Center for Quantum Devices - Most Downloaded Journal Articles

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15.	High power, continuous wave, quantum cascade ring laser Y. Bai, S. Tsao, N. Bandyopadhyay, S. Slivken, Q.Y. Lu, D. Caffey, M. Pushkarsky, T. Day and M. Razeghi Applied Physics Letters, Vol. 99, No. 26, p. 261104-1-- December 26, 2011 ...[Visit Journal] We demonstrate a quantum cascade ring laser with high power room temperature continuous wave operation. A second order distributed feedback grating buried inside the waveguide provides both in-plane feedback and vertical power outcoupling. Total output power reaches 0.51 W at an emission wavelength around 4.85 μm. Single mode operation persists up to 0.4 W. The far field analysis indicates that the device operates in a high order mode. The magnetic and electric components of the ring-shaped lasing beam are in radial and azimuthal directions, respectively. [reprint (PDF)]
15.	Chemical lift-off and direct wafer bonding of GaN/InGaN P-I-N structures grown on ZnO K. Pantzas, D.J. Rogers, P. Bove, V.E. Sandana, F.H. Teherani, Y. El Gmili, M. Molinari, G. Patriarche, L. Largeau, O. Mauguin, S. Suresh, P.L. Voss, M. Razeghi, A. Ougazzaden Journal of Crystal Growth, Volume 435, Pages 105-109-- November 7, 2015 ...[Visit Journal] p-GaN/i-InGaN/n-GaN (PIN) structures were grown epitaxially on ZnO-buffered c-sapphire substrates by metal organic vapor phase epitaxy using the industry standard ammonia precursor for nitrogen. Scanning electron microscopy revealed continuous layers with a smooth interface between GaN and ZnO and no evidence of ZnO back-etching. Energy Dispersive X-ray Spectroscopy revealed a peak indium content of just under 5at% in the active layers. The PIN structure was lifted off the sapphire by selectively etching away the ZnO buffer in an acid and then direct bonded onto a glass substrate. Detailed high resolution transmission electron microscopy and grazing incidence X-ray diffraction studies revealed that the structural quality of the PIN structures was preserved during the transfer process. [reprint (PDF)]
15.	Molecular Beam Epitaxial Growth of High Quality InSb E. Michel, G. Singh, S. Slivken, C. Besikci, P. Bove, I. Ferguson, and M. Razeghi Applied Physics Letters 65 (26)-- December 26, 1994 ...[Visit Journal] In this letter we report on the growth of high quality InSb by molecular beam epitaxy that has been optimized using reflection high energy electron diffraction. A 4.8 µm InSb layer grown on GaAs at a growth temperature of 395 °C and a III/V incorporation ratio of 1:1.2 had an x-ray rocking curve of 158 arcsec and a Hall mobility of 92,300 cm²·V⁻¹ at 77 K. This is the best material quality obtained for InSb nucleated directly onto GaAs reported to date. [reprint (PDF)]
15.	Quantum-dot infrared photodetectors and focal plane arrays M. Razeghi, H. Lim, S. Tsao, M. Taguchi, W. Zhang, and A.A. Quivy SPIE Infrared Technology and Applications Conference, April 17-21, 2006, Orlando, FL Proceedings – Infrared Technology and Applications XXXII, Vol. 6206, p. 62060I-1-- April 21, 2006 ...[Visit Journal] We report our recent results about mid-wavelength infrared quantum-dot infrared photodetectors (QDIPs) grown by low-pressure metalorganic chemical vapor deposition. A very high responsivity and a very low dark current were obtained. A high peak detectivity of the order of 3×10¹² Jones was achieved at 77 K. The temperature dependent device performance was also investigated. The improved temperature insensitivity compared to QWIPs was attributed to the properties of quantum dots. The device showed a background limited performance temperature of 220 K with a 45° field of view and 300K background. [reprint (PDF)]
15.	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 ...[Visit Journal] 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. [reprint (PDF)]
15.	Characterization of ZnO thin films grown on c-sapphire by pulsed laser deposition as templates for regrowth of zno by metal organic chemical vapor deposition D. J. Rogers ; F. Hosseini Teherani ; C. Sartel ; V. Sallet ; F. Jomard ; P. Galtier ; M. Razeghi Proc. SPIE 7217, Zinc Oxide Materials and Devices IV, 72170F (February 17, 2009)-- February 17, 2009 ...[Visit Journal] The use of ZnO template layers grown Pulsed Laser Deposition (PLD) has been seen to produce dramatic improvements in the surface morphology, crystallographic quality and optical properties of ZnO layers grown on c-sapphire substrates by Metal Organic Chemical Vapor Deposition. This paper provides complementary details on the PLD-grown ZnO template properties. [reprint (PDF)]
15.	GaInAs/InP nanopillar arrays for long wavelength infrared detection A. Gin, Y. Wei, A. Hood, D. Hoffman, M. Razeghi and G.J. Brown SPIE Conference, Jose, CA, Vol. 5732, pp. 350-- January 22, 2005 ...[Visit Journal] Nanopillar devices have been fabricated from GaInAs/InP QWIP material grown by MOCVD. Using electron beam lithography and reactive ion etching techniques, large, regular arrays of nanopillars with controllable diameters ranging from 150 nm to less than 40 nm have been reproducibly formed. Photoluminescence experiments demonstrate a strong peak wavelength blue shift for nanopillar structures compared to the as-grown quantum well material. Top and bottom metal contacts have been realized using a polyimide planarization and etchback procedure. I-V and noise measurements have been performed. Optical measurements indicate photoconductive response in selected nanopillar arrays. Device peak wavelength response occurs at about 8 µm with peak device responsivity of 420 mA/W. Peak detectivity of 3×10⁸ cm·Hz^½/W has been achieved at -1V bias and 30 K. [reprint (PDF)]
15.	Passivation of Type-II InAs/GaSb Superlattice Photodiodes A. Gin, Y. Wei, J. Bae, A. Hood, J. Nah, and M. Razeghi International Conference on Metallurgical Coatings and Thin Films (ICMCTF), San Diego, CA; Thin Solid Films 447-448-- January 30, 2004 ...[Visit Journal] Recently, excellent infrared detectors have been demonstrated using Type-II InAs/GaSb superlattice materials sensitive at wavelengths from 3 μm to greater than 32 μm. These results indicate that Type-II superlattice devices may challenge the preponderance of HgCdTe and other state-of-the-art infrared material systems. As such, surface passivation is becoming an increasingly important issue as progress is made towards the commercialization of Type-II devices and focal plane array applications. This work focuses on initial attempts at surface passivation of Type-II InAs/GaSb superlattice photodiodes using PECVD-grown thin layers of SiO₂. Our results indicate that silicon dioxide coatings deposited at various temperatures improve photodetector resistivity by several times. Furthermore, reverse-bias dark current has been reduced significantly in passivated devices. [reprint (PDF)]
15.	Room Temperature Operation of InTlSb Infrared Photodetectors on GaAs J.D. Kim, E. Michel, S. Park, J. Xu, S. Javadpour and M. Razeghi Applied Physics Letters 69 (3)-- August 15, 1996 ...[Visit Journal] Long-wavelength InTlSb photodetectors operating at room temperature are reported. The photo- detectors were grown on (100) semi-insulating GaAs substrates by low-pressure metalorganic chemical vapor deposition. Photoresponse of InTlSb photodetectors is observed up to 11 µm at room temperature. The maximum responsivity of an In_0.96Tl_0.04Sb photodetector is about 6.64 V/W at 77 K, corresponding to a detectivity of about 7.64 × 10⁸ cm·Hz^½/W. The carrier lifetime in InTlSb photodetectors derived from the stationary photoconductivity is 10–50 ns at 77 K. [reprint (PDF)]
15.	Minority electron unipolar photodetectors based on Type-II InAs/GaSb/AlSb superlattices for very long wavelength infrared detection B.M. Nguyen, S. Abdollahi Pour, S. Bogdanov and M. Razeghi SPIE Proceedings, San Francisco, CA (January 22-28, 2010), Vol. 7608, p. 760825-1-- January 22, 2010 ...[Visit Journal] The bandstructure tunability of Type-II antimonide-based superlattices has been significantly enhanced since the introduction of the M-structure superlattice, resulting in significant improvements of Type-II superlattice infrared detectors. By using M-structure, we developed the pMp design, a novel infrared photodetector architecture that inherits the advantages of traditional photoconductive and photovoltaic devices. This minority electron unipolar device consists of an M-structure barrier layer blocking the transport of majority holes in a p-type semiconductor, resulting in an electrical transport due to minority carriers with low current density. Applied for the very long wavelength detection, at 77K, a 14µm cutoff detector exhibits a dark current 3.3 mA·cm⁻², a photoresponsivity of 1.4 A/W at 50mV bias and the associated shot-noise detectivity of 4x10¹⁰ Jones. [reprint (PDF)]
15.	Suppression of surface leakage in gate controlled type-II InAs/GaSb mid-infrared photodetectors G. Chen; B.-M. Nguyen; A.M. Hoang; E.K. Huang; S.R. Darvish; M. Razeghi Proc. SPIE 8268, Quantum Sensing and Nanophotonic Devices IX, 826811 (January 20, 2012)-- January 20, 2012 ...[Visit Journal] One of the biggest challenges of improving the electrical performance in Type II InAs/GaSb superlattice photodetector is suppressing the surface leakage. Surface leakage screens important bulk dark current mechanisms, and brings difficulty and uncertainty to the material optimization and bulk intrinsic parameters extraction such as carrier lifetime and mobility. Most of surface treatments were attempted beyond the mid-infrared (MWIR) regime because compared to the bulk performance, surface leakage in MWIR was generally considered to be a minor factor. In this work, we show that below 150K, surface leakage still strongly affects the electrical performance of the very high bulk performance p-π-M-n MWIR photon detectors. With gating technique, we can effectively eliminate the surface leakage in a controllable manner. At 110K, the dark current density of a 4.7 μm cut-off gated photon diode is more than 2 orders of magnitude lower than the current density in SiO₂ passivated ungated diode. With a quantum efficiency of 48%, the specific detecivity of gated diodes attains 2.5 x 10¹⁴ cm·Hz^1/2/W, which is 3.6 times higher than that of ungated diodes. [reprint (PDF)]
15.	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-- July 12, 2016 ...[Visit Journal] 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 (PDF)]
15.	RT-CW: widely tunable semiconductor THz QCL sources M. Razeghi; Q. Y. Lu Proceedings Volume 9934, Terahertz Emitters, Receivers, and Applications, 993406-1-- September 26, 2017 ...[Visit Journal] Distinctive position of Terahertz (THz) frequencies (ν~0.3 -10 THz) in the electromagnetic spectrum with their lower quantum energy compared to IR and higher frequency compared to microwave range allows for many potential applications unique to them. Especially in the security side of the THz sensing applications, the distinct absorption spectra of explosives and related compounds in the range of 0.1–5 THz makes THz technology a competitive technique for detecting hidden explosives. A compact, high power, room temperature continuous wave terahertz source emitting in a wide frequency range will greatly boost the THz applications for the diagnosis and detection of explosives. Here we present a new strong-coupled strain-balanced quantum cascade laser design for efficient THz generation based intracavity DFG. Room temperature continuous wave operation with electrical frequency tuning range of 2.06-4.35 THz is demonstrated [reprint (PDF)]
15.	High-speed short wavelength infrared heterojunction phototransistors based on type II superlattices Jiakai Li; Arash Dehzangi; Donghai Wu; Manijeh Razeghi Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 1128813-- January 31, 2020 ...[Visit Journal] A two terminal short wavelength infrared heterojunction phototransistors based on type-II InAs/AlSb/GaSb on GaSb substrate are designed fabricated and presented. With the base thickness of 40 nm, the device exhibited 100% cut-off wavelengths of ~2.3 μm at 300K. The saturated peak responsivity value is of 325.5 A/W at 300K, under front-side illumination without any anti-reflection coating. A saturated optical gain at 300K was 215 a saturated dark current shot noise limited specific detectivity of 4.9×10¹¹ cm·Hz^½/W at 300 K was measured. Similar heterojunction phototransistor structure was grown and fabricated with different method of processing for high speed testing. For 80 μm diameter circular diode size under 20 V applied reverse bias, a −3 dB cut-off frequency of 1.0 GHz was achieved, which showed the potential of type-II superlattice based heterojunction phototransistors to be used for high speed detection. [reprint (PDF)]
15.	InAs quantum dot infrared photodetectors on InP by MOCVD W. Zhang, H. Lim, M. Taguchi, A. Quivy and M. Razeghi SPIE Conference, San Jose, CA, Vol. 6127, pp. 61270M -- January 23, 2006 ...[Visit Journal] We report our recent results of InAs quantum dots grown on InP substrate by low-pressure metalorganic chemical vapor deposition (MOCVD) for the application of quantum dot infrared photodetector (QDIP). We have previously demonstrated the first InP-based QDIP with a peak detection wavelength at 6.4 µm and a detectivity of 10¹⁰ cm·Hz^½/W at 77K. Here we show our recent work toward shifting the detection wavelength to the 3-5 µm middlewavelength infrared (MWIR) range. The dependence of the quantum dot on the growth conditions is studied by atomic force microscopy, photoluminescence and Fourier transform infrared spectroscopy. Possible ways to increase the quantum efficiency of QDIPs are discussed. [reprint (PDF)]
15.	Scale-up of the Chemical Lift-off of (In)GaN-based p-i-n Junctions from Sapphire Substrates Using Sacrificial ZnO Template Layers D. J. Rogers, S. Sundaram, Y. El Gmili, F. Hosseini Teherani, P. Bove, V. Sandana, P. L. Voss, A. Ougazzaden, A. Rajan, K.A. Prior, R. McClintock, & M. Razeghi Proc. SPIE 9364, Oxide-based Materials and Devices VI, 936424 -- March 24, 2015 ...[Visit Journal] (In)GaN p-i-n structures were grown by MOVPE on both GaN- and ZnO-coated c-sapphire substrates. XRD studies of the as-grown layers revealed that a strongly c-axis oriented wurtzite crystal structure was obtained on both templates and that there was a slight compressive strain in the ZnO underlayer which increased after GaN overgrowth. The InGaN peak position gave an estimate of 13.6at% for the indium content in the active layer. SEM and AFM revealed that the top surface morphologies were similar for both substrates, with an RMS roughness (5 μm x 5 μm) of about 10 nm. Granularity appeared slightly coarser (40nm for the device grown on ZnO vs 30nm for the device grown on the GaN template) however. CL revealed a weaker GaN near band edge UV emission peak and a stronger broad defect-related visible emission band for the structure grown on the GaN template. Only a strong ZnO NBE UV emission was observed for the sample grown on the ZnO template. Quarter-wafer chemical lift-off (CLO) of the InGaN-based p-i-n structures from the sapphire substrate was achieved by temporary-bonding the GaN surface to rigid glass support with wax and then selectively dissolving the ZnO in 0.1M HCl. XRD studies revealed that the epitaxial nature and strong preferential c-axis orientation of the layers had been maintained after lift-off. This demonstration of CLO scale-up, without compromising the crystallographic integrity of the (In)GaN p-i-n structure opens up the perspective of transferring GaN based devices off of sapphire substrates industrially. [reprint (PDF)]
15.	High-Power (~9 μm) Quantum Cascade Lasers S. Slivken, Z. Huang, A. Evans, and M. Razeghi Virtual Journal of Nanoscale Science and Technology 5 (22)-- June 3, 2002 ...[Visit Journal][reprint (PDF)]
15.	Background limited performance of long wavelength infrared focal plane arrays fabricated from type-II InAs/GaSb M-structure superlattice P.Y. Delaunay, B.M. Nguyen and M. Razeghi SPIE Porceedings, Vol. 7298, Orlando, FL 2009, p. 72981Q-- April 13, 2009 ...[Visit Journal] Recent advances in growth techniques, structure design and processing have lifted the performance of Type-II InAs/GaSb superlattice photodetectors. The introduction of a M-structure design improved both the dark current and R0A of Type-II photodiodes. This new structure combined with a thick absorbing region demonstrated background limited performance at 77K for a 300K background and a 2-π field of view. A focal plane array with a 9.6 μm 50% cutoff wavelength was fabricated with this design and characterized at 80K. The dark current of individual pixels was measured around 1.3 nA, 7 times lower than previous superlattice FPAs. This led to a higher dynamic range and longer integration times. The quantum efficiency of detectors without anti-reflective coating was 72%. The noise equivalent temperature difference reached 23 mK. The deposition of an anti-reflective coating improved the NEDT to 20 mK and the quantum efficiency to 89%. [reprint (PDF)]
15.	Highly Conductive Co-Doped Ga2O3Si-In Grown by MOCVD Junhee Lee, Honghyuk Kim, Lakshay Gautam and Manijeh Razeghi Coatings 2021, 11(3), 287; https://doi.org/10.3390/coatings11030287 ...[Visit Journal] We report a highly conductive gallium oxide doped with both silicon and indium grown on c-plane sapphire substrate by MOCVD. From a superlattice structure of indium oxide and gallium oxide doped with silicon, we obtained a highly conductive material with an electron hall mobility up to 150 cm2/V·s with the carrier concentration near 2 × 1017 cm−3. However, if not doped with silicon, both Ga2O3:In and Ga2O3 are highly resistive. Optical and structural characterization techniques such as X-ray, transmission electron microscope, and photoluminescence, reveal no significant incorporation of indium into the superlattice materials, which suggests the indium plays a role of a surfactant passivating electron trapping defect levels. [reprint (PDF)]
15.	Room temperature continuous wave THz frequency comb based on quantum cascade lasers M. Razeghi; Q. Y. Lu; F. H. Wang; D. H. Wu; S. Slivken Proc. SPIE 11124, Terahertz Emitters, Receivers, and Applications X, 1112407-- September 6, 2019 ...[Visit Journal] Frequency combs, spectra of phase-coherent equidistant lines, have revolutionized time and frequency metrology. The recently developed quantum cascade laser (QCL) comb has exhibits great potential with high power and broadband spectrum. However, in the terahertz (THz) range, cryogenic cooling has to be applied for THz QCL combs. We report a room temperature THz frequency comb at 3.0 THz based on difference-frequency generation from a mid-IR QCL comb. A largely detuned distributed-feedback grating is integrated into the QCL cavity to provide the single mode operation as well as enhanced spatial hole-burning effect for multimode comb operation. Multiheterodyne spectroscopy with multiple equally spaced lines by beating it with a reference Fabry-Pérot comb confirms the THz comb operation. This type of THz comb provides a new solution to chip-based high-speed high-resolution THz spectroscopy with compact size at room temperature. [reprint (PDF)]
15.	Solar-Blind Deep UV Avalanche Photodetectors Using Reduced Area Epitaxy Lakshay Gautam , Junhee Lee, Michael Richards, and Manijeh Razeghi , Lakshay Gautam, Manijeh Razeghi, IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 59, NO. 6, 10.1109/JQE.2023.3325254 ...[Visit Journal] We report high gain avalanche photodetectors operating in the deep UV wavelength regime. The high gain was leveraged through reduced area epitaxy by patterning AlN on Sapphire substrate. This helps in a substantial reduction of crack formation due to overgrowth on individually isolated AlN mesas. Reproducible gain on the order of 105 was reported for multiple diodes in different areas of 320 × 256 focal plane array. [reprint (PDF)]
15.	Quantum Light: Unlocking the Invisible and Transforming the Possible M. Razeghi Journal of the Franklin Institute, 108997 (2026) ...[Visit Journal] Manijeh Razeghi explores the future of quantum photonics in the article. Drawing on her work engineering and detecting light across wavelengths from deep ultraviolet to terahertz, Razeghi describes how advances in quantum light could open new possibilities in public health, sensing, high-speed communication, energy and exploration. [reprint (PDF)]
15.	Very High Average Power at Room Temperature from λ ~ 5.9 μm Quantum Cascade Lasers J.S. Yu, S. Slivken, A. Evans, J. David and M. Razeghi Virtual Journal of Nanoscale Science & Technology 26-- May 26, 2003 ...[Visit Journal][reprint (PDF)]
15.	UV photodetectors based on Al_xGa_1-xN grown by MOCVD A. Saxler, D. Walker, X. Zhang, P. Kung, J. Xu, and M. Razeghi SPIE Photonics West '96 Photodetectors: Materials and Devices; Proceedings 2685-- January 27, 1996 ...[Visit Journal] Metalorganic chemical vapor deposition was used to deposit Al_xGa_1-xN active layers with varying aluminum compositions on basal plane sapphire substrate. Al_xGa_1-xN (x < 0.5) ultraviolet photodetectors have been fabricated and characterized with cut-off wavelengths as short as 260 nm. Carrier lifetimes on the order of 10 milliseconds were estimated from frequency dependent measurements of the responsivity. [reprint (PDF)]
15.	Evaluation of the Band Offsets of GaAs-GaInP Multilayers by Electroreflectance Razeghi M., D. Yang, J.W. Garland, Z. Zhang, D. Xue SPIE Proceedings, Vol. 1676, pp. 130-- January 1, 1992 ...[Visit Journal] We report the first band offset measurement of GaAs/Ga_0.51In_0.49P multiquantum wells and superlattices by electrolyte electroreflectance spectroscopy. The conduction and valence band discontinuities (Delta) Ec equals 159 ± 4 meV and (Delta) Ev equals 388 ± 6 meV have been measured. The values found for the conduction band, heavy-hole and light-hole masses in the GaInP barriers and GaAs wells and for the split-off well mass are in excellent agreement with the literature. The intraband, intersubband transition energies, which are important for III - V infrared detection devices, also were directly measured. [reprint (PDF)]

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