Center for Quantum Devices - Most Downloaded Journal Articles

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20.	Growth and characterization of InAs/GaSb Type-II superlattices for long-wavelength infrared detectors H. Mohseni, E. Michel, M. Razeghi, W. Mitchel, and G. Brown SPIE Conference, San Jose, CA, -- January 28, 1998 ...[Visit Journal] We report the molecular beam epitaxial growth and characterization of InAs/GaSb superlattices grown on semi- insulating GaAs substrate for long wavelength IR detectors. Photoconductive detectors fabricated from the superlattices showed 80% cut-off at 11.6 μm and peak responsivity of 6.5 V/W with Johnson noise limited detectivity of 2.36 x 10⁹ cm·Hz^½/W at 10.7 μm at 78 K. The responsivity decreases at higher temperatures with a T^-2 behavior rather than exponential decay, and at room temperature the responsivity is about 660 mV/W at 11 μm. Lower Auger recombination rate in this system provides comparable detectivity to the best HgCdTe detectors at 300K. Higher uniformity over large areas, simpler growth and the possibility of having read-out circuits in the same GaAs chip are the advantages of this system over HgCdTe detectors for near room temperature operation. [reprint (PDF)]
20.	High-brightness LWIR quantum cascade lasers F. Wang, S. Slivken, and M. Razeghi F. Wang, S. Slivken, and M. Razeghi, High-brightness LWIR quantum cascade lasers, Optics Letters, vol. 46, No. 20, 5193 ...[Visit Journal] Long-wave infrared (LWIR, lambda~8-12 um) quantum cascade lasers (QCLs) are drawing increasing interest, as they provide the possibility of long-distance transmission of light through the atmosphere owing to the reduced water absorption. However, their development has been lagging behind the shorter wavelength QCLs due to much bigger technological challenges. In this Letter, through band structure engineering based on a highly localized diagonal laser transition strategy and out-coupler design using an electrically isolated taper structure, we demonstrate high beam quality single-mode LWIR QCLs with high-brightness (2.0 MW cm^-2 sr^-1 for lambda~10 um, 2.2 MW cm^-2 sr^-1 for lambda~9 um, 5.0 MW cm^-2 sr^-1 for lambda~8 um) light extraction from a single facet in continuous-wave operation at 15 ^oC. These results mark an important milestone in exploring the lighting capability of inter-sub-band semiconductor lasers in the LWIR spectral range. [reprint (PDF)]
20.	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 ...[Visit Journal] 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 (PDF)]
20.	Optical Coatings by ion-beam sputtering deposition for long-wave infrared quantum cascade lasers J. Nguyen, J.S. Yu, A. Evans, S. Slivken and M. Razeghi Applied Physics Letters, 89 (11)-- September 11, 2006 ...[Visit Journal] The authors report on the development of high-reflection and multilayer antireflection coatings using ion-beam sputtering deposition for long-wave infrared (λ~9.4 μm) quantum cascade lasers. A metallic high-reflection coating structure using Y₂O₃ and Au is demonstrated to achieve a high reflectance of 96.70%, and the use of a multilayer anti-reflection coating structure using PbTe and ZnO is demonstrated to achieve a very low reflectance of 1.64%. [reprint (PDF)]
20.	Type-II InAs/GaSb Superlattices and Detectors with Cutoff Wavelength Greater Than 18 μm M. Razeghi, Y. Wei, A. Gin, G.J. Brown and D. Johnstone Proceedings of the SPIE, San Jose, CA, Vol. 4650, 111 (2002)-- January 25, 2002 ...[Visit Journal] The authors report the most recent advances in Type-II InAs/GaSb superlattice materials and photovoltaic detectors. Lattice mismatch between the substrate and the superlattice has been routinely achieved below 0.1%, and less than 0.0043% as the record. The FWHM of the zeroth order peak from x-ray diffraction has been decreased below 50 arcsec and a record of less than 44arcsec has been achieved. High performance detectors with 50% cutoff beyond 18 micrometers up to 26 micrometers have been successfully demonstrated. The detectors with a 50% cut-off wavelength of 18.8 micrometers showed a peak current responsivity of 4 A/W at 80K, and a peak detectivity of 4.5¹⁰ cm·Hz^½·W^-1 was achieved at 80K at a reverse bias of 110 mV under 300 K 2(pi) FOV background. Some detectors showed a projected 0% cutoff wavelength up to 28~30 micrometers . The peak responsivity of 3Amp/Watt and detectivity of 4.25¹⁰ cm·Hz^½·W^-1 was achieved under -40mV reverse bias at 34K for these detectors. [reprint (PDF)]
19.	InAsSbP/InAsSb/InAs Laser Diodes λ = 3.2 μm) Grown by Low-Pressure Metalorganic Chemical Vapor Deposition J. Diaz, G. Lukas, D. Wu, S. Kim, M. Erdtmann, E. Kaas, and M. Razeghi Applied Physics Letters 70 (1)-- January 6, 1997 ...[Visit Journal] We report metal–organic chemical-vapor deposition-grown double heterostructure InAsSbP/InAsSb/InAs diode lasers emitting at 3.2 μm operating at temperatures up to 220 K with threshold current density of 40 A/cm² at 77 K and characteristic temperature up to 42 K. Output powers as high as 260 mW in pulse mode and 60 mW in continuous wave operation have been obtained from an uncoated 100 μm stripe-width broad-area laser at 77 K. Comparison with theory shows that there is no significant nonradiative recombination mechanism for these lasers at 77 K. [reprint (PDF)]
19.	Geiger-Mode Operation of AlGaN Avalanche Photodiodes at 255 nm Lakshay Gautam, Alexandre Guillaume Jaud, Junhee Lee, Gail J. Brown, Manijeh Razeghi Published in: IEEE Journal of Quantum Electronics ( Volume: 57, Issue: 2, April 2021) ...[Visit Journal] We report the Geiger mode operation of back-illuminated AlGaN avalanche photodiodes. The devices were fabricated on transparent AlN templates specifically for back-illumination to leverage hole-initiated multiplication. The spectral response was analyzed with a peak detection wavelength of 255 nm with an external quantum efficiency of ~14% at zero bias. Low-photon detection capabilities were demonstrated in devices with areas 25 μm×25 μm. Single photon detection efficiencies of ~5% were achieved. [reprint (PDF)]
19.	Low Dark Current Deep UV AlGaN Photodetectors on AlN Substrate Lakshay Gautam, Junhee Lee, Gail Brown, Manijeh Razeghi IEEE Journal of Quantum Electronics, vol. 58, no. 3, pp. 1-5, June 2022, Art no. 4000205 ...[Visit Journal] We report high quality, low dark current, deep Ultraviolet AlGaN/AlN Photodetectors on AlN substrate. AlGaN based Photodetectors are grown and fabricated both on AlN and Sapphire substrates with the same epilayer structure. Subsequently, electrical characteristics of both photodetectors on AlN substrate and Sapphire are compared. A reduction of 4 orders of magnitude of dark current density is reported in UV detectors grown on AlN substrate with respect to Sapphire substrate. [reprint (PDF)]
19.	Top-emission ultraviolet light-emitting diodes with peak emission at 280 nm A. Yasan, R. McClintock, K. Mayes, S.R. Darvish, P. Kung, and M. Razeghi Applied Physics Letters 81 (5)-- July 29, 2002 ...[Visit Journal] We demonstrate light emission at 280 nm from UV light-emitting diodes consisting of AlInGaN/AlInGaN multiple quantum wells. Turn-on voltage of the devices is ~5 V with a differential resistance of ~40 Ω. The peak emission wavelength redshifts ~1 nm at high injection currents. [reprint (PDF)]
19.	Engineering future light emitting diodes and photovoltaics with inexpensive materials: Integrating ZnO and Si into GaN-based devices C. Bayram ; K. T. Shiu ; Y. Zhu ; C. W. Cheng ; D. K. Sadana ; F. H. Teherani ; D. J. Rogers ; V. E. Sandana ; P. Bove ; Y. Zhang ; S. Gautier ; C.-Y. Cho ; E. Cicek ; Z. Vashaei ; R. McClintock ; M. Razeghi Proc. SPIE 8626, Oxide-based Materials and Devices IV, 86260L (March 18, 2013)-- March 18, 2013 ...[Visit Journal] Indium Gallium Nitride (InGaN) based PV have the best fit to the solar spectrum of any alloy system and emerging LED lighting based on InGaN technology and has the potential to reduce energy consumption by nearly one half while enabling significant carbon emission reduction. However, getting the maximum benefit from GaN diode -based PV and LEDs will require wide-scale adoption. A key bottleneck for this is the device cost, which is currently dominated by the substrate (i.e. sapphire) and the epitaxy (i.e. GaN). This work investigates two schemes for reducing such costs. First, we investigated the integration of Zinc Oxide (ZnO) in InGaN-based diodes. (Successful growth of GaN on ZnO template layers (on sapphire) was illustrated. These templates can then be used as sacrificial release layers for chemical lift-off. Such an approach provides an alternative to laser lift-off for the transfer of GaN to substrates with a superior cost-performance profile, plus an added advantage of reclaiming the expensive single-crystal sapphire. It was also illustrated that substitution of low temperature n-type ZnO for n-GaN layers can combat indium leakage from InGaN quantum well active layers in inverted p-n junction structures. The ZnO overlayers can also double as transparent contacts with a nanostructured surface which enhances light in/out coupling. Thus ZnO was confirmed to be an effective GaN substitute which offers added flexibility in device design and can be used in order to simultaneously reduce the epitaxial cost and boost the device performance. Second, we investigated the use of GaN templates on patterned Silicon (100) substrates for reduced substrate cost LED applications. Controlled local metal organic chemical vapor deposition epitaxy of cubic phase GaN with on-axis Si(100) substrates was illustrated. Scanning electron microscopy and transmission electron microscopy techniques were used to investigate uniformity and examine the defect structure in the GaN. Our results suggest that groove structures are very promising for controlled local epitaxy of cubic phase GaN. Overall, it is concluded that there are significant opportunities for cost reduction in novel hybrid diodes based on ZnO-InGaN-Si hybridization. [reprint (PDF)]
19.	AlGaN-based deep-ultraviolet 320 x 256 focal plane array E. Cicek, Z. Vashaei, E.K. Huang, R. McClintock and M. Razeghi OSA Optics Letters, Vol. 37, No. 5, p. 896-898-- March 1, 2012 ...[Visit Journal] We report the synthesis, fabrication, and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, Al_xGa_1−xN–based detectors, fully realized within our research laboratory. We implemented a pulse atomic layer deposition technique for the metalorganic chemical vapor deposition growth of thick, high-quality, crack-free, high Al composition Al_xGa_1−xN layers. The FPA is hybridized to a matching ISC 9809 readout integrated circuit and operated in a SE-IR camera system. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower, and falling off three orders of magnitude by ∼285 nm. By developing an opaque masking technology, the visible response of the ROIC is significantly reduced; thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allows the FPA to achieve high external quantum efficiency (EQE); at 254 nm, average pixels showed unbiased peak responsivity of 75 mA∕W, which corresponds to an EQE of ∼37%. Finally, the uniformity of the FPA and imaging properties are investigated. [reprint (PDF)]
19.	320x256 Solar-Blind Focal Plane Arrays based on Al_xGa_1-xN R. McClintock, K. Mayes, A. Yasan, D. Shiell, P. Kung, and M. Razeghi Applied Physics Letters, 86 (1)-- January 3, 2005 ...[Visit Journal] We report AlGaN-based back-illuminated solar-blind ultraviolet focal plane arrays operating at a wavelength of 280 nm. The electrical characteristics of the individual pixels are discussed, and the uniformity of the array is presented. The p–i–n photodiode array was hybridized to a 320×256 read-out integrated circuit entirely within our university research lab, and a working 320×256 camera was demonstrated. Several example solar-blind images from the camera are also provided. [reprint (PDF)]
19.	Resonant cavity enhanced heterojunction phototransistors based on type-II superlattices Jiakai Li, Arash Dehzangi, Donghai Wu, Ryan McClintock, Manijeh Razeghi Infrared Physics & Technology Available online 27 October 2020, 103552 https://doi.org/10.1016/j.infrared.2020.103552-- October 27, 2020 ...[Visit Journal] Resonant cavity enhanced heterojunction phototransistor based on InAs/GaSb/AlSb type-II superlattice grown by molecular beam epitaxy has been demonstrated. The resonant wavelength was designed to be at near 1.9 μm wavelength range at room temperature. An eleven-pair lattice matched GaSb-AlAsSb quarter-wavelength Bragg reflector was used in the RCE-HPT to enhance the photoresponse. The device showed the wavelength selectivity and a cavity enhancement of the responsivity at 1.9 μm at room temperature. [reprint (PDF)]
19.	High power, low divergent, substrate emitting quantum cascade ring laser in continuous wave operation D. H. Wu and M. Razeghi APL Materials 5, 035505-- March 21, 2017 ...[Visit Journal] We demonstrate a surface grating coupled substrate emitting quantum cascade ring laser with high power room temperature continuous wave operation at 4.64 μm μm . A second order surface metal/semiconductor distributed-feedback grating is used for in-plane feedback and vertical out-coupling. A device with 400 μm μm radius ring cavity exhibits an output power of 202 mW in room temperature continuous wave operation. Single mode operation with a side mode suppression ratio of 25 dB is obtained along with a good linear tuning with temperature. The far field measurement exhibits a low divergent concentric ring beam pattern with a lobe separation of ∼0.34°, which indicates that the device operates in fundamental mode (n = 1). [reprint (PDF)]
19.	Interface-induced Suppression of the Auger Recombination in Type-II InAs/GaSb Superlattices H. Mohseni, V.I. Litvinov and M. Razeghi Physical Review B 58 (23)-- December 15, 1998 ...[Visit Journal] The temperature dependence of the nonequilibrium carriers lifetime has been deduced from the measurement of the photocurrent response in InAs/GaSb superlattices. Based on the temperature dependence of the responsivity and modeling of the transport parameters we have found that the carrier lifetime weakly depends on temperature in the high-temperature region. This indicates the temperature dependence of the Auger recombination rate with no threshold that differs it from that in the bulk material and can be attributed to the interface-induced suppression of the Auger recombination in thin quantum wells. [reprint (PDF)]
19.	Comparison of Trimethylgallium and Triethylgallium for the Growth of GaN A. Saxler, D. Walker, P. Kung, X. Zhang, M. Razeghi, J. Solomon, W. Mitchel, and H.R. Vydyanath Applied Physics Letters 71 (22)-- December 1, 1997 ...[Visit Journal] GaN films grown by low-pressure metalorganic chemical vapor deposition using trimethylgallium and triethylgallium as gallium precursors are compared. The films were characterized by x-ray diffraction, Hall effect, photoluminescence, secondary ion mass spectroscopy, and etch pit density measurements. GaN layers grown using triethylgallium exhibited superior electrical and optical properties and a lower carbon impurity concentration. [reprint (PDF)]
19.	EPR STUDY OF Mn 2. AROUND THE FERROELASTIC TRANSITION POINT OF Pb3(PO4)2 M. Razeghi, B. Houlier and M. Yuste M. Razeghi et al. EPR STUDY OF Mn 2. AROUND THE FERROELASTIC TRANSITION POINT OF Pb3(PO4)2, Solid State Communications, Vol. 26, pp. 665-668. -- January 26, 1978 ...[Visit Journal] The spin Hamiltonian parameters of Mn 2÷ have been measured above and below the transition point (180"C) of the lead phosphate. They show that Mn 2+ substitutes a Pbl ion. Between 175 and 180vC the principal axis OX of the fine tensor is parallel to the wave vector of the soft mode which condensates at the transition point. An exaltation of the linewidth is observed. The linewidth remains constant within 50C of Te; in this temperature range, the "static regime" is achieved, and the correlation time of the fluctuations is less than 10 -s sec. [reprint (PDF)]
19.	Thermal imaging based on high-performance InAs/InP quantum-dot infrared photodetector operating at high temperature M. Razeghi; H. Lim; S. Tsao; H. Seo; W. Zhang Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS.15-16:[4382251] (2007).-- October 21, 2007 ...[Visit Journal] We report a room temperature operating and high-performance InAs quantum-dot infrared photodetector on InP substrate and thermal imaging of 320times256 focal plane array based on this device up to 200 K. [reprint (PDF)]
19.	Phase-locked, high power, mid-infrared quantum cascade laser array W. Zhou, S. Slivken, and M. Razeghi Applied Physics Letters 112, 181106-- May 4, 2018 ...[Visit Journal] We demonstrate phase-locked, high power quantum cascade laser arrays, which are combined using a monolithic, tree array multimode interferometer, with emission wavelengths around 4.8 μm. A maximum output power of 15 W was achieved from an eight-element laser array, which has only a slightly higher threshold current density and a similar slope efficiency compared to a Fabry-Perot laser of the same length. Calculated multimode interferometer splitting loss is on the order of 0.27 dB for the in-phase supermode. In-phase supermode operation with nearly ideal behavior is demonstrated over the working current range of the array. [reprint (PDF)]
19.	4.5 mW Operation of AlGaN-based 267 nm Deep-Ultraviolet Light-Emitting Diodes A. Yasan, R. McClintock, K. Mayes, D. Shiell, L. Gautero, S.R. Darvish, P. Kung and M. Razeghi Applied Physics Letters, 83 (23)-- December 8, 2003 ...[Visit Journal] We demonstrate 4.5 mW output power from AlGaN-based single quantum well ultraviolet light-emitting diodes at a very short wavelength of 267 nm in pulsed operation mode. The output power in continuous-wave mode reaches a value of 165 µW at an injected current of 435 mA. The measurements were done on arrays of four devices flip chip bonded to AlN submounts for thermal management. [reprint (PDF)]
19.	Positive and negative luminescence in binary Type-II InAs/GaSb superlattice photodiodes D. Hoffman and M. Razeghi SPIE Conference, San Jose, CA, Vol. 6127, pp. 61271H-- January 23, 2006 ...[Visit Journal] In the present work, we show measurements of both positive and negative luminescence of binary Type-II InAs/GaSb superlattice photodiodes in the 3 to 13 μm spectral range. Through a radiometric calibration technique, we demonstrate temperature independent negative luminescence efficiencies of 45 % in the midwavelength (MWIR) sample from 220 K to 320 K without anti-reflective coating and values reaching 35 % in the long wavelength infrared (LWIR) spectrum sample. [reprint (PDF)]
19.	III-Nitride Avalanche Photodiodes P. Kung, R. McClintock, J. Pau Vizcaino, K. Minder, C. Bayram and M. Razeghi SPIE Conference, January 25-29, 2007, San Jose, CA Proceedings – Quantum Sensing and Nanophotonic Devices IV, Vol. 6479, p. 64791J-1-12-- January 29, 2007 ...[Visit Journal] Wide bandgap III-Nitride semiconductors are a promising material system for the development of ultraviolet avalanche photodiodes (APDs) that could be a viable alternative to photomultiplier tubes. In this paper, we report the epitaxial growth and physical properties of device quality GaN layers on high quality AlN templates for the first backilluminated GaN p-i-n APD structures on transparent sapphire substrates. Under low bias and linear mode avalanche operation where they exhibited gains near 1500 after undergoing avalanche breakdown. The breakdown electric field in GaN was determined to be 2.73 MV/cm. The hole impact ionization coefficients were shown to be greater than those of electrons. [reprint (PDF)]
19.	Recent progress of quantum cascade laser research from 3 to 12 μm at the Center for Quantum Devices MANIJEH RAZEGHI,* WENJIA ZHOU,STEVEN SLIVKEN,QUAN-YONG LU,DONGHAI WU, AND RYAN MCCLINTOC Applied Optics Vol. 56, No. 31 -- October 10, 2017 ...[Visit Journal] The quantum cascade laser (QCL) is becoming the leading laser source in the mid-infrared (mid-IR) range, which contains two atmospheric transmission windows and many molecular fingerprint absorption features. Since its first demonstration in 1994, the QCL has undergone tremendous development in terms of the output power, wall plug efficiency, wavelength coverage, tunability and beam quality. At the Center for Quantum Devices, we have demonstrated high-power continuous wave operation of QCLs covering a wide wavelength range from 3 to 12 μm, with power output up to 5.1 W at room temperature. Recent research has resulted in power scaling in pulsed mode with up to 203 W output, electrically tunable QCLs based on monolithic sampled grating design, heterogeneous QCLs with a broad spectral gain, broadly tunable on-chip beam-combined QCLs, QCL-based mid-IR frequency combs, and fundamental mode surface emitting quantum cascade ring lasers. The developed QCLs will be the basis for a number of next-generation spectroscopy and sensing systems. [reprint (PDF)]
19.	Long-Wavelength InAsSb Photoconductors Operated at Near Room Temperatures (200-300 K) J.D. Kim, D. Wu, J. Wojkowski, J. Piotrowski, J. Xu, and M. Razeghi Applied Physics Letters., 68 (1),-- January 1, 1996 ...[Visit Journal] Long-wavelength InAs_1−xSb_x photoconductors operated without cryogenic cooling are reported. The devices are based on p-InAs_1−xSb_x/p-InSb heterostructures grown on (100) semi-insulating GaAs substrates by low pressure metalorganic chemical vapor deposition (LP‐MOCVD). Photoreponse up to 14 μm has been obtained in a sample with x=0.77 at 300 K, which is in good agreement with the measured infrared absorption spectra. The corresponding effective lifetime of ≊0.14 ns at 300 K has been derived from stationary photoconductivity. The Johnson noise limited detectivity at λ=10.6 μm is estimated to be about 3.27×10⁷ cm· Hz^½/W at 300 K. [reprint (PDF)]
19.	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-- February 2, 2015 ...[Visit Journal] 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 (PDF)]

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