Center for Quantum Devices - Most Downloaded Journal Articles

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9.	Type-II superlattice photodetectors for MWIR to VLWIR focal plane arrays M. Razeghi, Y. Wei, A. Hood, D. Hoffman, B.M. Nguyen, P.Y. Delaunay, E. Michel and R. McClintock SPIE Infrared Technology and Applications Conference, April 17-21, 2006, Orlando, FL Proceedings – Infrared Technology and Applications XXXII, Vol. 6206, p. 62060N-1-- April 21, 2006 ...[Visit Journal] Results obtained on GaSb/InAs Type-II superlattices have shown performance comparable to HgCdTe detectors, with the promise of higher performance due to reduced Auger recombination and dark current through improvements in device design and material quality. In this paper, we discuss advancements in Type-II IR sensors that cover the 3 to > 30 µm wavelength range. Specific topics covered will be device design and modeling using the Empirical Tight Binding Method (ETBM), material growth and characterization, device fabrication and testing, as well as focal plane array processing and imaging. Imaging has been demonstrated at room temperature for the first time with a 5 µm cutoff wavelength 256×256 focal plane array. [reprint (PDF)]
9.	Quntum Cascade Laser Breakthrough for Advanced Remote Detection Manijeh Razeghi, Wenjia Zhou, Donghai Wu, Ryan McClintock, and Steven Slivken Photonics Spectra, November issue-- November 1, 2016 ...[Visit Journal] The atoms in a molecule can bend, stretch and rotate with respect to one another, and these excitations are largely optically active. Most molecules, from simple to moderately complex, have a characteristic absorption spectrum in the 3- to 14-µrn wavelength range that can be uniquely identified and quantified in real time. Infrared spectroscopy has been used to study these absorption features and develop different molecular "fingerprints."
9.	High performance long wavelength infrared mega-pixel focal plane array based on type-II superlattices P. Manurkar, S.R. Darvish, B.M. Nguyen, M. Razeghi and J. Hubbs Applied Physics Letters, Vol. 97, No 19, p. 193505-1-- November 8, 2010 ...[Visit Journal] A large format 1k × 1k focal plane array (FPA) is realized using type-II superlattice photodiodes for long wavelength infrared detection. Material growth on a 3 in. GaSb substrate exhibits a 50% cutoff wavelength of 11 μm across the entire wafer. The FPA shows excellent imaging. Noise equivalent temperature differences of 23.6 mK at 81 K and 22.5 mK at 68 K are achieved with an integration time of 0.13 ms, a 300 K background and f/4 optics. We report a dark current density of 3.3×10⁻⁴ A·cm⁻² and differential resistance-area product at zero bias R₀A of 166 Ω·cm² at 81 K, and 5.1×10⁻⁵ A·cm⁻² and 1286 Ω·cm², respectively, at 68 K. The quantum efficiency obtained is 78%. [reprint (PDF)]
9.	Quantum Hall effect in In0.53Ga0.47As-InP heterojunctions with two populated electric subbands Y. Guldner, J. P. Vieren, and M. Voos F. Delahaye and D. Dominguez J. P. Hirtz and M. Razeghi Phys. Rev. B 33, 3990 1986-- March 15, 1986 ...[Visit Journal] Quantum-Hall-effect and Shubnikov–de Haas measurements are presented for InxGa1−xAs?(hyInP heterojunctions with two populated electric subbands and low electron density (𝑛𝑠≤5×1011 cm−2). The Shubnikov–de Haas oscillations clearly show two different periodicities. An anomalous behavior of the quantum Hall effect is observed, in particular some plateaus are missing and other plateaus are enhanced. Precise measurements of the Hall resistance have been performed and it is shown that the resistance of the i=2 plateau is equal to its theoretical value h/2𝑒2 with an uncertainty of ∼10−8. [reprint (PDF)]
8.	Breakthroughs Bring THz Spectroscopy, Sensing Closer to Mainstream Manijeh Razeghi, Quanyong Lu, Santanu Manna, Donghai Wu & Steven Slivken Photnics Spectra, December Issue, pp. 48-- December 1, 2016 ...[Visit Journal] The terahertz (THz) electromagnetic spectrum (1 to 10 THz), sitting between the infrared wavelengths on the higher frequency side and microwaves on the lower frequency side, lies unique and important properties. THz waves can pass through a number of materials, including synthetics, textiles, paper and cardboard. Many biomolecules, proteins, explosives or narcotics feature characteristic absorption I ines - so-called spectral "fingerprints" - at frequencies between 1 and 10 THz.
8.	III-Nitride/Ga2O3 heterostructure for future power electronics: opportunity and challenges Nirajman Shrestha, Jun Hee Lee, F. H. Teherani, Manijeh Razeghi Proc. of SPIE Vol. 12895, Quantum Sensing and Nano Electronics and Photonics XX, 128950B (28 January - 1 February 2024, San Francisco)http://dx.doi.org/10.1117/12.3011688 ...[Visit Journal] Ga2O3 has become the new focal point of high-power semiconductor device research due to its superior capability to handle high voltages in smaller dimensions and with higher efficiencies compared to other commercialized semiconductors. However, the low thermal conductivity of the material is expected to limit device performance. To compensate for the low thermal conductivity of Ga2O3 and to achieve a very high density 2-dimensional electron gas (2DEG), an innovative idea is to combine Ga2O3 with III-Nitrides (which have higher thermal conductivity), such as AlN. However, metal-polar AlN/β-Ga2O3 heterojunction provides type-II heterojunction which are beneficial for optoelectronic application, because of the negative value of specific charge density. On the other hand, N-polar AlN/β- Ga2O3 heterostructures provide higher 2DEG concentration and larger breakdown voltage compared to conventional AlGaN/GaN devices. This advancement would allow the demonstration of RF power transistors with a 10x increase in power density compared to today’s State of the Art (SoA) and provide a solution to size, weight, and power-constrained applications [reprint (PDF)]
8.	Low pressure metalorganic chemical vapor deposition of InP and related compounds M. Razeghi, M. A. Poisson, J. P. Larivain & J. P. Duchemin Razeghi, M., Poisson, M.A., Larivain, J.P. et al. Low pressure metalorganic chemical vapor deposition of InP and related compounds. J. Electron. Mater. 12, 371–395 (1983). https://doi.org/10.1007/BF02651138-- March 1, 1983 ...[Visit Journal] The low pressure metalorganic chemical vapor deposition epitaxial growth and characterization of InP, Ga0.47In0.53 As and GaxIn1-xAsyP1-y, lattice-matched to InP substrate are described. The layers were found to have the same etch pit density (EPD) as the substrate. The best mobility obtained for InP was 5300 cm2 V−1S−1 at 300 K and 58 900 cm2 V−1 S−1 at 772K, and for GaInAs was 11900 cm2 V−1 S−1 at 300 K, 54 600 cm2 V−1 S−1 at 77 K and 90 000 cm V−1S−1 at 2°K. We report the first successful growth of a GaInAs-InP superlattice and the enhanced mobility of a two dimensional electron gas at a GaInAs -InP heterojunction grown by LP-MO CVD. LP MO CVD material has been used for GaInAsPInP, DH lasers emitting at 1.3 um and 1.5 um. These devices exhibit a low threshold current, a slightly higher than liquid phase epitaxy devices and a high differential quantum efficiency of 60%. Fundamental transverse mode oscillation has been achieved up to a power outpout of 10 mW. Threshold currents as low as 200 mA dc have been measured for devices with a stripe width of 9 um and a cavity length of 300 um for emission at 1.5 um. Values of T in the range 64–80 C have been obtained. Preliminary life testing has been carried out at room temperature on a few laser diodes (λ = 1.5μm). Operation at constant current for severalthousand hours has been achieved with no change in the threshold current. [reprint (PDF)]
8.	Near milliwatt power AlGaN-based ultraviolet light emitting diodes based on lateral epitaxial overgrowth of AlN on Si(111) Y. Zhang, S. Gautier, C. Cho, E. Cicek, Z, Vashaei, R. McClintock, C. Bayram, Y. Bai and M. Razeghi Applied Physics Letters, Vol. 102, No. 1, p. 011106-1-- January 7, 2013 ...[Visit Journal] We report on the growth, fabrication, and device characterization of AlGaN-based thin-film ultraviolet (UV) (λ ∼ 359 nm) light emitting diodes (LEDs). First, AlN/Si(111) template is patterned. Then, a fully coalesced 7-μm-thick lateral epitaxial overgrowth (LEO) of AlN layer is realized on patterned AlN/Si(111) template followed by UV LED epi-regrowth. Metalorganic chemical vapor deposition is employed to optimize LEO AlN and UV LED epitaxy. Back-emission UV LEDs are fabricated and flip-chip bonded to AlN heat sinks followed by Si(111) substrate removal. A peak pulsed power and slope efficiency of ∼0.6 mW and ∼1.3 μW/mA are demonstrated from these thin-film UV LEDs, respectively. For comparison, top-emission UV LEDs are fabricated and back-emission LEDs are shown to extract 50% more light than top-emission ones. [reprint (PDF)]
8.	High-performance InP-based midinfrared quantum cascade lasers at Northwestern University M. Razeghi, Y. Bai, S. Slivken, and S.R. Darvish SPIE Optical Engineering, Vol. 49, No. 11, November 2010, p. 111103-1-- November 15, 2010 ...[Visit Journal] We present recent performance highlights of midinfrared quantum cascade lasers (QCLs) based on an InP material system. At a representative wavelength around 4.7 µm, a number of breakthroughs have been achieved with concentrated effort. These breakthroughs include watt-level continuous wave operation at room temperature, greater than 50% peak wall plug efficiency at low temperatures, 100-W-level pulsed mode operation at room temperature, and 10-W-level pulsed mode operation of photonic crystal distributed feedback quantum cascade lasers at room temperature. Since the QCL technology is wavelength adaptive in nature, these demonstrations promise significant room for improvement across a wide range of mid-IR wavelengths. [reprint (PDF)]
8.	Transport and photodetection in self-assembled semiconductor quantum dots M Razeghi, H Lim, S Tsao, J Szafraniec, W Zhang, K Mi and B Movaghar Nanotechnology 16 219-- January 7, 2005 ...[Visit Journal] A great step forward in science and technology was made when it was discovered that lattice mismatch can be used to grow highly ordered, artificial atom-like structures called self-assembled quantum dots. Several groups have in the meantime successfully demonstrated useful infrared photodetection devices which are based on this technology. The new physics is fascinating, and there is no doubt that many new applications will be found when we have developed a better understanding of the underlying physical processes, and in particular when we have learned how to integrate the exciting new developments made in nanoscopic addressing and molecular self-assembly methods with semiconducting dots. In this paper we examine the scientific and technical questions encountered in current state of the art infrared detector technology and suggest ways of overcoming these difficulties. Promoting simple physical pictures, we focus in particular on the problem of high temperature detector operation and discuss the origin of dark current, noise, and photoresponse. [reprint (PDF)]
8.	Surface leakage investigation via gated type-II InAs/GaSb long-wavelength infrared photodetectors G. Chen, E.K. Huang, A.M. Hoang, S. Bogdanov, S.R. Darvish, and M. Razeghi Applied Physics Letters, Vol. 101, No. 21, p. 213501-1-- November 19, 2012 ...[Visit Journal] By using gating technique, surface leakage generated by SiO₂ passivation in long-wavelength infrared type-II superlattice photodetector is suppressed, and different surface leakage mechanisms are disclosed. By reducing the SiO₂ passivation layer thickness, the saturated gated bias is reduced to −4.5 V. At 77 K, dark current densities of gated devices are reduced by more than 2 orders of magnitude, with 3071 Ω·cm² differential-resistance-area product at −100 mV. With quantum efficiency of 50%, the 11 μm 50% cut-off gated photodiode has a specific detectivity of 7 × 10¹¹ Jones, and the detectivity stays above 2 × 10¹¹ Jones from 0 to −500 mV operation bias. [reprint (PDF)]
7.	Deep ultraviolet (254 nm) focal plane array E. Cicek, Z. Vashaei, R. McClintock, and M. Razeghi SPIE Proceedings, Conference on Infrared Sensors, Devices and Applications; and Single Photon Imaging II, Vol. 8155, p. 81551O-1-- August 21, 2011 ...[Visit Journal] We report the synthesis, fabrication and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, Al_xGa_1-xN-based detectors, fully realized within our research laboratory. We implemented a novel pulsed atomic layer deposition technique for the metalorganic chemical vapor deposition (MOCVD) growth of crackfree, thick, and high Al composition Al_xGa_1-xN layers. Following the growth, the wafer was processed into a 320 × 256 array of 25 μm × 25 μm pixels on a 30 μm pixel-pitch and surrounding mini-arrays. A diagnostic mini-array was hybridized to a silicon fan-out chip to allow the study of electrical and optical characteristics of discrete pixels of the FPA. At a reverse bias of 1 V, an average photodetector exhibited a low dark current density of 1.12×10^-8 A·cm^-2. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower and falling off three orders of magnitude by 285 nm. After indium bump deposition and dicing, the FPA is hybridized to a matching ISC 9809 readout integrated circuit (ROIC). By developing a novel masking technology, we significantly reduced the visible response of the ROIC and thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allowed the FPA to achieve high external quantum efficiency (EQE): at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated. [reprint (PDF)]
7.	Room Temperature Epitaxy of Ni1−xMgxO on c Plane Sapphire by Plasma Assisted Pulsed Laser Deposition David J. Rogers, Eric V. Sandana, Ferechteh H. Teherani, M. Razeghi physica status solidi (b) 2026, 263 (7), e202500648. ...[Visit Journal] This paper reports on room-temperature (RT) epitaxial growth of NiO and Ni1-xMgxO (x ≈ 0.50) thin films on c-plane sapphire (0001) using plasma-assisted pulsed laser deposition. Optical transmission reveals absorption edges at ~3.6 eV (NiO) and ~4.4 eV (Ni0.5Mg0.50O), confirming bandgap engineering via Mg incorporation consistent with prior alloy data. X-ray reflectivity (XRR) indicates smooth surfaces and thicknesses of ~60 nm (NiO) and ~65 nm (Ni0.5Mg0.50O). High-resolution X-ray diffraction 2θ/ω scans indicate fcc (111) orientation for both films; ω-rocking curves exhibit full width half maxima of 0.07°—remarkably low mosaic spread for RT-grown oxides. (002) pole figures display six-fold symmetry, evidencing epitaxial relationships featuring two rotational domains (±60°) about [111] on c-sapphire. AFM (1 µm × 1 µm) yields root mean square roughness of ~0.5 nm (NiO) and ~2.6 nm (Ni0.5Mg0.50O). Four-point probe gives ρ ≈ 26 Ω·cm (NiO) and insulating behavior for Ni0.5Mg0.50O, consistent with bandgap widening and reduced hole concentration. These results establish RT epitaxial Mg-alloyed NiO with exceptional crystallinity, directly relevant to Ga2O3 heterojunctions for power electronics and solar-blind ultra violet C-band photodetectors, where tunable band alignment and sharp interfaces are critical. [reprint (PDF)]
6.	Strain-Induced Metastable Phase Stabilization in Ga₂O₃ Thin Films Yaobin Xu, Ji-hyeon Park, Zhenpeng Yao, Christopher Wolverton, Manijeh Razeghi, Jinsong Wu, and Vinayak P. Dravid Acs Appl Mater Inter 11 (5), 5536 (2019)-- January 10, 2019 ...[Visit Journal] It is well known that metastable and transient structures in bulk can be stabilized in thin films via epitaxial strain (heteroepitaxy) and appropriate growth conditions that are often far from equilibrium. However, the mechanism of heteroepitaxy, particularly how the nominally unstable or metastable phase gets stabilized, remains largely unclear. This is especially intriguing for thin film Ga₂O₃, where multiple crystal phases may exist under varied growth conditions with spatial and dimensional constraints. Herein, the development and distribution of epitaxial strain at the Ga₂O₃/Al₂O₃ film-substrate interfaces is revealed down to the atomic resolution along different orientations, with an aberration-corrected scanning transmission electron microscope (STEM). Just a few layers of metastable α-Ga₂O₃ structure were found to accommodate the misfit strain in direct contact with the substrate. Following an epitaxial α-Ga₂O₃ structure of about couple unit cells, several layers (4~5) of transient phase appear as the intermediate structure to release the misfit strain. Subsequent to this transient crystal phase, the nominally unstable κ-Ga₂O₃ phase is stabilized as the major thin film phase form. We show that the epitaxial strain is gracefully accommodated by rearrangement of the oxygen polyhedra. When the structure is under large compressive strain, Ga3+ ions occupy only the oxygen octahedral sites to form a dense structure. With gradual release of the compressive strain, more and more Ga3+ ions occupy the oxygen tetrahedral sites, leading to volumetric expansion and the phase transformation. The structure of the transition phase is identified by high resolution electron microscopy (HREM) observation, complemented by the density functional theory (DFT) calculations. This study provides insights from the atomic scale and their implications for the design of functional thin film materials using epitaxial engineering.
6.	Unleashing light: a deep dive into quantum cascade laser dynamics through power, precision, and performance Xiaohan Yu, Yanbo Bai, Feihu Wang, Steve Slivken, Nirajman Shrestha, Ruiming Zhang, Nil Ozcevik, Manijeh Razeghi Proc. SPIE 13908, Quantum Sensing and Nano Electronics and Photonics XXII, 139080U (20 March 2026); https://doi.org/10.1117/12.3082051 ...[Visit Journal] In this study, we explore the complex interplay of structural design and performance metrics in InGaAs/InAlAs/InP ridge waveguide quantum cascade lasers (QCLs) by combining theoretical modeling with rigorous experimental validation. By assuming mirror loss corresponding to a facet reflectivity of R = 0.275, which represents the Fresnel reflectance of uncoated InP facets, we investigated the impact of cavity length on threshold current density and slope efficiency by analyzing Power–Current–Voltage (PIV) characteristics of uncoated QCLs with lengths of 3mm, 4mm, and 5mm. Slope efficiencies were extracted and corrected for single-facet detection. By leveraging fitting techniques across multiple datasets and laser structure, we quantified internal and external quantum efficiencies and determined the transparency current density using graphical and analytical methods. A linear regression of inverse external efficiency versus inverse mirror loss enabled estimation of the internal quantum efficiency, highlighting the direct influence of fabrication parameters on laser output. With a linear fit of threshold current density versus mirror loss, the transparency current density was calculated. This work not only reinforces foundational laser physics principles but also provides a hands-on methodology for analyzing active device parameters with practical implications in tunable mid-infrared sources, spectroscopy, and optical sensing. [reprint (PDF)]
5.	InAs/InAs_1-XSb_x Type-II Superlattices for High-Performance Long-Wavelength Infrared Medical Thermography Manijeh Razeghi, Abbas Haddadi, Guanxi Chen, Romain Chevallier and Ahn Minh Hoang ECS Trans. 2015 66(7): 109-116-- June 1, 2015 ...[Visit Journal] We present the demonstration of a high-performance long-wavelength infrared nBn photodetectors based on InAs/InAs_1-xSb_x type-II superlattices on GaSb substrate. The photodetector’s 50% cut-off wavelength was ~10 μm at 77K. The photodetector with a 6 μm-thick absorption region exhibited a peak responsivity of 4.47 A/W at 7.9 μm, corresponding to a quantum efficiency of 54% at -90 mV applied bias voltage under front-side illumination and without any anti-reflection coating. With an R×A of 119 Ω·cm² and a dark current density of 4.4×10^-4 A/cm² under -90 mV applied bias voltage at 77 K, the photodetector exhibited a specific detectivity of 2.8×10¹¹ Jones. This photodetector opens a new horizon for making infrared imagers with higher sensitivity for medical thermography.
5.	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.
5.	Improved performance of quantum cascade lasers through a scalable, manufacturable epitaxial-side-down mounting process A. Tsekoun, R. Go, M. Pushkarsky, M. Razeghi, and C. Kumar N. Patel Proceedings of the National Academy of Sciences 103 (13)-- March 26, 2006 ...[Visit Journal] We report substantially improved performance of high-power quantum cascade lasers (QCLs) by using epitaxial-side-down mounting that provides superior heat dissipation properties. We used aluminum nitride as the heatsink material and gold–tin eutectic solder. We have obtained continuous wave power output of 450 mW at 20°C from mid-IR QCLs. The improved thermal management achieved with epitaxial-side-down mounting combined with a highly manufacturable and scalable assembly process should permit incorporation of mid-IR QCLs in reliable instrumentation.
5.	Engineering the Fermi Level in NiO Thin Films D. Rogers, E. Sandana, M. Chamberlin, F. Teherani; V. Safarov, M. Konczykowski, R. Grasset, A. Alessi, H. Drouhin ; M. Razeghi SPIE OPTO PC13897 (2026) ...[Visit Journal] We investigate practical routes to engineer the Fermi level—and thus the effective work function—of p-type nickel oxide (NiO) thin films grown on c-sapphire by plasma-assisted pulsed laser deposition (PA-PLD) at room temperature (RT). We examine three levers: (i) oxygen-rich growth at low substrate temperature, (ii) post-deposition annealing in air or oxygen across 320–620 °C, and (iii) impurity (Li) acceptor doping. RT-grown NiO exhibits high crystalline quality with (111) out-of-plane orientation, narrow rocking-curve width, and a film thickness near 60 nm. RT epitaxy yields the lowest resistivity among the studied conditions, and resistance increases progressively with temperature for iso-chronic post-annealing in air. Oxygen ambient post-annealing shows no distinctive monotonic trend in resistivity, although the conductivity falls off for annealing over about 500°C. Optical transmission spectra suggest progressive healing of in-gap defect states with post-annealing temperature. Doping NiO with 20at% of Li lowers resistivity relative to undoped NiO by an order of magnitude. Post-annealing at 300°C under oxygen ambient significantly boosts conductivity. Over a decade of storage, all films exhibited significant loss of conductivity, underscoring the need for stabilisation strategies. The results map practical processing windows to tune the NiO Fermi level for integration in oxide heterojunctions (e.g., p-NiO/n-Ga2O3) used in ultraviolet detection and wide-bandgap electronics. [reprint (PDF)]
5.	An accurate method to check chemical interfaces of epitaxial III‐V compounds R. Bisaro; G. Laurencin; A. Friederich; M. Razeghi Appl. Phys. Lett. 40 (11): 978–980 (1982)-- June 1, 1982 ...[Visit Journal] We have developed a method of chemical beveling coupled with line scan Auger measurements to check abrupt interfaces of epitaxial III‐V compounds. Interface widths between 53 and 89 Å have been measured by this method for an InP/Ga0.47In0.53As/InP double heterostructure grown by low pressure metalorganic chemical vapor deposition. The ultimate width checkable by this method lies between 10 and 15 Å and is of the order of magnitude of the escape depth of the Auger electrons selected. [reprint (PDF)]
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5.	Midinfrared Semiconductor Photonics – A Roadmap:Quantum Cascade Lasers MANIJEH RAZEGHI arXiv:2511.03868 [physics.optics] ...[Visit Journal] Mid-wave infrared (IR) quantum cascade lasers (QCLs) offer high output power, excellent efficiency, broad wavelength tunability, and elevated operating temperatures, especially when operating in the 3–12 μm wavelength range. These characteristics make them highly promising for a wide range of applications, including high-resolution molecular spectroscopy, ultra-low-loss optical fiber communications using fluoride-based glasses (with attenuation below 2.5×10⁻⁴ dB/km), trace gas detection, air pollution monitoring (as many molecules, particularly hydrocarbons, exhibiting strong absorption lines in this spectral region), and medical diagnostics. This article presents a comprehensive overview of the development of QCLs, highlighting key milestones, the current state of the technology, and future directions, framed within the broader context of the Semiconductor Mid-Infrared Photonics Roadmap.
4.	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.
4.	Nitrides push performance of UV photodiodes Can Bayram; Manijeh Razeghi Laser Focus World. 45(9), pp. 47-51 (2009)-- September 1, 2009 ...[Visit Journal] The nitrides are known to be useful for creating the UV single-photon detectors with efficiencies of 20%, with its considerable advantages that could further enable quantum computing and data encryption. Such detectors would be well suited for numerous applications in the defense, commercial, and scientific arenas, including covert space-to-space communications, early missile-threat detection, chemical and biological threat detection and spectroscopy. The use of SAM regions is a common approach to reducing multiplication noise and enhancing gain through impact-ionization engineering that could benefit from the higher ionization coefficient by offering lower noise performance and higher gain. The ADPs also enables the realization of single-photon detection by using Geiger-mode operation, which entails operating the ADPs well above the breakdown voltage and using pulse-quenching circuitry.

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