Center for Quantum Devices - Most Downloaded Journal Articles

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14.	Demonstration of long wavelength infrared Type-II InAs/InAs_1-xSb_x superlattices photodiodes on GaSb substrate grown by metalorganic chemical vapor deposition D. H. Wu, A. Dehzangi, Y. Y. Zhang, M. Razeghi Applied Physics Letters 112, 241103-- June 12, 2018 ...[Visit Journal] We report the growth and characterization of long wavelength infrared type-II InAs/InAs_1−xSb_x superlattices photodiodes with a 50% cut-off wavelength at 8.0 μm on GaSb substrate grown by metalorganic chemical vapor deposition. At 77 K, the photodiodes exhibited a differential resistance at zero bias (R₀A) 8.0 Ω·cm², peak responsivity of 1.26 A/W corresponding to a quantum efficiency of 21%. A specific detectivity of 5.4×10¹⁰ cm·Hz^1/2/W was achieved at 7.5 μm. [reprint (PDF)]
14.	Investigation of MgZnO/ZnO heterostructures grown on c-sapphire substrates by pulsed laser deposition D. J. Rogers ; F. Hosseini Teherani ; P. Bove ; A. Lusson ; M. Razeghi Proc. SPIE 8626, Oxide-based Materials and Devices IV, 86261X (March 18, 2013)-- March 18, 2013 ...[Visit Journal] MgZnO thin films were grown on c-sapphire and ZnO-coated c-sapphire substrates by pulsed laser deposition from a ZnMgO target with 4 at% Mg. The MgZnO grown on the ZnO underlayer showed significantly better crystal quality than that grown directly on sapphire. AFM studies revealed a significant deterioration in surface morphology for the MgZnO layers compared with the ZnO underlayer. Optical transmission studies indicated a MgZnO bandgap of 3.61eV (compared with 3.34eV for the ZnO), which corresponds to a Mg content of about 16.1 at%. The MgZnO/ZnO heterojunction showed an anomalously low resistivity, which was more than two orders of magnitude less than the MgZnO layer and an order of magnitude lower than that for the ZnO layer. It was suggested that this may be attributable to the presence of a 2D electron gas at the ZnMgO/ZnO heterointerface. [reprint (PDF)]
14.	Non-equilibrium radiation of long wavelength InAs/GaSb superlattice photodiodes D. Hoffman, A. Hood, F. Fuchs and M. Razeghi Journal of Applied Physics 99-- February 15, 2006 ...[Visit Journal] The emission behavior of binary-binary type-II InAs/GaSb superlattice photodiodes has been studied in the spectral range between 8 and 13 μm. With a radiometric calibration of the experimental setup the internal and external quantum efficiencies have been determined in the temperature range between 80 and 300 K for both the negative and positive luminescences. [reprint (PDF)]
14.	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)]
14.	High Power, Continuous-Wave, Quantum Cascade Lasers for MWIR and LWIR Applications S. Slivken, A. Evans, J.S. Yu, S.R. Darvish and M. Razeghi SPIE Conference, San Jose, CA, Vol. 6127, pp. 612703-- January 23, 2006 ...[Visit Journal] Over the past several years, our group has endeavored to develop high power quantum cascade lasers for a variety of remote and high sensitivity infrared applications. The systematic optimization of laser performance has allowed for demonstration of high power, continuous-wave quantum cascade lasers operating above room temperature. Since 2002, the power levels for individual devices have jumped from 20 mW to 600 mW. Expanding on this development, we have able to demonstrate continuous wave operation at many wavelengths throughout the mid- and far-infrared spectral range, and have now achieved >100 mW output in the 4.0 to 9.5 µm range. [reprint (PDF)]
14.	Monolithic integrated photoreceiver for 1.3–1.55‐μm wavelengths: Association of a Schottky photodiode and a field‐effect transistor on GaInP‐GaInAs heteroepitaxy A. Hosseini Therani; D. Decoster; J. P. Vilcot; M. Razeghi J. Appl. Phys. 64, 2215–2218 (1988) -- March 24, 1988 ...[Visit Journal] We present a monolithic integrated circuit associating a Schottky photodiode and a field-effect transistor which has been fabricated, for the first time, on G8.0.49 InO.51 P /GaO,47 Ino.53 As strained heteroepitaxiaI material. Static, dynamic, and noise properties of the Schottky photodiode, the field-effect transistor, and the integrated circuit have been investigated and are reported. As an example, dynamic responsivity up to 50 A/W can be achieved at 1.3-pm wavelength for the integrated photoreceiver. The performance of the device is discussed, taking into account the integrated circuit design and the main characteristics of the material. [reprint (PDF)]
14.	Sb-based infrared materials and photodetectors for the near room temperature applications J.D. Kim, E. Michel, H. Mohseni, J. Wojkowski, J.J. Lee and M. Razeghi SPIE Conference, San Jose, CA, Vol. 2999, pp. 55-- February 12, 1997 ...[Visit Journal] We report on the growth of InSb, InAsSb, and InTlSb alloys for infrared photodetector applications. The fabrication and characterization of photodetectors based on these materials are also reported. Both photoconductive and photovoltaic devices are investigated. The materials and detector structures were grown on (100) and (111)B semi-insulating GaAs and GaAs coated Si substrates by low pressure metalorganic chemical vapor deposition and solid source molecular beam epitaxy. Photoconductive detectors fabricated from InAsSb and InTlSb have been operated in the temperature range from 77 K to 300 K. The material parameters for photovoltaic device structures have been optimized through theoretical calculations based on fundamental mechanisms. InSb p-i-n photodiodes with 77 K peak responsivities approximately 103 V/W were grown on Si and (111) GaAs substrates. An InAsSb photovoltaic detector with a composition of x equals 0.85 showed photoresponse up to 13 micrometers at 300 K with a peak responsivity of 9.13 X 10-2 V/W at 8 micrometers . The RoA product of InAsSb detectors has been theoretically and experimentally analyzed. [reprint (PDF)]
14.	Negative luminescence of InAs/GaSb superlattice photodiodes F. Fuchs, D. Hoffman, A. Gin, A. Hood, Y. Wei, and M. Razeghi Phys. Stat. Sol. C 3 (3)-- February 22, 2006 ...[Visit Journal] The emission behaviour of InAs/GaSb superlattice photodiodes has been studied in the spectral range between 8 µm and 13 μm. With a radiometric calibration of the experimental set-up the internal quantum efficiency has been determined in the temperature range between 80 K and 300 K for both, the negative and positive luminescence. The quantitative analysis of the internal quantum efficiency of the non-equilibrium radiation enables the determination of the Auger coefficient. [reprint (PDF)]
14.	Hybrid green LEDs based on n-ZnO/(InGaN/GaN) multi-quantum-wells/p-GaN C. Bayram, F. Hosseini Teherani, D.J. Rogers and M. Razeghi SPIE Proceedings, San Jose, CA Volume 7217-0P-- January 26, 2009 ...[Visit Journal] Hybrid green light-emitting diodes (LEDs) comprised of n-ZnO/(InGaN/GaN) multi-quantum-wells/p-GaN were grown on semi-insulating AlN/sapphire using pulsed laser deposition for the n-ZnO and metal organic chemical vapor deposition for the other layers. X-ray diffraction revealed that high crystallographic quality was preserved after the n- ZnO growth. LEDs showed a turn-on voltage of 2.5 V and a room temperature electroluminescence (EL) centered at 510 nm. A blueshift and narrowing of the EL peak with increasing current was attributed to bandgap renormalization. The results indicate that hybrid LED structures could hold the prospect for the development of green LEDs with superior performance. [reprint (PDF)]
14.	New design strategies for multifunctional and inexpensive quantum cascade lasers Steven Slivken; Manijeh Razeghi Proc. SPIE 10926, Quantum Sensing and Nano Electronics and Photonics XVI, 1092611-- February 1, 2019 ...[Visit Journal] This manuscript describes some of the new advances in active mid-infrared photonic integrated circuits enabled by new quantum cascade laser technologies. This includes monolithic beam steering which was achieved via the integration of a widely tunable QCL and a tapered grating outcoupler. A record 17.9 degrees of steering with a low divergence beam (0.5 degrees) was achieved. In addition, the use of surface emitting architectures is proposed as a means to reduce the manufacturing cost of next-generation QCLs. A reflective outcoupler is demonstrated which can allow for stable surface emission from a quantum cascade laser and has potential for cost-effective wafer-scale manufacturing. This outcoupler is integrated with an amplified, electrically tunable laser architecture to demonstrate high power surface emission at a wavelength near 4.9 μm. Single mode peak power up to 6.7 W is demonstrated with >6 W available over a 90 cm⁻¹ (215 nm) spectral range. All of this is achieved while maintaining a high quality output beam, similar to a standard edge emitter. [reprint (PDF)]
14.	Review of III-Nitride Optoelectronic Materials for light Emission and Detection M. Razeghi, A. Yasan, R. McClintock, K. Mayes, D. Shiell, S. Darvish, and P. Kung Physica Status Solidi C S141 - S148-- September 10, 2004 ...[Visit Journal] We review the significant achievements relating to optoelectronic devices based on III-nitrides at the center for quantum devices (CQD). Based on GaN/InGaN multiple-quantum well structures, we demonstrated blue laser diodes at a wavelength of 405 nm. This achievement was particularly significant at the time, because while no defect reduction technique was used, a fairly low threshold current density was achieved (3.8 kA/cm²). In the past few years, however, the interest has shifted towards shorter wavelength light emitters, i.e. ultraviolet LEDs and LDs. Lower crystalline quality and unsatisfactory doping levels of AlGaN compound semiconductors posed serious challenges en route to the realization of UV light emitters. However, steady progress in the growth of AlGaN and AlN epilayers made it possible to overcome some of the difficulties. To date, we have been able to demonstrate UV LEDs at wavelengths as short as 265 nm (corresponding to 45% Al in Al_xGa_1-xN) with optical output powers of over 5 mW. We have addressed the n-type AlGaN doping problem by using a Si-In co-doped scheme. We also employed high-quality AlGaN/AlN superlattice templates for the reduction of defects. We have also demonstrated 280 nm UV LEDs with output powers of over 6 mW and external quantum efficiencies of over 0.25%. Despite all the success in the realization of short-wavelength UV LEDs, UV laser diodes at these short wavelengths are yet to be realized. The main difficulties are the low material quality, high device resistance leading to excessive heating of the device, realization of smooth cavity mirrors, and issues related to the cracking of the material. We have also demonstrated different types of photodetectors in the UV range of the spectrum: photoconductors, MSM photodetector, Schottky barrier photodetectors, and p-i-n photodiodes to name a few. The most promising type of photodetector for realization of UV imaging focal plane arrays is the p-i-n photodiode. Realization of high-efficiency AlGaN-based p-i-n photodiodes becomes more difficult when considering the need for the collection of the light from the backside of the substrate. However, similar to our back-emission UV LED structure, we have demonstrated back-illuminated p-i-n solar-blind photodiodes with external quantum efficiencies as high as 68% under no applied bias and 74% under -5 V of bias. [reprint (PDF)]
14.	Dark current reduction in microjunction-based double electron barrier type-II InAs/InAsSb superlattice long-wavelength infrared photodetectors Romain Chevallier, Abbas Haddadi, & Manijeh Razeghi Scientific Reports 7, Article number: 12617-- October 3, 2017 ...[Visit Journal] Microjunction InAs/InAsSb type-II superlattice-based long-wavelength infrared photodetectors with reduced dark current density were demonstrated. A double electron barrier design was employed to reduce both bulk and surface dark currents. The photodetectors exhibited low surface leakage after passivation with SiO2, allowing the use of very small size features without degradation of the dark current. Fabricating microjunction photodetectors (25 × 25 µm² diodes with 10 × 10 µm² microjunctions) in combination with the double electron barrier design results in a dark current density of 6.3 × 10⁻⁶ A/cm² at 77 K. The device has an 8 µm cut-off wavelength at 77 K and exhibits a quantum efficiency of 31% for a 2 µm-thick absorption region, which results in a specific detectivity value of 1.2 × 10¹² cm·Hz^½/W. [reprint (PDF)]
14.	Finite-Size Scaling in the Dissipative Transport Regime Between Quantum Hall Plateaus Razeghi M., S. Koch, R.J. Hang, K.V. Klitzing, K. Ploog Koch, S., Haug, R.J., v. Klitzing, K., Ploog, K., Razeghi, M. (1992). Finite-Size Scaling in the Dissipative Transport Regime Between Quantum Hall Plateaus. In: Bauer, G., Kuchar, F., Heinrich, H. (eds) Low-Dimensional Electronic Systems. Springer Series in Solid-State Sciences, vol 111. Springer, Berlin, Heidelberg.-- January 1, 1993 ...[Visit Journal] The magnetoresistance of a two-dimensional electron gas shows a novel scaling behaviour in the dissipative transport regime between adjacent integer quantum Hall plateaus when studied in samples of different size. At low temperatures (≥ 25mK) the phase coherence length L in may exceed the size W of small samples (W ≥ 8µm). Under these conditions the width ΔB of the magnetic field region where dissipative transport is observed becomes independent of temperature. Then ΔB only depends on the size of the sample and increases with decreasing size. Thus the critical exponent v of the localization length ξ ∝ (ΔB)−v can be determined directly. The resulting exponent v = 2.3±0.1 does not depend on the specific sample and, furthermore, is independent of the (spin-resolved) Landau level. This experimental result agrees with the predictions of several theoretical approaches to the metal-insulator transition in the quantum Hall regime. The effect described occurs both in Hall bars and in Corbino geometries, with essentially identical results. On the other hand, in a Landau level where spin-splitting is not resolved, a considerably larger value of v = 6.5 ± 0.6 is observed for the localization length exponent. [reprint (PDF)]
14.	Electrically pumped photonic crystal distributed feedback quantum cascade lasers Y. Bai, S.R. Darvish, S. Slivken, P. Sung, J. Nguyen, A. Evans, W. Zhang, and M. Razeghi Applied Physics Letters, Vol. 91, No. 14, p. 141123-1-- October 1, 2007 ...[Visit Journal] We demonstrate electrically pumped, room temperature, single mode operation of photonic crystal distributed feedback (PCDFB) quantum cascade lasers emitting at ~4.75 µm. Ridge waveguides of 100 µm width were fabricated with both PCDFB and Fabry-Pérot feedback mechanisms. The Fabry-Pérot device has a broad emitting spectrum and a double lobed far-field character. The PCDFB device, as expected, has primarily a single spectral mode and a diffraction limited far field characteristic with a full angular width at half maximum of 2.4°. This accomplishment represents the first step in power scaling of single mode, midinfrared laser diodes operating at room temperature. [reprint (PDF)]
14.	The new oxide paradigm for solid state ultraviolet photodetectors D. J. Rogers, P. Bove, X. Arrateig, V. E. Sandana, F. H. Teherani, M. Razeghi, R. McClintock, E. Frisch, S. Harel, Proceedings Volume 10533, Oxide-based Materials and Devices IX; 105331P-- March 22, 2018 ...[Visit Journal] The bandgap of wurzite ZnO layers grown on 2 inch diameter c-Al₂O₃ substrates by pulsed laser deposition was engineered from 3.7 to 4.8 eV by alloying with Mg. Above this Mg content the layers transformed from single phase hcp to mixed hcp/fcc phase before becoming single phase fcc above a bandgap of about 5.5 eV. Metal-Semiconductor-Metal (MSM) photodetectors based on gold Inter-Digitated-Transducer structures were fabricated from the single phase hcp layers by single step negative photolithography and then packaged in TO5 cans. The devices gave over 6 orders of magnitude of separation between dark and light signal with solar rejection ratios (I270 : I350) of over 3 x 10⁵ and dark signals of 300 pA (at a bias of −5V). Spectral responsivities were engineered to fit the “Deutscher Verein des Gas- und Wasserfaches” industry standard form and gave over two decade higher responsivities (14 A/W, peaked at 270 nm) than commercial SiC based devices. Homogeneous Ga₂O₃ layers were also grown on 2 inch diameter c-Al₂O₃ substrates by PLD. Optical transmission spectra were coherent with a bandgap that increased from 4.9 to 5.4 eV when film thickness was decreased from 825 to 145 nm. X-ray diffraction revealed that the films were of the β-Ga₂O₃ (monoclinic) polytype with strong (−201) orientation. β-Ga₂O₃ MSM photodetectors gave over 4 orders of magnitude of separation between dark and light signal (at −5V bias) with dark currents of 250 pA and spectral responsivities of up to 40 A/W (at -0.75V bias). It was found that the spectral responsivity peak position could be decreased from 250 to 230 nm by reducing film thickness from 825 to 145 nm. This shift in peak responsivity wavelength with film thickness (a) was coherent with the apparent bandgap shift that was observed in transmission spectroscopy for the same layers and (b) conveniently provides a coverage of the spectral region in which MgZnO layers show fcc/hcp phase mixing. [reprint (PDF)]
14.	High-performance bias-selectable dual-band mid-/long-wavelength infrared photodetectors and focal plane arrays based on InAs/GaSb Type-II superlattices M. Razeghi; A. Haddadi; A.M. Hoang; G. Chen; S. Ramezani-Darvish; P. Bijjam Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 87040S (June 11, 2013)-- June 11, 2013 ...[Visit Journal] We report a bias selectable dual-band mid-wave infrared (MWIR) and long-wave infrared (LWIR) co-located detector with 3 μm active region thickness per channel that is highly selective and can perform under high operating temperatures for the MWIR band. Under back-side illumination, a temperature evolution study of the MWIR detector's electro-optical performance found the 300 K background-limit with 2π field-of-view to be achieved below operating temperatures of 160 K, at which the temperature's 50% cutoff wavelength was 5.2 μm. The measured current reached the system limit of 0.1 pA at 110 K for 30 μm pixel-sized diodes. At 77 K, where the LWIR channel operated with a 50% cutoff wavelength at 11.2 μm, an LWIR selectivity of ∼17% was achieved in the MWIR wave band between 3 and 4.7 μm, making the detector highly selective. [reprint (PDF)]
14.	Recent advances in antimonide-based gap-engineered Type-II superlattices material system for 2 and 3 colors infrared imagers Manijeh. Razeghi, Abbas Haddadi, Arash Dehzangi, Romain Chevallier, and Thomas Yang Proceedings of SPIE 10177, Infrared Technology and Applications XLIII, 1017705-- May 9, 2017 ...[Visit Journal] InAs/InAs_1-xSb_x/AlAs_1-xSb_x type-II superlattices (T2SLs) is a system of multi-interacting quantum wells. Since its introduction, this material system has drawn a lot of attention especially for infrared detection. In recent years, InAs/InAs_1- xSb_x/AlAs_1-xSb_x T2SL material system has experienced incredible improvements in material quality, device structure designs and device fabrication process which elevated the performances of T2SL-based photodetectors to a comparable level to the state-of-the-art material systems for infrared detection such as Mercury Cadmium Telluride (MCT). In this paper, we will present the current status of InAs/InAs_1-xSb_x/AlAs_1-xSb_x T2SL-based photodetectors for detection in different infrared regions, from short-wavelength (SWIR) to long-wavelength (LWIR) infrared, and the future outlook of this material system. [reprint (PDF)]
14.	Infrared detection from GaInAs/InP nanopillar arrays A. Gin, B. Movaghar, M. Razeghi and G.J. Brown Nanotechnology 16-- July 1, 2005 ...[Visit Journal] We report on the photoresponse from large arrays of 40 nm radius nanopillars with sensitivity in the long-wavelength infrared regime. Using photoluminescence techniques, a peak wavelength blue shift of approximately 5 meV was observed at 30 K from GaInAs/InP nanopillar structures, indicating carrier confinement effects. Responsivity measurements at 30 K indicated peak wavelength response at about 8 µm with responsivity of 420 mA/W at −2 V bias. We have also measured the noise and estimated the peak detectivity to be 3×10⁸ cm·Hz^½·W⁻¹ at 1 V reverse bias and 30 K. A maximum internal quantum efficiency of 4.5% was derived from experiment. Both the photo and the dark transport have been successfully modeled as processes that involve direct and indirect field-assisted tunneling as well as thermionic emission. The best agreement with experiment was obtained when allowances were made for the non-uniformity of barrier widths and electric field heating of carriers above the lattice temperature. [reprint (PDF)]
14.	High power continuous wave operation of single mode quantum cascade lasers up to 5 W spanning λ∼3.8-8.3 µm Quanyong Lu, Steven Slivken, Donghai Wu, and Manijeh Razeghi Optics Express Vol. 28, Issue 10, pp. 15181-15188-- May 4, 2020 ...[Visit Journal] In this work, we report high power continuous wave room-temperature operation single mode quantum cascade lasers in the mid-infrared spectral range from 3.8 to 8.3 µm. Single mode robustness and dynamic range are enhanced by optimizing the distributed feedback grating coupling design and the facet coatings. High power single mode operation is secured by circumventing the over-coupling issue and spatial hole burning effect. Maximum single-facet continuous-wave output power of 5.1 W and wall plug efficiency of 16.6% is achieved at room temperature. Single mode operation with a side mode suppression ratio of 30 dB and single-lobed far field with negligible beam steering is observed. The significantly increased power for single mode emission will boost the QCL applications in long-range free-space communication and remote sensing of hazardous chemicals. [reprint (PDF)]
14.	Low irradiance background limited type-II superlattice MWIR M-barrier imager E.K. Huang, S. Abdollahi Pour, M.A. Hoang, A. Haddadi, M. Razeghi and M.Z. Tidrow OSA Optics Letters (OL), Vol. 37, No. 11, p. 2025-2027-- June 1, 2012 ...[Visit Journal] We report a type-II superlattice mid-wave infrared 320 × 256 imager at 81 K with the M-barrier design that achieved background limited performance (BLIP) and ∼99%operability. The 280 K blackbody’s photon irradiance was limited by an aperture and a band-pass filter from 3.6 μm to 3.8 μm resulting in a total flux of ∼5 × 10¹² ph·cm⁻²·s⁻¹. Under these low-light conditions, and consequently the use of a 13.5 ms integration time, the imager was observed to be BLIP thanks to a ∼5 pA dark current from the 27 μm wide pixels. The total noise was dominated by the photon flux and read-out circuit which gave the imager a noise equivalent input of ∼5 × 10¹⁰ ph·cm⁻²·s⁻¹ and temperature sensitivity of 9 mK with F∕2.3 optics. Excellent imagery obtained using a 1-point correction alludes to the array’s uniform responsivity. [reprint (PDF)]
14.	First observation of the quantum Hall effect in a Ga0.47In0.53As‐InP heterostructure with three electric subbands M. Razeghi; J. P. Duchemin; J. C. Portal; L. Dmowski; G. Remeni; R. J. Nicholas; A. Briggs M. Razeghi, J. P. Duchemin, J. C. Portal, L. Dmowski, G. Remeni, R. J. Nicholas, A. Briggs; First observation of the quantum Hall effect in a Ga0.47In0.53As‐InP heterostructure with three electric subbands. Appl. Phys. Lett. 17 March 1986; 48 (11)-- March 17, 1986 ...[Visit Journal] Shubnikov–de Haas and quantum Hall effects have been studied in GaInAs‐InP heterojunctions grown by modified low pressure metalorganic chemical vapor deposition. In contrast to the results reported up till now on GaInAs‐InP heterojunctions with nearly the same channel electron density, not one but three electric subbands, E0, E1, and E2, are occupied in zero magnetic field. Two electric subbands E0 and E1 contribute to the quantum Hall effect. Magnetic depopulation of the higher (E1 and E2) subbands is observed in both perpendicular and tilted magnetic field orientations. This enables a demonstration of the importance of intersubband scattering in resistivity and cyclotron resonance. [reprint (PDF)]
14.	ZnO 3D flower-like nanostructure synthesized on GaN epitaxial layer by simple route hydrothermal process J.M. Jung, C.R. Kim, H. Ryu, M. Razeghi and W.G. Jung Journal of Alloys and Compounds-- September 15, 2007 ...[Visit Journal] The 3D type, flower-like ZnO nanostructures from particle to flower-like or chestnut bur are fabricated on the GaN epitaxial layer substrate through the simple-route hydrothermal process. Structural characterization was made for the ZnO 3D nanostructures synthesized in different pH ranging from 9.5 to 11.0. The growth model was proposed and discussed regarding the fabrication mechanism and morphology of ZnO 3D flower-like nanostructure. The flower-like ZnO is composed of many thin single crystals ZnO nanorods. Bigger and thicker ZnO structure is fabricated with the increase of pH in solution. The enhanced UV emission in the PL measurement and the spectra in the Raman spectroscopy for ZnO–GaN heterojunction material were discussed. [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.	AlGaN ultraviolet detectors M. Razeghi and A. Rogalski, SPIE Conference, San Jose, CA, -- February 12, 1997 ...[Visit Journal] Hitherto, the semiconductor ultraviolet (UV) detectors have been mainly fabricated using Si. Industries such as the aerospace, automotive, petroleum, and others have continuously provided the impetus pushing the development of fringe technologies which are tolerant of increasingly high temperatures and hostile environments. As a result, the main efforts are currently directed to anew generation of UV detectors fabricated from wide-band-gap semiconductors between them the most promising are diamond and AlGaN. The latest progress in development of AlGaN UV detectors is described in detail. [reprint (PDF)]
14.	Electroluminescence at 375 nm from a Zn0/GaN:Mg/c-Al₂O₃ heterojunction light emitting diodes D.J. Rogers, F.Hosseini Teherani, A. Yasan, K. Minder, P. Kung, and M. Razeghi Applied Physics Letters, 88 (14)-- April 13, 2006 ...[Visit Journal] n-ZnO/p-GaN:Mg heterojunction light emitting diode (LED) mesas were fabricated on c-Al₂O₃ substrates using pulsed laser deposition for the ZnO and metal organic chemical vapor deposition for the GaN:Mg. Room temperature (RT) photoluminescence (PL) showed an intense main peak at 375 nm and a negligibly low green emission indicative of a near band edge excitonic emission from a ZnO layer with low dislocation/defect density. The LEDs showed I-V characteristics confirming a rectifying diode behavior and a RT electroluminescence (EL) peaked at about 375 nm. [reprint (PDF)]

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