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Monolithic terahertz source
Monolithic terahertz source
Q. Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai and M. Razeghi
Nature Photonics | Research Highlights -- July 31, 2014
To date, the production of continuous-wave terahertz (THz) sources based on intracavity difference-frequency generation from mid-infrared quantum cascade lasers operating at room temperature has proved elusive. A critical problem is that, to achieve a large nonlinear susceptibility for frequency conversion, the active region of the quantum cascade laser requires high doping, which elevates the lasing threshold current density. Now, Quan-Yong Lu and colleagues from Northwestern University in the USA have overcome this problem and demonstrated a room-temperature continuous-wave THz source based on difference-frequency generation in quantum cascade lasers. They designed quantum-well structures based on In0.53Ga0.47As/In0.52Al0.48As material system for two mid-infrared wavelengths. The average doping in the active region was about 2.5 × 1016 cm−3. A buried ridge, buried composite distributed-feedback waveguide with the Čerenkov phase-matching scheme was used to reduce the waveguide loss and enhance heat dissipation. As a result, single-mode emission at 3.6 THz was observed at 293 K. The continuous-wave THz power reached 3 μW with a conversion efficiency of 0.44 mW W−2 from mid-infrared to THz waves. Using a similar device design, a THz peak power of 1.4 mW was achieved in pulse mode. reprint
52.  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
Continuous operation of a monolithic semiconductor terahertz source at room temperature
Continuous operation of a monolithic semiconductor terahertz source at room temperature
Q. Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai, and M. Razeghi
Appl. Phys. Lett. 104, 221105 (2014)-- June 3, 2014
We demonstrate room temperature continuous wave THz sources based on intracavity difference-frequency generation from mid-infrared quantum cascade lasers. Buried ridge, buried composite distributed-feedback waveguide with Čerenkov phase-matching scheme is used to reduce the waveguide loss and enhance the heat dissipation for continuous wave operation. Continuous emission at 3.6 THz with a side-mode suppression ratio of 20 dB and output power up to 3 μW are achieved, respectively. THz peak power is further scaled up to 1.4 mW in pulsed mode by increasing the mid-infrared power through increasing the active region doping and device area. reprint
54.  Superlattice-based quantum devices: from theory to practical applications
M. Razeghi
Waves in Random and Complex Media, -- April 23, 2014
The concepts of resonant tunneling and superlattices were first developed by Esaki and Tsu. What started with the new physics of the Esaki tunnel diode has matured into nanoscale engineering of semiconductors superlattices to create whole synthetic band structures. While working at Thomson CSF in France, Manijeh Razeghi went on to develop the metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy growth of superlattice material as reported in my seminal volumes of The MOCVD Challenge. After years of considerable effort to bring this technology to maturity, we now see the results of this formidable new science in almost every electronic and photonic device that we encounter. Among the most successful triumphs are the type-II superlattice photodetectors and quantum cascade lasers – these technologies have demonstrated the beauty of turning fundamental concepts into practical devices, thanks to advanced growth technologies. This enables us to design and realize compact devices capable of mimicking or even exceeding nature. Using superlattice to pioneer the development of quantum systems is driving the research work at the Center for Quantum Devices.
55.  Novel Method for Reclaim/Reuse of Bulk GaN Substrates using Sacrifical ZnO Release Layers
A. Rajan, S. Sundaram, Y. El Gmili, P. L. Voss, K. Pantzas, T. Moudakir, A. Ougazzaden, D. J. Rogers, F. Hosseini Teherani, V. E. Sandana, P. Bove, K. Prior, R. McClintock & M. Razeghi
Proc. SPIE 8987, Oxide-based Materials and Devices V, 898719-- April 2, 2014
Free-standing (0002)-oriented GaN substrates (f = 2”) were coated with 200 nm of ZnO and used as templates for the growth of GaN thin films. SEM and AFM revealed that such GaN layers had a relatively homogenous surface morphology with an RMS roughness (5 μm x 5 μm) of less than 4nm. XRD studies revealed strained ZnO growth on the GaN substrate and the reproduction of the substrate rocking curve for the GaN overlayers after only a hundred nm of growth, thus indicating that the GaN films had superior crystallographic quality compared to those grown on sapphire or ZnO/sapphire substrates. Quarter-wafer areas of GaN were removed from the GaN substrate (by selective chemical etching away of the ZnO interlayer). The expensive GaN substrates were then reclaimed/reused (without the need for polishing) for a second cycle of ZnO and GaN growth, which gave similar XRD, SEM, CL and AFM results to the first cycle. reprint
56.  Cubic Phase GaN on Nano-grooved Si (100) via Maskless Selective Area Epitaxy
Bayram, C., Ott, J. A., Shiu, K.-T., Cheng, C.-W., Zhu, Y., Kim, J., Razeghi, M. and Sadana, D. K.
Adv. Funct. Mater. 2014-- April 1, 2014
A method of forming cubic phase (zinc blende) GaN (referred as c-GaN) on a CMOS-compatible on-axis Si (100) substrate is reported. Conventional GaN materials are hexagonal phase (wurtzite) (referred as h-GaN) and possess very high polarization fields (∼MV/cm) along the common growth direction of <0001>. Such large polarization fields lead to undesired shifts (e.g., wavelength and current) in the performance of photonic and vertical transport electronic devices. The cubic phase of GaN materials is polarization-free along the common growth direction of <001>, however, this phase is thermodynamically unstable, requiring low-temperature deposition conditions and unconventional substrates (e.g., GaAs). Here, novel nano-groove patterning and maskless selective area epitaxy processes are employed to integrate thermodynamically stable, stress-free, and low-defectivity c-GaN on CMOS-compatible on-axis Si. These results suggest that epitaxial growth conditions and nano-groove pattern parameters are critical to obtain such high quality c-GaN. InGaN/GaN multi-quantum-well structures grown on c-GaN/Si (100) show strong room temperature luminescence in the visible spectrum, promising visible emitter applications for this technology. reprint
57.  Evaluating the size-dependent quantum efficiency loss in a SiO2-Y2O3 hybrid gated type-II InAs/GaSb long-infrared photodetector array
G. Chen , A. M. Hoang , and M. Razeghi
Applied Physics Letters 104 , 103509 (2014)-- March 14, 2014
Growing Y2O3 on 20 nm SiO2 to passivate a 11 μm 50% cut-off wavelength long-wavelength infrared type-II superlattice gated photodetector array reduces its saturated gate bias (VGsat ) to −7 V. Size-dependent quantum efficiency (QE) losses are evaluated from 400 μm to 57 μm size gated photodiode. Evolution of QE of the 57 μm gated photodiode with gate bias and diode operation bias reveals different surface recombination mechanisms. At 77 K and VG,sat , the 57 μm gated photodiode exhibits QE enhancement from 53% to 63%, and it has 1.2 × 10−5 A/cm² dark current density at −200 mV, and a specific detectivity of 2.3 × 1012 Jones. reprint
58.  Nickel oxide growth on Si (111), c-Al2O3 and FTO/glass by pulsed laser deposition
V. E. Sandana ; D. J. Rogers ; F. Hosseini Teherani ; P. Bove ; R. McClintock ; M. Razeghi
03/07/2014-- March 7, 2014
NiO was grown on Si (111), c-Al2O3 and FTO/glass substrates by pulsed laser deposition (PLD). X-Ray Diffraction (XRD) and scanning electron microscope (SEM) studies revealed that layers grown on c-Al2O3 were fcc NiO with a dense morphology of cubic grains that were strongly (111) oriented along the growth direction. The relatively low ω rocking curve linewidth, of 0.12°suggests that there may have been epitaxial growth on the c-Al2O3 substrate. XRD and SEM indicated that films grown on Si (111) were also fcc NiO, with cubic grains, but that the grain orientation was random. This is consistent with the presence of an amorphous SiO2 layer at the surface of the Si substrate, which precluded epitaxial growth. NiO grown at lower temperature (200°C) on temperature-sensitive FTO/glass substrates showed no evidence of crystallinity in XRD and SEM studies. After flash annealing in air, however, peaks characteristic of randomly oriented fcc NiO appeared in the XRD scans and the surface morphology became more granular in appearance. Such layers appear promising for the development of future dye-sensitised solar cell devices based on NiO grown by PLD. reprint
59.  Generation-recombination and trap-assisted tunneling in long wavelength infrared minority electron unipolar photodetectors based on InAs/GaSb superlattice
F. Callewaert, A.M. Hoang, and M. Razeghi
Applied Physics Letters, 104, 053508 (2014)-- February 6, 2014
A long wavelength infrared minority electron unipolar photodetector based on InAs/GaSb type-II superlattices is demonstrated. At 77 K, a dark current of 3 × 10−5 A/cm² and a differential resistance-area of 3 700 Ω·cm² are achieved at the turn-on bias, with a 50%-cutoff of 10.0 μm and a specific detectivity of 6.2 × 1011 Jones. The dark current is fitted as a function of bias and temperature using a model combining generation-recombination and trap-assisted tunneling. Good agreement was observed between the theory and the experimental dark current. reprint
60.  Investigation of the factors influencing nanostructure array growth by PLD towards reproducible wafer-scale growth
Vinod E. Sandana; David. J. Rogers; Ferechteh Hosseini Teherani; Philippe Bove; Manijeh Razeghi
physica status solidi (a) Applications and Materials Science. Volume 211, Issue 2, pages 449–454, (February 2014)-- January 14, 2014
The growth of catalyst-free ZnO nanostructure arrays on silicon (111) substrates by pulsed laser deposition was investigated. Without an underlayer, randomly oriented, micron-scale structures were obtained. Introduction of a c-axis oriented ZnO underlayer resulted in denser arrays of vertically oriented nanostructures with either tapering, vertical-walled or broadening forms, depending on background Ar pressure. Nanostructure pitch seemed to be determined by underlayer grain size while nanostructure widths could be narrowed from ∼100–500 to ∼10–50 nm by a 50 °C increase in growth temperature. A dimpled underlayer topography correlated with the moth-eye type arrays while a more granular surface was linked to vertically walled nanocolumns. Between-wafer reproducibility was demonstrated for both moth-eye and vertical nanocolumn arrays. Broadening nanostructures proved difficult to replicate, however. Full 2 inch wafer coverage was obtained by rastering the target with the laser beam. reprint
61.  Extended electrical tuning of quantum cascade lasers with digital concatenated gratings
S. Slivken, N. Bandyopadhyay, Y. Bai, Q. Y. Lu, and M. Razeghi
Appl. Phys. Lett. 103, 231110 (2013)-- December 6, 2013
In this report, the sampled grating distributed feedback laser architecture is modified with digital concatenated gratings to partially compensate for the wavelength dependence of optical gain in a standard high efficiency quantum cascade laser core. This allows equalization of laser threshold over a wide wavelength range and demonstration of wide electrical tuning. With only two control currents, a full tuning range of 500 nm (236 cm−1) has been demonstrated. Emission is single mode, with a side mode suppression of >20 dB. reprint
62.  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
63.  Room temperature compact THz sources based on quantum cascade laser technology
M. Razeghi; Q.Y. Lu; N. Bandyopadhyay; S. Slivken; Y. Bai
Proc. SPIE 8846, Terahertz Emitters, Receivers, and Applications IV, 884602 (September 24, 2013)-- November 24, 2013
We present the high performance THz sources based on intracavity difference-frequency generation from mid-infrared quantum cascade lasers. Room temperature single-mode operation in a wide THz spectral range of 1-4.6 THz is demonstrated from our Čerenkov phase-matched THz sources with dual-period DFB gratings. High THz power up to 215 μW at 3.5 THz is demonstrated via epi-down mounting of our THz device. The rapid development renders this type of THz sources promising local oscillators for many astronomical and medical applications. reprint
64.  AlxGa1-xN-based back-illuminated solar-blind photodetectors with external quantum efficiency of 89%
E. Cicek, R. McClintock, C. Y. Cho, B. Rahnema, and M. Razeghi
Appl. Phys. Lett. 103, 191108 (2013)-- November 5, 2013
We report on high performance AlxGa1−xN-based solar-blind ultraviolet photodetector (PD) array grown on sapphire substrate. First, high quality, crack-free AlN template layer is grown via metalorganic chemical vapor deposition. Then, we systematically optimized the device design and material doping through the growth and processing of multiple devices. After optimization, uniform and solar-blind operation is observed throughout the array; at the peak detection wavelength of 275 nm, 729 μm² area PD showed unbiased peak external quantum efficiency and responsivity of ∼80% and ∼176 mA/W, respectively, increasing to 89% under 5 V of reverse bias. Taking the reflection loses into consideration, the internal quantum efficiency of these optimized PD can be estimated to be as high as ∼98%. The visible rejection ratio measured to be more than six orders of magnitude. Electrical measurements yielded a low-dark current density: <2 × 10−9 A/cm², at 10 V of reverse bias. reprint
Recent advances in mid infrared (3-5 μm) quantum cascade lasers
Recent advances in mid infrared (3-5 μm) quantum cascade lasers
Manijeh Razeghi; Neelanjan Bandyopadhyay; Yanbo Bai; Quanyong Lu; Steven Slivken
Optical Materials Express, Vol. 3, Issue 11, pp. 1872-1884 (2013)-- November 2, 2013
Quantum cascade laser (QCL) is an important source of electromagnetic radiation in mid infrared region. Recent research in mid-IR QCLs has resulted in record high wallplug efficiency (WPE), high continuous wave (CW) output power, single mode operation and wide tunability. CW output power of 5.1 W with 21% WPE has been achieved at room temperature (RT). A record high WPE of 53% at 40K has been demonstrated. Operation wavelength of QCL in CW at RT has been extended to as short as 3μm. Very high peak power of 190 W has been obtained from a broad area QCL of ridge width 400μm. 2.4W RT, CW power output has been achieved from a distributed feedback (DFB) QCL. Wide tuning based on dual section sample grating DFB QCLs has resulted in individual tuning of 50cm-1 and 24 dB side mode suppression ratio with continuous wave power greater than 100 mW. reprint
66.  AlxGa1−xN-based solar-blind ultraviolet photodetector based on lateral epitaxial overgrowth of AlN on Si substrate
E. Cicek, R. McClintock, C. Y. Cho, B. Rahnema, and M. Razeghi
Appl. Phys. Lett. 103, 181113 (2013)-- October 30, 2013
We report on AlxGa1−xN-based solar-blind ultraviolet (UV) photodetector (PD) grown on Si(111) substrate. First, Si(111) substrate is patterned, and then metalorganic chemical vapor deposition is implemented for a fully-coalesced ∼8.5 μm AlN template layer via a pulsed atomic layer epitaxial growth technique. A back-illuminated p-i-n PD structure is subsequently grown on the high quality AlN template layer. After processing and implementation of Si(111) substrate removal, the optical and electrical characteristic of PDs are studied. Solar-blind operation is observed throughout the array; at the peak detection wavelength of 290 nm, 625 μm² area PD showed unbiased peak external quantum efficiency and responsivity of ∼7% and 18.3 mA/W, respectively, with a UV and visible rejection ratio of more than three orders of magnitude. Electrical measurements yielded a low-dark current density below 1.6 × 10−8 A/cm² at 10 V reverse bias. reprint
67.  SOLID-STATE DEEP UV EMITTERS/DETECTORS: Zinc oxide moves further into the ultraviolet
David J. Rogers; Philippe Bove; Eric V. Sandana; Ferechteh Hosseini Teherani; Ryan McClintock; Manijeh Razeghi
Laser Focus World. 2013;49(10):33-36.-- October 10, 2013
Latest advancements in the alloying of zinc oxide (ZnO) with magnesium (Mg) can offer an alternative to (Al) GaN-based emitters/detectors in the deep UV with reduced lattice and efficiency issues. The emerging potential of ZnO for UV emitter and detector applications is the result of a long, concerted, and fruitful R&D effort that has led to more than 7000 publications in 2012. ZnO is considered to be a potentially superior material for use in LEDs and laser diodes due to its larger exciton binding energy, as compared with 21 meV for GaN. Wet etching is also possible for ZnO with nearly all dilute acids and alkalis, while GaN requires hydrofluoric (HF) acid or plasma etching. High-quality ZnO films can be grown more readily on mismatched substrates and bulk ZnO substrates have better availability than their GaN equivalents.
68.  Thermal conductivity tensors of the cladding and active layers of antimonide infrared lasers and detectors
Chuanle Zhou, I. Vurgaftman, C. L. Canedy, C. S. Kim, M. Kim, W. W. Bewley, C. D. Merritt, J. Abell, J. R. Meyer, A. Hoang, A. Haddadi, M. Razeghi, and M. Grayson
Optical Materials Express. 2013;3(10):1632-1640.-- October 1, 2013
The in-plane and cross-plane thermal conductivities of the cladding layers and active quantum wells of interband cascade lasers and type-II superlattice infrared detector are measured by the 2-wire 3ω method. The layers investigated include InAs/AlSb superlattice cladding layers, InAs/GaInSb/InAs/AlSb W-active quantum wells, an InAs/GaSb superlattice absorber, an InAs/GaSb/AlSb M-structure, and an AlAsSb digital alloy. The in-plane thermal conductivity of the InAs/AlSb superlattice is 4-5 times higher than the cross-plane value. The isotropic thermal conductivity of the AlAsSb digital alloy matches a theoretical expectation, but it is one order of magnitude lower than the only previously-reported experimental value. reprint
69.  Growth of “moth-eye” ZnO nanostructures on Si(111), c-Al2O3, ZnO and steel substrates by pulsed laser deposition
Vinod E. Sandana, David J. Rogers, Ferechteh Hosseini Teherani, Philippe Bove, Michael Molinari, Michel Troyon, Alain Largeteau, Gérard Demazeau, Colin Scott, Gaelle Orsal, Henri-Jean Drouhin, Abdallah Ougazzaden, Manijeh Razeghi
Phys. Status Solidi C., 1-5 (2013)-- August 6, 2013
Self-forming, vertically-aligned, arrays of black-body-like ZnO moth-eye nanostructures were grown on Si(111), c-Al2O3, ZnO and high manganese austenitic steel substrates using Pulsed Laser Deposition. X-ray diffraction (XRD) revealed the nanostructures to be well-crystallised wurtzite ZnO with strong preferential c-axis crystallographic orientation along the growth direction for all the substrates. Cathodoluminescence (CL) studies revealed emission characteristic of the ZnO near band edge for all substrates. Such moth-eye nanostructures have a graded effective refractive index and exhibit black-body characteristics. Coatings with these features may offer improvements in photovoltaic and LED performance. Moreover, since ZnO nanostructures can be grown readily on a wide range of substrates it is suggested that such an approach could facilitate growth of GaN-based devices on mismatched and/or technologically important substrates, which may have been inaccessible till present. reprint
70.  Investigation of impurities in type-II InAs/GaSb superlattices via capacitance-voltage measurement
G. Chen, A. M. Hoang, S. Bogdanov, A. Haddadi, P. R. Bijjam, B.-M. Nguyen, and M. Razeghi
Applied Physics Letters 103, 033512 (2013)-- July 17, 2013
Capacitance-voltage measurement was utilized to characterize impurities in the non-intentionally doped region of Type-II InAs/GaSb superlattice p-i-n photodiodes. Ionized carrier concentration versus temperature dependence revealed the presence of a kind of defects with activation energy below 6 meV and a total concentration of low 1015 cm−3. Correlation between defect characteristics and superlattice designs was studied. The defects exhibited a p-type behavior with decreasing activation energy as the InAs thickness increased from 7 to 11 monolayers, while maintaining the GaSb thickness of 7 monolayers. With 13 monolayers of InAs, the superlattice became n-type and the activation energy deviated from the p-type trend. reprint
71.  Room temperature terahertz quantum cascade laser sources with 215 μW output power through epilayer-down mounting
Q. Y. Lu, N. Bandyopadhyay, S. Slivken, Y. Bai, and M. Razeghi
Appl. Phys. Lett. 103, 011101 (2013)-- July 1, 2013
We report room temperature terahertz (THz) quantum cascade laser sources with high power based on difference frequency generation. The device is Čerenkov phase matched and spectrally purified with an integrated dual-period distributed-feedback grating. Symmetric current injection and epilayer-down mounting of the device onto a patterned submount are used to improve the electrical uniformity and heat removal, respectively. The epilayer-down mounting also allows for THz anti-reflective coating to enhance the THz outcoupling efficiency. Single mode emission at 3.5 THz with a side-mode suppression ratio and output power up to 30 dB and 215  μW are obtained, respectively. reprint
72.  Advances in antimonide-based Type-II superlattices for infrared detection and imaging at center for quantum devices
M. Razeghi, A. Haddadi, A.M. Hoang, E.K. Huang, G. Chen, S. Bogdanov, S.R. Darvish, F. Callewaert, R. McClintock
Infrared Physics & Technology, Volume 59, Pages 41-52 (2013)-- July 1, 2013
Type-II InAs/GaSb superlattices (T2SLs), a system of multi-interacting quantum wells, was introduced by Nobel Laureate L. Esaki in the 1970s. Since then, this material system has drawn a lot of attention especially for infrared detection. In recent years, T2SL material system has experienced incredible improvements in material quality, device structure designs and device fabrication process which elevated the performances of T2SL-based photo-detectors 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 T2SL-based photo-detectors and focal plane arrays for imaging in different infrared regions, from SWIR to VLWIR, and the future outlook of this material system. reprint
73.  High-performance bias-selectable dual-band Short-/Mid-wavelength infrared photodetectors and focal plane arrays based on InAs/GaSb/AlSb Type-II superlattices
M. Razeghi; A.M. Hoang; A. Haddadi; G. Chen; S. Ramezani-Darvish; P. Bijjam; P. Wijewarnasuriy; E. Decuir
Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 87041W (June 18, 2013)-- June 18, 2013
We report a bias selectable dual-band Type-II superlattice-based short-wave infrared (SWIR) and mid-wave infrared (MWIR) co-located photodetector capable of active and passive imaging. A new double-layer etch-stop scheme is introduced for back-side-illuminated photodetectors, which enhanced the external quantum efficiency both in the SWIR and MWIR spectral regions. Temperature-dependent dark current measurements of pixel-sized 27 μm detectors found the dark current density to be ∼1×10-5 A/cm2 for the ∼4.2 μm cut-off MWIR channel at 140 K. This corresponded to a reasonable imager noise equivalent difference in temperature of ∼49 mK using F/2.3 optics and a 10 ms integration time (tint), which lowered to ∼13 mK at 110 K using and integration time of 30 ms, illustrating the potential for high-temperature operation. The SWIR channel was found to be limited by readout noise below 150 K. An excellent imagery from the dual-band imager exemplifying pixel coincidence is shown. reprint
74.  High-performance bias-selectable dual-band mid-/long-wavelength infrared photodetectors and focal plane arrays based on InAs/GaSb Type-II superlattices
M. Razeghi; A. Haddadi; A.M. Hoang; G. Chen; S. Ramezani-Darvish; P. Bijjam
Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 87040S (June 11, 2013)-- June 11, 2013
We report a bias selectable dual-band mid-wave infrared (MWIR) and long-wave infrared (LWIR) co-located detector with 3 μm active region thickness per channel that is highly selective and can perform under high operating temperatures for the MWIR band. Under back-side illumination, a temperature evolution study of the MWIR detector's electro-optical performance found the 300 K background-limit with 2π field-of-view to be achieved below operating temperatures of 160 K, at which the temperature's 50% cutoff wavelength was 5.2 μm. The measured current reached the system limit of 0.1 pA at 110 K for 30 μm pixel-sized diodes. At 77 K, where the LWIR channel operated with a 50% cutoff wavelength at 11.2 μm, an LWIR selectivity of ∼17% was achieved in the MWIR wave band between 3 and 4.7 μm, making the detector highly selective. reprint
75.  Sensitive detection of CO and N2O using a high power CW 4.61 μm dfb-QCL based QEPAS sensor
Yufei Ma; Rafał Lewicki; Manijeh Razeghi; Xin Yu; Frank K. Tittel
CLEO: Science and Innovations, CLEO_SI 2013. 2013:JW2A.80-- June 9, 2013
A high power CW DFB-QCL based CO and N2O QEPAS sensor demonstrating the MDL of 1.5 ppbv and 23 ppbv, respectively was developed. Continuous monitoring of atmospheric CO and N2O concentration levels were performed.

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