Center for Quantum Devices - Most Downloaded Journal Articles

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3.	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)]
3.	Fabrication and characterization of novel hybrid green light emitting didoes based on substituting n-type ZnO for n-type GaN in an inverted p-n junction C. Bayram, D. Rogers, F. H. Teherani, and M. Razeghi Journal of Vacuum Science and Technology B, Vol. 27, No. 3, May/June, p. 1784-1788-- May 29, 2009 ...[Visit Journal] Details of the fabrication and characterization of hybrid green light emitting diodes, composed of n-ZnO/(InGaN/GaN) multi-quantum-wells/p-GaN on AlN/sapphire, are reported. Scanning electron microscope, atomic force microscopy, high resolution x-ray diffraction, and photoluminescence were used to study the hybrid device. The effects of solvents, annealing, and etching on n-ZnO are discussed. Successful hybridization of ZnO and (In)GaN into a green light emitting diode was realized. [reprint (PDF)]
3.	Demonstration of high performance bias-selectable dual-band short-/mid-wavelength infrared photodetectors based on type-II InAs/GaSb/AlSb superlattices A.M. Hoang, G. Chen, A. Haddadi and M. Razeghi Applied Physics Letters, Vol. 102, No. 1, p. 011108-1-- January 7, 2013 ...[Visit Journal] High performance bias-selectable dual-band short-/mid-wavelength infrared photodetector based on InAs/GaSb/AlSb type-II superlattice with designed cut-off wavelengths of 2 μm and 4 μm was demonstrated. At 150 K, the short-wave channel exhibited a quantum efficiency of 55%, a dark current density of 1.0 × 10⁻⁹ A/cm² at −50 mV bias voltage, providing an associated shot noise detectivity of 3.0 × 10¹³ Jones. The mid-wavelength channel exhibited a quantum efficiency of 33% and a dark current density of 2.6 × 10⁻⁵ A/cm² at 300 mV bias voltage, resulting in a detectivity of 4.0 × 10¹¹ Jones. The spectral cross-talk between the two channels was also discussed for further optimization. [reprint (PDF)]
3.	Gain and recombination dynamics in photodetectors made with quantum nanostructures: The quantum dot in a well and the quantum well B. Movaghar, S. Tsao, S. Abdollahi Pour, T. Yamanaka, and M. Razeghi Physical Review B, Vol. 78, No. 11-- September 15, 2008 ...[Visit Journal] We consider the problem of charge transport and recombination in semiconductor quantum well infrared photodetectors and quantum-dot-in-a-well infrared detectors. The photoexcited carrier relaxation is calculated using rigorous random-walk and diffusion methods, which take into account the finiteness of recombination cross sections, and if necessary the memory of the carrier generation point. In the present application, bias fields are high and it is sufficient to consider the drift limited regime. The photoconductive gain is discussed in a quantum-mechanical language, making it more transparent, especially with regard to understanding the bias and temperature dependence. Comparing experiment and theory, we can estimate the respective recombination times. The method developed here applies equally well to nanopillar structures, provided account is taken of changes in mobility and trapping. Finally, we also derive formulas for the photocurrent time decays, which in a clean system at high bias are sums of two exponentials. [reprint (PDF)]
3.	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)]
3.	High-performance short-wavelength infrared photodetectors based on type-II InAs/InAs_1-xSb_x/AlAs_1-xSb_x superlattices M. Razeghi, A. Haddadi, X. V. Suo, S. Adhikary, P. Dianat, R. Chevallier, A. M. Hoang, A. Dehzangi Proc. SPIE 9819, Infrared Technology and Applications XLII, 98190A -- May 20, 2016 ...[Visit Journal] We present a high-performance short-wavelength infrared n-i-p photodiode, whose structure is based on type-II superlattices with InAs/InAs_1-xSb_x/AlAs_1-xSb_x on GaSb substrate. At room temperature (300K) with front-side illumination, the device shows the peak responsivity of 0.47 A/W at 1.6mm, corresponding to 37% quantum efficiency at zero bias. At 300K, the device has a 50% cut-off wavelength of ~1.8mm. For −50mV applied bias at 300 K the photodetector has dark current density of 9.6x10^-5 A/cm² and RxA of 285 Ω•cm², and it revealed a detectivity of 6.45x10¹⁰ cm•Hz^½/W. Dark current density reached to 1.3x10^-8 A/cm² at 200 K, with 36% quantum efficiency which leads to the detectivity value of 5.66x10¹² cm•Hz^½/W. [reprint (PDF)]
3.	High Frequency Extended Short-Wavelength Infrared Heterojunction Photodetectors Based on InAs/GaSb/AlSb Type-II Superlattices Romain Chevallier, Abbas Haddadi, Ryan McClintock, Arash Dehzangi , Victor Lopez-Dominguez, Pedram Khalili Amiri, Manijeh Razeghi IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 54, NO. 6-- December 1, 2018 ...[Visit Journal] InAs/GaSb/AlSb type-II superlattice-based photodetectors, with 50% cut-off wavelength of 2.1 µm and a −3 dB cut-off frequency of 4.8 GHz, are demonstrated, for 10 µm diameter circular mesas under 15 V applied reverse bias. A study of the cut-off frequency with applied bias and mesa size was performed to evaluate some of the limiting factors of photodetectors high frequency performance. [reprint (PDF)]
3.	p-Type thin film field effect transistors based on lithium-doped nickel oxide channels grown by pulsed laser deposition V. E. Sandana; D. J. Rogers; F. H. Teherani; P. Bove; R. McClintock; M. Razeghi SPIE Proceedings Volume 10919, Oxide-based Materials and Devices X; 109191H -- March 12, 2019 ...[Visit Journal] Staggered back-gated Field Effect Transistor (FET) structures were made by growing Li-doped NiO on Si₃N₄/SiO₂/Si (111) using room temperature pulsed laser deposition. Optical studies showed over 80% transmission for the NiO:Li channel at wavelengths > 500nm. The MISFET revealed rectifying transfer characteristics, with a V_ON close to zero, a channel mobility of ~ 1 cm²/V·s, a gate leakage current (at +5V) of 0.8 mA and an ION/IOFF ratio (at a Vgs of −15V) of ~ 10³. The transistors showed enhancement-mode output characteristics indicative of a p-type channel with sharp pinchoff, hard saturation, a comparatively high (milliampere range) Id and a relatively low on-resistance of ~11 kΩ. Hence the adoption of Li doping in NiO channels would appear to be a promising approach to obtain p-type TFTs with superior transparency, speed and energy efficiency. [reprint (PDF)]
3.	High operating temperature MWIR photon detectors based on Type-II InAs/GaSb superlattice M. Razeghi, B.M. Nguyen, P.Y. Delaunay, S. Abdollahi Pour, E.K.W. Huang, P. Manukar, S. Bogdanov, and G. Chen SPIE Proceedings, San Francisco, CA (January 22-28, 2010), Vol. 7608, p. 76081Q-1-- January 22, 2010 ...[Visit Journal] Recent efforts have been paid to elevate the operating temperature of Type-II InAs/GaSb superlattice Mid Infrared photon detectors. Optimized growth parameters and interface engineering technique enable high quality material with a quantum efficiency above 50%. Intensive study on device architecture and doping profile has resulted in almost one order of magnitude of improvement to the electrical performance and lifted up the 300 K-background BLIP operation temperature to 166 K. At 77 K, the ~4.2 µm cut-off devices exhibit a differential resistance area product in excess of the measurement system limit (10⁶ Ω·cm²) and a detectivity of 3x10¹³ cm·Hz^½·W⁻¹. High quality focal plane arrays were demonstrated with a noise equivalent temperature of 10 mK at 77 K. Uncooled camera is capable to capture hot objects such as soldering iron. [reprint (PDF)]
3.	Combined resonant tunneling and rate equation modeling of terahertz quantum cascade lasers Zhichao Chen , Andong Liu, Dong Chang , Sukhdeep Dhillon , Manijeh Razeghi , Feihu Wang Journal of Applied Physics, 135, 115703 ...[Visit Journal] Terahertz (THz) quantum cascade lasers (QCLs) are technologically important laser sources for the THz range but are complex to model. An efficient extended rate equation model is developed here by incorporating the resonant tunneling mechanism from the density matrix formalism, which permits to simulate THz QCLs with thick carrier injection barriers within the semi-classical formalism. A self-consistent solution is obtained by iteratively solving the Schrödinger-Poisson equation with this transport model. Carrier-light coupling is also included to simulate the current behavior arising from stimulated emission. As a quasi-ab initio model, intermediate parameters such as pure dephasing time and optical linewidth are dynamically calculated in the convergence process, and the only fitting parameters are the interface roughness correlation length and height. Good agreement has been achieved by comparing the simulation results of various designs with experiments, and other models such as density matrix Monte Carlo and non-equilibrium Green’s function method that, unlike here, require important computational resources. The accuracy, compatibility, and computational efficiency of our model enables many application scenarios, such as design optimization and quantitative insights into THz QCLs. Finally, the source code of the model is also provided in the supplementary material of this article for readers to repeat the results presented here, investigate and optimize new designs. [reprint (PDF)]
3.	Low Noise Short Wavelength Infrared Avalanche Photodetector Using SB-Based Strained Layer Superlattice Arash Dehzangi, Jiakai Li, Manijeh Razeghi Photonics 2021, 8(5), 148; https://doi.org/10.3390/photonics8050148 Received: 8 March 2021 / Revised: 12 April 2021 / Accepted: 25 April 2021 / Published: 30 April 2021 ...[Visit Journal] We demonstrate low noise short wavelength infrared (SWIR) Sb-based type II superlattice (T2SL) avalanche photodiodes (APDs). The SWIR GaSb/(AlAsSb/GaSb) APD structure was designed based on impact ionization engineering and grown by molecular beam epitaxy on a GaSb substrate. At room temperature, the device exhibits a 50% cut-off wavelength of 1.74 µm. The device was revealed to have an electron-dominated avalanching mechanism with a gain value of 48 at room temperature. The electron and hole impact ionization coefficients were calculated and compared to give a better prospect of the performance of the device. Low excess noise, as characterized by a carrier ionization ratio of ~0.07, has been achieved. [reprint (PDF)]
3.	Background–limited long wavelength infrared InAs/InAsSb type-II superlattice-based photodetectors operating at 110 K Abbas Haddadi, Arash Dehzangi, Sourav Adhikary, Romain Chevallier, and Manijeh Razeghi APL Materials 5, 035502 -- February 13, 2017 ...[Visit Journal] We report the demonstration of high-performance long-wavelength infrared (LWIR) nBn photodetectors based on InAs/InAsSb type-II superlattices. A new saw-tooth superlattice design was used to implement the electron barrier of the photodetectors. The device exhibited a cut-off wavelength of ∼10 μm at 77 K. The photodetector exhibited a peak responsivity of 2.65 A/W, corresponding to a quantum efficiency of 43%. With an R × A of 664 Ω·cm² and a dark current density of 8 × 10⁻⁵ A/cm², under −80 mV bias voltage at 77 K, the photodetector exhibited a specific detectivity of 4.72 × 10¹¹ Jones and a background–limited operating temperature of 110 K. [reprint (PDF)]
3.	Aluminum free GaInP/GaAs Quantum Well Infrared Photodetectors for Long Wavelength Detection C. Jelen, S. Slivken, J. Hoff, M. Razeghi, and G. Brown Applied Physics Letters 70 (3)-- January 20, 1997 ...[Visit Journal] We demonstrate quantum well infrared photodetectors based on a GaAs/Ga_0.51In_0.49P superlattice structure grown by gas-source molecular beam epitaxy. Wafers were grown with varying well widths. Wells of 40, 65, and 75 Å resulted in peak detection wavelengths of 10.4, 12.8, and 13.3 μm with a cutoff wavelength of 13.5, 15, and 15.5 μm, respectively. The measured peak and cutoff wavelengths match those predicted by eight band theoretical analysis. Measured dark currents were lower than equivalent GaAs/AlGaAs samples. [reprint (PDF)]
3.	High brightness angled cavity quantum cascade lasers D. Heydari, Y. Bai, N. Bandyopadhyay, S. Slivken, and M. Razeghi Applied Physics Letters 106, 091105-- March 6, 2015 ...[Visit Journal] A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 μm, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 μm. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm²·sr^-1 is obtained, which marks the brightest QCL to date. [reprint (PDF)]
3.	Observation of Room Temperature Surface-Emitting Stimulated Emission from GaN:Ge by Optical pumping X. Zhang, P. Kung, A. Saxler, D. Walker, and M. Razeghi Journal of Applied Physics 80 (11)-- December 1, 1996 ...[Visit Journal] Optically pumped surface-emitting stimulated emission at room temperature was observed from GaN:Ge grown by metalorganic chemical vapor deposition. The sample was optically pumped perpendicularly on the top surface while the stimulated emission was collected from the back colinearly with the pump beam. The cavity was formed by the GaN/air and GaN/sapphire interfaces without any other structure. The stimulated emission was gain guided by the pump beam. The threshold optical pump density for stimulated emission was approximately 2.8 MW/cm² and the linewidth was 2.5 nm. The emission from GaN:Ge showed a redshift as the pump density increased. The comparison between theoretical calculations and experimental results suggested that many-body interactions can account well for the redshift. [reprint (PDF)]
3.	Room temperature continuous wave operation of quantum cascade lasers with watt-level optical power Y. Bai, S.R. Darvish, S. Slivken, W. Zhang, A. Evans, J. Nguyen and M. Razeghi Applied Physics Letters, Vol. 92, No. 10, p. 101105-1-- March 10, 2008 ...[Visit Journal] We demonstrate quantum cascade lasers at an emitting wavelength of 4.6 µm, which are capable of room temperature, high power continuous wave (cw) operation. Buried ridge geometry with a width of 9.8 µm was utilized. A device with a 3 mm cavity length that was epilayer-down bonded on a diamond submount exhibited a maximum output power of 1.3 W at room temperature in cw operation. The maximum output power at 80 K was measured to be 4 W, with a wall plug efficiency of 27%. [reprint (PDF)]
3.	Compressively-strained multiple quantum well InAsSb lasers emitting at 3.6 μm grown by metal-organic chemical vapor deposition B. Lane, D. Wu, A. Rybaltowski, H. Yi, J. Diaz, and M. Razeghi Applied Physics Letters 70 (4)-- January 27, 1997 ...[Visit Journal] A compressively strained InAsSb/InAs multiple quantum-well (MQW) structure was grown by low-pressure metal-organic chemical vapor deposition. Maximum output power (from two facets) up to 1 W with differential efficiency about 70% was obtained from a MQW laser with stripe width of 100 μm and cavity length of 700 μm for emitting wavelength of 3.65 μm at 90 K in pulse mode operation. About 2 times lower threshold current density was obtained from the MQW lasers for a temperature range of 90 to 140 K compared to the double heterostructure lasers grown on the same growth conditions. [reprint (PDF)]
3.	High Power 280 nm AlGaN Light Emitting Diodes Based on an Asymmetric Single Quantum Well K. Mayes, A. Yasan, R. McClintock, D. Shiell, S.R. Darvish, P. Kung, and M. Razeghi Applied Physics Letters, 84 (7)-- February 16, 2004 ...[Visit Journal] We demonstrate high-power AlGaN-based ultraviolet light-emitting diodes grown on sapphire with an emission wavelength of 280 nm using an asymmetric single-quantum-well active layer configuration on top of a high-quality AlGaN/AlN template layer. An output power of 1.8 mW at a pulsed current of 400 mA was achieved for a single 300 µm×300 µm diode. This device reached a high peak external quantum efficiency of 0.24% at 40 mA. An array of four diodes produced 6.5 mW at 880 mA of pulsed current. [reprint (PDF)]
3.	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 ...[Visit Journal] 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 (PDF)]
3.	High Detectivity InGaAs/InGaP Quantum-Dot Infrared Photodetectors Grown by Low Pressure Metalorganic Chemical Vapor Deposition J. Jiang, S. Tsao, T. O'Sullivan, W. Zhang, H. Lim, T. Sills, K. Mi, M. Razeghi, G.J. Brown, and M.Z. Tidrow Virtual Journal of Nanoscale Science and Technology 9 (12)-- March 29, 2004 ...[Visit Journal][reprint (PDF)]
3.	Study of Au coated ZnO nanoarrays for surface enhanced Raman scattering chemical sensing Gre´gory Barbillon, Vinod E. Sandana,Christophe Humbert, Benoit Be´lier, David J. Rogers, Ferechteh H. Teherani, Philippe Bove Ryan McClintock and Manijeh Razeghid J. Mater. Chem. C, 2017, 5, 3528-- March 20, 2017 ...[Visit Journal] At present, the simultaneous attainment of good reproducibility and high enhancement factors (EF) are key challenges in the development of surface enhanced Raman scattering (SERS)substrates for improved chemical and biological sensing. SERS substrates are generally based on distributions of metallic nanoparticles/structures with different shapes and architectures which are prepared by either thermal dewetting, precipitation from colloidal suspensions1–4 or advanced (e.g. deep UV or electron beam (EBL)) lithographic techniques.5–9 Although such substrates can exhibit large Raman enhancements, the former two techniques (colloidal and thermal dewetting) give poor SERS reproducibility while deep UV and EBL are too expensive and/or complex for mass production.
3.	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 ...[Visit Journal] 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 (PDF)]
3.	High Power Mid-Infrared Quantum Cascade Lasers Grown on GaAs Steven Slivken and Manijeh Razeghi Photonics 2022, 9(4), 231 (COVER ARTICLE) ...[Visit Journal] The motivation behind this work is to show that InP-based intersubband lasers with high power can be realized on substrates with significant lattice mismatch. This is a primary concern for the integration of mid-infrared active optoelectronic devices on low-cost photonic platforms, such as Si. As evidence, an InP-based mid-infrared quantum cascade laser structure was grown on a GaAs substrate, which has a large (4%) lattice mismatch with respect to InP. Prior to laser core growth, a metamorphic buffer layer of InP was grown directly on a GaAs substrate to adjust the lattice constant. Wafer characterization data are given to establish general material characteristics. A simple fabrication procedure leads to lasers with high peak power (>14 W) at room temperature. These results are extremely promising for direct quantum cascade laser growth on Si substrates. [reprint (PDF)]
3.	High performance InAs quantum dot infrared photodetectors (QDIP) on InP by MOCVD W. Zhang, H. Lim, M. Taguchi, S. Tsao, J. Szafraniec, B. Movaghar, M. Razeghi, and M. Tidrow SPIE Conference, Jose, CA, Vol. 5732, pp. 326-- January 22, 2005 ...[Visit Journal] Inter-subband detectors such as quantum well infrared photodetectors (QWIP) have been widely used in infrared detection. Quantum dot infrared photodetectors (QDIPs) have been predicted to have better performance than QWIPs including higher operation temperature and normal incidence detection. Here we report our recent results of InAs QDIP grown on InP substrate by low-pressure metalorganic chemical vapor deposition (MOCVD). The device structures consist of multiple stacks of InAs quantum dots with InP barriers. High detectivities in the range of 10¹⁰cm·Hz^1/2/W were obtained at 77K. The measurements at higher temperatures show better temperature dependent performance than QWIP. However, the performances of QDIPs are still far from the expected. One of the reasons is the low quantum efficiency due to the low fill factor of quantum dots layer. Resonant cavity enhanced QDIP has been studied to increase the quantum efficiency. Different schemes of mirrors using free carrier plasma and distributed Bragg reflector are discussed. [reprint (PDF)]
3.	Solar-blind AlGaN photodiodes with very low cutoff wavelength D. Walker, V. Kumar, K. Mi, P. Sandvik, P. Kung, X.H. Zhang, and M. Razeghi Applied Physics Letters 76 (4)-- January 24, 2000 ...[Visit Journal] We report the fabrication and characterization of AlxGa1–xN photodiodes (x~0.70) grown on sapphire by low-pressure metalorganic chemical vapor deposition. The peak responsivity for –5 V bias is 0.11 A/W at 232 nm, corresponding to an internal quantum efficiency greater than 90%. The device response drops four orders of magnitude by 275 nm and remains at low response for the entire near-ultraviolet and visible spectrum. Improvements were made to the device design including a semitransparent Ni/Au contact layer and a GaN:Mg cap layer, which dramatically increased device response by enhancing the carrier collection efficiency. [reprint (PDF)]

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