 K and 3,081 at 150 K. The devices with 40 nm bases also exhibit remarkable enhancement in saturated current gain, with 17,690 at 77 K, and 19,050 at 150 K. reprint
 
13.  
Mid-wavelength infrared heterojunction phototransistors based on type-II InAs/AlSb/GaSb superlattices
Mid-wavelength infrared heterojunction phototransistors based on type-II InAs/AlSb/GaSb superlattices
A. Haddadi, S. Adhikary, A. Dehzangi, and M. Razeghi
Applied Physics Letters 109, 021107 (2016)-- July 12, 2016
A mid-wavelength infrared heterojunction phototransistor based on type-II InAs/AlSb/GaSb superlattices on GaSb substrate has been demonstrated. Near a wavelength of 4 μm saturated optical gains of 668 and 639 at 77 and 150 K, respectively, are demonstrated over a wide dynamic range. At 150 K, the unity optical gain collector dark current density and DC current gain are 1 × 10−3 A/cm² and 3710, respectively. This demonstrates the potential for use in high-speed applications. In addition, the phototransistor exhibits a specific detectivity value that is four times higher compared with a state-of-the-art type-II superlattice-based photodiode with a similar cut-off wavelength at 150 K. reprint
 
14.  
High-performance short-wavelength infrared photodetectors based on type-II InAs/InAs<sub>1-x</sub>Sb<sub>x</sub>/AlAs<sub>1-x</sub>Sb<sub>x</sub> superlattices
High-performance short-wavelength infrared photodetectors based on type-II InAs/InAs1-xSbx/AlAs1-xSbx superlattices
M. Razeghi, A. Haddadi, X. V. Suo, S. Adhikary, P. Dianat, R. Chevallier, A. M. Hoang, A. Dehzangi
Proc. SPIE 9819, Infrared Technology and Applications XLII, 98190A -- May 20, 2016
We present a high-performance short-wavelength infrared n-i-p photodiode, whose structure is based on type-II superlattices with InAs/InAs1-xSbx/AlAs1-xSbx on GaSb substrate. At room temperature (300K) with front-side illumination, the device shows the peak responsivity of 0.47 A/W at 1.6mm, corresponding to 37% quantum efficiency at zero bias. At 300K, the device has a 50% cut-off wavelength of ~1.8mm. For −50mV applied bias at 300 K the photodetector has dark current density of 9.6x10-5 A/cm² and RxA of 285 Ω•cm², and it revealed a detectivity of 6.45x1010 cm•Hz½/W. Dark current density reached to 1.3x10-8 A/cm² at 200 K, with 36% quantum efficiency which leads to the detectivity value of 5.66x1012 cm•Hz½/W. reprint
 
15.  
InAs/InAs<sub>1-x</sub>Sb<sub>x</sub> type-II superlattices for high performance long wavelength infrared detection
InAs/InAs1-xSbx type-II superlattices for high performance long wavelength infrared detection
M. Razeghi, A. Haddadi, A. M. Hoang, R. Chevallier, S. Adhikary, A. Dehzangi
Proc. SPIE 9819, Infrared Technology and Applications XLII, 981909-- May 20, 2016
We report InAs/InAs1-xSbx type-II superlattice base photodetector as high performance long-wavelength infrared nBn device grown on GaSb substrate. The device has 6 μm-thick absorption region, and shows optical performance with a peak responsivity of 4.47 A/W at 7.9 μm, which is corresponding to the quantum efficiency of 54% at a bias voltage of negative 90 mV, where no anti-reflection coating was used for front-side illumination. At 77K, the photodetector’s 50% cut-off wavelength was ~10 μm. The device shows the detectivity of 2.8x1011 cm•Hz½/W at 77 K, where RxA and dark current density were 119 Ω•cm² and 4.4x10-4 A/cm² , respectively, under -90 mV applied bias voltage reprint
 
16.  
High-performance short-wavelength infrared photodetectors based on type-II InAs/InAs1-xSbx/AlAs1-xSbx superlattices
High-performance short-wavelength infrared photodetectors based on type-II InAs/InAs1-xSbx/AlAs1-xSbx superlattices
A. Haddadi, X.V. Suo, S. Adhikary, P. Dianat, R. Chevallier, A.M. Hoang, and M. Razeghi
Applied Physics Letters 107 , 141104 (2015)-- October 5, 2015
A high-performance short-wavelength infrared n-i-p photodiode based on InAs/InAs1-xSbx/AlAs1-xSbx type-II superlattices on GaSb substrate has been demonstrated. The device is designed to have a 50% cut-off wavelength of ~1.8μm at 300K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.47 A/W at 1.6μm, corresponding to a quantum efficiency of 37% at zero bias under front-side illumination, without any anti-reflection coating. With an R×A of 285 Ω·cm² and a dark current density of 9.6×10-5 A/cm² under −50mV applied bias at 300 K, the photodiode exhibited a specific detectivity of 6.45×1010 cm·Hz½/W. At 200 K, the photodiode exhibited a dark current density of 1.3×10-8 A/cm² and a quantum efficiency of 36%, resulting in a detectivity of 5.66×1012 cm·Hz½/W. reprint
 
17.  
InAs/InAs<sub>1-X</sub>Sb<sub>x</sub> Type-II Superlattices for High-Performance Long-Wavelength Infrared Medical Thermography
InAs/InAs1-XSbx Type-II Superlattices for High-Performance Long-Wavelength Infrared Medical Thermography
Manijeh Razeghi, Abbas Haddadi, Guanxi Chen, Romain Chevallier and Ahn Minh Hoang
ECS Trans. 2015 66(7): 109-116-- June 1, 2015
We present the demonstration of a high-performance long-wavelength infrared nBn photodetectors based on InAs/InAs1-xSbx type-II superlattices on GaSb substrate. The photodetector’s 50% cut-off wavelength was ~10 μm at 77K. The photodetector with a 6 μm-thick absorption region exhibited a peak responsivity of 4.47 A/W at 7.9 μm, corresponding to a quantum efficiency of 54% at -90 mV applied bias voltage under front-side illumination and without any anti-reflection coating. With an R×A of 119 Ω·cm² and a dark current density of 4.4×10-4 A/cm² under -90 mV applied bias voltage at 77 K, the photodetector exhibited a specific detectivity of 2.8×1011 Jones. This photodetector opens a new horizon for making infrared imagers with higher sensitivity for medical thermography.
 
18.  
High power frequency comb based on mid-infrared quantum cascade laser at λ ~9μm
High power frequency comb based on mid-infrared quantum cascade laser at λ ~9μm
Q. Y. Lu, M. Razeghi, S. Slivken, N. Bandyopadhyay, Y. Bai, W. J. Zhou, M. Chen, D. Heydari, A. Haddadi, R. McClintock, M. Amanti, and C. Sirtori
Appl. Phys. Lett. 106, 051105 (2015)-- February 2, 2015
We investigate a frequency comb source based on a mid-infrared quantum cascade laser at λ ∼9 μm with high power output. A broad flat-top gain with near-zero group velocity dispersion has been engineered using a dual-core active region structure. This favors the locking of the dispersed Fabry-Pérot modes into equally spaced frequency lines via four wave mixing. A current range with a narrow intermode beating linewidth of 3 kHz is identified with a fast detector and spectrum analyzer. This range corresponds to a broad spectral coverage of 65 cm−1 and a high power output of 180 mW for ∼176 comb modes. reprint
 
19.  
Bias-selectable dual-band mid-/long-wavelength infrared photodetectors based on InAs/InAs<sub>1−x</sub>Sb<sub>x</sub> type-II superlattices
Bias-selectable dual-band mid-/long-wavelength infrared photodetectors based on InAs/InAs1−xSbx type-II superlattices
A. Haddadi, R. Chevallier, G. Chen, A. M. Hoang, and M. Razeghi
Applied Physics Letters 106 , 011104 (2015)-- January 8, 2015
A high performance bias-selectable mid-/long-wavelength infrared photodetector based on InAs/InAs1−xSbx type-II superlattices on GaSb substrate has been demonstrated. The mid- and long-wavelength channels' 50% cut-off wavelengths were ∼5.1 and ∼9.5 μm at 77 K. The mid-wavelength channel exhibited a quantum efficiency of 45% at 100 mV bias voltage under front-side illumination and without any anti-reflection coating. With a dark current density of 1 × 10−7 A/cm² under 100 mV applied bias, the mid-wavelength channel exhibited a specific detectivity of 8.2 × 1012 cm·Hz½·W-1 at 77 K. The long-wavelength channel exhibited a quantum efficiency of 40%, a dark current density of 5.7 × 10−4 A/cm² under −150 mV applied bias at 77 K, providing a specific detectivity value of 1.64 × 1011 cm·Hz½·W-1. reprint
 
20.  
Demonstration of type-II superlattice MWIR minority carrier unipolar imager for high operation temperature application
Demonstration of type-II superlattice MWIR minority carrier unipolar imager for high operation temperature application
Guanxi Chen, Abbas Haddadi, Anh-Minh Hoang, Romain Chevallier, and Manijeh Razeghi
Optics Letters Vol. 40, Iss. 1, pp. 29–32 (2015)-- December 18, 2014
An InAs/GaSb type-II superlattice-based mid-wavelength infrared (MWIR) 320×256 unipolar focal plane array (FPA) using pMp architecture exhibited excellent infrared image from 81 to 150 K and ∼98% operability, which illustrated the possibility for high operation temperature application. At 150 K and −50  mV operation bias, the 27 μm pixels exhibited dark current density to be 1.2×10−5  A/cm², with 50% cutoff wavelength of 4.9 μm, quantum efficiency of 67% at peak responsivity (4.6 μm), and specific detectivity of 1.2×1012 Jones. At 90 K and below, the 27 μm pixels exhibited system limited dark current density, which is below 1×10−9  A/cm², and specific detectivity of 1.5×1014 Jones. From 81 to 100 K, the FPA showed ∼11  mK NEDT by using F/2.3 optics and a 9.69 ms integration time. reprint
 
21.  
InAs/InAs<sub>1-x</sub>Sb<sub>x</sub> type-II superlattices for high performance long wavelength infrared detection
InAs/InAs1-xSbx type-II superlattices for high performance long wavelength infrared detection
A. Haddadi , G. Chen , R. Chevallier , A. M. Hoang , and M. Razeghi
Appl. Phys. Lett. 105, 121104 (2014)-- September 22, 2014
High performance long-wavelength infrared nBn photodetectors based on InAs/InAs1−xSbx type-II superlattices on GaSb substrate have been demonstrated. The photodetector's 50% cut-off wavelength was ∼10 μm at 77 K. The photodetector with a 6 μm-thick absorption region exhibited a peak responsivity of 4.47 A/W at 7.9 μm, corresponding to a quantum efficiency of 54% at −90 mV bias voltage under front-side illumination and without any anti-reflection coating. With an R × A of 119 Ω·cm² and a dark current density of 4.4 × 10−4 A/cm² under −90 mV applied bias at 77 K, the photodetector exhibited a specific detectivity of 2.8 × 1011 cm·Hz1/2·W-1. reprint
 
22.  
High Performance Solar-Blind Ultraviolet Focal Plane Arrays Based on AlGaN
High Performance Solar-Blind Ultraviolet Focal Plane Arrays Based on AlGaN
Erdem Cicek, Ryan McClintock, Abbas Haddadi, William A. Gaviria Rojas, and Manijeh Razeghi
IEEE Journal of Quantum Electronics, Vol. 50, Issue 8, p 591-595-- August 1, 2014
We report on solar-blind ultraviolet, AlxGa1-x N- based,p-i-n,focal plane array (FPA) with 92% operability. At the peak detection wavelength of 278 nm, 320×256-FP A-pixel showed unbiased peak external quantum efficiency (EQE) and responsivity of 49% and 109 mA/W, respectively, increasing to 66% under 5 volts of reverse bias. Electrical measurements yielded a low-dark current density: <7×10-9A/cm², at FPA operating voltage of 2 volts of reverse bias. reprint
 
23.  
Antimonide-Based Type II Superlattices:  A Superior Candidate for the Third Generation of Infrared Imaging Systems
Antimonide-Based Type II Superlattices: A Superior Candidate for the Third Generation of Infrared Imaging Systems
M. Razeghi, A. Haddadi, A.M. Hoang, G. Chen, S. Bogdanov, S.R. Darvish, F. Callewaert, P.R. Bijjam, and R. McClintock
Journal of ELECTRONIC MATERIALS, Vol. 43, No. 8, 2014-- August 1, 2014
Type II superlattices (T2SLs), a system of interacting multiquantum wells,were introduced by Nobel Laureate L. Esaki in the 1970s. Since then, this material system has drawn a lot of attention, especially for infrared detection and imaging. In recent years, the T2SL material system has experienced incredible improvements in material growth quality, device structure design, and device fabrication techniques that have elevated the performance of T2SL-based photodetectors and focal-plane arrays (FPAs) to a level comparable to state-of-the-art material systems for infrared detection and imaging, such as mercury cadmium telluride compounds. We present the current status of T2SL-based photodetectors and FPAs for imaging in different infrared regimes, from short wavelength to very long wavelength, and dual-band infrared detection and imaging, as well as the future outlook for this material system. reprint
 
24.  
High performance photodiodes based on InAs/InAsSb type-II superlattices for very long wavelength infrared detection
High performance photodiodes based on InAs/InAsSb type-II superlattices for very long wavelength infrared detection
A. M. Hoang, G. Chen, R. Chevallier, A. Haddadi, and M. Razeghi
Appl. Phys. Lett. 104, 251105 (2014)-- June 23, 2014
Very long wavelength infrared photodetectors based on InAs/InAsSb Type-II superlattices are demonstrated on GaSb substrate. A heterostructure photodiode was grown with 50% cut-off wavelength of 14.6 μm. At 77 K, the photodiode exhibited a peak responsivity of 4.8 A/W, corresponding to a quantum efficiency of 46% at −300 mV bias voltage from front side illumination without antireflective coating. With the dark current density of 0.7 A/cm², it provided a specific detectivity of 1.4 × 1010 Jones. The device performance was investigated as a function of operating temperature, revealing a very stable optical response and a background limited performance below 50 K. reprint
 
25.  Effect of sidewall surface recombination on the quantum efficiency in a Y2O3 passivated gated type-II InAs/GaSb long-infrared photodetector array
G. Chen, A. M. Hoang, S. Bogdanov, A. Haddadi, S. R. Darvish, and M. Razeghi
Appl. Phys. Lett. 103, 223501 (2013)-- November 25, 2013
Y2O3 was applied to passivate a long-wavelength infrared type-II superlattice gated photodetector array with 50% cut-off wavelength at 11 μm, resulting in a saturated gate bias that was 3 times lower than in a SiO2 passivated array. Besides effectively suppressing surface leakage, gating technique exhibited its ability to enhance the quantum efficiency of 100 × 100 μm size mesa from 51% to 57% by suppressing sidewall surface recombination. At 77 K, the gated photodetector showed dark current density and resistance-area product at −300 mV of 2.5 × 10−5 A/cm² and 1.3 × 104 Ω·cm², respectively, and a specific detectivity of 1.4 × 1012 Jones. reprint
 

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