Center for Quantum Devices - Most Downloaded Journal Articles

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14.	Conduction‐ and valence‐band offsets in GaAs/Ga0.51In0.49P single quantum wells grown by metalorganic chemical vapor deposition D. Biswas; N. Debbar; P. Bhattacharya; M. Razeghi; M. Defour; F. Omnes Appl. Phys. Lett. 56, 833–835 (1990)-- February 26, 1990 ...[Visit Journal] We have independently estimated the conduction- and valence-band offsets D.Ec and D.Ev in GaAs/Gao . 51 Ino49 P quantum wells by measuring the capacitance transient resulting from thermal emission of carriers from the respective wens. The heterostructure samples were grown by low-pressure metalorganic chemical vapor deposition. The band offsets are extrapolated from the emission activation energies with appropriate corrections. The estimated values of AEc and AEv are 0.198 and 0.285 eV, respectively. [reprint (PDF)]
14.	Antimonite-based gap-engineered type-II superlattice materials grown by MBE and MOCVD for the third generation of infrared imagers Manijeh Razeghi, Arash Dehzangi, Donghai Wu, Ryan McClintock, Yiyun Zhang, Quentin Durlin, Jiakai Li, Fanfei Meng Proc. SPIE Defense + Commercial Sensing,Infrared Technology and Applications XLV, 110020G -- May 7, 2019 ...[Visit Journal] Third generation of infrared imagers demand performances for higher detectivity, higher operating temperature, higher resolution, and multi-color detection all accomplished with better yield and lower manufacturing costs. Antimonidebased gap-engineered Type-II superlattices (T2SLs) material system is considered as a potential alternative for MercuryCadmium-Telluride (HgCdTe) technology in all different infrared detection regimes from short to very long wavelengths for the third generation of infrared imagers. This is due to the incredible growth in the understanding of its material properties and improvement of device processing which leads to design and fabrication of better devices. We will present the most recent research results on Antimonide-based gap-engineered Type-II superlattices, such as highperformance dual-band SWIR/MWIR photo-detectors and focal plane arrays for different infrared regimes, toward the third generation of infrared imaging systems at the Center for Zuantum Devices. Comparing metal-organic chemical vapor deposition (MOCVD), vs molecular beam epitaxy (MBE). [reprint (PDF)]
14.	Recent Advances in LWIR Type-II InAs/GaSb Superlattice Photodetectors and Focal Plane Arrays at the Center for Quantum Devices M. Razeghi, D. Hoffman, B.M. Nguyen, P.Y. Delaunay, E.K. Huang, M.Z. Tidrow, and V. Nathan IEEE Proceedings, Vol. 97, No. 6, p. 1056-1066-- June 1, 2009 ...[Visit Journal] In recent years, Type-II InAs/GaSb superlattice photo-detectors have experienced significant improvements in material quality, structural designs, and imaging applications. They now appear to be a possible alternative to the state-of-the-art HgCdTe (MCT) technology in the long and very long wavelength infrared regimes. At the Center for Quantum Devices, we have successfully realized very high quantum efficiency, very high dynamic differential resistance R₀A - product LWIR Type – II InAs/GaSb superlattice photodiodes with efficient surface passivation techniques. The demonstration of high quality LWIR Focal Plane Arrays that were 100 % fabricated in - house reaffirms the pioneer position of this university-based laboratory. [reprint (PDF)]
14.	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 ...[Visit Journal] 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 (PDF)]
14.	Uncooled operation of Type-II InAs/GaSb superlattice photodiodes in the mid- wavelength infrared range Y. Wei, A. Hood, H. Yau, A. Gin, M. Razeghi, M.Z. Tidrow, V. Natha Applied Physics Letters, 86 (23)-- June 6, 2005 ...[Visit Journal] We report high performance uncooled midwavelength infrared photodiodes based on interface-engineered InAs/GaSb superlattice. Two distinct superlattices were designed with a cutoff wavelength around 5 µm for room temperature and 77 K. The device quantum efficiency reached more than 25% with responsivity around 1 A/W. Detectivity was measured around 10⁹ cm·Hz^½/W at room temperature and 1.5×10¹³ cm·Hz^½/W at 77 K under zero bias. The devices were without antireflective coating. The device quantum efficiency stays at nearly the same level within this temperature range. Additionally, Wannier–Stark oscillations in the Zener tunneling current were observed up to room temperature. [reprint (PDF)]
14.	Tl incorporation in InSb and lattice contraction of In_1-xTl_xSb J.J. Lee and M. Razeghi Applied Physics Letters 76 (3)-- January 17, 2000 ...[Visit Journal] Ternary In_1−xTl_xSb thin films are grown by low pressure metalorganic chemical vapor deposition in the high In composition region. Infrared photoresponse spectra of the In_1−xTl_xSb epilayers show a clear shift toward a longer wavelength compared to that of InSb. Tl incorporation is confirmed by Auger electron spectroscopy. In contrast to the theoretical expectation, high resolution x-ray diffraction study reveals that the lattice of the In_1−xTl_xSb epilayers is contracted by the incorporation of Tl. As more Tl is incorporated, the lattice contraction is observed to increase gradually in the experimental range. A possible origin of this phenomenon is discussed. Our experimental results suggest that the Tl incorporation behavior in In_1−xTl_xSb differs from that of other group III impurities in III antimonides. [reprint (PDF)]
14.	1.2–1.6 μm GaxIn1−xAsyP1−y-InP DH lasers grown by LPMOCVD M. Razeghi, B. de Crémoux, J.P. Duchemin M. Razeghi, B. de Crémoux, J.P. Duchemin, 1.2–1.6 μm GaxIn1−xAsyP1−y-InP DH lasers grown by LPMOCVD, Journal of Crystal Growth, Volume 68, Issue 1, 1984, Pages 389-397,-- September 1, 1984 ...[Visit Journal] Room temperature pulse operation and continuous wave (CW) operation in the 1.2–1.6 μm region have been achieved in GaInAsP-InP DH lasers fabricated on material grown by LPMOCVD. Threshold currents density as low as 430 A/cm2 (cavity length of 950 μm) have been measured for devices emitting at 1.3 μm. Threshold current densities of 1060 A/cm2 (cavity length of 400 μm) have been obtained for devices emitting at 1.55 μm, with active layer thicknesses of 0.22 μm. Values of T0 between 60 and 70 K have been obtained. Fundamental transverse mode oscillation has been achieved (for CW operation) up to an output power of 10 mW. The preliminary results on the aging test are most encouraging and demonstrate that the LPMOCVD lasers emitting at 1.2–1.6 μm have comparable degradation rates to those of LPE lasers suggesting the LPMOCVD technique is promising for large scale production of laser diodes. [reprint (PDF)]
14.	Scaling in back-illuminated GaN avalanche photodiodes K. Minder, J.L. Pau, R. McClintock, P. Kung, C. Bayram, M. Razeghi and D. Silversmith Applied Physics Letters, Vol. 91, No. 7, p. 073513-1-- August 13, 2007 ...[Visit Journal] Avalanche p-i-n photodiodes of various mesa areas were fabricated on AlN templates for back illumination for enhanced performance through hole-initiated multiplication, and the effects of increased area on device performance were studied. Avalanche multiplication was observed in mesa sizes up to 14,063 µm^2 under linear mode operation. Uniform gain and a linear increase of the dark current with area were demonstrated. [reprint (PDF)]
14.	Performance analysis of infrared heterojunction phototransistors based on Type-II superlattices Jiakai Li, Arash Dehzangi, Manijeh Razeghi Infrared Physics & Technology Volume 113, March 2021, 103641 ...[Visit Journal] In this study, a comprehensive analysis of the n-p-n infrared heterojunction phototransistors (HPTs)based on Type-II superlattices has been demonstrated. Different kinds of Type-II superlattices were carefully chosen for the emitter, base, and collector to improve the optical performance. The effects of different device parameters include emitter doping concentration, base doping concentration, base thickness and energy bandgap difference between emitter and base on the optical gain of the HPTs have been investigated. By scaling the base thickness to 20 nm, the HPT exhibits an optical gain of 345.3 at 1.6 μm at room temperature. For a 10 μm diameter HPT device, a −3 dB cut-off frequency of 5.1 GHz was achieved under 20 V at 150 K. [reprint (PDF)]
14.	Optimizing facet coating of quantum cascade lasers for low power consumption Y. Bai, S.R. Darvish, N. Bandyopadhyay, S. Slivken and M. Razeghi Journal of Applied Physics, Vol. 109, No. 5, p. 053103-1-- March 1, 2011 ...[Visit Journal] Typical high power consumption (∼10 W) of mid-infrared quantum cascade lasers (QCLs) has been a serious limitation for applications in battery powered systems. A partial high-reflection (PHR) coating technique is introduced for power downscaling with shorter cavity lengths. The PHR coating consists of a double layer dielectric of SiO₂ and Ge. With this technique, a 4.6 μm QCL with an ultra low threshold power consumption of less than a watt (0.83 W) is demonstrated in room temperature continuous wave operation. At 25°C, the maximum output power and wall plug efficiency are 192 mW and 8.6%, respectively. [reprint (PDF)]
14.	Comprehensive study of blue and green multi-quantum-well light-emitting diodes grown on conventional and lateral epitaxial overgrowth GaN C. Bayram, J.L. Pau, R. McClintock and M. Razeghi Applied Physics B: Lasers and Optics, Vol. 95, p. 307-314-- November 29, 2008 ...[Visit Journal] Growths of blue and green multi-quantum wells (MQWs) and light-emitting diodes (LEDs) are realized on lateral epitaxial overgrowth (LEO) GaN, and compared with identical structures grown on conventional GaN. Atomic force microscopy is used to confirm the significant reduction of dislocations in the wing region of our LEO samples before active-region growth. Differences between surface morphologies of blue and green MQWs are analyzed. These MQWs are integrated into LEDs. All devices show a blue shift in the electroluminescence (EL) peak and narrowing in EL spectra with increasing injection current, both characteristics attributed to the band-gap renormalization. Green LEDs show a larger EL peak shift and a broader EL spectrum due to larger piezoelectric field and more indium segregation in the MQWs, respectively. Blue LEDs on LEO GaN show a higher performance than those on conventional GaN; however, no performance difference is observed for green LEDs on LEO GaN versus conventional GaN. The performance of the green LEDs is shown to be primarily limited by the active layer growth quality. [reprint (PDF)]
14.	Hybrid green LEDs with n-type ZnO substituted for N-type GaN in an inverted P-N junction F. Hosseini Teherani; M. Razeghi; D.J. Rogers; Can Bayram; R. McClintock LEOS Annual Meeting Conference Proceedings, LEOS '09. IEEE, [5343231] (2009) -- October 4, 2009 ...[Visit Journal] Recently, the GaN and ZnO materials systems have attracted considerable attention because of their use in a broad range of emerging applications including light-emitting diodes (LEDs) and solar cells. GaN and ZnO are similar materials with direct wide bandgaps, wurtzite crystal structure, high thermal stability and comparable thermal expansion coefficients, which makes them well suited for heterojunction fabrication. Two important advantages of GaN over ZnO are the reliable p-type doping and the mature know-how for bandgap engineering. Thus GaN-based LEDs can be made to emit from the deep UV right into the green through alloying with Al and In, respectively. The performance is not identical at all wavelengths, however, and the performance of InGaN-based green LEDs is still relatively poor. [reprint (PDF)]
14.	High Quantum Efficiency Solar-Blind Photodetectors R. McClintock, A. Yasan, K. Mayes, D. Shiell, S. Darvish, P. Kung and M. Razeghi SPIE Conference, Jose, CA, Vol. 5359, pp. 434-- January 25, 2004 ...[Visit Journal] We report AlGaN-based back-illuminated solar-blind p-i-n photodetectors with a record peak responsivity of 150 mA/W at 280 nm, corresponding to a high external quantum efficiency of 68%, increasing to 74% under 5 volts reverse bias. Through optimization of the p-AlGaN layer, we were able to remove the out-of-band negative photoresponse originating from the Schottky-like p-type metal contact, and hence significantly improve the degree of solar-blindness [reprint (PDF)]
14.	Demonstration of high performance long wavelength infrared Type-II InAs/GaSb superlattice photodidoe grown on GaAs substrate S. Abdollahi Pour, B.M. Nguyen, S. Bogdanov, E.K. Huang, and M. Razeghi Applied Physics Letters, Vol. 95, No. 17, p. 173505-- October 26, 2009 ...[Visit Journal] We report the growth and characterization of long wavelength infrared type-II InAs/GaSb superlattice photodiodes with a 50% cut-off wavelength at 11 µm, on GaAs substrate. Despite a 7.3% lattice mismatch to the substrate, photodiodes passivated with polyimide exhibit an R₀A value of 35 Ω·cm² at 77 K, which is in the same order of magnitude as reference devices grown on native GaSb substrate. With a reverse applied bias less than 500 mV, the dark current density and differential resistance-area product are close to that of devices on GaSb substrate, within the tolerance of the processing and measurement. The quantum efficiency attains the expected value of 20% at zero bias, resulting in a Johnson limited detectivity of 1.1×10¹¹ Jones. Although some difference in performances is observed, devices grown on GaAs substrate already attained the background limit performance at 77 K with a 300 K background and a 2-π field of view. [reprint (PDF)]
14.	Recent progress of widely tunable, CW THz sources based QCLs at room temperature Manijeh Razeghi Terahertz Science and Technology, Vol.10, No.4, pp. 87-151-- December 7, 2017 ...[Visit Journal] The THz spectral region is of significant interest to the scientific community, but is one of the hardest regions to access with conventional technology. A wide range of compelling new applications are initiating a new revolution in THz technology, especially with regard to the development of compact and versatile devices for THz emission and detection. In this article, recent advances with regard to III-V semiconductor optoelectronics are explored with emphasis on how these advances will lead to the next generation of THz component technology [reprint (PDF)]
14.	Infrared Imaging Arrays Using Advanced III-V Materials and technology M. Razeghi, J.D. Kim, C. Jelen, S. Slivken, E. Michel, H. Mohseni, J.J. Lee, J. Wojkowski, K.S. Kim, H.I. Jeon, and J. X IEEE Proceedings, Advanced Workshop on Frontiers in Electronics (WOFE), Tenerife, Spain;-- January 6, 1997 ...[Visit Journal] Photodetectors operating in the 3-5 and 8-12 μm atmospheric windows are of great importance for applications in infrared (IR) thermal imaging. HgCdTe has been the dominant material system for these applications. However, it suffers from instability and non-uniformity problems over large areas due to high Hg vapor pressure during the material, growth. There has been a lot of interest in the use of heteroepitaxially grown Sb-based alloys, its strained layer superlattices, and GaAs based quantum wells as alternatives to MCT. This interest has been driven by the advanced material growth and processing technology available for the III-V material system [reprint (PDF)]
14.	High-power λ ~ 9.5 µm quantum-cascade lasers operating above room temperature in continuous-wave mode J.S. Yu, S. Slivken, A. Evans, S.R. Darvish, J. Nguyen, and M. Razeghi Applied Physics Letters, 88 (9)-- February 27, 2006 ...[Visit Journal] We report high-power continuous-wave (cw) operation of λ~9.5 μm quantum-cascade lasers to a temperature of 318 K. A high-reflectivity-coated 19-μm-wide and 3-mm-long device exhibits cw output powers as high as 150 mW at 288 K and still 22 mW at 318 K. In cw operation at 298 K, a threshold current density of 1.57 kA/cm², a slope efficiency of 391 mW/A, and a maximum wall-plug efficiency of 0.71% are obtained. [reprint (PDF)]
14.	High-power, room-temperature and continuous-wave operation of distributed-feedback quantum-cascade lasers at λ = 4.8 µm J.S. Yu, S. Slivken, S.R. Darvish, A. Evans, B. Gokden and M. Razeghi Virtual Journal of Nanoscale Science and Technology 12 (5)-- August 1, 2005 ...[Visit Journal][reprint (PDF)]
14.	Defects in Organometallic Vapor-Phase Epitaxy-Grown GaInP Layers Feng S.L., Bourgoin J.C., Omnes F., and Razeghi M. Applied Physics Letters 59 (8), p. 941-- May 28, 1991 ...[Visit Journal] Non-intentionally doped metalorganic vapor‐phase epitaxy Ga_1−x InxP layers, having an alloy composition (x = 0.49) corresponding to a lattice matched to GaAs, grown by metalorganic chemical vapor deposition, have been studied by capacitance‐voltage and deep-level transient spectroscopy techniques. They are found to exhibit a free‐carrier concentration at room temperature of the order of 10¹⁵ cm⁻³. Two electron traps have been detected. The first one, at 75 meV below the conduction band, is in small concentration (∼10¹³ cm⁻³) while the other, at about 0.9 eV and emitting electrons above room temperature, has a concentration in the range 10¹⁴–10¹⁵ cm⁻³. [reprint (PDF)]
14.	Wafer-scale epitaxial lift-off of optoelectronic grade GaN from a GaN substrate using a sacrificial ZnO interlayer Akhil Rajan, David J Rogers, Cuong Ton-That, Liangchen Zhu, Matthew R Phillips, Suresh Sundaram, Simon Gautier, Tarik Moudakir, Youssef El-Gmili, Abdallah Ougazzaden, Vinod E Sandana, Ferechteh H Teherani, Philippe Bove, Kevin A Prior, Zakaria Djebbour, Ryan McClintock and Manijeh Razeghi Journal of Physics D: Applied Physics, Volume 49, Number 31 -- July 15, 2016 ...[Visit Journal] Full 2 inch GaN epilayers were lifted off GaN and c-sapphire substrates by preferential chemical dissolution of sacrificial ZnO underlayers. Modification of the standard epitaxial lift-off (ELO) process by supporting the wax host with a glass substrate proved key in enabling full wafer scale-up. Scanning electron microscopy and x-ray diffraction confirmed that intact epitaxial GaN had been transferred to the glass host. Depth-resolved cathodoluminescence (CL) analysis of the bottom surface of the lifted-off GaN layer revealed strong near-band-edge (3.33 eV) emission indicating a superior optical quality for the GaN which was lifted off the GaN substrate. This modified ELO approach demonstrates that previous theories proposing that wax host curling was necessary to keep the ELO etch channel open do not apply to the GaN/ZnO system. The unprecedented full wafer transfer of epitaxial GaN to an alternative support by ELO offers the perspective of accelerating industrial adoption of the expensive GaN substrate through cost-reducing recycling. [reprint (PDF)]
14.	Comparison of the Physical Properties of GaN Thin Films Deposited on (0112) and (0001) Sapphire Substrates C.J. Sun and M. Razeghi Applied Physics Letters 63 (7)-- August 16, 1993 ...[Visit Journal] A direct comparison of the physical properties of GaN thin films is made as a function of the choice of substrate orientations. Gallium nitride single crystals were grown on (0001) and (0112) sapphire substrates by metalorganic chemical vapor deposition. Better crystallinity with fine ridgelike facets is obtained on the (0112) sapphire. Also lower carrier concentration and higher mobilities indicate both lower nitrogen vacancies and less oxygen incorporation on the (0112) sapphire. The results of this study show better physical properties of GaN thin films achieved on (0112) sapphire. [reprint (PDF)]
14.	High quantum efficiency two color type-II InAs/GaSb n-i-p-p-i-n photodiodes P.Y. Delaunay, B.M. Nguyen, D. Hoffman, A. Hood, E.K. Huang, M. Razeghi, and M.Z. Tidrow Applied Physics Letters, Vol. 92, No. 11, p. 111112-1-- March 17, 2008 ...[Visit Journal] A n-i-p-p-i-n photodiode based on type-II InAs/GaSb superlattice was grown on a GaSb substrate. The two channels, with respective 50% of responsivity cutoff wavelengths at 7.7 and 10 µm, presented quantum efficiencies (QEs) of 47% and 39% at 77 K. The devices can be operated as two diodes for simultaneous detection or as a single n-i-p-p-i-n detector for sequential detection. In the latter configuration, the QEs at 5.3 and 8.5 µm were measured as high as 40% and 39% at 77 K. The optical cross-talk between the two channels could be reduced from 0.36 to 0.08 by applying a 50 mV bias. [reprint (PDF)]
14.	Growth and Optimization of GaInAsP/InP Material System for Quantum Well Infrared Photodetector Applications M. Erdtmann, J. Jiang, A. Matlis, A. Tahraoui, C. Jelen, M. Razeghi, and G. Brown SPIE Conference, San Jose, CA, -- January 26, 2000 ...[Visit Journal] Multi-quantum well structures of Ga_xIn_1-xAs_yP_1-y were grown by metalorganic chemical vapor deposition for the fabrication of quantum well IR photodetectors. The thickness and composition of the wells was determined by high-resolution x-ray diffraction and photoluminescence experiments. The intersubband absorption spectrum of the Ga_0.47In_0.53As/InP, Ga_0.38In_0.62As_0.80P_0.20 (1.55 μm)/InP, and Ga_0.27In_0.73As_0.57P_0.43 (1.3 μm))/InP quantum wells are found to have cutoff wavelengths of 9.3 μm, 10.7 micrometers , and 14.2 μm respectively. These wavelengths are consistent with a conduction band offset to bandgap ratio of approximately 0.32. Facet coupled illumination responsivity and detectivity are reported for each composition. [reprint (PDF)]
14.	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 ...[Visit Journal] 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 (PDF)]
14.	Avalanche Photodetector Based on InAs/InSb Superlattice Arash Dehzangi, Jiakai Li, Lakshay Gautam and Manijeh Razeghi Quantum rep. 2020, 2(4), 591-599; https://doi.org/10.3390/quantum2040041 (registering DOI)-- December 4, 2020 ...[Visit Journal] This work demonstrates a mid-wavelength infrared InAs/InSb superlattice avalanche photodiode (APD). The superlattice APD structure was grown by molecular beam epitaxy on GaSb substrate. The device exhibits a 100 % cut-off wavelength of 4.6 µm at 150 K and 4.30 µm at 77 K. At 150 and 77 K, the device responsivity reaches peak values of 2.49 and 2.32 A/W at 3.75 µm under −1.0 V applied bias, respectively. The device reveals an electron dominated avalanching mechanism with a gain value of 6 at 150 K and 7.4 at 77 K which was observed under −6.5 V bias voltage. The gain value was measured at different temperatures and different diode sizes. The electron and hole impact ionization coefficients were calculated and compared to give a better prospect of the performance of the device. [reprint (PDF)]

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