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Sample records for multilayer optical thin

  1. Optical Characterization of Multilayer Thin Film Cu_xIn_2-xSe_2^*

    NASA Astrophysics Data System (ADS)

    Raffaelle, R. P.; Friedfeld, R.; Mantovani, J. G.

    1996-03-01

    Cu_xIn_2-xSe2 is one of the most promising thin film solar cell materials, due to its ideal optical and electrical properties. We have been electrochemically depositing multilayer structures based on the Cu_xIn_2-xSe2 system. The interest in multilayer structures is due to their proposed use in increasing thin film solar cell efficiency. A comparison of the multilayers to ordinary bulk films is made using optical spectroscopy. The optical band gaps for these nanoscale layered films is determined as a function of their modulation wavelengths and compared to theoretical predictions. * This work was supported by the Southeastern University Research Association in collaboration with Oak Ridge National Laboratory and the Florida Solar Energy Center.

  2. Magneto-optical and magnetic properties in a Co/Pd multilayered thin film

    NASA Astrophysics Data System (ADS)

    Nwokoye, Chidubem A.; Bennett, Lawrence H.; Della Torre, Edward; Ghahremani, Mohammadreza; Narducci, Frank A.

    2017-01-01

    The paper describes investigation of ferromagnetism at low temperatures. We explored the magneto-optical properties, influenced by photon-magnon interactions, of a ferromagnetic Co/Pd multilayered thin film below and above the magnon Bose-Einstein Condensation (BEC) temperature. Analyses of SQUID and MOKE low temperature experimental results reveal a noticeable phase transition in both magnetic and magneto-optical properties of the material at the BEC temperature.

  3. Extremely high rate deposition of polymer multilayer optical thin film materials

    SciTech Connect

    Affinito, J.D.

    1993-01-01

    This paper highlights a new technique for extremely high rate deposition of optical dielectric films (vacuum deposition of polymer multilayer thin films). This is a way to produce multilayer optical filters comprised of thousands of layers of either linear or nonlinear optical materials. The technique involves the flash evaporation of an acrylic monomer onto a moving substrate; the monomer is then cured. Acrylic polymers deposited to date are very clear for wavelengths between 0.35 and 2.5 [mu]m; they have extinction coefficients of k[approx]10[sup [minus]7]. Application of electric field during cross linking can polarize (''pole'') the film to greatly enhance the nonlinear optical properties. ''Poling'' films with the polymer multilayer technique offers advantages over conventional approaches, in that the polarization should not decay over time. Battelle's Pacific Northwest Laboratory is well suited for bringing linear and nonlinear polymer multilayer optical filter technology to manufacturing production status for batch and wide area web applications. 10 figs.

  4. Extremely high rate deposition of polymer multilayer optical thin film materials

    SciTech Connect

    Affinito, J.D.

    1993-03-01

    This paper highlights a new technique for extremely high rate deposition of optical dielectric films (vacuum deposition of polymer multilayer thin films). This is a way to produce multilayer optical filters comprised of thousands of layers of either linear or nonlinear optical materials. The technique involves the flash evaporation of an acrylic monomer onto a moving substrate; the monomer is then cured. Acrylic polymers deposited to date are very clear for wavelengths between 0.35 and 2.5 {mu}m; they have extinction coefficients of k{approx}10{sup {minus}7}. Application of electric field during cross linking can polarize (``pole``) the film to greatly enhance the nonlinear optical properties. ``Poling`` films with the polymer multilayer technique offers advantages over conventional approaches, in that the polarization should not decay over time. Battelle`s Pacific Northwest Laboratory is well suited for bringing linear and nonlinear polymer multilayer optical filter technology to manufacturing production status for batch and wide area web applications. 10 figs.

  5. Porphyrin Molecular Multilayer Thin-Films on Gold (111) Electrodes for Electro-optical Applications

    NASA Astrophysics Data System (ADS)

    Krawicz, Alexandra; Qian, Guoguang; Lewis, Kim; Dinolfo, Peter

    2012-02-01

    We have developed a Layer-by-Layer (LbL) method for the fabrication of thin-film molecular multilayers on gold (111) electrodes. Copper(I) catalyzed azide-alkyne cycloaddition (CuAAC) coupling reactions were used for surface attachment and subsequent LbL deposition of porphyrin building blocks. The electrochemical and photophysical properties of the thin-films can be tuned through synthetic modification of the individual components, resulting in new porphyrin multilayers for applications in light harvesting and molecular electronics. Herein, we demonstrate the reproducible growth trends and optical properties of these films. Multilayer growth was followed by UV-Vis absorption and reflectance spectroscopy. Film thickness (FT) and optical constants were obtained from spectroscopic ellipsometry. Topology and surface roughness was examined by TM-AFM, while the copper content was quantified by XPS. The redox characteristics were studied by electrochemical methods, whereas the conductance of individual porphyrin constructs was examined by STM using the molecular break junction method. The multilayers show consistent linear growth in absorbance and FT over tens of layers and continuity in their molecular structure.

  6. Methanol selective fibre-optic gas sensor with a nanoporous thin film of organic-inorganic hybrid multilayers

    NASA Astrophysics Data System (ADS)

    Wang, T.; Okuda, H.; Lee, S.-W.

    2015-07-01

    The development of an evanescent wave optical fibre (EWOF) sensor modified with an organic-inorganic hybrid nanoporous thin film for alcohol vapor detection was demonstrated. The optical fibre with a core diameter of 200 μm was bent into U-shape probe optic fibre to enhance the penetation depth of light transferred into the evanescent filed. The bended region of the fibre was modified with a multilayered thin film of poly(allyamine hydrochloride) and silica nanoparticels, (PAH/SiO2)n, by a layer-by-layer (LbL) film deposition technique, followed by infusion of tetrakis(4- sulfophenyl)porphine, TPPS. The mesoporous film structure showed high sensitivity and selectivity to methanol by the aid of the TPPS infused inside the film. The optical sensor response was reversible and reproducible over many times of exposures to analytes, which was caused by the change in refractive index (RI) of the film.

  7. Investigation of non-quarter wave design on multilayer optical thin film coatings from a heat transfer point of view

    NASA Astrophysics Data System (ADS)

    Ocak, Mustafa; Sert, Cüneyt; Okutucu, Tuba Ö.

    2013-11-01

    In this study multilayer thin film optical coatings, which are indispensable parts of optical systems are investigated from a heat transfer point of view. Laser irradiation induced temperature distribution on a multilayer coating stack is obtained by discretizing the heat diffusion equation using the finite volume method. In order to obtain mathematical representation of the energy flow and Electric Field Intensity (EFI) through the stack, Maxwell equations are solved by using the commercial software MacLeod®. Laser energy, which is absorbed by the multilayer stack in terms of heat, is calculated as a function of space and time by using the computed EFI, coating materials' optical properties and Gaussian laser beam parameters. Computed heat load is used in the finite volume solver ANSYS FLUENT® through a user defined function. Temperature distribution on a 19 layer HR multilayer coating stack irradiated by 1064 nm laser beam are obtained for both quarter wave and non-quarter wave designed configurations. Results of numerical simulations show that maximum temperature rise is seen in the first high index layer for quarter wave design (QWD). In addition to that, high temperatures are also seen in film/film interfaces, which is associated to both EFI distribution on the stack and wide differences in material properties between high and low index film layers. Non-quarter wave design (NQWD) is seen to be successful in decreasing temperatures at high index layers and at film/film interfaces. But it also changes the EFI distribution inside the multilayer stack, increasing absorbed laser energy and resulting in higher temperatures at modified low index layers.

  8. Applications of thin-film multilayered structures to figured X-ray optics; Proceedings of the Meeting, San Diego, CA, August 20-22, 1985. Volume 563

    SciTech Connect

    Marshall, G.F.

    1985-01-01

    Papers are presented on a sputter deposition system for controlled fabrication of multilayers, space qualification of multilayered optics, the development of single and multilayered Wolter X-ray microscopes, and an X-ray microscope using multilayer optics with a laser-produced plasma source. Also considered are multilayer mirrors as X-ray filters for slit scan radiography, a structural study of multiayered vanadium/nickel superlattices, synchrotron based measurements of the soft X-ray performance of thin film multilayer structures, and measurement of multilayer mirror reflectivity and stimulated emission in the XUV spectral region. Other topics include the construction of a multilayered telescope for solar coronal studies from space, layered synthetic microstructures for solar EUV telescopes, multilayers on flexible mica, and LSM-based X-ray diagnostics for magnetic fusion energy applications. Papers are also presented on multilayer structures for X-ray laser cavities, layered synthetic microstructures for long wavelength X-ray spectrometry, the performance of an LSM spectrogoniometer for characteristic X-ray lines, and measurements of surface roughness transducers at angstrom levels using X-ray interferometry.

  9. Optical bandgap of single- and multi-layered amorphous germanium ultra-thin films

    SciTech Connect

    Liu, Pei; Zaslavsky, Alexander; Longo, Paolo; Pacifici, Domenico

    2016-01-07

    Accurate optical methods are required to determine the energy bandgap of amorphous semiconductors and elucidate the role of quantum confinement in nanometer-scale, ultra-thin absorbing layers. Here, we provide a critical comparison between well-established methods that are generally employed to determine the optical bandgap of thin-film amorphous semiconductors, starting from normal-incidence reflectance and transmittance measurements. First, we demonstrate that a more accurate estimate of the optical bandgap can be achieved by using a multiple-reflection interference model. We show that this model generates more reliable results compared to the widely accepted single-pass absorption method. Second, we compare two most representative methods (Tauc and Cody plots) that are extensively used to determine the optical bandgap of thin-film amorphous semiconductors starting from the extracted absorption coefficient. Analysis of the experimental absorption data acquired for ultra-thin amorphous germanium (a-Ge) layers demonstrates that the Cody model is able to provide a less ambiguous energy bandgap value. Finally, we apply our proposed method to experimentally determine the optical bandgap of a-Ge/SiO{sub 2} superlattices with single and multiple a-Ge layers down to 2 nm thickness.

  10. Performance Investigation of Multilayer MoS2 Thin-Film Transistors Fabricated via Mask-free Optically Induced Electrodeposition.

    PubMed

    Li, Meng; Liu, Na; Li, Pan; Shi, Jialin; Li, Guangyong; Xi, Ning; Wang, Yuechao; Liu, Lianqing

    2017-03-08

    Transition metal dichalcogenides, particularly MoS2, have recently received enormous interest in explorations of the physics and technology of nanodevice applications because of their excellent optical and electronic properties. Although monolayer MoS2 has been extensively investigated for various possible applications, its difficulty of fabrication renders it less appealing than multilayer MoS2. Moreover, multilayer MoS2, with its inherent high electronic/photonic state densities, has higher output driving capabilities and can better satisfy the ever-increasing demand for versatile devices. Here, we present multilayer MoS2 back-gate thin-film transistors (TFTs) that can achieve a relatively low subthreshold swing of 0.75 V/decade and a high mobility of 41 cm(2)·V(-1)·s(-1), which exceeds the typical mobility value of state-of-the-art amorphous silicon-based TFTs by a factor of 80. Ag and Au electrode-based MoS2 TFTs were fabricated by a convenient and rapid process. Then we performed a detailed analysis of the impacts of metal contacts and MoS2 film thickness on electronic performance. Our findings show that smoother metal contacts exhibit better electronic characteristics and that MoS2 film thickness should be controlled within a reasonable range of 30-40 nm to obtain the best mobility values, thereby providing valuable insights regarding performance enhancement for MoS2 TFTs. Additionally, to overcome the limitations of the conventional fabrication method, we employed a novel approach known as optically induced electrodeposition (OIE), which allows the flexible and precise patterning of metal films and enables rapid and mask-free device fabrication, for TFT fabrication.

  11. Verification of antiferromagnetic exchange coupling at room temperature using polar magneto-optic Kerr effect in thin EuS/Co multilayers with perpendicular magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Goschew, A.; Scott, M.; Fumagalli, P.

    2016-08-01

    We report on magneto-optic Kerr measurements in polar geometry carried out on a series of thin Co/EuS multilayers on suitable Co/Pd-multilayer substrates. Thin Co/EuS multilayers of a few nanometers individual layer thickness usually have their magnetization in plane. Co/Pd multilayers introduce a perpendicular magnetic anisotropy in the Co/EuS layers deposited on top, thus making it possible to measure magneto-optic signals in the polar geometry in remanence in order to study exchange coupling. Magneto-optic Kerr-effect spectra and hysteresis loops were recorded in the visible and ultraviolet photon-energy range at room temperature. The EuS contribution to the magneto-optic signal is extracted at 4.1 eV by combining hysteresis loops measured at different photon energies with polar magneto-optic Kerr-effect spectra recorded in remanence and in an applied magnetic field of 2.2 T. The extracted EuS signal shows clear signs of antiferromagnetic coupling of the Eu magnetic moments to the Co layers. This implies that the ordering temperature of at least a fraction of the EuS layers is above room temperature proving that magneto-optic Kerr-effect spectroscopy can be used here as a quasi-element-specific method.

  12. Multilayer Optical Learning Networks

    NASA Astrophysics Data System (ADS)

    Wagner, Kelvin; Psaltis, Demetri

    1987-08-01

    In this paper we present a new approach to learning in a multilayer optical neural network which is based on holographically interconnected nonlinear Fabry-Perot etalons. The network can learn the interconnections that form a distributed representation of a desired pattern transformation operation. The interconnections are formed in an adaptive and self aligning fashion, as volume holographic gratings in photorefractive crystals. Parallel arrays of globally space integrated inner products diffracted by the interconnecting hologram illuminate arrays of nonlinear Fabry-Perot etalons for fast thresholding of the transformed patterns. A phase conjugated reference wave interferes with a backwards propagating error signal to form holographic interference patterns which are time integrated in the volume of the photorefractive crystal in order to slowly modify and learn the appropriate self aligning interconnections. A holographic implementation of a single layer perceptron learning procedure is presented that can be extendept ,to a multilayer learning network through an optical implementation of the backward error propagation (BEP) algorithm.

  13. Determination of the embedded thermo-optical expansion coefficients of PbTe and ZnSe thin film infrared multilayers.

    PubMed

    Hawkins, Gary J; Stolberg-Rohr, Thomine

    2015-06-15

    This paper reports the first derived thermo-optical properties for vacuum deposited infrared thin films embedded in multilayers. These properties were extracted from the temperature-dependence of manufactured narrow bandpass filters across the 4-17 µm mid-infrared wavelength region. Using a repository of spaceflight multi-cavity bandpass filters, the thermo-optical expansion coefficients of PbTe and ZnSe were determined across an elevated temperature range 20-160 °C. Embedded ZnSe films showed thermo-optical properties similar to reported bulk values, whilst the embedded PbTe films of lower optical density, deviate from reference literature sources. Detailed knowledge of derived coefficients is essential to the multilayer design of temperature-invariant narrow bandpass filters for use in non-cooled infrared detection systems. We further present manufacture of the first reported temperature-invariant multi-cavity narrow bandpass filter utilizing PbS chalcogenide layer material.

  14. Optically transparent thin-film transistors based on 2D multilayer MoS2 and indium zinc oxide electrodes

    NASA Astrophysics Data System (ADS)

    Kwon, Junyeon; Hong, Young Ki; Kwon, Hyuk-Jun; Park, Yu Jin; Yoo, Byungwook; Kim, Jiwan; Grigoropoulos, Costas P.; Oh, Min Suk; Kim, Sunkook

    2015-01-01

    We report on optically transparent thin film transistors (TFTs) fabricated using multilayered molybdenum disulfide (MoS2) as the active channel, indium tin oxide (ITO) for the back-gated electrode and indium zinc oxide (IZO) for the source/drain electrodes, respectively, which showed more than 81% transmittance in the visible wavelength. In spite of a relatively large Schottky barrier between MoS2 and IZO, the n-type behavior with a field-effect mobility (μeff) of 1.4 cm2 V-1 s-1 was observed in as-fabricated transparent MoS2 TFT. In order to enhance the performances of transparent MoS2 TFTs, a picosecond pulsed laser was selectively irradiated onto the contact region of the IZO electrodes. Following laser annealing, μeff increased to 4.5 cm2 V-1 s-1, and the on-off current ratio (Ion/Ioff) increased to 104, which were attributed to the reduction of the contact resistance between MoS2 and IZO.

  15. Ultra-thin multilayer capacitors.

    SciTech Connect

    Renk, Timothy Jerome; Monson, Todd C.

    2009-06-01

    The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric constant, and standoff voltage. For successful device construction, there are a number of challenging requirements including achieving correct stoichiometric and crystallographic composition of the deposited PLZT, as well as the creation of a defect free homogenous film. This report details some success in satisfying these requirements, although 900 C temperatures were necessary for PLZT perovskite phase formation. These temperatures were applied to a previously deposited multi-layer film which was then post-annealed to this temperature. The film exhibited mechanical distress attributable to differences in the coefficient of thermal expansion (CTE) of the various layers. This caused significant defects in the deposited films that led to shorts across devices. A follow-on single layer deposition without post-anneal produced smooth layers with good interface behavior, but without the perovskite phase formation. These issues will need to be addressed in order for ion beam deposited MLCCs to become a viable technology. It is possible that future in-situ heating during deposition may address both the CTE issue, and result in lowered processing temperatures, which in turn could raise the probability of successful MLCC formation.

  16. Multilayer optical dielectric coating

    DOEpatents

    Emmett, John L.

    1990-01-01

    A highly damage resistant, multilayer, optical reflective coating includes alternating layers of doped and undoped dielectric material. The doping levels are low enough that there are no distinct interfaces between the doped and undoped layers so that the coating has properties nearly identical to the undoped material. The coating is fabricated at high temperature with plasma-assisted chemical vapor deposition techniques to eliminate defects, reduce energy-absorption sites, and maintain proper chemical stoichiometry. A number of differently-doped layer pairs, each layer having a thickness equal to one-quarter of a predetermined wavelength in the material are combined to form a narrowband reflective coating for a predetermined wavelength. Broadband reflectors are made by using a number of narrowband reflectors, each covering a portion of the broadband.

  17. Optical thin film devices

    NASA Astrophysics Data System (ADS)

    Mao, Shuzheng

    1991-11-01

    Thin film devices are applied to almost all modern scientific instruments, and these devices, especially optical thin film devices, play an essential role in the performances of the instruments, therefore, they are attracting more and more attention. Now there are numerous kinds of thin film devices and their applications are very diversified. The 300-page book, 'Thin Film Device and Applications,' by Prof. K. L. Chopra gives some general ideas, and my paper also outlines the designs, fabrication, and applications of some optical thin film devices made in my laboratory. Optical thin film devices have been greatly developed in the recent decades. Prof. A. Thelan has given a number of papers on the theory and techniques, Prof. H. A. Macleod's book, 'Thin Film Optical Filters,' has concisely concluded the important concepts of optical thin film devices, and Prof. J. A. Dobrowobski has proposed many successful designs for optical thin film devices. Recently, fully-automatic plants make it easier to produce thin film devices with various spectrum requirements, and some companies, such as Balzers, Leybold AG, Satis Vacuum AG, etc., have manufactured such kinds of coating plants for research or mass-production, and the successful example is the production of multilayer antireflection coatings with high stability and reproducibility. Therefore, it could be said that the design of optical thin film devices and coating plants is quite mature. However, we cannot expect that every problem has been solved, the R&D work still continues, the competition still continues, and new design concepts, new techniques, and new film materials are continually developed. Meanwhile, the high-price of fully-automatic coating plants makes unpopular, and automatic design of coating stacks is only the technique for optimizing the manual design according to the physical concepts and experience, in addition, not only the optical system, but also working environment should be taken into account when

  18. Multilayer Thin Film Sensors for Damage Diagnostics

    NASA Astrophysics Data System (ADS)

    Protasov, A. G.; Gordienko, Y. G.; Zasimchuk, E. E.

    2006-03-01

    The new innovative approach to damage diagnostics within the production and maintenance/servicing procedures in industry is proposed. It is based on the real-time multiscale monitoring of the smart-designed multilayer thin film sensors of fatigue damage with the standard electrical input/output interfaces which can be connected to the embedded and on-board computers. The multilayer thin film sensors supply information about the actual unpredictable deformation damage, actual fatigue life, strain localization places, damage spreading, etc.

  19. Applications of multilayer optics

    NASA Astrophysics Data System (ADS)

    Wang, Zhanshan; Zhu, Jingtao; Mu, Baozhong; Zhang, Zhong; Wang, Fengli; Xu, Jing; Li, Wenbin; Chen, Lingyan

    2010-11-01

    Recent development of multilayer mirror and its applications in extreme ultraviolet (EUV), soft X-ray ranges in China was reviewed in this paper. Three types of multilayer mirrors were developed with special performance for dense plasma diagnostics, EUV astronomical observation. Firstly, dual-periodic W/B 4C multilayer mirror was designed for Kirkpatrick-Baez (K-B) microscopy working at TiKα line (4.75 keV), which is highly reflective both at hard X-ray (CuKα line at 8.05 keV) and soft X-ray (4.75 keV). Using this mirror, the K-B system can be aligned conveniently in air using hard X-ray instead of in vacuum. The second mirror is aperiodic Mg/SiC multilayer, also a bi-functional mirror with high reflectivity for He-II emission line (30.4 nm) but suppressing He-I emission line (58.4 nm) in astronomy observation, which will replace the traditional combination of periodic multilayer and the fragile film filter. This will be more safe in satellite launching. The third mirror is Mo/Si periodic multilayer, depositing on a parabolic substrate with diameter of 230 mm, which is designed for EUV telescope for imaging of solar corona by selecting Fe-XII emission (19.5 nm). The uniformity of lateral layer thickness distribution is within ±0.3% along the diameter of mirror, measured by X-ray reflectometry. The measured peak reflectivity is 42% at the wavelength of 19.5 nm. All these multilayer mirrors were prepared by using magnetron sputtering system in our group.

  20. Experimental evidence for an optical interference model for vibrational sum frequency generation on multilayer organic thin film systems. II. Consideration for higher order terms.

    PubMed

    O'Brien, Daniel B; Massari, Aaron M

    2015-01-14

    The generalized optical interference model for interfacial contributions to vibrational sum frequency generation (VSFG) spectroscopic signals from organic thin film systems is extended to include a description of optical interferences contained in the thin film bulk response. This is based on electric quadrupolar interactions with the input fields and includes a discussion on possible contribution from the electric quadrupolar polarization. VSFG data from the first of this two part report are analyzed and include effects from higher order responses, for both bulk and higher order interfacial terms. The results indicate that although it is capable of capturing many of the data features, the electric dipole treatment is likely not a complete description of the VSFG intensity data from this system. An analysis based on the signs of the resulting response amplitudes is used to deduce the relative magnitude of the electric dipole and higher order interfacial terms. It is found that the buried interface is closer to satisfying the electric dipole approximation, consistent with smaller field gradients due to closer index matching between the organic thin film and substrate relative to air. The procedure outlined in this work allows for the difficult task of deducing a physical picture of average molecular orientation at the buried interface of a multilayer organic thin film system while including higher order effects.

  1. Determination of effective optical constants of magnetic multilayers

    NASA Astrophysics Data System (ADS)

    Deeter, M. N.; Sarid, D.; England, C. D.; Bennett, W. R.; Falco, Charles M.

    1989-05-01

    The effective optical and magneto-optical constants of a series of Cu/Co multilayer films are determined experimentally and compared with a theoretical thin-film model based on the bulk optical constants of Cu and Co. In the multilayer series, the atomic percentages of Cu and Co were kept fixed and the period varied from 0.4 to 13.6 nm. Deviations from bulk-like behavior in the effective optical constants are observed for multilayers with periods less than 3 nm.

  2. Ar plasma irradiation improved optical and electrical properties of TiO₂/Ag/TiO₂ multilayer thin film.

    PubMed

    Fang, Yingcui; He, Jinjun; Zhang, Kang; Xiao, Chuanyun; Zhang, Bing; Shen, Jie; Niu, Haihong; Yan, Rong; Chen, Junling

    2015-12-01

    Embedding a thin metal layer between two thin dielectric or semiconductor layers [dielectric/metal/dielectric (DMD)] leads to a kind of transparent electrode that is promising as a substitute for the currently widely applied indium tin oxide electrode. However, the optical and electrical properties of DMD still wait for further improvement. In this study, Ar plasma irradiation (API) was, for the first time to our knowledge, applied to improve the optical and electrical properties of a TiO2/Ag/TiO2 electrode that was fabricated by electron-beam evaporation of TiO2 and electric-resistance heating of high purity Ag under vacuum. Ar plasma was produced by radio frequency glow discharge. The Ag layer was bombarded before the second layer of TiO2 was deposited. The electrode with configuration of TiO2 (24  nm)/Ag(14  nm)/TiO2 (24  nm) after API for 10 s shows excellent performance. The mean transmittance between 370 and 800 nm reaches 94% and the sheet resistance is as low as 6  Ω/sq, while Haacke's figure of merit is as high as 112×10(-3)  Ω(-1). The improvement mechanism is discussed based on field emission scanning electron microscope images and absorption spectra. The improvement is attributed to the fact that API reduces the localized surface plasmon resonance of Ag nanoparticles and makes the Ag film thinner and denser.

  3. Multilayer Thin-Film Microcapacitors

    NASA Technical Reports Server (NTRS)

    Thakoor, Sarita; Thakoor, Anil; Karmon, Dan

    1995-01-01

    Miniature capacitors containing multiple alternating thin-film dielectric and metal layers proposed, especially for use in integrated and hybrid electronic circuits. Because capacitance inversely proportional to thickness of dielectric layers, use of thin, high-quality dielectric layers affords capacitance and energy-storage densities much greater than now available. These devices much smaller and more reliable than state-of-art capacitors.

  4. Modeling and simulation of multilayered thin films for terahertz detection

    NASA Astrophysics Data System (ADS)

    Martin, Michael F.; Alves, Fabio; Santos, Ricardo A. T.; Grbovic, Dragoslav

    2014-06-01

    In this article we demonstrate a method based on Transfer Matrix (TMM) that can be used to analyze optical properties of multilayered thin films and planar metamaterials for terahertz (THz) detection. Producing and testing such films require host substrates that can be up to 4 orders of magnitude thicker than the THz-sensitive films. Therefore, the ability to efficiently model, simulate and accurately predict the optical properties of multilayered structures, with significant differences in thickness, is crucial to designing sensors with maximized absorption. This method, which provides an analytical tool, less computationally intensive then finite element modeling, can be used for films composed of any number of layers with arbitrary thicknesses, aspect ratios and arbitrary angles of incidence. Homogeneous or patterned (metamaterials) films can be modeled enabling accurate analysis of positive and negative index materials indistinctly. Reflection, transmission and absorption of metallic/dielectric nanolaminates, metallic thin films and planar metamaterial films are analyzed and compared with experimental measurements and FE simulations. Results show good agreement for a wide range of structures, materials and frequencies and indicate that the method has a great potential for design and optimization of sophisticated multilayered structures for THz detection and beyond.

  5. Thin film photovoltaic device with multilayer substrate

    DOEpatents

    Catalano, Anthony W.; Bhushan, Manjul

    1984-01-01

    A thin film photovoltaic device which utilizes at least one compound semiconductor layer chosen from Groups IIB and VA of the Periodic Table is formed on a multilayer substrate The substrate includes a lowermost support layer on which all of the other layers of the device are formed. Additionally, an uppermost carbide or silicon layer is adjacent to the semiconductor layer. Below the carbide or silicon layer is a metal layer of high conductivity and expansion coefficient equal to or slightly greater than that of the semiconductor layer.

  6. Figure correction of multilayer coated optics

    DOEpatents

    Chapman; Henry N. , Taylor; John S.

    2010-02-16

    A process is provided for producing near-perfect optical surfaces, for EUV and soft-x-ray optics. The method involves polishing or otherwise figuring the multilayer coating that has been deposited on an optical substrate, in order to correct for errors in the figure of the substrate and coating. A method such as ion-beam milling is used to remove material from the multilayer coating by an amount that varies in a specified way across the substrate. The phase of the EUV light that is reflected from the multilayer will be affected by the amount of multilayer material removed, but this effect will be reduced by a factor of 1-n as compared with height variations of the substrate, where n is the average refractive index of the multilayer.

  7. Nanomechanical Behavior of High Gas Barrier Multilayer Thin Films.

    PubMed

    Humood, Mohammad; Chowdhury, Shahla; Song, Yixuan; Tzeng, Ping; Grunlan, Jaime C; Polycarpou, Andreas A

    2016-05-04

    Nanoindentation and nanoscratch experiments were performed on thin multilayer films manufactured using the layer-by-layer (LbL) assembly technique. These films are known to exhibit high gas barrier, but little is known about their durability, which is an important feature for various packaging applications (e.g., food and electronics). Films were prepared from bilayer and quadlayer sequences, with varying thickness and composition. In an effort to evaluate multilayer thin film surface and mechanical properties, and their resistance to failure and wear, a comprehensive range of experiments were conducted: low and high load indentation, low and high load scratch. Some of the thin films were found to have exceptional mechanical behavior and exhibit excellent scratch resistance. Specifically, nanobrick wall structures, comprising montmorillonite (MMT) clay and polyethylenimine (PEI) bilayers, are the most durable coatings. PEI/MMT films exhibit high hardness, large elastic modulus, high elastic recovery, low friction, low scratch depth, and a smooth surface. When combined with the low oxygen permeability and high optical transmission of these thin films, these excellent mechanical properties make them good candidates for hard coating surface-sensitive substrates, where polymers are required to sustain long-term surface aesthetics and quality.

  8. Nanocomposite multilayer optically variable coatings

    NASA Astrophysics Data System (ADS)

    Lu, Junxia; Lai, Zhenquan; Wei, Jiandong; Zhang, Huilin; Deng, Zhongsheng; Zhang, Qinyuan; Wang, Jue

    2000-11-01

    The optically variable coatings can prevent counterfeiting of value documents. The cost of these coatings deposited by physical technology is very high. The sol-gel technology has the feature of a relatively lower cost and can be used to produce thin films with low refractive. We studied the optically variable coatings by the nano-composite technology (i.e., compound method of sol-gel technology and physical technology). The degree of color shift of some film structures with the viewing angle, including PET (substrate)/Cr/SiO2/Al and PET(sub.)/Cr/resin/Al etc., was calculated according to the color perception of human eyes. And the coatings produced were measured with the spectrometer.

  9. Optical multilayers with an amorphous fluoropolymer

    NASA Astrophysics Data System (ADS)

    Chow, Robert; Loomis, Gary E.; Lindsey, Edward F.

    1994-09-01

    Multilayered coatings were made by physical vapor deposition (PVD) of a perfluorinated amorphous polymer, Teflon AF2400, together with other optical materials. A high reflector at 1064 nm was made with ZnS and AF2400. An all-organic 1064-nm reflector was made from AF2400 and polyethylene. Oxide (HfO2, SiO2) compatibility was also tested. Each multilayer system adhered to itself. The multilayers were influenced by coating stress and unintentional temperature rises during PVD deposition.

  10. Neutron diffraction studies of thin film multilayer structures

    SciTech Connect

    Majkrzak, C.F.

    1985-01-01

    The application of neutron diffraction methods to the study of the microscopic chemical and magnetic structures of thin film multilayers is reviewed. Multilayer diffraction phenomena are described in general and in particular for the case in which one of the materials of a bilayer is ferromagnetic and the neutron beam polarized. Recent neutron diffraction measurements performed on some interesting multilayer systems are discussed. 70 refs., 5 figs.

  11. Graded period multilayer structures for X-ray optics

    NASA Astrophysics Data System (ADS)

    Biltoft, P. J.; Falabella, S.; Pombo, R. F.; Noble, E. H.

    1993-01-01

    Our goal for FY 91 was to develop the capability to deposit multilayer thin film coatings of prescribed period gradient onto planar and figured substrates. To accomplish this goal we have extended our use of deposition flux masking to create laterally graded multilayer coatings. In addition, we have constructed a planetary substrate rotation fixture for deposition of axisymmetric graded thickness multilayer structures on planar and figured optics. Materials combinations for the layered synthetic microstructures (LSM's) we have fabricated by these techniques include: tungsten/carbon, molybdenum/silicon, molybdenum disilicide/silicon and chromium carbide/carbon. Soft X-ray diffraction characterization of the LSM's has verified that we have deposited controlled thickness graded period structures.

  12. Multilayer optics for femtosecond-diffractometry

    NASA Astrophysics Data System (ADS)

    Wiesmann, J.; Hertlein, F.; Michaelsen, C.

    2009-08-01

    X-ray sources according to the principle of the "free electron laser" (FEL), will in future, be able to provide bright radiation with pulses in the femtosecond range. Even nowadays, home-lab X-ray sources with very short pulses in the sub-picosecond range are already available for lab experiments. These laser-based sources need different kinds of optics to direct the emitted X-rays onto the samples. On the one hand, the optics should transfer as much flux as possible and on the other hand, the brilliance and timestructure of the source should not be reduced too much. These requirements are fulfilled with 2-dimensional beam shaping multilayer optics. Their design, production and their influence on the shape of the X-ray beam will be explained in this contribution. The optics consist of bent substrates with shape tolerances below 100 nm, upon which multilayers are deposited with single layer thicknesses in the nanometer range and up to several hundreds of pairs of layers. Furthermore, these multilayers were designed with lateral thickness gradients within +/- 1% deviation of the ideal shape. This means that a deposition precision in the picometer range is required. We use magnetron sputtering methods for deposition, optical profilometry in order to characterize the shape of the optics and X-ray reflectometry to characterize the multilayers.

  13. Optical performance of LPP multilayer collector mirrors

    NASA Astrophysics Data System (ADS)

    Feigl, Torsten; Perske, Marco; Pauer, Hagen; Fiedler, Tobias; Yulin, Sergiy; Trost, Marcus; Schröder, Sven; Duparré, Angela; Kaiser, Norbert; Tünnermann, Andreas; Böwering, Norbert R.; Ershov, Alex I.; Hoffmann, Kay; La Fontaine, Bruno; Cummings, Kevin D.

    2012-03-01

    The usable power and the collector optics lifetime of high-power extreme ultraviolet light sources at 13.5 nm are considered as the major challenges in the transitioning of EUV lithography from the current pre-production phase to high volume manufacturing. We give a detailed performance summary of the large ellipsoidal multilayer collector mirrors used in Cymer's laser-produced plasma extreme ultraviolet light sources. In this paper we present the optical performance - reflectance and wavelength - of the multilayer-coated ellipsoidal collectors as well as a novel approach for the roughness characterization of large EUV mirror optics based on light scattering measurements at 442 nm. We also describe the optical performance and characteristics during operation of the light source and the substantial increase of collector lifetime by the implementation of new coating designs.

  14. Experimental evidence for an optical interference model for vibrational sum frequency generation on multilayer organic thin film systems. I. Electric dipole approximation.

    PubMed

    O'Brien, Daniel B; Massari, Aaron M

    2015-01-14

    In the field of vibrational sum frequency generation spectroscopy (VSFG) applied to organic thin film systems, a significant challenge to data analysis is in the accurate description of optical interference effects. Herein, we provide experimental evidence that a model recently developed in our lab provides an accurate description of this phenomenon. We studied the organic small molecule N,N'-dioctyl-3,4,9,10-perylenedicarboximide vapor deposited as a thickness gradient on silicon wafer substrates with two oxide thicknesses and two surface preps. VSFG data were obtained using the ssp and the sps polarization combinations in the imide carbonyl stretching region as a function of organic thickness. In this first of two reports, the data are modeled and interpreted within the ubiquitous electric dipole approximation for VSFG. The intrinsic sample responses are parameterized during the fitting routines while optical interference effects are simply calculated from the model using known refractive indices, thin film thicknesses, and beam angles. The results indicate that the thin film model provides a good description of optical interferences, indicating that interfacial terms are significant. Inconsistencies between the fitting results within the bounds of the electric dipole response motivate deliberation for additional effects to be considered in the second report.

  15. Experimental evidence for an optical interference model for vibrational sum frequency generation on multilayer organic thin film systems. I. Electric dipole approximation

    SciTech Connect

    O’Brien, Daniel B.; Massari, Aaron M.

    2015-01-14

    In the field of vibrational sum frequency generation spectroscopy (VSFG) applied to organic thin film systems, a significant challenge to data analysis is in the accurate description of optical interference effects. Herein, we provide experimental evidence that a model recently developed in our lab provides an accurate description of this phenomenon. We studied the organic small molecule N,N′-dioctyl-3,4,9,10-perylenedicarboximide vapor deposited as a thickness gradient on silicon wafer substrates with two oxide thicknesses and two surface preps. VSFG data were obtained using the ssp and the sps polarization combinations in the imide carbonyl stretching region as a function of organic thickness. In this first of two reports, the data are modeled and interpreted within the ubiquitous electric dipole approximation for VSFG. The intrinsic sample responses are parameterized during the fitting routines while optical interference effects are simply calculated from the model using known refractive indices, thin film thicknesses, and beam angles. The results indicate that the thin film model provides a good description of optical interferences, indicating that interfacial terms are significant. Inconsistencies between the fitting results within the bounds of the electric dipole response motivate deliberation for additional effects to be considered in the second report.

  16. Thin film multilayer filters for solar EUV telescopes.

    PubMed

    Chkhalo, N I; Drozdov, M N; Kluenkov, E B; Kuzin, S V; Lopatin, A Ya; Luchin, V I; Salashchenko, N N; Tsybin, N N; Zuev, S Yu

    2016-06-10

    Al, with a passband in the wavelength range of 17-60 nm, and Zr, with a passband in the wavelength range of 6.5-17 nm, thin films on a support grid or support membrane are frequently used as UV, visible, and near-IR blocking filters in solar observatories. Although they possess acceptable optical performance, these filters also have some shortcomings such as low mechanical strength and low resistance to oxidation. These shortcomings hinder meeting the requirements for filters of future telescopes. We propose multilayer thin film filters on the basis of Al, Zr, and other materials with improved characteristics. It was demonstrated that stretched multilayer films on a support grid with a mesh size up to 5 mm can withstand vibration loads occurring during spacecraft launch. A large mesh size is preferable for filters of high-resolution solar telescopes, since it allows image distortion caused by light diffraction on the support grid to be avoided. We have investigated the thermal stability of Al/Si and Zr/Si multilayers assuming their possible application as filters in the Intergelioprobe project, in which the observation of coronal plasma will take place close to the Sun. Zr/Si films show high thermal stability and may be used as blocking filters in the wavelength range of 12.5-17 nm. Al/Si films show lower thermal stability: a significant decrease in the film's transmission in the EUV spectral range and an increase in the visible spectrum have been observed. We suppose that the low thermal stability of Al/Si films restricts their application in the Intergelioprobe project. Thus, there is a lack of filters for the wavelength range of λ>17  nm. Be/Si and Cr/Si filters have been proposed for the wavelength range near 30.4 nm. Although these filters have lower transparency than Al/Si, they are superior in thermal stability. Multilayer Sc/Al filters with relatively high transmission at a wavelength of 58.4 nm (HeI line) and simultaneously sufficient rejection in the

  17. Developing Multilayer Thin Film Strain Sensors With High Thermal Stability

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Fralick, Gustave C.; Gonzalez, Jose M., III

    2006-01-01

    A multilayer thin film strain sensor for large temperature range use is under development using a reactively-sputtered process. The sensor is capable of being fabricated in fine line widths utilizing the sacrificial-layer lift-off process that is used for micro-fabricated noble-metal sensors. Tantalum nitride films were optimized using reactive sputtering with an unbalanced magnetron source. A first approximation model of multilayer resistance and temperature coefficient of resistance was used to set the film thicknesses in the multilayer film sensor. Two multifunctional sensors were fabricated using multilayered films of tantalum nitride and palladium chromium, and tested for low temperature resistivity, TCR and strain response. The low temperature coefficient of resistance of the films will result in improved stability in thin film sensors for low to high temperature use.

  18. Optics and multilayer coatings for EUVL systems

    SciTech Connect

    Soufli, R; Bajt, S; Hudyma, R M; Taylor, J S

    2008-03-21

    EUV lithography (EUVL) employs illumination wavelengths around 13.5 nm, and in many aspects it is considered an extension of optical lithography, which is used for the high-volume manufacturing (HVM) of today's microprocessors. The EUV wavelength of illumination dictates the use of reflective optical elements (mirrors) as opposed to the refractive lenses used in conventional lithographic systems. Thus, EUVL tools are based on all-reflective concepts: they use multilayer (ML) coated optics for their illumination and projection systems, and they have a ML-coated reflective mask.

  19. High quality transparent conductive Ag-based barium stannate multilayer flexible thin films.

    PubMed

    Wu, Muying; Yu, Shihui; He, Lin; Yang, Lei; Zhang, Weifeng

    2017-12-01

    Transparent conductive multilayer thin films of silver (Ag)-embedded barium stannate (BaSnO3) structures have been deposited onto flexible polycarbonate substrates by magnetron sputtering at room temperature to develop an indium free transparent flexible electrode. The effect of thicknesses of Ag mid-layer and barium stannate layers on optical and electrical properties were investigated, and the mechanisms of conduction and transmittance were discussed. The highest value of figure of merit is 25.5 × 10(-3) Ω(-1) for the BaSnO3/Ag/BaSnO3 multilayer flexible thin films with 9 nm thick silver mid-layer and 50 nm thick barium stannate layers, while the average optical transmittance in the visible range from 380 to 780 nm is above 87%, the resistivity is 9.66 × 10(-5) Ω · cm, and the sheet resistance is 9.89 Ω/sq. The change rate of resistivity is under 10% after repeated bending of the multilayer flexible thin films. These results indicate that Ag-based barium stannate multilayer flexible thin films can be used as transparent flexible electrodes in various flexible optoelectronic devices.

  20. Scanning Tunneling Microscopy of Multilayer Thin Film Solar Cell Materials^*

    NASA Astrophysics Data System (ADS)

    Mantovani, J. G.; Friedfeld, R.; Raffaelle, R. P.

    1996-03-01

    We have been investigating electrochemically deposited multilayer structures based on the Cu_xIn_2-xSe2 system for use in thin film solar cells. The interest in multilayer structures is due to their proposed use in increasing thin film solar cell efficiency. We have imaged the artificially imposed superstructure of our nanoscale multilayers using a scanning tunneling microscope. A comparison is made between the theoretically calculated modulation wavelengths and those generated by Fourier analysis of the scanning tunneling microscope images. A discussion of the use of photo-assisted tunneling spectroscopy in a modified STM is presented. * This work was supported by the Southeastern University Research Association in collaboration with Oak Ridge National Laboratory and the Florida Solar Energy Center.

  1. Nonlinear optical thin films

    NASA Technical Reports Server (NTRS)

    Leslie, Thomas M.

    1993-01-01

    A focused approach to development and evaluation of organic polymer films for use in optoelectronics is presented. The issues and challenges that are addressed include: (1) material synthesis, purification, and the tailoring of the material properties; (2) deposition of uniform thin films by a variety of methods; (3) characterization of material physical properties (thermal, electrical, optical, and electro-optical); and (4) device fabrication and testing. Photonic materials, devices, and systems were identified as critical technology areas by the Department of Commerce and the Department of Defense. This approach offers strong integration of basic material issues through engineering applications by the development of materials that can be exploited as the active unit in a variety of polymeric thin film devices. Improved materials were developed with unprecedented purity and stability. The absorptive properties can be tailored and controlled to provide significant improvement in propagation losses and nonlinear performance. Furthermore, the materials were incorporated into polymers that are highly compatible with fabrication and patterning processes for integrated optical devices and circuits. By simultaneously addressing the issues of materials development and characterization, keeping device design and fabrication in mind, many obstacles were overcome for implementation of these polymeric materials and devices into systems. We intend to considerably improve the upper use temperature, poling stability, and compatibility with silicon based devices. The principal device application that was targeted is a linear electro-optic modulation etalon. Organic polymers need to be properly designed and coupled with existing integrated circuit technology to create new photonic devices for optical communication, image processing, other laser applications such as harmonic generation, and eventually optical computing. The progression from microscopic sample to a suitable film

  2. Spin-orbit torque induced reversible coercivity change in Co/Pd multilayer thin films

    NASA Astrophysics Data System (ADS)

    Garcia, Davil; Lou, Paul C.; Butler, John; Kumar, Sandeep

    2016-11-01

    In this work, we report reversible reduction in coercivity of Co/Pd multilayer thin films under high-density direct current biasing. We carried out in-situ focused magneto optic Kerr effect based hysteresis measurement while the specimen was under DC bias. The experiments show a reversible reduction in coercivity during the application of direct current. We propose this reduction occurs due to the field like spin-orbit torque generated by spin Hall effect. These results are further supported by the anomalous Hall effect measurement, which do not show any change in coercivity. The magneto-optic Kerr measurement probes the surface (penetration depth) whereas anomalous Hall effect is a bulk transport behavior. These complimentary measurements prove that the origin of spin-orbit torques in ferromagnetic metal/ heavy metal multilayer thin films is spin-Hall effect.

  3. Polypeptide Chirality Influences Multilayer Thin Film Growth and Structure

    NASA Astrophysics Data System (ADS)

    Bell, Zephra; Khadka, Dhan; Haynie, Donald

    2011-03-01

    Polypeptide multilayer thin films are being developed for a variety of applications.These include coatings for implant devices and systems for drug delivery in thebiomedical sciences, and optical coatings. Subsequent polymer adsorption steps involve polymers of opposite polarity. Here, the polymers were polypeptides. This project compared the consequences of changing polypeptide chirality on film growth and structure. The peptides were poly(L-glutamic acid), its right-handed counterpart, poly(D-glutamic acid), and poly(lysine-tyrosine). The first two are negatively charged at neutral pH, the third one is positively charged. Poly(lysine-tyrosine)/poly(L-glutamic acid) films and poly(lysine-tyrosine)/poly(D-glutamic acid) films werefabricated on 1 mm-thick quartz plates. In one experiment, films were grown to 34layers. The UV absorption spectrum was taken after each layer deposited to determinethe rate of polymer self-assembly. Separately, UV or visible wavelength spectra wereobtained for films stained with a dye cooled/heated in the range 4-65 °C. In anotherexperiment, a mixture of poly-L-glutamic acid and poly-D-glutamic acid was used as thepolyanion for film buildup. The data show that poly(lysine-tyrosine)/poly(L-glutamicacid) films built up at a higher rate than the corresponding right-handed films.

  4. Thin-film optical initiator

    DOEpatents

    Erickson, Kenneth L.

    2001-01-01

    A thin-film optical initiator having an inert, transparent substrate, a reactive thin film, which can be either an explosive or a pyrotechnic, and a reflective thin film. The resultant thin-film optical initiator system also comprises a fiber-optic cable connected to a low-energy laser source, an output charge, and an initiator housing. The reactive thin film, which may contain very thin embedded layers or be a co-deposit of a light-absorbing material such as carbon, absorbs the incident laser light, is volumetrically heated, and explodes against the output charge, imparting about 5 to 20 times more energy than in the incident laser pulse.

  5. Multilayer Dielectric Transmissive Optical Phase Modulator

    NASA Technical Reports Server (NTRS)

    Keys, Andrew Scott; Fork, Richard Lynn

    2004-01-01

    A multilayer dielectric device has been fabricated as a prototype of a low-loss, low-distortion, transmissive optical phase modulator that would provide as much as a full cycle of phase change for all frequency components of a transmitted optical pulse over a frequency band as wide as 6.3 THz. Arrays of devices like this one could be an alternative to the arrays of mechanically actuated phase-control optics (adaptive optics) that have heretofore been used to correct for wave-front distortions in highly precise optical systems. Potential applications for these high-speed wave-front-control arrays of devices include agile beam steering, optical communications, optical metrology, optical tracking and targeting, directional optical ranging, and interferometric astronomy. The device concept is based on the same principle as that of band-pass interference filters made of multiple dielectric layers with fractional-wavelength thicknesses, except that here there is an additional focus on obtaining the desired spectral phase profile in addition to the device s spectral transmission profile. The device includes a GaAs substrate, on which there is deposited a stack of GaAs layers alternating with AlAs layers, amounting to a total of 91 layers. The design thicknesses of the layers range from 10 nm to greater than 1 micrometer. The number of layers and the thickness of each layer were chosen in a computational optimization process in which the wavelength dependences of the indices of refraction of GaAs and AlAs were taken into account as the design was iterated to maximize the transmission and minimize the group-velocity dispersion for a wavelength band wide enough to include all significant spectral components of the pulsed optical signal to be phase modulated.

  6. Optical localization in quasi-periodic multilayers

    NASA Astrophysics Data System (ADS)

    Vasconcelos, M. S.; Albuquerque, E. L.; Mariz, A. M.

    1998-07-01

    We investigate the optical transmission spectra of quasi-periodic dielectric multilayer slabs arranged in a fashion that exhibits what has been called deterministic disorders. They can be of the so-called substitutional sequences type, and are characterized by the nature of their Fourier spectrum, which can be dense pure point (e.g. a Fibonacci sequence) or singular continuous (e.g. Thue-Morse and double-period sequences). The transmission coefficients are conveniently derived by using a theoretical model based on the transfer-matrix approach. A comparison between the oblique-incidence optical transmission spectrum and the normal-incidence one shows quite a different transmission behaviours over a particular range of frequency.

  7. Characterizations of multilayer ZnO thin films deposited by sol-gel spin coating technique

    NASA Astrophysics Data System (ADS)

    Khan, M. I.; Bhatti, K. A.; Qindeel, Rabia; Alonizan, Norah; Althobaiti, Hayat Saeed

    In this work, zinc oxide (ZnO) multilayer thin films are deposited on glass substrate using sol-gel spin coating technique and the effect of these multilayer films on optical, electrical and structural properties are investigated. It is observed that these multilayer films have great impact on the properties of ZnO. X-ray Diffraction (XRD) confirms that ZnO has hexagonal wurtzite structure. Scanning Electron Microscopy (SEM) showed the crack-free films which have uniformly distributed grains structures. Both micro and nano particles of ZnO are present on thin films. Four point probe measured the electrical properties showed the decreasing trend between the average resistivity and the number of layers. The optical absorption spectra measured using UV-Vis. showed the average transmittance in the visible region of all films is 80% which is good for solar spectra. The performance of the multilayer as transparent conducting material is better than the single layer of ZnO. This work provides a low cost, environment friendly and well abandoned material for solar cells applications.

  8. Super-high density Si quantum dot thin film utilizing a gradient Si-rich oxide multilayer structure.

    PubMed

    Kuo, Kuang-Yang; Huang, Pin-Ruei; Lee, Po-Tsung

    2013-05-17

    A gradient Si-rich oxide multilayer (GSRO-ML) deposition structure is proposed to achieve super-high density Si quantum dot (QD) thin film formation while preserving QD size controllability for better photovoltaic properties. Our results indicate that the Si QD thin film using a GSRO-ML structure can efficiently increase the QD density and control the QD size. Its optical properties clearly promise the capability of effective bandgap engineering even though these QDs are closely formed. The Si QD thin film using a GSRO-ML structure obviously reveals better electro-optical properties than those using a [silicon dioxide/silicon-rich oxide] multilayer ([SiO2/SRO]-ML) structure owing to the better optical absorption and carrier transport properties. Therefore, we successfully demonstrate that our proposed GSRO-ML structure has great potential for application in solar cells integrating Si QD thin films.

  9. A Magnetron Sputter Deposition System for the Development of Multilayer X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Broadway, David; Ramsey, Brian; Gubarev, Mikhail

    2014-01-01

    The proposal objective is to establish the capability to deposit multilayer structures for x-ray, neutron, and EUV optic applications through the development of a magnetron sputtering deposition system. A specific goal of this endeavor is to combine multilayer deposition technology with the replication process in order to enhance the MSFC's position as a world leader in the design of innovative X-ray instrumentation through the development of full shell replicated multilayer optics. The development of multilayer structures is absolutely necessary in order to advance the field of X-ray astronomy by pushing the limit for observing the universe to ever increasing photon energies (i. e. up to 200 keV or higher); well beyond Chandra (approx. 10 keV) and NuStar's (approx. 75 keV) capability. The addition of multilayer technology would significantly enhance the X-ray optics capability at MSFC and allow NASA to maintain its world leadership position in the development, fabrication and design of innovative X-ray instrumentation which would be the first of its kind by combining multilayer technology with the mirror replication process. This marriage of these technologies would allow astronomers to see the universe in a new light by pushing to higher energies that are out of reach with today's instruments.To this aim, a magnetron vacum sputter deposition system for the deposition of novel multilayer thin film X-ray optics is proposed. A significant secondary use of the vacuum deposition system includes the capability to fabricate multilayers for applications in the field of EUV optics for solar physics, neutron optics, and X-ray optics for a broad range of applications including medical imaging.

  10. Reflectance, Optical Properties, and Stability of Molybdenum/Strontium and Molybdenum/Yttrium Multilayer Mirrors

    SciTech Connect

    Kjornrattanawanich, Benjawan

    2002-09-01

    The motivation of this work is to develop high reflectance normal-incidence multilayer mirrors in the 8-12 nm wavelength region for applications in astronomy and extreme ultraviolet lithography. To achieve this goal, Mo/Sr and Mo/Y multilayers were studied. These multilayers were deposited with a UHV magnetron sputtering system and their reflectances were measured with synchrotron radiation. High normal-incidence reflectances of 23% at 8.8 nm, 40.8% at 9.4 nm, and 48.3% at 10.5 nm were achieved. However, the reflectance of Mo/Sr multilayers decreased rapidly after exposure to air. Attempts to use thin layers of carbon to passivate the surface of Mo/Sr multilayers were unsuccessful. Experimental results on the refractive index $\\tilde{n}$ = 1-δ + iβ of yttrium and molybdenum in the 50-1300 eV energy region are reported in this work. This is the first time ever that values on the refractive index of yttrium are measured in this energy range. The absorption part β was determined through transmittance measurements. The dispersive part δ was calculated by means of the Kramers-Kronig formalism. The newly determined values of the refractive index of molybdenum are in excellent agreement with the published data. Those of yttrium are more accurate and contain fine structures around the yttrium M-absorption edges where Mo/Y multilayers operate. These improved sets of optical data lead to better design and modeling of the optical properties of Mo/Y multilayers. The reflectance quality of Mo/Y multilayers is dependent on their optical and structural properties. To correlate these properties with the multilayer reflectance, x-ray diffraction, Rutherford backscattering spectrometry, and transmission electron microscopy were used to analyze samples. Normal-incidence reflectances of 32.6% at 9.27 nm, 38.4% at 9.48 nm, and 29.6% at 9.46 nm were obtained from three representative Mo/Y multilayers which had about 0%, 25%, and 39% atomic oxygen assimilated in their yttrium layers

  11. Multilayer thin-film inspection through measurements of reflection coefficients.

    PubMed

    Wu, Kai; Lee, Cheng-Chung; Brock, Neal J; Kimbrough, Brad

    2011-08-15

    A vibration-insensitive interferometer is described to measure the thickness, refraction index and surface profile of thin-film stack at normal incidence. By satisfying the continuous boundary conditions of electric and magnetic fields at interfaces in a multilayer film stack, the reflection coefficient phase of the thin-film stack can be distinguished from the phase of spatial path difference, thus thickness and refraction index can be extracted. The experiment results showed that the measurement precision is significantly increased after the phase analysis was added into the reflectance analysis.

  12. Multilayer optical disc system using homodyne detection

    NASA Astrophysics Data System (ADS)

    Kurokawa, Takahiro; Ide, Tatsuro; Tanaka, Yukinobu; Watanabe, Koichi

    2014-09-01

    A write/read system using high-productivity multilayer optical discs was developed. The recording medium used in the system consists of planar recording layers and a separated guide layer, and is fabricated by web coating and lamination process. The recording layers in the medium are made of one-photon-absorption material, on which data can be recorded with a normal laser diode. The developed system is capable of focusing and tracking on the medium and amplifying readout signals by using phase-diversity homodyne detection. A highly layer-selective focusing method using homodyne detection was also proposed. This method obtains stable focus-error signals with clearly separated S-shaped curves even when layer spacing is quite narrow, causing large interlayer crosstalk. Writing on the medium and reading with the signal amplification effect of homodyne detection was demonstrated. In addition, the effectiveness of the method was experimentally evaluated.

  13. Method to adjust multilayer film stress induced deformation of optics

    DOEpatents

    Spiller, Eberhard A.; Mirkarimi, Paul B.; Montcalm, Claude; Bajt, Sasa; Folta, James A.

    2000-01-01

    Stress compensating systems that reduces/compensates stress in a multilayer without loss in reflectivity, while reducing total film thickness compared to the earlier buffer-layer approach. The stress free multilayer systems contain multilayer systems with two different material combinations of opposite stress, where both systems give good reflectivity at the design wavelengths. The main advantage of the multilayer system design is that stress reduction does not require the deposition of any additional layers, as in the buffer layer approach. If the optical performance of the two systems at the design wavelength differ, the system with the poorer performance is deposited first, and then the system with better performance last, thus forming the top of the multilayer system. The components for the stress reducing layer are chosen among materials that have opposite stress to that of the preferred multilayer reflecting stack and simultaneously have optical constants that allow one to get good reflectivity at the design wavelength. For a wavelength of 13.4 nm, the wavelength presently used for extreme ultraviolet (EUV) lithography, Si and Be have practically the same optical constants, but the Mo/Si multilayer has opposite stress than the Mo/Be multilayer. Multilayer systems of these materials have practically identical reflectivity curves. For example, stress free multilayers can be formed on a substrate using Mo/Be multilayers in the bottom of the stack and Mo/Si multilayers at the top of the stack, with the switch-over point selected to obtain zero stress. In this multilayer system, the switch-over point is at about the half point of the total thickness of the stack, and for the Mo/Be--Mo/Si system, there may be 25 deposition periods Mo/Be to 20 deposition periods Mo/Si.

  14. Design and optimization of microbolometer multilayer optical cavity

    NASA Astrophysics Data System (ADS)

    Awad, E.; Al-Khalli, N.; Abdel-Rahman, M.; Debbar, N.; Alduraibi, M.

    2015-03-01

    Microbolometers are the most widely used detectors in long-wave infrared uncooled thermal imagers. An optical cavity is required within a microbolometer structure to increase its optical absorption. In this work we present a detailed study on the design and optimization of a microbolometer optical cavity using Essential-Macleod package. In the simulations, the cavity is considered as thin film multi-layers that form cascaded Fabry-Perot optical cavities. In the design phase, the layers structures are selected including materials and initial thickness. The absorbing layers are chosen to be vanadium-pentoxide (V2O5) and titanium (Ti). In the optimization phase, the designed layer thicknesses are varied to maximize optical absorption within the absorbing layers. The simulations show that Ti layer absorption dominates over V2O5 layer. Also, the optimization proves that the air-gap cavity thickness is not simply quarter-wavelength because of the complex cascaded Fabry-Perot structure. The optimized air-gap thickness here is ≈3.5 µm at 10.6µm wavelength.

  15. Design and optimization of microbolometer multilayer optical cavity

    SciTech Connect

    Awad, E.; Al-Khalli, N.; Debbar, N.; Abdel-Rahman, M.; Alduraibi, M.

    2015-03-30

    Microbolometers are the most widely used detectors in long-wave infrared uncooled thermal imagers. An optical cavity is required within a microbolometer structure to increase its optical absorption. In this work we present a detailed study on the design and optimization of a microbolometer optical cavity using Essential-Macleod package. In the simulations, the cavity is considered as thin film multi-layers that form cascaded Fabry-Perot optical cavities. In the design phase, the layers structures are selected including materials and initial thickness. The absorbing layers are chosen to be vanadium-pentoxide (V{sub 2}O{sub 5}) and titanium (Ti). In the optimization phase, the designed layer thicknesses are varied to maximize optical absorption within the absorbing layers. The simulations show that Ti layer absorption dominates over V{sub 2}O{sub 5} layer. Also, the optimization proves that the air-gap cavity thickness is not simply quarter-wavelength because of the complex cascaded Fabry-Perot structure. The optimized air-gap thickness here is ≈3.5 µm at 10.6µm wavelength.

  16. Super stretchy polymer multilayer thin films with tunable gas barrier

    NASA Astrophysics Data System (ADS)

    Xiang, Fangming; Ward, Sarah; Givens, Tara; Grunlan, Jaime

    2015-03-01

    Super stretchy multilayer thin film assemblies with tunable gas barrier were fabricated using layer-by-layer (LbL) assembly. Unlike ionically-bonded gas barrier coatings that exhibit mud-cracking after 10% strain, hydrogen-bonded polyethylene oxide (PEO) and polyacrylic acid (PAA) multilayer thin films show no cracking after 100% strain due to low modulus. It is believed that the exceptional elasticity of this thin film originates from the intrinsic elasticity of PEO and the moderate hydrogen bond strength between PEO and PAA. The oxygen transmission rate (OTR) of a 1.58 mm thick natural rubber sheet can be reduced 10 times with a 367-nm-thick PAA/PEO nanocoating. This gas barrier improvement is largely retained after 100% strain. The modulus and oxygen permeability of PAA/PEO assembly can be tailored through altering the assembling pH. By setting the assembling pH to 2.75, a 50% reduction in permeability can be achieved, while maintaining the elasticity of the assembly. These findings mark the first super stretchy gas barrier thin film, which is useful for elastomeric substrates designed to hold air pressure.

  17. Thin θ -film optics

    NASA Astrophysics Data System (ADS)

    Huerta, Luis

    2016-12-01

    A Chern-Simons theory in 3D is accomplished by the so-called θ term in the action (θ /2 )∫F ∧F , which contributes only to observable effects on the boundaries of such a system. When electromagnetic radiation interacts with the system, the wave is reflected and its polarization is rotated at the interface, even when both the θ system and the environment are pure vacuum. These topics have been studied extensively. Here, we investigate the optical properties of a thin θ film, where multiple internal reflections could interfere coherently. The cases of pure vacuum and a material with magnetoelectric properties are analyzed. It is found that the film reflectance is enhanced compared to ordinary non-θ systems and the interplay between magnetoelectric properties and the θ parameter yield film opacity and polarization properties which could be interesting in the case of topological insulators, among other topological systems.

  18. Strong ultraviolet and violet emissions from ZnO/TiO2 multilayer thin films

    NASA Astrophysics Data System (ADS)

    Xu, Linhua; Zheng, Gaige; Wu, Hongyan; Wang, Junfeng; Gu, Fang; Su, Jing; Xian, Fenglin; Liu, Zhanhui

    2013-06-01

    ZnO/TiO2 multilayer thin films were prepared by electron beam evaporation and the influence of annealing temperature on their structural and optical properties was investigated. The analyses of X-ray diffraction (XRD) show that TiO2 in the as-deposited ZnO/TiO2 multilayer thin film as well as in that one annealed at 300 °C is amorphous. When the annealing temperature is increased up to 400 °C, the TiO2 is transformed into a brookite phase. Eventually, the TiO2 is transformed into an anatase phase with the annealing temperature rising up to 500 °C. However, ZnO in these composite films all crystallizes in a wurtzite structure and has a preferred orientation along the (0 0 2) direction whether the ZnO/TiO2 multilayer thin film is annealed or not. The photoluminescence spectra show that all the samples have two strong emission peaks including an ultraviolet (UV) peak and a violet peak. The strong UV and violet co-emissions in ZnO materials is seldom reported previously. With the increase of annealing temperature, both the UV and violet emissions are enhanced. However, the intensity of UV emission is increased faster than that of the violet emission under the same annealing temperature. The mechanism of the violet emission and the reason for the variations of the UV and violet emissions with the different annealing temperatures are analyzed.

  19. Articles including thin film monolayers and multilayers

    DOEpatents

    Li, DeQuan; Swanson, Basil I.

    1995-01-01

    Articles of manufacture including: (a) a base substrate having an oxide surface layer, and a multidentate ligand, capable of binding a metal ion, attached to the oxide surface layer of the base substrate, (b) a base substrate having an oxide surface layer, a multidentate ligand, capable of binding a metal ion, attached to the oxide surface layer of the base substrate, and a metal species attached to the multidentate ligand, (c) a base substrate having an oxide surface layer, a multidentate ligand, capable of binding a metal ion, attached to the oxide surface layer of the base substrate, a metal species attached to the multidentate ligand, and a multifunctional organic ligand attached to the metal species, and (d) a base substrate having an oxide surface layer, a multidentate ligand, capable of binding a metal ion, attached to the oxide surface layer of the base substrate, a metal species attached to the multidentate ligand, a multifunctional organic ligand attached to the metal species, and a second metal species attached to the multifunctional organic ligand, are provided, such articles useful in detecting the presence of a selected target species, as nonliear optical materials, or as scavengers for selected target species.

  20. Multilayer injection moulding of thick-walled optical plastics parts

    NASA Astrophysics Data System (ADS)

    Hopmann, Ch.; Neuss, A.; Weber, M.; Walach, P.

    2014-05-01

    Optical components are often thick-walled. The cycle time of precise polymer optics with a wall thickness of more than 20 mm exceeds several minutes. The multilayer injection moulding or compression moulding lowers the cycle time and increases the quality of the moulded parts. For the production of multilayer moulded lenses the mould design plays an important role. An innovative mould concept is presented with the possiblity to produce double or triple layer lenses. To ensure the quality and the endurance of multilayer moulded optical components in their applications, the cohesion in the interface is important. Tensile shear tests show the ability of multilayer moulded parts with high cohesion values for optical applications.

  1. Optical Properties of Multilayer CdSe/POLYMER Structures

    NASA Astrophysics Data System (ADS)

    Red'Ko, V. P.; Voitenkov, A. I.; Kovalenko, O. E.

    The effects of preparation condition, concentration and size of particles upon optical and photoelectrical characteristics of multilayer structures CdSe/polyethylene terephthalate obtained by electron-beam evaporation were investigated.

  2. Switching between optical bistability and multistability in plasmonic multilayer nanoparticles

    NASA Astrophysics Data System (ADS)

    Daneshfar, Nader; Naseri, Tayebeh

    2017-01-01

    We study the nonlinear optical response of multilayer metallic nanoparticles driven by an electromagnetic wave, which can show large field enhancement, hence significantly enhancing optical processes. In addition to optical bistability (OB), we find that optical multistability (OM), which plays a more important role in some applications than OB, is achievable and can be obtained in a multilayer plasmonic nanoparticle. Our results demonstrate that owing to strong localized fields created in the core and each layer of multilayer nanoshells, which occurs in the particles at frequencies close to the surface plasmon resonance, multilayer nanoparticles are promising systems with unique optical characteristics to control the light by light at the nanometer scale. It is demonstrated that OB can be converted to OM via adjusting the wavelength of the applied field and the size of the nanoshell, and the system can manifest optical hysteresis. It is found that the optical bistable or multistable threshold and the shape of hysteresis loops are strongly dependent on the thickness of shells, the incident wavelength, the permittivity of the surrounding medium, and the composition of the core and the inner/outer layers. We also give a discussion on the impact of the exciton-plasmon interaction and the intrinsic size effect on the nonlinear optical response of multilayer spherical nanoparticles.

  3. Recurrent methods of the minimization of optical multilayer structures for fiber-optic communication facilities

    NASA Astrophysics Data System (ADS)

    Bagmanov, Valeriy H.; Kostrov, Sergey V.; Sultanov, Albert H.

    2008-12-01

    Optical multilayer selective mirror (OMSM) are widely used in different applications of fiber optic telecommunications. In this paper we represent the solution for synthesis of OMSM for constructing wavelength division multiplexing (WDM) optical filter used in add/drop multiplexers.

  4. Spin-orbit torque induced reversible coercivity change in Co/Pd multilayer thin films

    NASA Astrophysics Data System (ADS)

    Kumar, Sandeep

    In this work we report reversible reduction in coercivity of Co/Pd multilayer thin films under high-density direct current biasing. We carried out in-situ focused magneto optic Kerr effect based hysteresis measurement while the specimen was under DC bias. The experiments show a reversible reduction in coercivity during the application of direct current. We propose this reduction occurs due to the spin-orbit torques (Rashba) generated at high current densities. Using an in-situ transmission electron microscope biasing experiment, we also showed the presence of dissymmetric lattice structure of Co/Pd multilayers. Our results suggest that the Rashba torque is the dominant spin-orbit torque since coercivity change is a bulk phenomenon as compared to spin Hall effect.

  5. Highly stable thin film transistors using multilayer channel structure

    NASA Astrophysics Data System (ADS)

    Nayak, Pradipta K.; Wang, Zhenwei; Anjum, D. H.; Hedhili, M. N.; Alshareef, H. N.

    2015-03-01

    We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO2) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60 °C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO2 layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO2 layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

  6. Highly stable thin film transistors using multilayer channel structure

    SciTech Connect

    Nayak, Pradipta K.; Wang, Zhenwei; Anjum, D. H.; Hedhili, M. N.; Alshareef, H. N.

    2015-03-09

    We report highly stable gate-bias stress performance of thin film transistors (TFTs) using zinc oxide (ZnO)/hafnium oxide (HfO{sub 2}) multilayer structure as the channel layer. Positive and negative gate-bias stress stability of the TFTs was measured at room temperature and at 60 °C. A tremendous improvement in gate-bias stress stability was obtained in case of the TFT with multiple layers of ZnO embedded between HfO{sub 2} layers compared to the TFT with a single layer of ZnO as the semiconductor. The ultra-thin HfO{sub 2} layers act as passivation layers, which prevent the adsorption of oxygen and water molecules in the ZnO layer and hence significantly improve the gate-bias stress stability of ZnO TFTs.

  7. Investigation of multi-layer thin films for energy storage.

    SciTech Connect

    Renk, Timothy Jerome; Monson, Todd

    2009-01-01

    We investigate here the feasibility of increasing the energy density of thin-film capacitors by construction of a multi-layer capacitor device through ablation and redeposition of the capacitor materials using a high-power pulsed ion beam. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The dielectric capacitor filler material was a composition of Lead-Lanthanum-Zirconium-Titanium oxide (PLZT). The energy storage can be increased by using material of intrinsically high dielectric constant, and constructing many thin layers of this material. For successful device construction, there are a number of challenging requirements including correct stoichiometric and crystallographic composition of the deposited PLZT. This report details some success in satisfying these requirements, even though the attempt at device manufacture was unsuccessful. The conclusion that 900 C temperatures are necessary to reconstitute the deposited PLZT has implications for future manufacturing capability.

  8. Optical Properties of Multi-Layered Insulation

    NASA Technical Reports Server (NTRS)

    Rodriguez, Heather M.; Abercromby, Kira J.; Barker, Edwin

    2007-01-01

    Multi-layer insulation, MLI, is a material used on rocket bodies and satellites mainly for thermal insulation. MLI can be comprised of a variety of materials, layer numbers, and dimensions based on its purpose. A common composition of MLI consists of outer facing copper-colored Kapton with an aluminized backing for the top and bottom layers and the middle consisting of alternating layers of DARCON or Nomex netting with aluminized Mylar. If this material became separated from the spacecraft or rocket body its orbit would vary greatly in eccentricity due to its high area to mass (A/m) and susceptibility to solar radiation pressure perturbations. Recently a debris population was found with high A/m, which could be MLI. Laboratory photometric measurements of one intact piece and three different layers of MLI is presented in an effort to predict the characteristics of a MLI light curve and aid in identifying the source of the new population. For this paper, the layers used will be consistent with the common MLI mentioned in the above paragraph. Using a robotic arm, the piece was rotated from 0-360 degrees in one degree increments along the object s longest axis. Laboratory photometric data was recorded with a CCD camera using various filters (Johnson B, Johnson V and Bessell R). The measurements were taken at an 18 degree (light-object-camera) phase angle. As expected, the MLI pieces showed characteristics similar to a bimodal magnitude plot of a flat plate, but with more photometric features, dependant upon the layer of MLI. Time exposures varied from piece to piece such that the amount of pixels saturated would be minimal. In addition to photometric laboratory measurements, laboratory spectral measurements are shown for the same MLI samples. Spectral data will be combined to match the wavelength region of photometric data so a measure of truth can be established for the photometric measurements. Spectral data shows a strong absorption feature near 4800 angstroms

  9. Multilayer cloud detection and retrieval of cloud physical and optical properties from thermal infrared measurements

    NASA Astrophysics Data System (ADS)

    Iwabuchi, H.; Tokoro, Y.; Saito, M.; Putri, N. S.; Katagiri, S.; Sekiguchi, M.

    2015-12-01

    Recent studies using active remote sensing have revealed significant occurrence of multi-layer cloud. Detection of multi-layer cloud is important in passive remote sensing for quality assessment of cloud property retrieval and identification of uncertain retrievals. An algorithm using several thermal infrared (TIR) bands at 6-13.5 micron wavelengths to detect multilayer cloud and retrieve cloud physical and optical properties including cloud thermodynamic phase is developed. This significantly extends applicability of passive remote sensing and improves accuracy of cloud property retrieval. The method uses the split window bands as well as the carbon dioxide and water vapor absorption bands. The forward model uses the two-stream approximation to solve radiative transfer with gaseous absorption treated by the correlated-k distribution method. Brightness temperature errors are evaluated by model-to-model and model-to-measurement comparisons. Top pressure of lower cloud in multi-layer cloud column can be retrieved if the upper cloud optical thickness is less than 6. The optimal estimation method is used to simultaneously infer several cloud properties including water path, effective particle radius and cloud-top pressure. The method is applied to the Moderate Resolution Imaging Spectroradiometer (MODIS) using 10 TIR bands and compared to MODIS operational product and active remote sensing measurements, showing promising results. The TIR method well detects optically thin clouds and retrieve their properties with relatively high accuracy. Particularly, cloud-top of optically thin cloud is estimated well. Multi-layer cloud detection works usually, while the TIR measurements miss very thin cloud that appears near the tropopause. The algorithm will be applied to frequent observation data from a new Japanese geostationary satellite, Himawari-8.

  10. Functional Multilayered Transparent Conducting Oxide Thin Films for Photovoltaic Devices

    SciTech Connect

    Noh, J. H.; Lee, S.; Kim, J. Y.; Lee, J. K.; Han, H. S.; Cho, C. M.; Cho, I. S.; Jung, H. S.; Hong, K. S.

    2009-01-01

    In this study, we present a thermally stable multilayered transparent conducting oxide (TCO) functionalized for dye-sensitized solar cells (DSSCs). Nb-doped TiO{sub 2} (NTO) layers deposited on conventional Sn-doped In{sub 2}O{sub 3} (ITO) substrates using pulsed laser deposition (PLD) enhanced the optical-to-electrical conversion efficiency of the DSSCs by as much as 17% compared to that of bare ITO-based DSSCs. The electrical properties and J-V characteristics of the multilayered NTO/ITO films showed that the improved cell performance was due to the facilitated charge injection from TiO{sub 2} to ITO that resulted from the formation of an ohmic contact with ITO, as well as the conserved high conductivity of ITO after the oxidizing annealing process. Moreover, the NTO/ITO-based DSSC exhibited higher efficiency than a F-doped SnO{sub 2}(FTO)-based one, which demonstrates that optimization of multilayered NTO-based TCOs is a realistic approach for achieving highly efficient photoenergy conversion devices.

  11. Study of NbC thin films for soft X-ray multilayer applications

    SciTech Connect

    Singh, Amol E-mail: rrcat.amol@gmail.com; Modi, Mohammed H.; Lodha, G. S.; Rajput, Parasmani; Jha, S. N.

    2015-06-24

    Compound materials are being used in soft x-ray and Extreme ultraviolet (EUV) optics applications. Structural properties of compound materials changes drastically when ultrathin films are formed from bulk material. Structural properties need to be investigated to determine the suitability of compound materials in soft x-ray multilayer applications. In the present study Niobium carbide (NbC) thin films were deposited using ion beam sputtering of an NbC target on Si (100) substrate. Thickness roughness and film mass density was determined from the X-ray reflectivity (XRR) data. XRR data revealed that the film mass density was increasing with increase in film thickness. For 500Ǻ thick film, mass density of 6.85 g/cm{sup 3}, close to bulk density was found. Rms roughness for all the films was less than 10Å. Local structure of NbC thin films was determined from EXAFS measurements. The EXAFS data showed an increase in Nb-C and Nb-(C)-Nb peak ratio approaches towards bulk NbC with increasing thickness of NbC. From the present study, NbC thin films were found suitable for actual use in soft x-ray multilayer applications.

  12. Atomic layer deposition of thin superconducting films and multilayers

    NASA Astrophysics Data System (ADS)

    Proslier, Thomas; Klug, Jeffrey; Groll, Nikolas; Altin, Serdar; Becker, Nicholas

    2012-02-01

    We report the use of atomic layer deposition (ALD) to synthesize thin superconducting films and multilayer superconductor-insulator (S-I) heterostructures including: nitrides, carbides, and silicides, nitrides of molybdenum and titanium, and Nb1-xTixN/AlN-based S-I heterostructures. The atomic-scale thickness control afforded by ALD enables the study of superconductivity and associated phenomena in homogeneous layers in the ultra-thin film limit. Two-dimensional superconductivity in such films is of interest from a fundamental point of view, as a new effect has recently been discovered at ultra-low temperature in thin superconducting films made by ALD: the super-insulating transition. Furthermore, the ALD technique applied to superconducting films opens the way for a variety of applications, including improving the performance and decreasing the cost of high energy particle accelerators, superconducting wires for energy storage, and bolometers for radiation detection. In this respect, we will present results on the ALD growth processes, the metallurgy and superconducting properties of these coatings.

  13. Thin Aerogel as a Spacer in Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Moroz, Nancy

    2015-01-01

    Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on rea-lworld tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

  14. Thin Aerogel as a Spacer in Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Moroz, Nancy

    2015-01-01

    Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on real-world tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

  15. Investigation of optical and interfacial properties of Ag/Ta{sub 2}O{sub 5} metal dielectric multilayer structure

    SciTech Connect

    Sarkar, P. Jena, S.; Tokas, R. B.; Thakur, S.; Sahoo, N. K.; Rao, K. D.; Misal, J. S.; Prathap, C.

    2015-06-24

    One-dimensional periodic metal-dielectric multilayer thin film structures consisting of Ag and Ta{sub 2}O{sub 5} alternating layers are deposited on glass substrate using RF magnetron sputtering technique. The spectral property of the multilayers has been investigated using spectrophotometry technique. The optical parameters such as refractive index, extinction coefficient, band gap etc., along with film thickness as well as the interfacial layer properties which influence these properties have been probed with spectroscopic ellipsometry technique. Atomic force microscopy has been employed to characterize morphological properties of this metal-dielectric multilayer.

  16. Multilayer thin film design as far ultraviolet polarizers

    NASA Technical Reports Server (NTRS)

    Kim, Jongmin; Zukic, Muamer; Torr, Douglas T.

    1993-01-01

    We use a concept of induced transmission and absorption to design multilayer thin film reflection polarizers in the FUV region. We achieve high s-polarization reflectance and a high degree of polarization by means of a MgF2/Al/MgF2 three layer structure on an opaque thick film of aluminum as the substrate. For convenience they are designed at a 45 deg angle of incidence. For example, our polarizer designed for the Lyman-alpha line (121.6 nm) has 88.67 percent reflectance for the s-polarization case, and 1.21 percent for the p-polarization case, with a degree of polarization of 97.31 percent. If we make a double surface polarizer with this design, it will have a degree of polarization of 99.96 percent and s-polarization throughput of 78.62 percent.

  17. Solid-state dewetting of magnetic binary multilayer thin films

    NASA Astrophysics Data System (ADS)

    Esterina, Ria; Liu, X. M.; Adeyeye, A. O.; Ross, C. A.; Choi, W. K.

    2015-10-01

    We examined solid-state dewetting behavior of magnetic multilayer thin film in both miscible (CoPd) and immiscible (CoAu) systems and found that CoPd and CoAu dewetting stages follow that of elemental materials. We established that CoPd alloy morphology and dewetting rate lie in between that of the elemental materials. Johnson-Mehl-Avrami analysis was utilized to extract the dewetting activation energy of CoPd. For CoAu, Au-rich particles and Co-rich particles are distinguishable and we are able to predict the interparticle spacings and particle densities for the particles that agree well with the experimental results. We also characterized the magnetic properties of CoPd and CoAu nanoparticles.

  18. Glassy dynamics in CuMn thin-film multilayers

    NASA Astrophysics Data System (ADS)

    Zhai, Qiang; Harrison, David C.; Tennant, Daniel; Dalhberg, E. Dan; Kenning, Gregory G.; Orbach, Raymond L.

    2017-02-01

    Thin-film multilayered spin-glass CuMn/Cu structures display glassy dynamics. The freezing temperature Tf was measured for 40 layers of CuMn films of thickness L =4.5 ,9.0 , and 20.0 nm, sandwiched between nonmagnetic Cu layers of thickness ≈60 nm. The Kenning effect, Tf∝lnL , is shown to follow from power-law dynamics where the correlation length grows from nucleation as ξ (t ,T ) =c1a0(t/τ0) c2(T /Tg) , leading to [(Tf/Tg) c2ln(tco/τ0) ] +lnc1=ln(L /a0) . Here, Tg is the bulk spin-glass temperature, c1 and c2 are constants determined from the spin-glass dynamics, tco is the time for the correlation length to grow to the film thickness, τ0 is a characteristic exchange time ≈ℏ /kBTg , and a0 is the average Mn-Mn separation. For t ≥tco , the magnetization dynamics are simple activated, with a single activation energy Δmax(L ) /kBTg=(1 /c2) [ln(L /a0) -lnc1] that does not change with time. Values for all these parameters are found for the three values of L explored in these measurements. We find experimentally Δmax(L ) /kB =907 , 1246, and 1650 K, respectively, for the three CuMn thin-film multilayer thicknesses, consistent with power-law dynamics. We perform a similar analysis based on the activated dynamics of the droplet model and find a much larger spread for Δmax(L ) than found experimentally.

  19. Athermalization and thermal characteristics of multilayer diffractive optical elements.

    PubMed

    Wang, Ju; Xue, Changxi

    2015-11-20

    A mathematical model to analyze the thermal characteristics of the multilayer diffractive optical elements (MLDOEs) is presented with consideration of the thermal characteristics for the refractive optical elements and single-layer diffractive optical elements. The analysis process of athermalization for MLDOEs by using the opto-thermal expansion coefficient of optical materials is given. Meanwhile, the microstructure heights of surface relief MLDOEs, the optical path difference, and the polychromatic integral diffraction efficiency with the ambient temperature changed are analyzed. The analysis results can be used to guide an athermalization design for the hybrid refractive-diffractive optical systems with MLDOEs.

  20. Self-Assembled Multilayer Structure and Enhanced Thermochromic Performance of Spinodally Decomposed TiO2-VO2 Thin Film.

    PubMed

    Sun, Guangyao; Zhou, Huaijuan; Cao, Xun; Li, Rong; Tazawa, Masato; Okada, Masahisa; Jin, Ping

    2016-03-23

    Composite films of VO2-TiO2 were deposited on sapphire (11-20) substrate by cosputtering method. Self-assembled well-ordered multilayer structure with alternating Ti- and V-rich epitaxial thin layer was obtained by thermal annealing via a spinodal decomposition mechanism. The structured thermochromic films demonstrate superior optical modulation upon phase transition, with significantly reduced transition temperature. The results provide a facile and novel approach to fabricate smart structures with excellent performance.

  1. Thin display optical projector

    DOEpatents

    Veligdan, James T.

    1999-01-01

    An optical system (20) projects light into a planar optical display (10). The display includes laminated optical waveguides (12) defining an inlet face (14) at one end and an outlet screen (16) at an opposite end. A first mirror (26) collimates light from a light source (18) along a first axis, and distributes the light along a second axis. A second mirror (28) collimates the light from the first mirror along the second axis to illuminate the inlet face and produce an image on the screen.

  2. Antifouling coating of cellulose acetate thin films with polysaccharide multilayers.

    PubMed

    Mohan, Tamilselvan; Kargl, Rupert; Tradt, Karin Eva; Kulterer, Martin R; Braćić, Matej; Hribernik, Silvo; Stana-Kleinschek, Karin; Ribitsch, Volker

    2015-02-13

    In this investigation, partially deacetylated cellulose acetate (DCA) thin films were prepared and modified with hydrophilic polysaccharides with the layer-by-layer (LbL) technique. As polysaccharides, chitosan (CHI) and carboxymethyl cellulose (CMC) were used. DCA thin films were manufactured by exposing spin coated cellulose acetate to potassium hydroxide solutions for various times. The deacetylation process was monitored by attenuated total reflectance-infrared spectroscopy, film thickness and static water contact angle measurements. A maximum of three bilayers was created from the alternating deposition of CHI and CMC on the DCA films under two different conditions namely constant ionic strengths and varying pH values of the CMC solutions. Precoatings of CMC at pH 2 were used as a base layer. The sequential deposition of CMC and CHI was investigated with a quartz crystal microbalance with dissipation, film thickness, static water contact angle and atomic force microscopy (AFM) measurements. The versatility and applicability of the developed functional coatings was shown by removing the multilayers by rinsing with mixtures containing HCl/NaCl. The developed LbL coatings are used for studying the fouling behavior of bovine serum albumin (BSA).

  3. Investigation of Electrical and Optical Properties of Highly Transparent TCO/Ag/TCO Multilayer.

    PubMed

    Kim, Sunbo; Lee, Jaehyeong; Dao, Vinh Ai; Ahn, Shihyun; Hussain, Shahzada Qamar; Park, Jinjoo; Jung, Junhee; Lee, Chan; Song, Bong-Shik; Choi, Byoungdeog; Lee, Youn-Jung; Iftiquar, S M; Yi, Junsin

    2015-03-01

    Transparent conductive oxides (TCOs) have been widely used as transparent electrodes for opto-electronic devices, such as solar cells, flat-panel displays, and light-emitting diodes, because of their unique characteristics of high optical transmittance and low electrical resistivity. Among various TCO materials, zinc oxide based films have recently received much attention because they have advantages over commonly used indium and tin-based oxide films. Most TCO films, however, exhibit valleys of transmittance in the wavelength range of 550-700 nm, lowering the average transmittance in the visible region and decreasing short-circuit current (Isc) of solar cells. A TCO/Ag/TCO multi-layer structure has emerged as an attractive alternative because it provides optical characteristics without the valley of transmittance compared with a 100-nm-thick single-layer TCO. In this article, we report the electrical, optical and surface properties of TCO/Ag/TCO. These multi-layers were deposited at room temperature with various Ag film thicknesses from 5 to 15 nm while the thickness of TCO thin film was fixed at 40 nm. The TCO/Ag/TCO multi-layer with a 10-nm-thick Ag film showed optimum transmittance in the visible (400-800 nm) wavelength region. These multi-layer structures have advantages over TCO layers of the same thickness.

  4. Indentation-derived elastic modulus of multilayer thin films: Effect of unloading induced plasticity

    SciTech Connect

    Jamison, Ryan Dale; Shen, Yu -Lin

    2015-08-13

    Nanoindentation is useful for evaluating the mechanical properties, such as elastic modulus, of multilayer thin film materials. A fundamental assumption in the derivation of the elastic modulus from nanoindentation is that the unloading process is purely elastic. In this work, the validity of elastic assumption as it applies to multilayer thin films is studied using the finite element method. The elastic modulus and hardness from the model system are compared to experimental results to show validity of the model. Plastic strain is shown to increase in the multilayer system during the unloading process. Additionally, the indentation-derived modulus of a monolayer material shows no dependence on unloading plasticity while the modulus of the multilayer system is dependent on unloading-induced plasticity. Lastly, the cyclic behavior of the multilayer thin film is studied in relation to the influence of unloading-induced plasticity. Furthermore, it is found that several cycles are required to minimize unloading-induced plasticity.

  5. Roll-to-Roll sputtered ITO/Cu/ITO multilayer electrode for flexible, transparent thin film heaters and electrochromic applications

    PubMed Central

    Park, Sung-Hyun; Lee, Sang-Mok; Ko, Eun-Hye; Kim, Tae-Ho; Nah, Yoon-Chae; Lee, Sang-Jin; Lee, Jae Heung; Kim, Han-Ki

    2016-01-01

    We fabricate high-performance, flexible, transparent electrochromic (EC) films and thin film heaters (TFHs) on an ITO/Cu/ITO (ICI) multilayer electrode prepared by continuous roll-to-roll (RTR) sputtering of ITO and Cu targets. The RTR-sputtered ICI multilayer on a 700 mm wide PET substrate at room temperature exhibits a sheet resistance of 11.8 Ω/square and optical transmittance of 73.9%, which are acceptable for the fabrication of flexible and transparent EC films and TFHs. The effect of the Cu interlayer thickness on the electrical and optical properties of the ICI multilayer was investigated in detail. The bending and cycling fatigue tests demonstrate that the RTR-sputtered ICI multilayer was more flexible than a single ITO film because of high strain failure of the Cu interlayer. The flexible and transparent EC films and TFHs fabricated on the ICI electrode show better performances than reference EC films and TFHs with a single ITO electrode. Therefore, the RTR-sputtered ICI multilayer is the best substitute for the conventional ITO film electrode in order to realize flexible, transparent, cost-effective and large-area EC devices and TFHs that can be used as flexible and smart windows. PMID:27653830

  6. Roll-to-Roll sputtered ITO/Cu/ITO multilayer electrode for flexible, transparent thin film heaters and electrochromic applications

    NASA Astrophysics Data System (ADS)

    Park, Sung-Hyun; Lee, Sang-Mok; Ko, Eun-Hye; Kim, Tae-Ho; Nah, Yoon-Chae; Lee, Sang-Jin; Lee, Jae Heung; Kim, Han-Ki

    2016-09-01

    We fabricate high-performance, flexible, transparent electrochromic (EC) films and thin film heaters (TFHs) on an ITO/Cu/ITO (ICI) multilayer electrode prepared by continuous roll-to-roll (RTR) sputtering of ITO and Cu targets. The RTR-sputtered ICI multilayer on a 700 mm wide PET substrate at room temperature exhibits a sheet resistance of 11.8 Ω/square and optical transmittance of 73.9%, which are acceptable for the fabrication of flexible and transparent EC films and TFHs. The effect of the Cu interlayer thickness on the electrical and optical properties of the ICI multilayer was investigated in detail. The bending and cycling fatigue tests demonstrate that the RTR-sputtered ICI multilayer was more flexible than a single ITO film because of high strain failure of the Cu interlayer. The flexible and transparent EC films and TFHs fabricated on the ICI electrode show better performances than reference EC films and TFHs with a single ITO electrode. Therefore, the RTR-sputtered ICI multilayer is the best substitute for the conventional ITO film electrode in order to realize flexible, transparent, cost-effective and large-area EC devices and TFHs that can be used as flexible and smart windows.

  7. The Role of Annealing Process in Ag-Based BaSnO3 Multilayer Thin Films.

    PubMed

    Wu, Muying; Yu, Shihui; He, Lin; Yang, Lei; Zhang, Weifeng

    2016-12-01

    The BaSnO3/Ag/BaSnO3 multilayer structure was designed and fabricated on a quartz glass by magnetron sputtering, followed by an annealing process at a temperature from 150 to 750 °C in air. In this paper, we investigated the influence of the annealing temperature on the structural, optical, and electrical properties of the multilayers and proposed the mechanisms of conduction and transmittance. The maximum value of the figure of merit of 31.8 × 10(-3) Ω(-1) was achieved for the BaSnO3/Ag/BaSnO3 multilayer thin films annealed at 150 °C, while the average optical transmittance in the visible ranges was >84 %, the resistivity was 5.71 × 10(-5) Ω cm, and the sheet resistance was 5.57 Ω/sq. When annealed at below 600 °C, the values of resistivity and transmittance of the multilayers were within an acceptable range (resistivity <5.0 × 10(-4) Ω cm, transmittance >80 %). The observed property of the multilayer film is suitable for the application of transparent conductive electrodes.

  8. Simulated vibrational sum frequency generation from a multilayer thin film system with two active interfaces.

    PubMed

    O'Brien, Daniel B; Massari, Aaron M

    2013-04-21

    In the field of surface-specific vibrational sum frequency generation spectroscopy (VSFG) on organic thin films, optical interferences combined with the two-interface problem presents a challenge in terms of qualitative assessment of the data and quantitative modeling. The difficulty is amplified when considering systems comprised of more than a single material thin film layer. Recently, in our lab we have developed a generalized model that describes thin film interference in interface-specific nonlinear optical spectroscopies from arbitrary multilayer systems. Here, we apply the model to simulate VSFG spectra from the simplest multilayer: a system of two thin films, one of which is an organic small molecule and the other is a dielectric layer on a semiconductor substrate system where we idealize that the organic interfaces are equally VSFG active. Specifically, we consider the molecule N,N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) deposited on a silicon wafer with a thermally grown oxide dielectric. We present results for the four polarization experiments that sample the nonzero nonlinear susceptibility elements of macroscopically centrosymmetric materials (ssp, sps, pss, and ppp) and in two mIR frequency windows (the imide carbonyl stretches around 1680 cm(-1) and the alkyl stretches around 2900 cm(-1)) as a function of both thin film thicknesses with fixed input beam angles. We use frequency dependent refractive indices for all materials. The goal is to illustrate some of the intricacies contained in the intensity data of such systems. Of particular interest is the effect of the relative polar orientation of modes at the interfaces and the possibility of designing a system where the collected signal is exclusively attributable to a single interface. Our calculations indicate that in order to unambiguously identify the relative polar orientation one must experimentally vary an additional system parameter such as thin film thickness or input beam angle

  9. Thin optical display panel

    DOEpatents

    Veligdan, James Thomas

    1997-01-01

    An optical display includes a plurality of optical waveguides each including a cladding bound core for guiding internal display light between first and second opposite ends by total internal reflection. The waveguides are stacked together to define a collective display thickness. Each of the cores includes a heterogeneous portion defining a light scattering site disposed longitudinally between the first and second ends. Adjacent ones of the sites are longitudinally offset from each other for forming a longitudinal internal image display over the display thickness upon scattering of internal display light thereagainst for generating a display image. In a preferred embodiment, the waveguides and scattering sites are transparent for transmitting therethrough an external image in superposition with the display image formed by scattering the internal light off the scattering sites for defining a heads up display.

  10. Optically active polyelectrolyte multilayers as membranes for chiral separations.

    PubMed

    Rmaile, Hassan H; Schlenoff, Joseph B

    2003-06-04

    Ultrathin films of chiral polyelectrolyte complex, prepared by the multilayering process, exhibit selectivity in the membrane separations of optically active compounds, such as l- and d-ascorbic acid. The flux through these polyelectrolyte multilayers, PEMUs, is exceptionally high and may be controlled by the concentration of salt present in the permeating solutions. Both in-situ ATR-FTIR and chiral capillary electrochromatography indicate that flux selectivity is mainly kinetically controlled, stemming from a difference in diffusion rates of various enantiomers through PEMUs, rather than a difference in partitioning.

  11. A concept for a soft gamma-ray concentrator using thin-film multilayer structures

    NASA Astrophysics Data System (ADS)

    Bloser, Peter F.; Shirazi, Farzane; Echt, Olof; Krzanowski, James E.; Legere, Jason S.; McConnell, Mark L.; Tsavalas, John G.; Wong, Emily N.; Aliotta, Paul H.

    2016-07-01

    We are investigating the use of thin-film, multilayer structures to form optics capable of concentrating soft gamma rays with energies greater than 100 keV, beyond the reach of current grazing-incidence hard X-ray mirrors. Alternating layers of low- and high-density materials (e.g., polymers and metals) will channel soft gamma-ray photons via total external reflection. A suitable arrangement of bent structures will then concentrate the incident radiation to a point. Gamma-ray optics made in this way offer the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and opening the field up to balloon-borne instruments. Following initial investigations conducted at Los Alamos National Laboratory, we have constructed and tested a prototype structure using spin coating combined with magnetron sputtering. We are now investigating whether it is possible to grow such flexible multi-layer structures with the required thicknesses and smoothness more quickly by using magnetron sputter and pulsed laser deposition techniques. We present the latest results of our fabrication and gamma-ray channeling tests, and describe our modeling of the sensitivity of potential concentrator-based telescope designs. If successful, this technology offers the potential for transformational increases in sensitivity while dramatically improving the system-level performance of future high-energy astronomy missions through reduced mass and complexity.

  12. Fabrication of multilayered thin films via spin-assembly

    DOEpatents

    Chiarelli, Peter A.; Robinson, Jeanne M.; Casson, Joanna L.; Johal, Malkiat S.; Wang, Hsing-Lin

    2007-02-20

    An process of forming multilayer thin film heterostructures is disclosed and includes applying a solution including a first water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species onto a substrate to form a first coating layer on the substrate, drying the first coating layer on the substrate, applying a solution including a second water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species onto the substrate having the first coating layer to form a second coating layer on the first coating layer wherein the second water-soluble polymer is of a different material than the first water-soluble polymer, and drying the second coating layer on the first coating layer so as to form a bilayer structure on the substrate. Optionally, one or more additional applying and drying sequences can be repeated with a water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species, so that a predetermined plurality of layers are built up upon the substrate.

  13. Method for measurement of diffusivity: Calorimetric studies of Fe/Ni multilayer thin films

    SciTech Connect

    Liu, JX; Barmak, K

    2015-07-15

    A calorimetric method for the measurement of diffusivity in thin film multilayers is introduced and applied to the Fe Ni system. Using this method, the diffusivity in [Fe (25 nm)/Ni (25 nm)](20) multilayer thin films is measured as 4 x 10(-3)exp(-1.6 +/- 0.1 eV/ k(B)T) cm(2)/s, respectively. The diffusion mechanism in the multilayers and its relevance to laboratory synthesis of L1(0) ordered FeNi are discussed. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. Method to adjust multilayer film stress induced deformation of optics

    DOEpatents

    Mirkarimi, Paul B.; Montcalm, Claude

    2000-01-01

    A buffer-layer located between a substrate and a multilayer for counteracting stress in the multilayer. Depositing a buffer-layer having a stress of sufficient magnitude and opposite in sign reduces or cancels out deformation in the substrate due to the stress in the multilayer. By providing a buffer-layer between the substrate and the multilayer, a tunable, near-zero net stress results, and hence results in little or no deformation of the substrate, such as an optic for an extreme ultraviolet (EUV) lithography tool. Buffer-layers have been deposited, for example, between Mo/Si and Mo/Be multilayer films and their associated substrate reducing significantly the stress, wherein the magnitude of the stress is less than 100 MPa and respectively near-normal incidence (5.degree.) reflectance of over 60% is obtained at 13.4 nm and 11.4 nm. The present invention is applicable to crystalline and non-crystalline materials, and can be used at ambient temperatures.

  15. An offset multilayered optic sensor for shear and pressure measurement

    NASA Astrophysics Data System (ADS)

    Liu, Chao-Shih; Chou, Gai-Wen; Lyu, Yi-Lang; Reinhall, Per G.; Wang, Wei-Chih

    2008-03-01

    Simultaneous recording of shear and pressure is an important requirement for study the causes of foot ulceration. In order to obtain a more robust and meaningful picture of what is occurring on the plantar surface of the foot, we have developed a multi-layered optical bend loss sensor that can be accommodated for shear and pressure measurement of an extended area. The sensor is made of two layers of crisscross fiberoptic sensor array separated by an elastomeric layer. Each sensing layer has multiple fibers molded into a thin polydimethylsiloxane (PDMS) substrate to form a mesh array. The top layer uses 6 fibers to create a 3 by 3 mesh with 9 intersection points and the bottom layer uses 8 fibers to create a 4 by 4 mesh with 16 intersection points. The space between the adjacent fibers is 0.5cm. Measuring changes of light intensity transmitted through the fiber provides information about the force induced changes of the fiber's radius of curvature. Pressure is measured based on the force induced light loss from the two affected crossing fibers divided by each sensing area. Shear was measured based on the relative position changes on these pressure points between the two fiber mesh layers. The design is an offset layout because the intersection points of the top and bottom layer are offset by 0.25 cm which can increase the shear sensing sensitivity. For testing the sensor with various loading condition, a neural network algorithm is induced to identify the loading pattern and the shear direction. Three loading patterns with 5 different loading directions were tested and a >90% accuracy was obtained using an algorithm using 2 neural networks.

  16. Thin-Film Multilayer Filter Designs For Hybrid Solar Energy Conversion Systems

    NASA Astrophysics Data System (ADS)

    DeSandre, L.; Song, D. Y.; Macleod, H. A.; Jacobson, M. R.; Osborn, D. E.

    1985-12-01

    The efficiency of hybrid photothermal/photovoltaic energy conversion can be increased by separating the solar spectrum into portions matched to the photothermal and photovoltaic processes. Thin-film multilayer filters can implement this concept; five such filters consisting of all-dielectric or metal-dielectric layers have been designed. The transmission profile of each design is calculated by computer, considering dispersion, absorption, and angle of incidence effects. These profiles are compared and evaluated with respect to the desired spectral performance. The most successful candidate design is an optical minus filter consisting of Ti02, Zr02, and Si02. Results show very sharp selection of the targeted photovoltaic spectral region and low ripple in the transmission region outside the bandstop.

  17. Bi-phase transition diagrams of metallic thin multilayers

    SciTech Connect

    Li, J.C.; Liu, W.; Jiang, Q. . E-mail: jiangq@jlu.edu.cn

    2005-02-01

    Phase transitions of metallic multilayers induced by differences in interface energy are considered thermodynamically, based on a thermodynamic model for interface energy and the Goldschmidt premise for lattice contraction. Bi-phase transition diagrams of Co/Cr, Zr/Nb, Ti/Nb and Ti/Al multilayers are constructed, which are in agreement with experimental results.

  18. Ferroelectric properties of PZT/BFO multilayer thin films prepared using the sol-gel method.

    PubMed

    Jo, Seo-Hyeon; Lee, Sung-Gap; Lee, Young-Hie

    2012-01-05

    In this study, Pb(Zr0.52Ti0.48)O3/BiFeO3 [PZT/BFO] multilayer thin films were fabricated using the spin-coating method on a Pt(200 nm)/Ti(10 nm)/SiO2(100 nm)/p-Si(100) substrate alternately using BFO and PZT metal alkoxide solutions. The coating-and-heating procedure was repeated several times to form the multilayer thin films. All PZT/BFO multilayer thin films show a void-free, uniform grain structure without the presence of rosette structures. The relative dielectric constant and dielectric loss of the six-coated PZT/BFO [PZT/BFO-6] thin film were approximately 405 and 0.03%, respectively. As the number of coatings increased, the remanent polarization and coercive field increased. The values for the BFO-6 multilayer thin film were 41.3 C/cm2 and 15.1 MV/cm, respectively. The leakage current density of the BFO-6 multilayer thin film at 5 V was 2.52 × 10-7 A/cm2.

  19. Optimization of Broadband Optical Response of Multilayer Nanospheres

    DTIC Science & Technology

    2012-07-27

    optimization-based theoretical approach to tailor the optical response of silver /silica multilayer nanospheres over the visible spectrum. We show that the...structure that provides the largest cross-section per volume/mass, averaged over a wide frequency range, is the silver coated silica sphere. We also show...Lett. 104, 207402 (2010). 2. X. Huang, S. Neretina, and M. A. El-Sayed, “Gold nanorods : From synthesis and properties to biological and biomedical

  20. Structural and thickness dependence of polar SMOKE spectra : first-principles determinations for Co thin films and multilayers

    NASA Astrophysics Data System (ADS)

    Kim, Miyoung; Freeman, A. J.; Wu, Ruqian

    1998-03-01

    We performed first principles calculations of the polar surface magneto-optical Kerr effect (SMOKE) for free standing fcc Co thin films with various number of layers and for Co/Pt multilayers. The local density full-potential linearized augmented plane wave (FLAPW) ( E. Wimmer, H. Krakauer, M. Weinert and A. J. Freeman, Phys. Rev. B 24), 864 (1981) method was used to obtain semi-relativistic self-consistent charge densities. Spin-orbit coupling was treated in a second variational manner and then the Kerr angles were determined using the optical condutivity tensor obtained from linear response theory. We find that the Co monolayer exhibits a totally different SMOKE from that of bulk Co, while the SMOKE of Co thin films with 3 or more layers recover the bulk characteristics but with different peak positions dependent on the thickness. The electronic and magnetic structures and spin- and l-decomposed conductivities are presented to illustrate the thickness dependence. Also the calculated result for Co/Pt multilayers will be presented and discussed with a comparison of experiments on multilayers and alloys to describe the structural dependence of SMOKE.

  1. Simulation and Optimization of Soft Gamma-Ray Concentrator Using Thin Film Multilayer Structures

    NASA Astrophysics Data System (ADS)

    Shirazi, Farzane; Bloser, Peter F.; Aliotta, Paul H.; Echt, Olof; Krzanowski, James E.; Legere, Jason S.; McConnell, Mark L.; Tsavalas, John G.; Wong, Emily N.; Kippen, R. Marc

    2016-04-01

    We are reporting the investigation result of channeling and concentrating soft gamma rays (above 100 keV) using multilayer thin films of alternating low and high-density materials. This will enable future telescopes for higher energies with same mission parameters already proven by NuSTAR. Base on initial investigations at Los Alamos National Laboratory (LANL) we are investigating of producing these multilayers with the required thicknesses and smoothness using magnetron sputter (MS) and pulsed laser deposition (PLD) techniques. A suitable arrangement of bent multilayer structures of alternating low and high-density materials will channel soft gamma-ray photons via total external reflection and then concentrate the incident radiation to a point. The high-energy astrophysics group at the UNH Space Science Center (SSC) is testing these structures for their ability to channel 122 keV gamma rays in the laboratory. In addition of experimental works, we have been working on gamma ray tracing model of the concentrator by IDL, making use of optical properties calculated by the IMD software. This modeling allows us to calculate efficiency and focal length for different energy bands and materials and compare them with experimental result. Also we will combine concentrator modeling result and detector simulation by Geant4 to archive a complete package of gamma-ray telescope simulation. If successful, this technology will offer the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and opening the field up to balloon-borne instruments and providing greatly increased sensitivity for modest cost and complexity.

  2. Design and performance analysis of multilayer nested grazing incidence optics

    NASA Astrophysics Data System (ADS)

    Zuo, Fuchang; Deng, Loulou; Mei, Zhiwu; Li, Liansheng; Lv, Zhengxin

    2014-10-01

    We have developed X-ray grazing incidence optics with a single mirror. Although t can be used to demonstrate and test on the ground to verify the feasibility of X-ray detection system, it is unable to meet the requirements of X-ray pulsar navigation due to small effective area and large mass. There is an urgent need to develop multilayer nested grazing incidence optics, which consists of multilayer mirrors to form a coaxial and confocal system to maximize the use of space and increase the effective area. In this paper, aiming at the future demand of X-ray pulsar navigation, optimization and analysis of nested X-ray grazing incidence optics was carried out, the recurrence relations between the layers of mirrors were derived, reasonable initial structural parameters and stray light reduction method was given, and theoretical effective collection area was calculated. The initial structure and stray light eliminating structure are designed. The optical-mechanical-thermal numerical model was established using optical analysis software and finite element software for stray light analysis, focusing performance analysis, tolerance analysis, and mechanical analysis, providing evidence and guidance for the processing and alignment of nested X-ray grazing incidence optics.

  3. Investigation of optical properties of multilayer dielectric structures using prism-coupling technique

    SciTech Connect

    Sokolov, V I; Glebov, V N; Malyutin, A M; Molchanova, S I; Khaydukov, E V; Panchenko, V Ya

    2015-09-30

    A method based on resonant excitation of waveguide modes with a prism coupler is proposed for measuring the thickness and refractive index of thin-film layers in multilayer dielectric structures. The peculiarities of reflection of TE- and TM-polarised light beams from a structure comprising eleven alternating layers of zinc sulfide (ZnS) and magnesium barium fluoride (MgBaF{sub 4}), whose thicknesses are much less than the wavelength of light, are investigated. Using the mathematical model developed, we have calculated the coefficients of reflection of collimated TE and TM light beams from a multilayer structure and determined the optical constants and thicknesses of the structure layers. The refractive indices of the layers, obtained for TE and TM polarisation of incident light, are in good agreement. The thicknesses of ZnS and MgBaF{sub 4} layers, found for different polarisations, coincide with an accuracy of ±1%. Thus, we have demonstrated for the first time that the prism-coupling technique allows one to determine the optical properties of thin-film structures when the number of layers in the structure exceeds ten layers. (integrated optics)

  4. Spectral tailoring of nanoscale EUV and soft x-ray multilayer optics

    NASA Astrophysics Data System (ADS)

    Huang, Qiushi; Medvedev, Viacheslav; van de Kruijs, Robbert; Yakshin, Andrey; Louis, Eric; Bijkerk, Fred

    2017-03-01

    Extreme ultraviolet and soft X-ray (XUV) multilayer optics have experienced significant development over the past few years, particularly on controlling the spectral characteristics of light for advanced applications like EUV photolithography, space observation, and accelerator- or lab-based XUV experiments. Both planar and three dimensional multilayer structures have been developed to tailor the spectral response in a wide wavelength range. For the planar multilayer optics, different layered schemes are explored. Stacks of periodic multilayers and capping layers are demonstrated to achieve multi-channel reflection or suppression of the reflective properties. Aperiodic multilayer structures enable broadband reflection both in angles and wavelengths, with the possibility of polarization control. The broad wavelength band multilayer is also used to shape attosecond pulses for the study of ultrafast phenomena. Narrowband multilayer monochromators are delivered to bridge the resolution gap between crystals and regular multilayers. High spectral purity multilayers with innovated anti-reflection structures are shown to select spectrally clean XUV radiation from broadband X-ray sources, especially the plasma sources for EUV lithography. Significant progress is also made in the three dimensional multilayer optics, i.e., combining micro- and nanostructures with multilayers, in order to provide new freedom to tune the spectral response. Several kinds of multilayer gratings, including multilayer coated gratings, sliced multilayer gratings, and lamellar multilayer gratings are being pursued for high resolution and high efficiency XUV spectrometers/monochromators, with their advantages and disadvantages, respectively. Multilayer diffraction optics are also developed for spectral purity enhancement. New structures like gratings, zone plates, and pyramids that obtain full suppression of the unwanted radiation and high XUV reflectance are reviewed. Based on the present achievement

  5. Three-dimensional measurement of multilayer thin films based on scanning white light interferometer

    NASA Astrophysics Data System (ADS)

    Shi, Zhendong; Zhang, Lin; Ren, Huan; Yuan, Quan; Yang, Yi; Ma, Hua

    2016-09-01

    For multilayer films system, in order to obtain the thickness and surface profile in each layer of thin film, a method to measure the 3D morphology of a multilayer films system based on scanning white light interferometer has been proposed in this article. At first, the mathematical relationship between reflection phase and thickness of each film layer has been obtained by using the electromagnetic field boundary conditions. Then, a nonlinear least square algorithm has been used to fit the reflection phase which had been found through a scanning white light interferometer, in this way the linear and nonlinear terms of the reflection phase have been separated, which made it possible to measure top-layer surface profile and thickness of each thin film layer respectively and avoided the interference with each other, because the linear term is related to the top layer's surface profile but the nonlinear term is correlated to the thickness of each film layer in multilayer thin films system. Thus, the three-dimensional morphology of multilayer thin films system could be reconstructed. Experimental results showed this method was effective in the three-dimensional morphology measurement for multilayer thin films. And the measurement could be completed just using the existing commercial scanning white light interferometer, as a consequence the measurement cost is low, and the operation will be quite simple.

  6. New method of two-photon multi-layer optical disc storage

    NASA Astrophysics Data System (ADS)

    Jiang, Bing; Shen, Zhaolong; Cai, Jianwen; Tang, Huohong; Xing, Hui; Huang, Wenhao

    2006-02-01

    Multi-layer data storage based on nonlinear effect caused by two-photon absorption is an attractive approach in the field of mass data storage. A two-photon multi-layer optical disc storage system with disc rotation structure has been proposed. The multi-layer fluorescent disc used in this system consists of three layers. A transparent substrate (under layer) and a thin reflective layer (middle layer) are bonded together forming a kind of structure similar to DVD disc, which is necessary to servo the vertical and radial deviation. Two-photon bits are recorded in top layer. The storage system has two modules: servo module and confocal module. The former keeps following the vertical and radial deviations by means of focusing and tracking servo technologies used in current two-dimensional optical storage devices, so the system can be compatible with CD/DVD. According to the driving signal of actuators in servo pick-up, the confocal module can also follow the disc deviation in both recording and reading processes. The servo module has been finished and the result of preliminary experiment is presented. Using the actuator and the objective lens (NA 0.6) in SANYO pick-up, we successfully recorded and read three data layers in photobleaching material with a homemade femtosecond laser. The layer separation was 15μm and the transverse bit separation was 4 μm.

  7. Multi-Layer Laminated Thin Films for Inflatable Structures

    NASA Technical Reports Server (NTRS)

    Yavrouian, Andre; Plett, Gary; Mannella, Jerami

    2005-01-01

    Special-purpose balloons and other inflatable structures would be constructed as flexible laminates of multiple thin polymeric films interspersed with layers of adhesive, according to a proposal. In the original intended application, the laminate would serve as the envelope of the Titan Aerobot a proposed robotic airship for exploring Titan (one of the moons of Saturn). Potential terrestrial applications for such flexible laminates could include blimps and sails. In the original application, the multi-layered laminate would contain six layers of 0.14-mil (0.0036-mm)-thick Mylar (or equivalent) polyethylene terephthalate film with a layer of adhesive between each layer of Mylar . The overall thickness and areal density of this laminate would be nearly the same as those of 1-mil (0.0254-mm)-thick monolayer polyethylene terephthalate sheet. However, the laminate would offer several advantages over the monolayer sheet, especially with respect to interrelated considerations of flexing properties, formation of pinholes, and difficulty or ease of handling, as discussed next. Most of the damage during flexing of the laminate would be localized in the outermost layers, where the radii of bending in a given bend would be the largest and, hence, the bending stress would be the greatest. The adverse effects of formation of pinholes would be nearly completely mitigated in the laminate because a pinhole in a given layer would not propagate to adjacent layers. Hence, the laminate would tend to remain effective as a barrier to retain gas. Similar arguments can be made regarding cracks: While a crack could form as a result of stress or a defect in the film material, a crack would not propagate into adjacent layers, and the adjacent layer(s) would even arrest propagation of the crack. In the case of the monolayer sheet, surface damage (scratches, dents, permanent folds, pinholes, and the like) caused by handling would constitute or give rise to defects that could propagate through

  8. Origin of universal optical conductivity and optical stacking sequence identification in multilayer graphene.

    PubMed

    Min, Hongki; MacDonald, A H

    2009-08-07

    We show that the origin of the universal optical conductivity in a normal N-layer graphene multilayer is an emergent chiral symmetry which guarantees that sigma(omega) = Nsigma_{uni} in both low and high-frequency limits. [sigma_{uni} = (pi/2)e;{2}/h]. We use this physics to relate intermediate frequency conductivity trends to qualitative characteristics of the multilayer stacking sequence.

  9. Closed-form Maker fringe formulas for poled polymer thin films in multilayer structures.

    PubMed

    Park, Dong Hun; Herman, Warren N

    2012-01-02

    We report new closed-form expressions for Maker fringes of anisotropic and absorbing poled polymer thin films in multilayer structures that include back reflections of both fundamental and second-harmonic waves. The expressions, based on boundary conditions at each interface, can be applied to multilayer structures containing a buffer and a transparent conducting oxide layer, which might enhance multiple reflections of fundamental and second-harmonic waves inside a nonlinear thin film layer. This formulation facilitates Maker fringe analysis for a sample containing additional multilayer structures on either side of a poled polymer thin film. Experimental data and numerical simulations are given to indicate the importance of inclusion of such a reflective layer in analyses for reliable characterization of second-harmonic tensor elements.

  10. Oxygen barrier of multilayer thin films comprised of polysaccharides and clay.

    PubMed

    Laufer, Galina; Kirkland, Christopher; Cain, Amanda A; Grunlan, Jaime C

    2013-06-05

    Multilayered thin films of chitosan (CH), carrageenan (CR) and montmorillonite (MMT) clay, deposited using the layer-by-layer technique, were studied in an effort to produce fully renewable polysaccharide-based thin films with low oxygen permeability. Ten 'trilayers' of CH/MMT/CR (<40 nm thick) on PET film reduced its oxygen permeability (1.76×10(-15) cm(3) cm/cm(2) s Pa) by an order of magnitude under dry conditions. By adding an additional layer of CH to the trilayer sequence, a 'quadlayer' film of CH/CR/CH/MMT (<60 nm thick) was created, which was able to reduce oxygen permeability of PET by two orders of magnitude under the same conditions. This high oxygen barrier is believed to be due to the unique nanostructure of these films, often referred to as a "nanobrick wall" structure, as well as a strong association amongst the oppositely charged polysaccharides. Combining fully renewable and food contact approved ingredients with high gas barrier and optical transparency makes this technology promising as a foil replacement for food packaging.

  11. Multi-layer boron thin-film detectors for neutrons

    SciTech Connect

    Wang, Zhehui; Morris, Christopher L

    2010-01-01

    Intrinsic efficiencies of the multilayer boron detectors have been examined both theoretically and experimentally. It is shown that due to the charge loss in the boron layers, the practical efficiencies of most multi-layer {sup 10}B detectors are limited up to about 42%, much less than 77% of the 2 bar 2-inch diameter {sup 3}He detectors. It is suggested that the same charge loss mechanism will prevent essentially all substrate-based boron detectors from ever reaching the efficiencies of high-pressure {sup 3}He tubes, independent of the substrate geometry and material composition (including silicon). Meanwhile, the experimental data indicate that the multi-layer approach can increase the efficiencies up to the theoretical limit. Good n/{gamma} discrimination has also achieved using the ionization charnber technique.

  12. Optical transmission through generalized third-order Fibonacci multilayers

    NASA Astrophysics Data System (ADS)

    Hu, Xubo; Yang, Xiangbo; Liu, Songhao

    2014-06-01

    In this paper, by means of three kinds of methods we study the transmission properties of the light through the quasiperiodic multilayers vertically following the generalized third-order Fibonacci (GTOF) sequences. By means of the decomposition-substitution (DS) method we predict that the GTOF systems possess an interesting four-cycle transmissive characteristic at the central wavelength. Based on the electromagnetic wave theory, we then deduce the formulae of propagation matrices and transmission coefficients analytically at the central wavelength and obtain the numerical simulation results at the same time. The results obtained by three kinds of methods accord with each other and three kinds of methods are complementary. The cyclic transmissive characteristics may be useful for the designing of some optical memories, optical logical gates, and other optical controlling devices.

  13. Development and characterization of monolithic multilayer Laue lens nanofocusing optics

    DOE PAGES

    Nazaretski, E.; Xu, W.; Bouet, N.; ...

    2016-06-27

    In this study, we have developed an experimental approach to bond two independent linear Multilayer Laue Lenses (MLLs) together. A monolithic MLL structure was characterized using ptychography at 12 keV photon energy, and we demonstrated 12 nm and 24 nm focusing in horizontal and vertical directions, respectively. Fabrication of 2D MLL optics allows installation of these focusing elements in more conventional microscopes suitable for x-ray imaging using zone plates, and opens easier access to 2D imaging with high spatial resolution in the hard x-ray regime.

  14. Development and characterization of monolithic multilayer Laue lens nanofocusing optics

    NASA Astrophysics Data System (ADS)

    Nazaretski, E.; Xu, W.; Bouet, N.; Zhou, J.; Yan, H.; Huang, X.; Chu, Y. S.

    2016-06-01

    We have developed an experimental approach to bond two independent linear Multilayer Laue Lenses (MLLs) together. A monolithic MLL structure was characterized using ptychography at 12 keV photon energy, and we demonstrated 12 nm and 24 nm focusing in horizontal and vertical directions, respectively. Fabrication of 2D MLL optics allows installation of these focusing elements in more conventional microscopes suitable for x-ray imaging using zone plates, and opens easier access to 2D imaging with high spatial resolution in the hard x-ray regime.

  15. Indentation-derived elastic modulus of multilayer thin films: Effect of unloading induced plasticity

    DOE PAGES

    Jamison, Ryan Dale; Shen, Yu -Lin

    2015-08-13

    Nanoindentation is useful for evaluating the mechanical properties, such as elastic modulus, of multilayer thin film materials. A fundamental assumption in the derivation of the elastic modulus from nanoindentation is that the unloading process is purely elastic. In this work, the validity of elastic assumption as it applies to multilayer thin films is studied using the finite element method. The elastic modulus and hardness from the model system are compared to experimental results to show validity of the model. Plastic strain is shown to increase in the multilayer system during the unloading process. Additionally, the indentation-derived modulus of a monolayermore » material shows no dependence on unloading plasticity while the modulus of the multilayer system is dependent on unloading-induced plasticity. Lastly, the cyclic behavior of the multilayer thin film is studied in relation to the influence of unloading-induced plasticity. Furthermore, it is found that several cycles are required to minimize unloading-induced plasticity.« less

  16. Sigma-pi molecular dielectric multilayers for low-voltage organic thin-film transistors.

    PubMed

    Yoon, Myung-Han; Facchetti, Antonio; Marks, Tobin J

    2005-03-29

    Very thin (2.3-5.5 nm) self-assembled organic dielectric multilayers have been integrated into organic thin-film transistor structures to achieve sub-1-V operating characteristics. These new dielectrics are fabricated by means of layer-by-layer solution phase deposition of molecular silicon precursors, resulting in smooth, nanostructurally well defined, strongly adherent, thermally stable, virtually pinhole-free, organosiloxane thin films having exceptionally large electrical capacitances (up to approximately 2,500 nF.cm(-2)), excellent insulating properties (leakage current densities as low as 10(-9) A.cm(-2)), and single-layer dielectric constant (k)of approximately 16. These 3D self-assembled multilayers enable organic thin-film transistor function at very low source-drain, gate, and threshold voltages (<1 V) and are compatible with a broad variety of vapor- or solution-deposited p- and n-channel organic semiconductors.

  17. A Multilayered Thin Film Insulator for Harsh Environments

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Fralick, Gustave C.; Blaha, Charles A.; Busfield, A. Rachel; Thomas, Valarie D.

    2002-01-01

    The status of work to develop a reliable high temperature dielectric thin film for use with thin film sensors is presented. The use of thin films to electrically insulate thin film sensors on engine components minimizes the intrusiveness of the sensor and allows a more accurate measurement of the environment. A variety of insulating films were investigated for preventing electrical shorting caused by insulator failure between the sensor and the component. By alternating layers of sputtered high temperature ceramics, a sequence of insulating layers was devised that prevents pinholes from forming completely through the insulator and maintains high electrical resistivity at high temperatures. The major technical challenge remaining is to optimize the fabrication of the insulator with respect to composition to achieve a reliable high temperature insulating film. Data from the testing of various potentially insulating thin film systems is presented and their application to thin film sensors is also discussed.

  18. Critical optical properties of AA-stacked multilayer graphenes

    NASA Astrophysics Data System (ADS)

    Chiu, Chih-Wei; Chen, Szu-Chao; Huang, Yuan-Cheng; Shyu, Feng-Lin; Lin, Ming-Fa

    2013-07-01

    The band structures and optical properties of AA-stacked multilayer graphenes are calculated by the tight-binding model and gradient approximation. For a nL-layer AA-stacked graphene, there are nL peaks at both low and middle frequencies. The threshold energy of odd-layer graphene is much lower than that of even-layer graphene for nL<10. The differences in the electronic structures and optical properties between the odd and even layers are reduced with increasing nL. When nL grows to 30 (200), the spectra of 2D graphene are almost identical to those of 3D graphite at middle (low) frequencies.

  19. Multilayer Ni/Fe thin films as oxygen evolution catalysts for solar fuel production

    NASA Astrophysics Data System (ADS)

    Biset-Peiró, M.; Murcia-López, S.; Fàbrega, C.; Morante, J. R.; Andreu, T.

    2017-03-01

    The slow kinetics and high overpotential of the oxygen evolution reaction is one of the main limiting factors to achieve the minimum required performances of the so-called photoelectrochemical water splitting systems. An oxygen evolution catalyst (OEC) becomes essential in order to perform this process with higher efficiency. Herein, we report the physical, optical and electrochemical characterization of multilayer Ni/Fe thin films as earth-abundant OEC, to avoid the use of platinum group metals (PGM). Uniform films of thicknesses ranging from 1 to 10 nm were fabricated by sequential and alternate thermal evaporation of Ni and Fe. It was found that the successive deposition allows the fabrication of a Ni terminated surface that does not need activation due to the Fe underlayer. The lowest overpotential achieved for NiFe was 370 mV at 10 mA cm‑2 and a Tafel slope of 37 mV dec‑1 with 1 nm thickness and 95% transmittance. Finally, NiFe OEC was implemented on top of Mo:BiVO4 photoanodes which resulted in a reduction of the open circuit potential of 0.2 V and up to five fold increase of the oxidation efficiency at 0.7 VRHE. The results presented facilitate the practical implementation of BiVO4 photoanodes in tandem configuration for bias free photoassisted water splitting.

  20. High color fidelity thin film multilayer systems for head-up display use

    NASA Astrophysics Data System (ADS)

    Tsou, Yi-Jen D.; Ho, Fang C.

    1996-09-01

    Head-up display is gaining increasing access in automotive vehicles for indication and position/navigation purposes. An optical combiner, which allows the driver to receive image information from outside and inside of the automobile, is the essential part of this display device. Two multilayer thin film combiner coating systems with distinctive polarization selectivity and broad band spectral neutrality are discussed. One of the coating systems was designed to be located at the lower portion of the windshield. The coating reduced the exterior glare by approximately 45% and provided about 70% average see-through transmittance in addition to the interior information display. The other coating system was designed to be integrated with the sunshield located at the upper portion of the windshield. The coating reflected the interior information display while reducing direct sunlight penetration to 25%. Color fidelity for both interior and exterior images were maintained in both systems. This facilitated the display of full-color maps. Both coating systems were absorptionless and environmentally durable. Designs, fabrication, and performance of these coating systems are addressed.

  1. Patterning of magnetic thin films and multilayers using nanostructured tantalum gettering templates.

    PubMed

    Qiu, Wenlan; Chang, Long; Lee, Dahye; Dannangoda, Chamath; Martirosyan, Karen; Litvinov, Dmitri

    2015-03-25

    This work demonstrates that a nonmagnetic thin film of cobalt oxide (CoO) sandwiched between Ta seed and capping layers can be effectively reduced to a magnetic cobalt thin film by annealing at 200 °C, whereas CoO does not exhibit ferromagnetic properties at room temperature and is stable at up to ∼400 °C. The CoO reduction is attributed to the thermodynamically driven gettering of oxygen by tantalum, similar to the exothermic reduction-oxidation reaction observed in thermite systems. Similarly, annealing at 200 °C of a nonmagnetic [CoO/Pd]N multilayer thin film sandwiched between Ta seed and Ta capping layers results in the conversion into a magnetic [Co/Pd]N multilayer, a material with perpendicular magnetic anisotropy that is of interest for magnetic data storage applications. A nanopatterning approach is introduced where [CoO/Pd]N multilayers is locally reduced into [Co/Pd]N multilayers to achieve perpendicular magnetic anisotropy nanostructured array. This technique can potentially be adapted to nanoscale patterning of other systems for which thermodynamically favorable combination of oxide and gettering layers can be identified.

  2. Optical and spectral tunability of multilayer spherical and cylindrical nanoshells

    NASA Astrophysics Data System (ADS)

    Daneshfar, Nader; Bazyari, Khashayar

    2014-08-01

    This theoretical work presents a comparative study of the optical properties and spectral tunability of hybrid multilayer spherical and cylindrical nanoshells based on the quasi-static approximation of classical electrodynamics. The interband transitions have been considered using the Drude-Lorentz model for the complex dielectric function of metallic layers because the optical properties of metals arise from both the optical excitation of interband transitions and the free-electron response. A general formula for N-ayer concentric nanoshells is arranged, and numerical calculations are performed for the four-layer nanoshells as an example. We have analyzed in detail different configurations of nanoshells such as dielectric-metal-dielectric-metal with dielectric core, metal-dielectric-metal-dielectric with metal core and semiconductor-metal-dielectric-metal with semiconductor core because composition of nanoshells have dramatic influence on their optical properties. The absorbance spectrum behavior of the shell thicknesses, surrounding medium, shape and composition of each layer of the nanoshell is numerically investigated.

  3. Optical transmission spectra in quasiperiodic multilayered photonic structure

    NASA Astrophysics Data System (ADS)

    de Medeiros, F. F.; Albuquerque, E. L.; Vasconcelos, M. S.

    2006-10-01

    Optical transmission spectra in quasiperiodic multilayered photonic structures, composed of both positive (SiO2) and negative refractive index materials, are calculated by using a theoretical model based on the transfer matrix approach for normal incidence geometry. The quasiperiodic structures are substitutional sequences, characterized by the nature of their Fourier spectrum, which can be dense pure point (e.g. Fibonacci sequence) or singular continuous (e.g. Thue-Morse and double-period sequences). The transmission spectra for the case where both refractive indices can be approximated by a different constant show a unique mirror symmetrical profile, with no counterpart for the positive refractive index case, as well as a striking self-similar behaviour related to the Fibonacci sequence. For a more realistic frequency-dependent refractive index, the transmission spectra are characterized by a rich transmission profile of Bragg peaks with no more self-similarity or mirror symmetry.

  4. Kinetic Monte Carlo Simulation of Epitaxial Thin Film Growth: Formation of Submonolayer Islands and Multilayer Mounds

    SciTech Connect

    Evans, J. W.; Thiel, P. A.; Li, Maozhi

    2007-06-14

    We consider homoepitaxy (or low-misfit heteroepitaxy) via vapor deposition or MBE under UHV conditions. Thin film growth is initiated by nucleation and growth of 2D islands in the submonolayer regime. For atoms subsequently deposited on top of islands, a step edge barrier often inhibits downward transport and produces kinetic roughening during multilayer growth. Such unstable growth is characterized by the formation of 3D mounds (multilayer stacks of 2D islands). Kinetic Monte Carlo (KMC) simulation of suitable atomistic lattice-gas models can address fundamental or general issues related to both submonolayer and multilayer film evolution, and can also provide a predictive tool for morphological evolution in specific systems. Examples of the successes of KMC modeling are provided for metal homoepitaxial film growth, specifically for contrasting behavior in the classic Ag/Ag(100) and Ag/Ag(111) systems.

  5. MultiLayer solid electrolyte for lithium thin film batteries

    DOEpatents

    Lee, Se -Hee; Tracy, C. Edwin; Pitts, John Roland; Liu, Ping

    2015-07-28

    A lithium metal thin-film battery composite structure is provided that includes a combination of a thin, stable, solid electrolyte layer [18] such as Lipon, designed in use to be in contact with a lithium metal anode layer; and a rapid-deposit solid electrolyte layer [16] such as LiAlF.sub.4 in contact with the thin, stable, solid electrolyte layer [18]. Batteries made up of or containing these structures are more efficient to produce than other lithium metal batteries that use only a single solid electrolyte. They are also more resistant to stress and strain than batteries made using layers of only the stable, solid electrolyte materials. Furthermore, lithium anode batteries as disclosed herein are useful as rechargeable batteries.

  6. Zirconia-parylene multilayer thin films for enhanced fracture resistance of dental ceramics.

    PubMed

    Teixeira, E C; Piascik, J R; Stoner, B R; Thompson, J Y

    2009-10-01

    Recent research has shown that the application of specific thin films can enhance the material properties of a laminate construct. In this study, the effect of different mono/multilayered films on the strength of a ceramic specimen is demonstrated. It is well established that cracks can initiate and/or propagate from the internal surfaces of all-ceramic dental restorations. Modifying that surface by thin-film deposition might help increase clinical longevity and applicability. Specimens were divided into the following groups according to different surface treatments received: uncoated (control group), 10 microm yttria-stabilized zirconia (YSZ) thin film, 10 microm parylene thin film, 9.75 microm YSZ + 0.25 microm parylene film, and a multilayered film (five layers of 1.25 microm YSZ + 0.75 microm parylene). Depositions were performed using a radio-frequency magnetron sputter system (working pressure 15 mT, 150 degrees C, 30:1 Ar/O2 gas ratio) to produce the YSZ layers, and a vapour deposition process was used to produce the parylene layers. Flexural strength measurements were carried out by three-point bending (span = 10 mm) in a servo-electric material testing system in deioinized (DI) water (37 degrees C). The results showed that the strength of the specimen significantly increased with the deposition of all types of coating, showing the greatest increase with the multilayered film (approximately 32 per cent). It is hypothesized that a multilayer thin film (brittle/ductile) can promote crack deflection, causing strength enhancement of the brittle construct.

  7. Optical phonons in PbTe/CdTe multilayer heterostructures

    SciTech Connect

    Novikova, N. N.; Yakovlev, V. A.; Kucherenko, I. V.; Karczewski, G.; Aleshchenko, Yu. A.; Muratov, A. V.; Zavaritskaya, T. N.; Melnik, N. N.

    2015-05-15

    The infrared reflection spectra of PbTe/CdTe multilayer nanostructures grown by molecular-beam epitaxy are measured in the frequency range of 20–5000 cm{sup −1} at room temperature. The thicknesses and high-frequency dielectric constants of the PbTe and CdTe layers and the frequencies of the transverse optical (TO) phonons in these structures are determined from dispersion analysis of the spectra. It is found that the samples under study are characterized by two TO phonon frequencies, equal to 28 and 47 cm{sup −1}. The first frequency is close to that of TO phonons in bulk PbTe, and the second is assigned to the optical mode in structurally distorted interface layers. The Raman-scattering spectra upon excitation with the radiation of an Ar{sup +} laser at 514.5 nm are measured at room and liquid-nitrogen temperatures. The weak line at 106 cm{sup −1} observed in these spectra is attributed to longitudinal optical phonons in the interface layers.

  8. Nanomechanical investigation of thin-film electroceramic/metal-organic framework multilayers

    SciTech Connect

    Best, James P. E-mail: engelbert.redel@kit.edu Michler, Johann; Maeder, Xavier; Liu, Jianxi; Wang, Zhengbang; Tsotsalas, Manuel; Liu, Jinxuan; Gliemann, Hartmut; Weidler, Peter G.; Redel, Engelbert E-mail: engelbert.redel@kit.edu Wöll, Christof E-mail: engelbert.redel@kit.edu; Röse, Silvana; Oberst, Vanessa; Walheim, Stefan

    2015-09-07

    Thin-film multilayer stacks of mechanically hard magnetron sputtered indium tin oxide (ITO) and mechanically soft highly porous surface anchored metal-organic framework (SURMOF) HKUST-1 were studied using nanoindentation. Crystalline, continuous, and monolithic surface anchored MOF thin films were fabricated using a liquid-phase epitaxial growth method. Control over respective fabrication processes allowed for tuning of the thickness of the thin film systems with a high degree of precision. It was found that the mechanical indentation of such thin films is significantly affected by the substrate properties; however, elastic parameters were able to be decoupled for constituent thin-film materials (E{sub ITO} ≈ 96.7 GPa, E{sub HKUST−1} ≈ 22.0 GPa). For indentation of multilayer stacks, it was found that as the layer thicknesses were increased, while holding the relative thickness of ITO and HKUST-1 constant, the resistance to deformation was significantly altered. Such an observation is likely due to small, albeit significant, changes in film texture, interfacial roughness, size effects, and controlling deformation mechanism as a result of increasing material deposition during processing. Such effects may have consequences regarding the rational mechanical design and utilization of MOF-based hybrid thin-film devices.

  9. Multilayers for EUV, soft x-ray and x-ray optics

    NASA Astrophysics Data System (ADS)

    Wang, Zhanshan; Huang, Qiushi; Zhang, Zhong

    2016-02-01

    Driven by the requirements in synchrotron radiation applications, astronomical observation, and dense plasma diagnostics, the EUV, soft X-rays and X-rays multilayer optics have been tremendously developed. Based on the LAMP project for soft X-ray polarimetry, Co/C and Cr/C multilayers have been fabricated and characterized. Both Co/C and Cr/C multilayers reveal good optical performance working at 250 eV. Pd/Y multilayers have been successfully fabricated using reactive sputtering with nitrogen working at around 9.4 nm. EUV normal incidence Schwarzschild and soft X-ray grazing incidence KB microscopes were developed for ICF plasma diagnostics. This paper covers the outline of the multilayer optics and the current status in our lab.

  10. Improving the assembly speed, quality, and tunability of thin conductive multilayers.

    PubMed

    Gittleson, Forrest S; Kohn, David J; Li, Xiaokai; Taylor, André D

    2012-05-22

    While inhomogeneous thin conductive films have been sought after for their flexibility, transparency, and strength, poor control in the processing of these materials has restricted their application. The versatile layer-by-layer assembly technique allows greater control over film deposition, but even this has been hampered by the traditional dip-coating method. Here, we employ a fully automated spin-spray layer-by-layer system (SSLbL) to rapidly produce high-quality, tunable multilayer films. With bilayer deposition cycle times as low as 13 s (~50% of previously reported) and thorough characterization of film conductance in the near percolation region, we show that SSLbL permits nanolevel control over film growth and efficient formation of a conducting network not available with other methods of multilayer deposition. The multitude of variables from spray time, to spin rate, to active drying available with SSLbL makes films generated by this technique inherently more tunable and expands the opportunity for optimization and application of composite multilayers. A comparison of several polymer-CNT systems deposited by both spin-spray and dip-coating exemplifies the potential of SSLbL assembly to allow for rapid screening of multilayer films. Ultrathin polymer-CNT multilayers assembled by SSLbL were also evaluated as lithium-ion battery electrodes, emphasizing the practical application of this technique.

  11. TAPE CALENDERING MANUFACTURING PROCESS FOR MULTILAYER THIN-FILM SOLID OXIDE FUEL CELLS

    SciTech Connect

    Nguyen Minh; Kurt Montgomery

    2004-10-01

    This report summarizes the work performed by Hybrid Power Generation Systems, LLC during the Phases I and II under Contract DE-AC26-00NT40705 for the U. S. Department of Energy, National Energy Technology Laboratory (DOE/NETL) entitled ''Tape Calendering Manufacturing Process For Multilayer Thin-Film Solid Oxide Fuel Cells''. The main objective of this project was to develop the manufacturing process based on tape calendering for multilayer solid oxide fuel cells (SOFC's) using the unitized cell design concept and to demonstrate cell performance under specified operating conditions. Summarized in this report is the development and improvements to multilayer SOFC cells and the unitized cell design. Improvements to the multilayer SOFC cell were made in electrochemical performance, in both the anode and cathode, with cells demonstrating power densities of nearly 0.9 W/cm{sup 2} for 650 C operation and other cell configurations showing greater than 1.0 W/cm{sup 2} at 75% fuel utilization and 800 C. The unitized cell design was matured through design, analysis and development testing to a point that cell operation at greater than 70% fuel utilization was demonstrated at 800 C. The manufacturing process for both the multilayer cell and unitized cell design were assessed and refined, process maps were developed, forming approaches explored, and nondestructive evaluation (NDE) techniques examined.

  12. Shock compression response of highly reactive Ni + Al multilayered thin foils

    NASA Astrophysics Data System (ADS)

    Kelly, Sean C.; Thadhani, Naresh N.

    2016-03-01

    The shock-compression response of Ni + Al multilayered thin foils is investigated using laser-accelerated thin-foil plate-impact experiments over the pressure range of 2 to 11 GPa. The foils contain alternating Ni and Al layers (parallel but not flat) of nominally 50 nm bilayer spacing. The goal is to determine the equation of state and shock-induced reactivity of these highly reactive fully dense thin-foil materials. The laser-accelerated thin-foil impact set-up involved combined use of photon-doppler-velocimetry to monitor the acceleration and impact velocity of an aluminum flyer, and VISAR interferometry was used to monitor the back free-surface velocity of the impacted Ni + Al multilayered target. The shock-compression response of the Ni + Al target foils was determined using experimentally measured parameters and impedance matching approach, with error bars identified considering systematic and experimental errors. Meso-scale CTH shock simulations were performed using real imported microstructures of the cross-sections of the multilayered Ni + Al foils to compute the Hugoniot response (assuming no reaction) for correlation with their experimentally determined equation of state. It was observed that at particle velocities below ˜150 m/s, the experimentally determined equation of state trend matches the CTH-predicted inert response and is consistent with the observed unreacted state of the recovered Ni + Al target foils from this velocity regime. At higher particle velocities, the experimentally determined equation of state deviates from the CTH-predicted inert response. A complete and self-sustained reaction is also seen in targets recovered from experiments performed at these higher particle velocities. The deviation in the measured equation of state, to higher shock speeds and expanded volumes, combined with the observation of complete reaction in the recovered multilayered foils, confirmed via microstructure characterization, is indicative of the occurrence

  13. Near-field optical thin microcavity theory

    NASA Astrophysics Data System (ADS)

    Wu, Jiu Hui; Hou, Jiejie

    2016-01-01

    The thin microcavity theory for near-field optics is proposed in this study. By applying the power flow theorem and the variable theorem,the bi-harmonic differential governing equation for electromagnetic field of a three-dimensional thin microcavity is derived for the first time. Then by using the Hankel transform, this governing equation is solved exactly and all the electromagnetic components inside and outside the microcavity can be obtained accurately. According to the above theory, the near-field optical diffraction from a subwavelength aperture embedded in a thin conducting film is investigated, and numerical computations are performed to illustrate the edge effect by an enhancement factor of 1.8 and the depolarization phenomenon of the near-field transmission in terms of the distance from the film surface. This thin microcavity theory is verified by the good agreement between our results and those in the previous literatures. The thin microcavity theory presented in the study should be useful in the possible applications of the thin microcavities in near-field optics and thin-film optics.

  14. Recent progress in high-mobility thin-film transistors based on multilayer 2D materials

    NASA Astrophysics Data System (ADS)

    Hong, Young Ki; Liu, Na; Yin, Demin; Hong, Seongin; Kim, Dong Hak; Kim, Sunkook; Choi, Woong; Yoon, Youngki

    2017-04-01

    Two-dimensional (2D) layered semiconductors are emerging as promising candidates for next-generation thin-film electronics because of their high mobility, relatively large bandgap, low-power switching, and the availability of large-area growth methods. Thin-film transistors (TFTs) based on multilayer transition metal dichalcogenides or black phosphorus offer unique opportunities for next-generation electronic and optoelectronic devices. Here, we review recent progress in high-mobility transistors based on multilayer 2D semiconductors. We describe the theoretical background on characterizing methods of TFT performance and material properties, followed by their applications in flexible, transparent, and optoelectronic devices. Finally, we highlight some of the methods used in metal-semiconductor contacts, hybrid structures, heterostructures, and chemical doping to improve device performance.

  15. Multilayer bioactive glass/zirconium titanate thin films in bone tissue engineering and regenerative dentistry

    PubMed Central

    Mozafari, Masoud; Salahinejad, Erfan; Shabafrooz, Vahid; Yazdimamaghani, Mostafa; Vashaee, Daryoosh; Tayebi, Lobat

    2013-01-01

    Surface modification, particularly coatings deposition, is beneficial to tissue-engineering applications. In this work, bioactive glass/zirconium titanate composite thin films were prepared by a sol-gel spin-coating method. The surface features of the coatings were studied by scanning electron microscopy, atomic force microscopy, and spectroscopic reflection analyses. The results show that uniform and sound multilayer thin films were successfully prepared through the optimization of the process variables and the application of carboxymethyl cellulose as a dispersing agent. Also, it was found that the thickness and roughness of the multilayer coatings increase nonlinearly with increasing the number of the layers. This new class of nanocomposite coatings, comprising the bioactive and inert components, is expected not only to enhance bioactivity and biocompatibility, but also to protect the surface of metallic implants against wear and corrosion. PMID:23641155

  16. Development of the water window imaging X-ray microscope utilizing normal-incidence multilayer optics

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Shealy, David L.; Brinkley, B. R.; Baker, Phillip C.; Barbee, Troy W., Jr.; Walker, Arthur B. C., Jr.

    1991-01-01

    A water-window imaging X-ray telescope configured with normal-incidence multilayer X-ray mirrors has been developed to obtain images with unprecedented spatial resolution and contrast of carbon-based microstructures within living cells. The narrow bandpass response inherent in multilayer X-ray optics is accurately tuned to wavelengths within the water window.

  17. Edge Charge Neutralization of Clay for Improved Oxygen Gas Barrier in Multilayer Nanobrick Wall Thin Films.

    PubMed

    Song, Yixuan; Hagen, David A; Qin, Shuang; Holder, Kevin M; Falke, Kyle; Grunlan, Jaime C

    2016-12-21

    Layer-by-layer (LbL) assembled polymer-clay multilayer thin films are known to provide transparent and flexible gas barrier. In an effort to further lower the oxygen transmission rate (OTR) of these nanobrick wall thin films, sodium chloride was introduced into montmorillonite (MMT) suspension as an "indifferent electrolyte". At pH 6.5 the amphoteric edge sites of MMT have a neutral net charge, and a moderate concentration of NaCl effectively shields the charge from neighboring platelets, allowing van der Waals forces to attract the edges to one another. This edge-to-edge bonding creates a much more tortuous path for diffusing oxygen molecules. An eight-bilayer (BL) polyethylenimine (PEI)/MMT multilayer coating (∼50 nm thick), assembled with 5 mM NaCl in the aqueous clay suspension, exhibited an order of magnitude reduction in oxygen permeability (∼4 × 10(-20) cm(3)·cm/(cm(2)·Pa·s)) relative to its salt-free counterpart. This result represents the best barrier among polymer-clay bilayer systems, which is also lower than SiOx or AlxOy thin films. At higher NaCl concentration, the strong charge screening causes edge-to-face bonding among MMT nanoplatelets, which leads to misalignment in assembled films and increased OTR. This "salty-clay" strategy provides an efficient way to produce better multilayer oxygen barrier thin films by altering ionic strength of the MMT suspension. This simple modification reduces the number of layers necessary for high gas barrier, potentially making these multilayer films interesting for commercial packaging applications.

  18. Selective structuring of multi-layer functional thin films using a laser-induced shockwave delamination process

    NASA Astrophysics Data System (ADS)

    Ehrhardt, M.; Lorenz, P.; Bayer, L.; Molpeceres, C.; Ramirez, C. Antonio Herrera; Zimmer, K.

    2016-03-01

    The laser assisted micro structuring of thin films especially for electronic applications without influence the functionality of the multi-layer system e.g. due to melting products is a challenge for the laser micro machining techniques. The P2 scribing of copper indium gallium selenide (CIGS) solar cells on stainless steel carrier foil was studied using shockwave- induced film delamination (SWIFD) patterning. The delamination process is induced by a shock wave generated by the laser ablation of the rear side of the carrier foil. In the present study UV nanosecond laser pulses provided by a KrF excimer laser were used to induce the SWIFD process. The morphology and size of the achieved thin-film structures were studied in dependence on various laser irradiation parameters by optical and scanning electron microscopy (SEM). Furthermore, the materials composition after the laser patterning was analyzed by energy dispersive X-ray spectroscopy (EDX). The temporal sequences of processes involved in the SWIFD process were analyzed with high speed shadowgraph experiments. The results of the present study shows that in dependence on the laser parameter used a large process window exist in which the CIGS thin film can be removed from the substrate without visible thermal modification of the CIGS thin film.

  19. Optical properties of dielectric thin films including quantum dots

    NASA Astrophysics Data System (ADS)

    Flory, F.; Chen, Y. J.; Lee, C. C.; Escoubas, L.; Simon, J. J.; Torchio, P.; Le Rouzo, J.; Vedraine, S.; Derbal-Habak, Hassina; Ackermann, Jorg; Shupyk, Ivan; Didane, Yahia

    2010-08-01

    Depending on the minimum size of their micro/nano structure, thin films can exhibit very different behaviors and optical properties. From optical waveguides down to artificial anisotropy, through diffractive optics and photonic crystals, the application changes when decreasing the minimum feature size. Rigorous electromagnetic theory can be used to model most of the components but when the size is of a few nanometers, quantum theory has also to be used. These materials including quantum structures are of particular interest for other applications, in particular for solar cells, because of their luminescent and electronic properties. We show that the properties of electrons in multiple quantum wells can be easily modeled with a formalism similar to that used for multilayer waveguides. The effects of different parameters, in particular coupling between wells and well thickness dispersion, on possible discrete energy levels or energy band of electrons and on electron wave functions is given. When such quantum confinement appears the spectral absorption and the extinction coefficient dispersion with wavelength is modified. The dispersion of the real part of the refractive index can then be deduced from the Kramers- Krönig relations. Associated with homogenization theory this approach gives a new model of refractive index for thin films including quantum dots. Absorption spectra of samples composed of ZnO quantum dots in PMMA layers are in preparation are given.

  20. FMR in evaporated single and multilayer thin Fe films

    SciTech Connect

    Layadi, A.; Artman, J.O.; Hall, B.O.; Hoffman, R.A.; Jensen, C.L.; Chakrabarti, D.J.; Saunders, D.A.

    1988-11-15

    We have used ferromagnetic resonance (FMR) at 33 GHz to study the properties of a number of evaporated thin Fe film systems. Values for effective anisotropy field H/sub K//sub eff/ , g value, and exchange constant A were derived. For Fe on glass, chemically bondH/sub K//sub eff/ chemically bond was found to increase with increasing thickness. These changes were attributed to stress which decreased with film thickness. The presence of a Cu or a Ti underlayer did not seem to affect H/sub K//sub eff/ for films grown at room temperature. However, Fe/Ti/glass films made at higher substrate temperatures, T/sub s/, did show an increase in chemically bondH/sub K//sub eff/ chemically bond. The appearance of a spin-wave mode in the Fe films enables us to compute the exchange constant A for Fe, A = (2.12 +- 0.14) x 10/sup -6/ ergs cm/sup -1/. The coupling between two thin Fe films through an intervening Cu layer was investigated. A model predicting the number and position of the peaks in the spectrum as a function of coupling is presented. From experiment it was observed that the coupling remains almost constant through the 50--5-nm Cu thickness range but rises sharply at 2-nm Cu thickness.

  1. Hard X-Ray Scanning Microscope with Multilayer Laue Lens Nanofocusing Optics

    SciTech Connect

    Nazaretski, Evgeny

    2016-11-08

    Evgeny Nazaretski, a physicist at Brookhaven Lab’s National Synchrotron Light Source II, spearheaded the development of a one-of-a-kind x-ray microscope with novel nanofocusing optics called multilayer Laue lenses.

  2. Hard X-Ray Scanning Microscope with Multilayer Laue Lens Nanofocusing Optics

    ScienceCinema

    Nazaretski, Evgeny

    2016-11-23

    Evgeny Nazaretski, a physicist at Brookhaven Lab’s National Synchrotron Light Source II, spearheaded the development of a one-of-a-kind x-ray microscope with novel nanofocusing optics called multilayer Laue lenses.

  3. High temperature stability multilayers for EUV condenser optics

    SciTech Connect

    Bajt, S; Stearns, D G

    2005-05-03

    We investigate the thermal stability of Mo/SiC multilayer coatings at elevated temperatures. Transmission electron microscopy and x-ray diffraction studies show that upon annealing a thermally-induced structural relaxation occurs that transforms the polycrystalline Mo and amorphous SiC layers in as-deposited multilayers into amorphous Mo-Si-C alloy and crystalline SiC, respectively. After this relaxation process is complete the multilayer is stable at temperatures up to 400 C.

  4. Atomic scale analysis of phase formation and diffusion kinetics in Ag/Al multilayer thin films

    NASA Astrophysics Data System (ADS)

    Aboulfadl, Hisham; Gallino, Isabella; Busch, Ralf; Mücklich, Frank

    2016-11-01

    Thin films generally exhibit unusual kinetics leading to chemical reactions far from equilibrium conditions. Binary metallic multilayer thin films with miscible elements show some similar behaviors with respect to interdiffusion and phase formation mechanisms. Interfacial density, lattice defects, internal stresses, layer morphologies and deposition conditions strongly control the mass transport between the individual layers. In the present work, Ag/Al multilayer thin films are used as a simple model system, in which the effects of the sputtering power and the bilayer period thickness on the interdiffusion and film reactions are investigated. Multilayers deposited by DC magnetron sputtering undergo calorimetric and microstructural analyses. In particular, atom probe tomography is extensively used to provide quantitative information on concentration gradients, grain boundary segregations, and reaction mechanisms. The magnitude of interdiffusion was found to be inversely proportional to the period thickness for the films deposited under the same conditions, and was reduced using low sputtering power. Both the local segregation at grain boundaries as well as pronounced non-equilibrium supersaturation effects play crucial roles during the early stages of the film reactions. For multilayers with small periods of 10 nm supersaturation of the Al layers with Ag precedes the polymorphic nucleation and growth of the hcp γ-Ag2Al phase. In larger periods the γ phase formation is triggered at junctions between grain boundaries and layers interfaces, where the pathway to heterogeneous nucleation is local supersaturation. Other Ag-rich phases also form as intermediate phases due to asymmetric diffusion rates of parent phases in the γ phase during annealing.

  5. Soft X-ray imaging of thick carbon-based materials using the normal incidence multilayer optics.

    PubMed

    Artyukov, I A; Feschenko, R M; Vinogradov, A V; Bugayev, Ye A; Devizenko, O Y; Kondratenko, V V; Kasyanov, Yu S; Hatano, T; Yamamoto, M; Saveliev, S V

    2010-10-01

    The high transparency of carbon-containing materials in the spectral region of "carbon window" (lambda approximately 4.5-5nm) introduces new opportunities for various soft X-ray microscopy applications. The development of efficient multilayer coated X-ray optics operating at the wavelengths of about 4.5nm has stimulated a series of our imaging experiments to study thick biological and synthetic objects. Our experimental set-up consisted of a laser plasma X-ray source generated with the 2nd harmonics of Nd-glass laser, scandium-based thin-film filters, Co/C multilayer mirror and X-ray film UF-4. All soft X-ray images were produced with a single nanosecond exposure and demonstrated appropriate absorption contrast and detector-limited spatial resolution. A special attention was paid to the 3D imaging of thick low-density foam materials to be used in design of laser fusion targets.

  6. Highly Crystalline CVD-grown Multilayer MoSe2 Thin Film Transistor for Fast Photodetector

    PubMed Central

    Jung, Chulseung; Kim, Seung Min; Moon, Hyunseong; Han, Gyuchull; Kwon, Junyeon; Hong, Young Ki; Omkaram, Inturu; Yoon, Youngki; Kim, Sunkook; Park, Jozeph

    2015-01-01

    Hexagonal molybdenum diselenide (MoSe2) multilayers were grown by chemical vapor deposition (CVD). A relatively high pressure (>760 Torr) was used during the CVD growth to achieve multilayers by creating multiple nuclei based on the two-dimensional crystal growth model. Our CVD-grown multilayer MoSe2 thin-film transistors (TFTs) show p-type-dominant ambipolar behaviors, which are attributed to the formation of Se vacancies generated at the decomposition temperature (650 °C) after the CVD growth for 10 min. Our MoSe2 TFT with a reasonably high field-effect mobility (10 cm2/V · s) exhibits a high photoresponsivity (93.7 A/W) and a fast photoresponse time (τrise ~ 0.4 s) under the illumination of light, which demonstrates the practical feasibility of multilayer MoSe2 TFTs for photodetector applications. PMID:26477744

  7. Mechanics of Thin Films

    DTIC Science & Technology

    1992-02-06

    S. Hwang, Thermal conductivity of thin films: measurement and microstructural effects, in Thin- film heat transfer, properties and processing, ed...thermal, electrical, optical and magnetic properties . As typical examples we mention microelectronics, optical coatings and multilayers for use in optical...interplay between mechanical properties (elastic moduli), thermal properties (thermal conductivity, thermal expansion coefficient), and optical

  8. X-ray and optical characterization of multilayer semiconductor waveguides

    NASA Astrophysics Data System (ADS)

    Durand, Olivier; Leo, Giuseppe; Masini, Gianlorenzo; Colace, Lorenzo; Marcadet, Xavier; Berger, Vincent; Assanto, Gaetano

    2001-05-01

    Nowadays refractive-index engineering has become a challenging area for experimentalists in semiconductor integrated optics, whereas design constraints are often more strict than both standard technology tolerances and model accuracies. In fact, it is crucial to non-destructively evaluate thicknesses and refractive indices of a multilayer waveguide independently, and to this aim we resorted to X-ray reflectometry and effective index measurements on MBE-grown AlGaAs waveguides, respectively. With the first technique interference effects (Kiessig fringes) arise, which are related to layer thicknesses. By standard data processing, thickness accuracies of +/- 0.05 nm are readily achieved. Effective index measurements were performed at several wavelengths on both slab and rib waveguides, through grating-assisted distributed coupling with both photoresist and etched gratings. Effective indices were determined with an absolute precision as good as 1/2000, adequate for phase matching in parametric devices. Merging thickness and effective index evaluations, the refractive indices of the constituent layers were determined with unprecedented accuracies, in substantial agreement with existing models.

  9. Magneto-optical coupling in ferromagnetic thin films investigated by vector-magneto-optical generalized ellipsometry

    NASA Astrophysics Data System (ADS)

    Mok, K.; Kovács, G. J.; McCord, J.; Li, L.; Helm, M.; Schmidt, H.

    2011-09-01

    We performed generalized Mueller matrix ellipsometry measurements in a magnetic field of arbitrary orientation and magnitude up to 400 mT at room temperature and probed the magneto-optical response of capped, ferromagnetic Fe, Ni20Fe80, Co, Ni80Fe20, and Ni thin films on ZnO substrates in the spectral range from 300 to 1100 nm. We determined the off-diagonal elements in the magneto-optical dielectric tensor under saturated magnetization conditions in the sample surface plane via a model analysis. The off-diagonal elements depend on the net spin polarization and the electronic band structure of the ferromagnetic thin films. For the pure ferromagnetic metals Fe, Co, and Ni, the converted off-diagonal elements agree well with the reported experimental optical conductivity data. As a result we use the extracted wavelength-dependent magneto-optical coupling constant to predict the wavelength-dependent magneto-optical response of different Ni/Fe multilayer structures.

  10. Tracing the 4000 year history of organic thin films: From monolayers on liquids to multilayers on solidsa)

    NASA Astrophysics Data System (ADS)

    Greene, J. E.

    2015-03-01

    The recorded history of organic monolayer and multilayer thin films spans approximately 4000 years. Fatty-acid-based monolayers were deposited on water by the ancients for applications ranging from fortune telling in King Hammurabi's time (˜1800 BC, Mesopotamia) to stilling choppy waters for sailors and divers as reported by the Roman philosopher Pliny the Elder in ˜78 AD, and then much later (1774) by the peripatetic American statesman and natural philosopher Benjamin Franklin, to Japanese "floating-ink" art (suminagashi) developed ˜1000 years ago. The modern science of organic monolayers began in the late-1800s/early-1900s with experiments by Lord Rayleigh and the important development by Agnes Pockels, followed two decades later by Irving Langmuir, of the tools and technology to measure the surface tension of liquids, the surface pressure of organic monolayers deposited on water, interfacial properties, molecular conformation of the organic layers, and phase transitions which occur upon compressing the monolayers. In 1935, Katherine Blodgett published a landmark paper showing that multilayers can be synthesized on solid substrates, with controlled thickness and composition, using an apparatus now known as the Langmuir-Blodgett (L-B) trough. A disadvantage of LB films for some applications is that they form weak physisorbed bonds to the substrate. In 1946, Bigelow, Pickett, and Zisman demonstrated, in another seminal paper, the growth of organic self-assembled monolayers (SAMs) via spontaneous adsorption from solution, rather than from the water/air interface, onto SiO2 and metal substrates. SAMs are close-packed two-dimensional organic crystals which exhibit strong covalent bonding to the substrate. The first multicomponent adsorbed monolayers and multilayer SAMs were produced in the early 1980s. Langmuir monolayers, L-B multilayers, and self-assembled mono- and multilayers have found an extraordinarily broad range of applications including controlled wetting

  11. Tracing the 4000 year history of organic thin films: From monolayers on liquids to multilayers on solids

    SciTech Connect

    Greene, J. E.

    2015-03-15

    The recorded history of organic monolayer and multilayer thin films spans approximately 4000 years. Fatty-acid-based monolayers were deposited on water by the ancients for applications ranging from fortune telling in King Hammurabi's time (∼1800 BC, Mesopotamia) to stilling choppy waters for sailors and divers as reported by the Roman philosopher Pliny the Elder in ∼78 AD, and then much later (1774) by the peripatetic American statesman and natural philosopher Benjamin Franklin, to Japanese “floating-ink” art (suminagashi) developed ∼1000 years ago. The modern science of organic monolayers began in the late-1800s/early-1900s with experiments by Lord Rayleigh and the important development by Agnes Pockels, followed two decades later by Irving Langmuir, of the tools and technology to measure the surface tension of liquids, the surface pressure of organic monolayers deposited on water, interfacial properties, molecular conformation of the organic layers, and phase transitions which occur upon compressing the monolayers. In 1935, Katherine Blodgett published a landmark paper showing that multilayers can be synthesized on solid substrates, with controlled thickness and composition, using an apparatus now known as the Langmuir-Blodgett (L-B) trough. A disadvantage of LB films for some applications is that they form weak physisorbed bonds to the substrate. In 1946, Bigelow, Pickett, and Zisman demonstrated, in another seminal paper, the growth of organic self-assembled monolayers (SAMs) via spontaneous adsorption from solution, rather than from the water/air interface, onto SiO{sub 2} and metal substrates. SAMs are close-packed two-dimensional organic crystals which exhibit strong covalent bonding to the substrate. The first multicomponent adsorbed monolayers and multilayer SAMs were produced in the early 1980s. Langmuir monolayers, L-B multilayers, and self-assembled mono- and multilayers have found an extraordinarily broad range of applications including

  12. Thin nearly wireless adaptive optical device

    NASA Technical Reports Server (NTRS)

    Knowles, Gareth J. (Inventor); Hughes, Eli (Inventor)

    2009-01-01

    A thin nearly wireless adaptive optical device capable of dynamically modulating the shape of a mirror in real time to compensate for atmospheric distortions and/or variations along an optical material is provided. The device includes an optical layer, a substrate, at least one electronic circuit layer with nearly wireless architecture, an array of actuators, power electronic switches, a reactive force element, and a digital controller. Actuators are aligned so that each axis of expansion and contraction intersects both substrate and reactive force element. Electronics layer with nearly wireless architecture, power electronic switches, and digital controller are provided within a thin-film substrate. The size and weight of the adaptive optical device is solely dominated by the size of the actuator elements rather than by the power distribution system.

  13. Thin, nearly wireless adaptive optical device

    NASA Technical Reports Server (NTRS)

    Knowles, Gareth (Inventor); Hughes, Eli (Inventor)

    2008-01-01

    A thin, nearly wireless adaptive optical device capable of dynamically modulating the shape of a mirror in real time to compensate for atmospheric distortions and/or variations along an optical material is provided. The device includes an optical layer, a substrate, at least one electronic circuit layer with nearly wireless architecture, an array of actuators, power electronic switches, a reactive force element, and a digital controller. Actuators are aligned so that each axis of expansion and contraction intersects both substrate and reactive force element. Electronics layer with nearly wireless architecture, power electronic switches, and digital controller are provided within a thin-film substrate. The size and weight of the adaptive optical device is solely dominated by the size of the actuator elements rather than by the power distribution system.

  14. Thin, nearly wireless adaptive optical device

    NASA Technical Reports Server (NTRS)

    Knowles, Gareth (Inventor); Hughes, Eli (Inventor)

    2007-01-01

    A thin, nearly wireless adaptive optical device capable of dynamically modulating the shape of a mirror in real time to compensate for atmospheric distortions and/or variations along an optical material is provided. The device includes an optical layer, a substrate, at least one electronic circuit layer with nearly wireless architecture, an array of actuators, power electronic switches, a reactive force element, and a digital controller. Actuators are aligned so that each axis of expansion and contraction intersects both substrate and reactive force element. Electronics layer with nearly wireless architecture, power electronic switches, and digital controller are provided within a thin-film substrate. The size and weight of the adaptive optical device is solely dominated by the size of the actuator elements rather than by the power distribution system.

  15. Finite element analysis and equivalent parallel-resistance model for conductive multilayer thin films

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Yi; Juang, Jia-Yang

    2016-07-01

    The standard collinear four-point probe method is an indispensable tool and has been extensively used for characterizing conductive thin films with homogeneous and isotropic electrical properties. In this paper, we conduct three-dimensional (3D) finite element simulations on conductive multilayer films to study the relationship between the reading of the four-point probe and the conductivity of the individual layers. We find that a multilayer film may be modeled as a simple equivalent circuit with multiple resistances, connected in parallel for a wide range of resistivity and thickness ratios, as long as its total thickness is smaller than approximately half of the probe spacing. As a result, we may determine the resistivity of each layer sequentially by applying the four-point probe, with the original correction factor π/ln(2), after deposition of each layer.

  16. Thin-film optical shutter. Final report

    SciTech Connect

    Matlow, S.L.

    1981-02-01

    A specific embodiment of macroconjugated macromolecules, the poly (p-phenylene)'s, has been chosen as the one most likely to meet all of the requirements of the Thin Film Optical Shutter project (TFOS). The reason for this choice is included. In order to be able to make meaningful calculations of the thermodynamic and optical properties of the poly (p-phenylene)'s a new quantum mechanical method was developed - Equilibrium Bond Length (EBL) Theory. Some results of EBL Theory are included.

  17. Polyelectrolyte-mediated assembly of copper-phthalocyanine tetrasulfonate multilayers and the subsequent production of nanoparticulate copper oxide thin films.

    PubMed

    Chickneyan, Zarui Sara; Briseno, Alejandro L; Shi, Xiangyang; Han, Shubo; Huang, Jiaxing; Zhou, Feimeng

    2004-07-01

    An approach to producing films of nanometer-sized copper oxide particulates, based on polyelectrolyte-mediated assembly of the precursor, copper(II)phthalocyanine tetrasulfonate (CPTS), is described. Multilayered CPTS and polydiallyldimethylammonium chloride (PDADMAC) were alternately assembled on different planar substrates via the layer-by-layer (LbL) procedure. The growth of CPTS multilayers was monitored by UV-visible spectrometry and quartz crystal microbalance (QCM) measurements. Both the UV-visible spectra and the QCM data showed that a fixed amount of CPTS could be attached to the substrate surface for a given adsorption cycle. Cyclic voltammograms at the CPTS/PDADMAC-covered gold electrode exhibited a decrease in peak currents with the layer number, indicating that the permeability of CPTS multilayers on the electrodes had diminished. When these CPTS multilayered films were calcined at elevated temperatures, uniform thin films composed of nanoparticulate copper oxide could be produced. Ellipsometry showed that the thickness of copper oxide nanoparticulate films could be precisely tailored by varying the thickness of CPTS multilayer films. The morphology and roughness of CPTS multilayer and copper oxide thin films were characterized by atomic force microscopy. X-ray diffraction (XRD) measurements indicated that these thin films contained both CuO and Cu2O nanoparticles. The preparation of such copper oxide thin films with the use of metal complex precursors represents a new route for the synthesis of inorganic oxide films with a controlled thickness.

  18. Giant optical nonlocality near the Dirac point in metal-dielectric multilayer metamaterials.

    PubMed

    Sun, Lei; Gao, Jie; Yang, Xiaodong

    2013-09-09

    The giant optical nonlocality near the Dirac point in lossless metal-dielectric multilayer metamaterials is revealed and investigated through the analysis of the band structure of the multilayer stack in the three-dimensional ω-k space, according to the transfer-matrix method with the optical nonlocal effect. The position of the Dirac point is analytically located in the ω-k space. It is revealed that the emergence of the Dirac point is due to the degeneracy of the symmetric and the asymmetric eigenmodes of the coupled surface plasmon polaritons. The optical nonlocality induced epsilon-near-zero frequency shift for the multilayer stack compared to the effective medium is studied. Furthermore, the giant optical nonlocality around the Dirac point is explored with the iso-frequency contour analysis, while the beam splitting phenomenon at the Dirac point due to the optical nonlocal effect is also demonstrated.

  19. Investigation of interface roughness cross-correlation properties of optical thin films from total scattering losses

    NASA Astrophysics Data System (ADS)

    Pan, Yongqiang; Wu, Zhensen; Hang, Lingxia

    2010-03-01

    The interface roughness and interface roughness cross-correlation properties affect the scattering losses of high-quality optical thin films. In this paper, the theoretical models of light scattering induced by surface and interface roughness of optical thin films are concisely presented. Furthermore, influence of interface roughness cross-correlation properties to light scattering is analyzed by total scattering losses. Moreover, single-layer TiO 2 thin film thickness, substrate roughness of K9 glass and ion beam assisted deposition (IBAD) technique effect on interface roughness cross-correlation properties are studied by experiments, respectively. A 17-layer dielectric quarter-wave high reflection multilayer is analyzed by total scattering losses. The results show that the interface roughness cross-correlation properties depend on TiO 2 thin film thickness, substrate roughness and deposition technique. The interface roughness cross-correlation properties decrease with the increase of film thickness or the decrease of substrates roughness. Furthermore, ion beam assisted deposition technique can increase the interface roughness cross-correlation properties of optical thin films. The measured total scattering losses of 17-layer dielectric quarter-wave high reflection multilayer deposited with IBAD indicate that completely correlated interface model can be observed, when substrate roughness is about 2.84 nm.

  20. Analysis of a Thin Optical Lens Model

    ERIC Educational Resources Information Center

    Ivchenko, Vladimir V.

    2011-01-01

    In this article a thin optical lens model is considered. It is shown that the limits of its applicability are determined not only by the ratio between the thickness of the lens and the modules of the radii of curvature, but above all its geometric type. We have derived the analytical criteria for the applicability of the model for different types…

  1. Dielectric and Optical Properties of Thin Films.

    DTIC Science & Technology

    1978-08-01

    Is const ructed from a thin slice of bismuth silicon oxlde,~ a cubic crystal exhibiting the Pockels effect. The crystal also is photoconductive when... Photoconductive diameter electro -optical crystal ~~~~~~~~~~~~~~~~~ i12SiO20) Electrode 2 Insulator layer Electrode 1 (paralene) Figure 1-1

  2. Aspects of Integrating Functional Electroceramic Material in Multilayer Thin Films for Image Sensing: Modeling and Experiment

    NASA Astrophysics Data System (ADS)

    Matin, M. A.; Oishi, K.; Katsuta, A.; Akai, D.; Sawada, K.; Ishida, M.

    2015-07-01

    Using combined experimental and simulation techniques, this study addresses the critical stress for peeling off crucial layer(s) in multilayered epitaxial functional thin films on n-Si(001) substrate. The thickness of platinum (Pt) and PZT thin films was varied from 22 nm to 142 nm and 90 nm to 450 nm, respectively. Residual stresses were measured by analyzing captured fringes using Newton's rings technique. Advanced finite element computation was next conducted to predict the evolution of residual stresses. Induced stresses in Pt thin film were found to be decreased with decreasing the thickness of film from 72 nm to 40 nm. In contrast, stresses are shown to be decreased with increasing the thickness of PZT film from 240 nm to 450 nm. The design of the pyroelectric multilayered sensors was thus optimized employing finite element (FE) simulation. Computed stresses were found to correlate well with that observed in experiments. FE simulations can thus be used as a tool to a priori predict the evolution of residual stresses, which may allow a fail-safe design before the fabrication of pyroelectric image sensors.

  3. Scanning probe microscopy: instrumentation and applications on thin films and magnetic multilayers.

    PubMed

    Karoutsos, Vagelis

    2009-12-01

    In this article we present a review on instrumentation and the modes of operation of a scanning probe microscope. In detail, we review the main techniques of Scanning Probe Microscopy (SPM), which are Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM), focusing our attention on the latter one. The AFM instrument provides information on the roughness and grain size of thin films. As an example we review recent results on two metallic thin film systems: thin Ag films deposited on glass, and Ni/Pt compositionally modulated multilayers deposited on glass, Si, and polyimide substrates. To show the validity of the grain size measurements, we compare the data with the ones resulting from X-ray diffraction (XRD) measurements. We show that the AFM results are reliable for grain diameters as small as 14 nm, which is approximately comparable to the tip radius. Finally, we deal with Magnetic Force Microscopy (MFM) results on Co/Pt and Co/Au multilayers. We observe perpendicularly magnetized domains. The domain configurations are correlated to the magnetization hysteresis curves.

  4. Producing ZnFe2O4 thin films from ZnO/FeO multilayers

    NASA Astrophysics Data System (ADS)

    Salcedo Rodríguez, Karen L.; Hoffmann, Martin; Golmar, Federico; Pasquevich, Gustavo; Werner, Peter; Hergert, Wolfram; Rodríguez Torres, Claudia E.

    2017-01-01

    The present work investigates the structural and magnetic properties of ZnFe2O4 thin films obtained from ZnO/FeO multilayers deposited on MgO substrate by DC reactive sputtering. We show that this method is good to grow efficiently ordered ZnFe2O4 films. The quality of the thin films is ensured by TEM measurements, which showed a well ordered film of ZnFe2O4. The magnetic properties of these thin films present still minimal differences when compared to bulk ZnFe2O4 powders. They exhibit a ferromagnetic-like behavior at low temperatures, whereas ZnFe2O4 is expected to be antiferromagnetic. We found that the magnetic signal originated from the film surface, where cation inversion was visible from grazing incidence X-ray fluorescence measurements. The inversion of Fe ions with Zn ions caused a magnetic spin glass state, which created then the ferromagnetic-like behavior differently to bulk ZnFe2O4. These facts point to possible routes in order to improve the growing process of ZnFe2O4 via ZnO/FeO multilayers.

  5. Theory and practical considerations of multilayer dielectric thin-film stacks in Ag-coated hollow waveguides.

    PubMed

    Bledt, Carlos M; Melzer, Jeffrey E; Harrington, James A

    2014-02-01

    This analysis explores the theory and design of dielectric multilayer reflection-enhancing thin film stacks based on high and low refractive index alternating layers of cadmium sulfide (CdS) and lead sulfide (PbS) on silver (Ag)-coated hollow glass waveguides (HGWs) for low loss transmission at midinfrared wavelengths. The fundamentals for determining propagation losses in such multilayer thin-film-coated Ag hollow waveguides is thoroughly discussed, and forms the basis for further theoretical analysis presented in this study. The effects on propagation loss resulting from several key parameters of these multilayer thin film stacks is further explored in order to bridge the gap between results predicted through calculation under ideal conditions and deviations from such ideal models that often arise in practice. In particular, the effects on loss due to the number of dielectric thin film layers deposited, deviation from ideal individual layer thicknesses, and surface roughness related scattering losses are presented and thoroughly investigated. Through such extensive theoretical analysis the level of understanding of the underlying loss mechanisms of multilayer thin-film Ag-coated HGWs is greatly advanced, considerably increasing the potential practical development of next-generation ultralow-loss mid-IR Ag/multilayer dielectric-coated HGWs.

  6. Thickness-dependent carrier transport and optically enhanced transconductance gain in III-VI multilayer InSe

    NASA Astrophysics Data System (ADS)

    Ho, Ching-Hwa

    2016-06-01

    Multilayer InSe with a thickness above ˜20 nm, is a direct semiconductor with a peak absorption wavelength approaching λ = 1000 nm, which is a promising candidate for solar-energy conversion and 2D optoelectronics devices. We present herein the experimental observations of thickness-dependent conductivity and photoconductive-responsivity spectrum in multilayer InSe as well as optically enhanced transconductance gain in the multilayer InSe metal-semiconductor-field-effect transistor (MESFET) illuminated by a halogen lamp. The voltage-current (V-I) measurement result shows multilayer InSe belongs to a p-type semiconductor, which can form a p-channel FET device. Thickness (t) dependent conductivity (σ) of multilayer InSe reveals about six-order variation from 5076 (Ω-cm)-1 (t = 5 nm) to 2.56 × 10-3 (Ω-cm)-1 (t = 184 μm, bulk) following a relationship of σ ∝ t -1.38. The highest conductivity in a thin InSe (e.g. t = 5 nm) is due to the increase of carrier density when the thickness is decreased. The photoresponsivity spectrum of a Ag-InSe-Ag multilayer photoconductor demonstrates a prominent peak absorption at 1.1 ˜ 1.3 eV, matches well with the direct-free-exciton energy of the InSe. A multilayer p-InSe MESFET was tested by V-I measurement. The transconductance was measured and determined to be {g}m={≤ft|\\tfrac{\\partial {{{I}}}{{D}}}{\\partial {{{V}}}{{G}}}\\right|}{{{V}}{{SD}}={{2V}}} = ({1.25 +/- 0.008})× {10}-4≤ft(\\tfrac{{{A}}}{{{V}}}\\right). The gm value will enhance about three times when the MESFET was placed under the illumination of a tungsten halogen lamp of a lower power density ˜0.5 mW · cm-2. All the experimental results demonstrate multilayer InSe a promising 2D material available for microelectronics and optoelectronics applications.

  7. Periodic nanostructures for tunable thin optics

    NASA Astrophysics Data System (ADS)

    Criante, L.; Di Fonzo, F.; Fumagalli, F.; Lanzani, G.; Passoni, L.; Scotognella, F.; Simoni, F.

    2015-08-01

    We report the realization and characterization of porous nanostructures where a periodic refractive index modulation is achieved by stacking layers with different nano-architectures. One multilayer photonic crystal has been fabricated starting from colloidal dispersion of silicon dioxide and zirconium dioxide using spin coating technique. Improved efficiency of Bragg reflectivity (up to 85%) has been obtained by a new bottom-up fabrication technique of photonic hierarchical nanostructures based on self-assembly from the gas-phase at low temperature whit a very thin (≍ 1 μm) photonic crystal devices. Due to the high porosity, these systems can be infiltrated with nematic liquid crystals leading to tuning of the Bragg reflection band by applying low voltages to the structure.

  8. Layer number dependent optical properties of multilayer hexagonal BN epilayers

    NASA Astrophysics Data System (ADS)

    Du, X. Z.; Uddin, M. R.; Li, J.; Lin, J. Y.; Jiang, H. X.

    2017-02-01

    Deep ultraviolet photoluminescence emission spectroscopy has been employed to probe the layer number dependent near band-edge transitions above 5 eV in multilayer hexagonal boron nitride (h-BN) epilayers grown by metal-organic chemical vapor deposition. Two emission lines near 5.30 and 5.47 eV were resolved at 10 K. These two emission lines share similar spectroscopic features, and their energy peak separation is nearly independent of the number of layers. The observed energy separation of ˜172 meV coincides well with the in-plane phonon vibration mode, E2g, having an energy of 1370 cm-1 (˜172 meV). The results suggested that the emission line at ˜5.30 eV and ˜5.47 eV are a donor-acceptor-pair transition and its one E2g phonon replica, respectively. When the number of layers decreases from 100 to 8, the emission peak positions (Ep) of both emission lines blueshifted monotonically, indicating the dimensionality effects on the optical properties of h-BN. The layer number dependence of Ep can be described by an empirical formula, which accounts for the variations of the energy bandgap and activation energies of impurities with the number of layers. The results revealed that the impurity activation energies and the carrier-phonon coupling strength increase as the dimensionality of h-BN scales from thick layer to monolayer, suggesting that it is more difficult to achieve conductivity control through doping in monolayer or few-layer h-BN than in thick h-BN.

  9. Development of high damage threshold multilayer thin film beam combiner for laser application

    NASA Astrophysics Data System (ADS)

    Nand, Mangla; Babita, Jena, S.; Tokas, R. B.; Rajput, P.; Mukharjee, C.; Thakur, S.; Jha, S. N.; Sahoo, N. K.

    2016-05-01

    A polarized wavelength multiplexer with high laser induced damage threshold has been developed to combine two laser beam of high peak power in the visible region. The present wavelength multiplexer is a multilayer thin film device deposited by reactive electron beam evaporation. The developed device is capable of combining two p-polarized laser beams of peak power density of 1.7 GW/cm2 at an angle of incidence of 45°. High transmission (T> 90%) in high pass region and high reflection (R> 99%) in stop band region have been achieved.

  10. Study on Ultrafast Photodynamics of Novel Multilayered Thin Films for Device Applications

    DTIC Science & Technology

    2007-11-02

    thin film as well as heavy metal nanoparticles embedded in melting glass optical materials. This effort included research on ultrafast passive optical...the initial focus was to develop heavy metal nanoparticle doped inorganic glass, which has been proven to show an enhanced chi(exp 3) effect. The other

  11. Wedged multilayer Laue Lens.

    SciTech Connect

    Conley, R.; Liu, C.; Qian, J.; Kewish, C. M.; Macrander, A. T.; Yan, H.; Kang, H. C.; Maser, J.; Stephenson, G. B.

    2008-05-01

    A multilayer Laue lens (MLL) is an x-ray focusing optic fabricated from a multilayer structure consisting of thousands of layers of two different materials produced by thin-film deposition. The sequence of layer thicknesses is controlled to satisfy the Fresnel zone plate law and the multilayer is sectioned to form the optic. An improved MLL geometry can be created by growing each layer with an in-plane thickness gradient to form a wedge, so that every interface makes the correct angle with the incident beam for symmetric Bragg diffraction. The ultimate hard x-ray focusing performance of a wedged MLL has been predicted to be significantly better than that of a nonwedged MLL, giving subnanometer resolution with high efficiency. Here, we describe a method to deposit the multilayer structure needed for an ideal wedged MLL and report our initial deposition results to produce these structures.

  12. Multilayer and grazing incidence X-ray/EUV optics; Proceedings of the Meeting, San Diego, CA, July 22-24, 1991

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B. (Editor)

    1992-01-01

    The present conference discusses the Advanced X-ray Astrophysics Facility (AXAF) calibration by means of synchrotron radiation and its X-ray reflectivity, X-ray scattering measurements from thin-foil X-ray mirrors, lobster-eye X-ray optics using microchannel plates, space-based interferometry at EUV and soft X-ray wavelengths, a water-window imaging X-ray telescope, a graded d-spacing multilayer telescope for high energy X-ray astronomy, photographic films for the multispectral solar telescope array, a soft X-ray ion chamber, and the development of hard X-ray optics. Also discussed are X-ray spectroscopy with multilayered optics, a slit aperture for monitoring X-ray experiments, an objective double-crystal spectrometer, a Ly-alpha coronagraph/polarimeter, tungsten/boron nitride multilayers for XUV optical applications, the evaluation of reflectors for soft X-ray optics, the manufacture of elastically bent crystals and multilayer mirrors, and selective photodevices for the VUV.

  13. Lipid Multilayer Grating Arrays Integrated by Nanointaglio for Vapor Sensing by an Optical Nose.

    PubMed

    Lowry, Troy W; Prommapan, Plengchart; Rainer, Quinn; Van Winkle, David; Lenhert, Steven

    2015-08-21

    Lipid multilayer gratings are recently invented nanomechanical sensor elements that are capable of transducing molecular binding to fluid lipid multilayers into optical signals in a label free manner due to shape changes in the lipid nanostructures. Here, we show that nanointaglio is suitable for the integration of chemically different lipid multilayer gratings into a sensor array capable of distinguishing vapors by means of an optical nose. Sensor arrays composed of six different lipid formulations are integrated onto a surface and their optical response to three different vapors (water, ethanol and acetone) in air as well as pH under water is monitored as a function of time. Principal component analysis of the array response results in distinct clustering indicating the suitability of the arrays for distinguishing these analytes. Importantly, the nanointaglio process used here is capable of producing lipid gratings out of different materials with sufficiently uniform heights for the fabrication of an optical nose.

  14. Bombardment induced ion transport - part IV: ionic conductivity of ultra-thin polyelectrolyte multilayer films.

    PubMed

    Wesp, Veronika; Hermann, Matthias; Schäfer, Martin; Hühn, Jonas; Parak, Wolfgang J; Weitzel, Karl-Michael

    2016-02-14

    The dependence of the ionic conductance of ultra-thin polyelectrolyte multilayer (PEM) films on the temperature and the number of bilayers has been investigated by the recently developed low energy bombardment induced ion transport (BIIT) method. To this end multilayers of alternating poly(sodium 4-styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) layers were deposited on a metal electrode and subsequently bombarded by a low energy potassium ion beam. Ions are transported through the film according to the laws of electro-diffusion towards a grounded backside electrode. They are neutralized at the interface between the polymer film and the metal electrode. The detected neutralization current scales linearly with the acceleration potential of the ion beam indicating Ohmic behavior for the (PAH/PSS)x multilayer, where x denotes the number of bilayers. The conductance exhibits a non-monotonic dependence on the number of bilayers, x. For 2 ≤ x ≤ 8 the conductance increases non-linearly with the number of bilayers. For x ≥ 8 the conductance decreases with increasing number of bilayers. The variation of the conductance is rationalized by a model accounting for the structure dependence of the conductivity. The thinnest sample for which the conductance has been measured is the single bilayer reflecting properties dominated by the interface. The activation energy for the ion transport is 0.49 eV.

  15. Nanomechanical characterization of multilayered thin film structures for digital micromirror devices.

    PubMed

    Wei, Guohua; Bhushan, Bharat; Joshua Jacobs, S

    2004-08-01

    The digital micromirror device (DMD), used for digital projection displays, comprises a surface-micromachined array of up to 2.07 million aluminum micromirrors (14 microm square and 15 microm pitch), which switch forward and backward thousands of times per second using electrostatic attraction. The nanomechanical properties of the thin-film structures used are important to the performance of the DMD. In this paper, the nanomechanical characterization of the single and multilayered thin film structures, which are of interest in DMDs, is carried out. The hardness, Young's modulus and scratch resistance of TiN/Si, SiO2/Si, Al alloy/Si, TiN/Al alloy/Si and SiO2/TiN/Al alloy/Si thin-film structures were measured using nanoindentation and nanoscratch techniques, respectively. The residual (internal) stresses developed during the thin film growth were estimated by measuring the radius of curvature of the sample before and after deposition. To better understand the nanomechanical properties of these thin film materials, the surface and interface analysis of the samples were conducted using X-ray photoelectron spectroscopy. The nanomechanical properties of these materials are analyzed and the impact of these properties on micromirror performance is discussed.

  16. Design and development of an in-line sputtering system and process development of thin film multilayer neutron supermirrors

    SciTech Connect

    Biswas, A.; Sampathkumar, R.; Kumar, Ajaya; Bhattacharyya, D.; Sahoo, N. K.; Lagoo, K. D.; Veerapur, R. D.; Padmanabhan, M.; Puri, R. K.; Bhattacharya, Debarati; Singh, Surendra; Basu, S.

    2014-12-15

    Neutron supermirrors and supermirror polarizers are thin film multilayer based devices which are used for reflecting and polarizing neutrons in various neutron based experiments. In the present communication, the in-house development of a 9 m long in-line dc sputtering system has been described which is suitable for deposition of neutron supermirrors on large size (1500 mm × 150 mm) substrates and in large numbers. The optimisation process of deposition of Co and Ti thin film, Co/Ti periodic multilayers, and a-periodic supermirrors have also been described. The system has been used to deposit thin film multilayer supermirror polarizers which show high reflectivity up to a reasonably large critical wavevector transfer of ∼0.06 Å{sup −1} (corresponding to m = 2.5, i.e., 2.5 times critical wavevector transfer of natural Ni). The computer code for designing these supermirrors has also been developed in-house.

  17. Brilliant iridescence of Morpho butterfly wing scales is due to both a thin film lower lamina and a multilayered upper lamina.

    PubMed

    Giraldo, M A; Stavenga, D G

    2016-05-01

    Butterflies belonging to the nymphalid subfamily, Morphinae, are famous for their brilliant blue wing coloration and iridescence. These striking optical phenomena are commonly explained as to originate from multilayer reflections by the ridges of the wing scales. Because the lower lamina of the scales of related nymphalid butterflies, the Nymphalinae, plays a dominant role in the wing coloration, by acting as a thin film reflector, we investigated single blue scales of three characteristic Morpho species: M. epistrophus, M. helenor and M. cypris. The experimental data obtained by spectrophotometry, scatterometry and scanning electron microscopy demonstrated that also in the Morpho genus the lower lamina of both the cover and ground scales acts as an optical thin film reflector, contributing importantly to the blue structural coloration of the wings. Melanin pigment has a contrast-enhancing function in a sub-class of ground scales.

  18. Optimizing vanadium pentoxide thin films and multilayers from dip-coated nanofluid precursors.

    PubMed

    Glynn, Colm; Creedon, Donal; Geaney, Hugh; O'Connell, John; Holmes, Justin D; O'Dwyer, Colm

    2014-02-12

    Using an alkoxide-based precursor, a strategy for producing highly uniform thin films and multilayers of V2O5 is demonstrated using dip coating. Defect-free and smooth films of V2O5 on different surfaces can be deposited from liquid precursors. We show how pinholes are formed due to heterogeneous nucleation during hydrolysis as the precursor forms a nanofluid. Using knowledge of instability formation often found in composite nanofluid films and the influence of cluster formation on the stability of these films, we show how polymer-precursor mixtures provide optimum uniformity and very low surface roughness in amorphous V2O5 and also orthorhombic V2O5 after crystallization by heating. Pinhole and roughness instability formation during the liquid stage of the nanofluid on gold and ITO substrates is suppressed giving a uniform coating. Practically, understanding evolution pathways that involve dewetting processes, nucleation, decomposition, or hydrolysis in complex nanofluids provides a route for improved uniformity of thin films. The method could be extended to improve the consistency in sequential or iterative multilayer deposits of a range of liquid precursors for functional materials and coatings.

  19. Recovery of Mo/Si multilayer coated optical substrates

    DOEpatents

    Baker, Sherry L.; Vernon, Stephen P.; Stearns, Daniel G.

    1997-12-16

    Mo/Si multilayers are removed from superpolished ZERODUR and fused silica substrates with a dry etching process that, under suitable processing conditions, produces negligible change in either the substrate surface figure or surface roughness. The two step dry etching process removes SiO.sub.2 overlayer with a fluroine-containing gas and then moves molybdenum and silicon multilayers with a chlorine-containing gas. Full recovery of the initial normal incidence extreme ultra-violet (EUV) reflectance response has been demonstrated on reprocessed substrates.

  20. Recovery of Mo/Si multilayer coated optical substrates

    DOEpatents

    Baker, S.L.; Vernon, S.P.; Stearns, D.G.

    1997-12-16

    Mo/Si multilayers are removed from superpolished ZERODUR and fused silica substrates with a dry etching process that, under suitable processing conditions, produces negligible change in either the substrate surface figure or surface roughness. The two step dry etching process removes SiO{sub 2} overlayer with a fluroine-containing gas and then moves molybdenum and silicon multilayers with a chlorine-containing gas. Full recovery of the initial normal incidence extreme ultra-violet (EUV) reflectance response has been demonstrated on reprocessed substrates. 5 figs.

  1. Polydiacetylene thin films for nonlinear optical applications

    NASA Technical Reports Server (NTRS)

    Paley, Mark S.

    1993-01-01

    One very promising class of organic compounds for nonlinear optical (NLO) applications are polydiacetylenes, which are novel in that they are highly conjugated polymers which can also be crystalline. Polydiacetylenes offer several advantages over other organic materials: because of their highly conjugated electronic structures, they are capable of possessing large optical nonlinearities with fast response times; because they are crystalline, they can be highly ordered, which is essential for optimizing their NLO properties; and, last, because they are polymeric, they can be formed as thin films, which are useful for device fabrication. We have actively been carrying out ground-based research on several compounds of interest.

  2. Development of extreme ultraviolet and soft x-ray multilayer optics for scientific studies with femtosecond/attosecond sources

    SciTech Connect

    Aquila, Andrew Lee

    2009-05-21

    The development of multilayer optics for extreme ultraviolet (EUV) radiation has led to advancements in many areas of science and technology, including materials studies, EUV lithography, water window microscopy, plasma imaging, and orbiting solar physics imaging. Recent developments in femtosecond and attosecond EUV pulse generation from sources such as high harmonic generation lasers, combined with the elemental and chemical specificity provided by EUV radiation, are opening new opportunities to study fundamental dynamic processes in materials. Critical to these efforts is the design and fabrication of multilayer optics to transport, focus, shape and image these ultra-fast pulses This thesis describes the design, fabrication, characterization, and application of multilayer optics for EUV femtosecond and attosecond scientific studies. Multilayer mirrors for bandwidth control, pulse shaping and compression, tri-material multilayers, and multilayers for polarization control are described. Characterization of multilayer optics, including measurement of material optical constants, reflectivity of multilayer mirrors, and metrology of reflected phases of the multilayer, which is critical to maintaining pulse size and shape, were performed. Two applications of these multilayer mirrors are detailed in the thesis. In the first application, broad bandwidth multilayers were used to characterize and measure sub-100 attosecond pulses from a high harmonic generation source and was performed in collaboration with the Max-Planck institute for Quantum Optics and Ludwig- Maximilians University in Garching, Germany, with Professors Krausz and Kleineberg. In the second application, multilayer mirrors with polarization control are useful to study femtosecond spin dynamics in an ongoing collaboration with the T-REX group of Professor Parmigiani at Elettra in Trieste, Italy. As new ultrafast x-ray sources become available, for example free electron lasers, the multilayer designs

  3. Stability of multilayers for short-wavelength optics

    SciTech Connect

    Ziegler, E.; Lepetre, Y.; Schuller, I.K.; Viccaro, P.J.; Spiller, E.

    1986-03-01

    A variety of multilayer mirrors with transition metal absorber layers (W-C, Wre-C, Co-C, and Cr-C) have been fabricated and tested up to 1000 C using standard 0.20 x-ray diffraction, Debye-Scherrer scattering and microcleavage transmission electron microscopy. The 0-20 x-ray diffraction during annealing shows the Bragg peak position to shift toward lower angles with increasing temperature. This irreversible shift starts at around 300 C and is equivalent to as much as 12% expansion of the multilayer period with a temperature change from ambient to 750 C. In all cases a crystallization occurs in the metal component between 650-750 C. The different types of crystalline compounds formed have been identified by the Debye-Scherrer technique. As a consequence of this crystallization abrupt changes occur in the multilayer structure. Electron microscopy shows that the surface roughness increases by formation of hillocks and the layered structure is destroyed. Moreover the x-ray reflectivity decreases considerably. The expansion and crystallization are of great importance in cases where a precise multilayer period is required or in devices intended for high x-ray flux applications.

  4. Preliminary investigation of changes in x-ray multilayer optics subjected to high radiation flux

    SciTech Connect

    Hockaday, M.P.; Blake, R.L.; Grosso, J.S.; Selph, M.M.; Klein, M.M.; Matuska, W. Jr.; Palmer, M.A.; Liefeld, R.J.

    1985-01-01

    A variety of metal multilayers was exposed to high x-ray flux using Sandia National Laboratories' PROTO II machine in the gas puff mode. Fluxes incident on the multilayers above 700 MW/cm/sup 2/ in total radiation, in nominal 20 ns pulses, were realized. The neon hydrogen- and helium-like resonance lines were used to probe the x-ray reflectivity properties of the multilayers as they underwent change of state during the heating pulse. A fluorescer-fiber optic-streak camera system was used to monitor the changes in x-ray reflectivity as a function of time and irradiance. Preliminary results are presented for a W/C multilayer. Work in progress to model the experiment is discussed. 13 refs., 4 figs.

  5. MoRu/Be multilayers for extreme ultraviolet applications

    DOEpatents

    Bajt, Sasa C.; Wall, Mark A.

    2001-01-01

    High reflectance, low intrinsic roughness and low stress multilayer systems for extreme ultraviolet (EUV) lithography comprise amorphous layers MoRu and crystalline Be layers. Reflectance greater than 70% has been demonstrated for MoRu/Be multilayers with 50 bilayer pairs. Optical throughput of MoRu/Be multilayers can be 30-40% higher than that of Mo/Be multilayer coatings. The throughput can be improved using a diffusion barrier to make sharper interfaces. A capping layer on the top surface of the multilayer improves the long-term reflectance and EUV radiation stability of the multilayer by forming a very thin native oxide that is water resistant.

  6. Modelling single shot damage thresholds of multilayer optics for high-intensity short-wavelength radiation sources.

    PubMed

    Loch, R A; Sobierajski, R; Louis, E; Bosgra, J; Bijkerk, F

    2012-12-17

    The single shot damage thresholds of multilayer optics for high-intensity short-wavelength radiation sources are theoretically investigated, using a model developed on the basis of experimental data obtained at the FLASH and LCLS free electron lasers. We compare the radiation hardness of commonly used multilayer optics and propose new material combinations selected for a high damage threshold. Our study demonstrates that the damage thresholds of multilayer optics can vary over a large range of incidence fluences and can be as high as several hundreds of mJ/cm(2). This strongly suggests that multilayer mirrors are serious candidates for damage resistant optics. Especially, multilayer optics based on Li(2)O spacers are very promising for use in current and future short-wavelength radiation sources.

  7. Suppression of Cross Contamination in Multi-Layer Thin Film Prepared by Using Rotating Hexagonal Sputtering Cathode.

    PubMed

    Park, Se Yeon; Choi, Bum Ho; Lee, Jong Ho

    2015-01-01

    In this study, single- and multi-layered thin films were prepared on a glass substrate using a newly developed rotating hexagonal sputtering cathode in a single chamber. The rotatinghexagonal sputtering cathode can install up to six different sputtering targets or six single targets in a cathode. Using the rotating hexagonal cathode, we prepared a single-layered AZO film and a multi-layer film to evaluate the performance of hexagonal gun. Cross-contamination, which is often observed in multi-layer thin film preparation, was suppressed to nearly zero by controlling process parameters and revising hardware. Energy-saving effects of five-layered glass were also verified by measuring the temperature.

  8. Generalized scattering-matrix approach for magneto-optics in periodically patterned multilayer systems

    NASA Astrophysics Data System (ADS)

    Caballero, B.; García-Martín, A.; Cuevas, J. C.

    2012-06-01

    We present here a generalization of the scattering-matrix approach for the description of the propagation of electromagnetic waves in nanostructured magneto-optical systems. Our formalism allows us to describe all the key magneto-optical effects in any configuration in periodically patterned multilayer structures. The method can also be applied to describe periodic multilayer systems comprising materials with any type of optical anisotropy. We illustrate the method with the analysis of a recent experiment in which the transverse magneto-optical Kerr effect was measured in an Fe film with a periodic array of subwavelength circular holes. We show, in agreement with the experiments, that the excitation of surface plasmon polaritons in this system leads to a resonant enhancement of the transverse magneto-optical Kerr effect.

  9. Generalized approach to design multi-layer stacks for enhanced optical detectability of ultrathin layers

    NASA Astrophysics Data System (ADS)

    Hutzler, A.; Matthus, C. D.; Rommel, M.; Frey, L.

    2017-01-01

    The optical detectability of ultrathin conductive films (down to one atomic layer) can be enhanced by choosing distinct layer-stacks. A simple analytical approach using the transfer matrix method is applied for calculating the reflectance of arbitrary multi-layer stack systems with and without the ultrathin layer of interest on top in a wide wavelength range, including both the visible spectrum and the ultraviolet spectrum. Then, the detectability defined by the Michelson contrast was calculated. Performing these calculations for thickness variations of the individual layers in the stack allows determining optimum layer thicknesses, e.g., maximum overall contrast or maximum contrast for a given wavelength. To demonstrate the validity of the methodology, two thin film stacks were investigated, which use p-type silicon as a substrate material and partially covered by a single-layer graphene as a top layer. For each stack, two samples with different layer thicknesses were fabricated and their experimentally determined reflectance was compared to the calculated values. The first system consists of a single SiO2 layer with a thickness of 147 nm and 304 nm, respectively, and the second is a double layer stack consisting of a Si3N4 layer with a thickness of 54 nm and 195 nm, respectively, on top of an 11 nm SiO2 film. The Michelson contrast of single-layer graphene flakes on the latter layer stacks becomes very high (absolute value of more than 0.3) in the visible wavelength range. Additionally, in the UV-B range a large difference in the reflection of selected SiO2 layer thicknesses on silicon substrates with and without single-layer graphene on top is found with a decrease in the measured reflectance of up to 33%. The measured and calculated values showed a high conformity suggesting this approach usable for the calculation of reflectance and transmittance properties of arbitrary layer stack systems including thin conductive layers.

  10. Comparing thin-sheet models with 3-D multilayer models for continental collision

    NASA Astrophysics Data System (ADS)

    Lechmann, S. M.; May, D. A.; Kaus, B. J. P.; Schmalholz, S. M.

    2011-10-01

    Various models have been proposed to explain tectonic deformations during continent collision. A frequently applied model is the thin viscous sheet model which is however not fully 3-D and assumes a priori diffuse thickening as the dominant deformation style. We compare a fully 3-D multilayer numerical model with a corresponding thin viscous sheet numerical model for the scenario of continent indentation. In our comparison we focus on the three basic viscous deformation styles thickening, buckling (folding) and lateral crustal flow. Both numerical models are based on the finite element method (FEM) and employ either a linear or power-law viscous rheology. The 3-D model consists of four layers representing a simplified continental lithosphere: strong upper crust, weak lower crust, strong upper mantle and weak lower mantle. The effective viscosity depth-profile in the 3-D model is used to calculate the depth-averaged effective viscosity used in the thin-sheet model allowing a direct comparison of both models. We quantify the differences in the strain rate and velocity fields, and investigate the evolution of crustal thickening, buckling and crustal flow resulting from the two models for two different phases of deformation: (1) indentation with a constant velocity and (2) gravitational collapse after a decrease of the indenting velocity by a factor of 5. The results indicate that thin-sheet models approximate well the overall large-scale lithospheric deformation, especially during indentation and for a linear viscous rheology. However, in the 3-D model, additional processes such as multilayer buckling and lower crustal flow emerge, which are ignored in the thin-sheet model but dominate the deformation style in the 3-D model within a range of a few hundreds of kilometres around the collision zone and indenter corner. Differences between the 3-D and thin-sheet model are considerably larger for a power-law viscous than for a linear viscous rheology. Buckling and lower

  11. Multilayer coated optics for an alpha-class extreme ultraviolet lithography system

    SciTech Connect

    Folta, J A; Grabner, R F; Hudyma, R M; Montcalm, C; Schmidt, M A; Spiller, E; Walton, C C; Wedowski, M

    1999-08-25

    We present the results of coating the first set of optical elements for an alpha-class extreme-ultraviolet (EUV) lithography system, the Engineering Test Stand (ETS). The optics were coated with Mo/Si multilayer mirrors using an upgraded DC-magnetron sputtering system. Characterization of the near-normal incidence EUV reflectance was performed using synchrotron radiation from the Advanced Light Source at the Lawrence Berkeley National Laboratory. Stringent requirements were met for these multilayer coatings in terms of reflectance, wavelength matching among the different optics, and thickness control across the diameter of each individual optic. Reflectances above 65% were achieved at 13.35 nm at near-normal angles of incidence. The run-to-run reproducibility of the reflectance peak wavelength was maintained to within 0.4%, providing the required wavelength matching among the seven multilayer-coated optics. The thickness uniformity (or gradient) was controlled to within {+-}0.25% peak-to-valley (P-V) for the condenser optics and {+-}0.1% P-V for the four projection optics, exceeding the prescribed specification for the optics of the ETS.

  12. Permanent laser conditioning of thin film optical materials

    DOEpatents

    Wolfe, C.R.; Kozlowski, M.R.; Campbell, J.H.; Staggs, M.; Rainer, F.

    1995-12-05

    The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold. 9 figs.

  13. Permanent laser conditioning of thin film optical materials

    DOEpatents

    Wolfe, C. Robert; Kozlowski, Mark R.; Campbell, John H.; Staggs, Michael; Rainer, Frank

    1995-01-01

    The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold.

  14. Deodorisation effect of diamond-like carbon/titanium dioxide multilayer thin films deposited onto polypropylene

    NASA Astrophysics Data System (ADS)

    Ozeki, K.; Hirakuri, K. K.; Masuzawa, T.

    2011-04-01

    Many types of plastic containers have been used for the storage of food. In the present study, diamond-like carbon (DLC)/titanium oxide (TiO2) multilayer thin films were deposited on polypropylene (PP) to prevent flavour retention and to remove flavour in plastic containers. For the flavour removal test, two types of multilayer films were prepared, DLC/TiO2 films and DLC/TiO2/DLC films. The residual gas concentration of acetaldehyde, ethylene, and turmeric compounds in bottle including the DLC/TiO2-coated and the DLC/TiO2/DLC-coated PP plates were measured after UV radiation, and the amount of adsorbed compounds to the plates was determined. The percentages of residual gas for acetaldehyde, ethylene, and turmeric with the DLC/TiO2 coated plates were 0.8%, 65.2% and 75.0% after 40 h of UV radiation, respectively. For the DLC/TiO2/DLC film, the percentages of residual gas for acetaldehyde, ethylene and turmeric decreased to 34.9%, 76.0% and 85.3% after 40 h of UV radiation, respectively. The DLC/TiO2/DLC film had a photocatalytic effect even though the TiO2 film was covered with the DLC film.

  15. A soft X-ray beam-splitting multilayer optic for the NASA GEMS Bragg Reflection Polarimeter

    SciTech Connect

    Allured, Ryan; Kaaret, Philip; Fernandez-Perea, Monica; Soufli, Regina; Alameda, Jennifer B.; Pivovaroff, Michael J.; Gullikson, Eric M.

    2013-04-12

    A soft X-ray, beam-splitting, multilayer optic has been developed for the Bragg Reflection Polarimeter (BRP) on the NASA Gravity and Extreme Magnetism Small Explorer Mission (GEMS). The optic is designed to reflect 0.5 keV X-rays through a 90° angle to the BRP detector, and transmit 2–10 keV X-rays to the primary polarimeter. The transmission requirement prevents the use of a thick substrate, so a 2 μm thick polyimide membrane was used. Atomic force microscopy has shown the membrane to possess high spatial frequency roughness less than 0.2 nm rms, permitting adequate X-ray reflectance. A multilayer thin film was especially developed and deposited via magnetron sputtering with reflectance and transmission properties that satisfy the BRP requirements and with near-zero stress. Furthermore, reflectance and transmission measurements of BRP prototype elements closely match theoretical predictions, both before and after rigorous environmental testing.

  16. A soft X-ray beam-splitting multilayer optic for the NASA GEMS Bragg Reflection Polarimeter

    DOE PAGES

    Allured, Ryan; Kaaret, Philip; Fernandez-Perea, Monica; ...

    2013-04-12

    A soft X-ray, beam-splitting, multilayer optic has been developed for the Bragg Reflection Polarimeter (BRP) on the NASA Gravity and Extreme Magnetism Small Explorer Mission (GEMS). The optic is designed to reflect 0.5 keV X-rays through a 90° angle to the BRP detector, and transmit 2–10 keV X-rays to the primary polarimeter. The transmission requirement prevents the use of a thick substrate, so a 2 μm thick polyimide membrane was used. Atomic force microscopy has shown the membrane to possess high spatial frequency roughness less than 0.2 nm rms, permitting adequate X-ray reflectance. A multilayer thin film was especially developedmore » and deposited via magnetron sputtering with reflectance and transmission properties that satisfy the BRP requirements and with near-zero stress. Furthermore, reflectance and transmission measurements of BRP prototype elements closely match theoretical predictions, both before and after rigorous environmental testing.« less

  17. Thin-film multilayer interconnect technology for YBa2Cu3O7 - x

    NASA Astrophysics Data System (ADS)

    Wellstood, F. C.; Kingston, J. J.; Clarke, John

    1994-01-01

    The construction of microelectronic circuits from high-transition-temperature (Tc) superconductors requires techniques for producing thin-film wires, insulating crossovers, and vias (window contacts) between wires. Together, these three components form a superconducting interconnect technology. The challenges encountered in developing such a technology for high-Tc superconductors involve factors associated with the materials, the circuits and the fabrication techniques. The use of pulsed laser deposition in conjunction with shadow mask patterning, photolithographic pattern definition, acid etching, ion-beam etching, and surface cleaning to produce multilayer interconnects from YBa2Cu3O7-x (YBCO) is discussed. These processes have been used to construct a variety of passive high-temperature superconducting components and circuits, including crossovers, window contacts, multiturn coils, and flux transformers. Integrated magnetometers incorporating superconducting quantum interference devices, multichip modules with semiconductor die bonded to YBCO interconnect structures, and analog-to-digital converters have also been successfully demonstrated.

  18. Mechanical properties of free-standing polycrystalline metallic thin films and multilayers

    NASA Astrophysics Data System (ADS)

    Huang, Haibo

    1998-11-01

    A laser-diffraction tensile tester and a balance-beam creep apparatus were improved and applied to the study of free standing polycrystalline thin films with a strong $ texture. Studied are electron beam deposited Ag, Cu, Al films, and Ag/Cu multilayers consisting of alternating Ag and Cu layers with 1:1 thickness ratio. All films have a total thickness around 3 mum. In tensile testing, a thin polymeric two-dimensional diffraction grid was deposited on the film surface by microlithographic techniques. Local strains were measured from the relative displacements of two diffracted laser spots. This allows determination of Young's modulus, Poisson's ratio and, since large strains can be measured, the yield stress, ultimate tensile strength and fracture strain. The average values of the Young moduli and Poisson ratios, determined from hundreds of measurements, are 63 GPa and 0.42 for Ag, 102 GPa and 0.37 for Cu, 57 GPa and 0.41 for Al, and 87.5 GPa and 0.38 for Ag/Cu multilayers. In all cases, the Young moduli are about 20% lower than the values calculated from the literature data and are independent of the bilayer repeat length, λ , in the Ag/Cu multilayers. No "supermodulus" effect was observed at small values of λ . An anelastic model was proposed to explain the low Young moduli, the hysteresis loops on the stress-strain curves, and a 4.3 pm 0.2 GPa/decade strain rate dependence of the Young modulus in Al. The ductility of the Ag/Cu multilayers decreases when λ is reduced. For λ 80 nm, the yield stress increases linearly with λsp{{-}alpha} where alpha = 0.244. The results are compared to the predictions of Hall-Petch-type models. In creep testing, steady-state creep rates were measured on Cu films as a function of stress and temperature. In the high temperature-low stress region (100-650spcircC, 5-90 MPa), the creep rate is described by dot\\varepsilon =A{\\cdot}sigmasp{n} exp\\{{-}Q/kT\\}. A core-diffusion controlled dislocation climb model was proposed to

  19. An Electrochemical Experiment Using an Optically Transparent Thin Layer Electrode

    ERIC Educational Resources Information Center

    DeAngelis, Thomas P.; Heineman, William R.

    1976-01-01

    Describes a unified experiment in which an optically transparent thin layer electrode is used to illustrate the techniques of thin layer electrochemistry, cyclic voltammetry, controlled potential coulometry, and spectroelectrochemistry. (MLH)

  20. Optical properties of multilayer bimetallic films obtained by laser deposition of colloidal particles

    NASA Astrophysics Data System (ADS)

    Antipov, A.; Arakelian, S.; Vartanyan, T.; Gerke, M.; Istratov, A.; Kutrovskaya, S.; Kucherik, A.; Osipov, A.

    2016-11-01

    The optical properties of multilayer bimetallic films composed of silver and gold nanoparticles have been investigated. The dependence of the transmission spectra of the films on their morphology is demonstrated. A finite-difference time-domain (FDTD) simulation has confirmed that there is a dependence of the transmission spectra on the average distance between particles and the number of deposited layers.

  1. Optical constants of materials in the EUV/soft x-ray region for multilayer mirror applications

    SciTech Connect

    Soufli, Regina

    1997-12-01

    The response of a given material to an incident electromagnetic wave is described by the energy dependent complex index of refraction n = 1 - δ + iβ. In the extreme ultraviolet (EUV)/soft x-ray spectral region, the need for accurate determination of n is driven by activity in areas such as synchrotron based research, EUV/x-ray lithography, x-ray astronomy and plasma applications. Knowledge of the refractive index is essential for the design of the optical components of instruments used in experiments and applications. Moreover, measured values of n may be used to evaluate solid state models for the optical behavior of materials. The refractive index n of Si, Mo and Be is investigated in the EUV/soft x-ray region. In the case of Si, angle dependent reflectance measurements are performed in the energy range 50-180 eV. The optical constants δ, β are both determined by fitting to the Fresnel equations. The results of this method are compared to the values in the 1993 atomic tables. Photoabsorption measurements for the optical constants of Mo are performed on C/Mo/C foils, in the energy range 60-930 eV. Photoabsorption measurements on Be thin films supported on silicon nitride membranes are performed, and the results are applied in the determination of the absorption coefficient of Be in the energy region 111.5-250 eV. The new results for Si and Mo are applied to the calculation of normal incidence reflectivities of Mo/Si and Mo/Be multilayer mirrors. These calculations show the importance of accurate knowledge of δ and β in the prediction and modeling of the performance of multilayer optics.

  2. Optical properties of multilayered Period-Doubling and Rudin-Shapiro porous silicon dielectric heterostructures

    NASA Astrophysics Data System (ADS)

    Agarwal, V.; Mora-Ramos, Miguel E.; Alvarado-Tenorio, B.

    2009-05-01

    To investigate the optical properties in quasi-regular porous-silicon-based dielectric Period-Doubling and Rudin-Shapiro multilayer systems, we study here the reflection of light from these structures. The Period-Doubling and Rudin-Shapiro structures are fabricated in such a way that the optical thickness of each layer is one quarter of 600 and 640 nm respectively. We find that porous silicon Period-Doubling dielectric multilayers could demonstrate the optical properties similar to the classical periodic Febry-Perot interference filters with one or multiple resonant peaks, but with an advantage of having total optical thickness much lesser than the periodic structures. Additionally, light propagation in porous silicon Rudin-Shapiro structures is investigated for the first time, both theoretically and experimentally. The reflectance spectra of the structures exhibit photonic band gaps centered at predetermined wavelengths. In both cases, numerical simulation of light transmission is performed using transfer matrix method.

  3. Influence of Ag thickness on structural, optical, and electrical properties of ZnS/Ag/ZnS multilayers prepared by ion beam assisted deposition

    NASA Astrophysics Data System (ADS)

    Leng, Jian; Yu, Zhinong; Xue, Wei; Zhang, Ting; Jiang, Yurong; Zhang, Jie; Zhang, Dongpu

    2010-10-01

    The structural, optical, and electrical characteristics of zinc sulfide (ZnS)/Ag/ZnS (ZAZ) multilayer films prepared by ion beam assisted deposition on k9 glass have been investigated as a function of Ag layer thickness. The characteristics of ZAZ multilayer are significantly improved up insertion of optimal Ag thickness between ZnS layers. The results show that due to bombardment of Ar ion beam, distinct Ag islands evolve into continuous Ag films at a thin Ag thickness of about 4 nm. The thinner Ag film as a thickness of 2 nm leads to high sheet resistance and low transmittance for the interface scattering induced by the Ag islands or noncontinuous films; and when the Ag thickness is over 4 nm, the ZAZ multilayer exhibits a remarkably reduced sheet resistance between 7-80 Ω/sq for the increase in carrier concentration and mobility of Ag layer, and a high transmittance over 90% for the interference phenomena of multilayers and low absorption and surface scattering of Ag layer. The ZAZ multilayer with 14 nm Ag film has a figure of merit up to 6.32×10-2 Ω-1, an average transmittance over 92% and a sheet resistance of 7.1 Ω/sq. The results suggest that ZAZ film has better optoelectrical properties than conditional indium tin oxide single layer.

  4. Characterization of amorphous multilayered ZnO-SnO{sub 2} heterostructure thin films and their field effect electronic properties

    SciTech Connect

    Lee, Su-Jae Hwang, Chi-Sun; Pi, Jae-Eun; Yang, Jong-Heon; Oh, Himchan; Cho, Sung Haeng; Cho, Kyoung-Ik; Chu, Hye Yong

    2014-11-17

    Multilayered ZnO-SnO{sub 2} heterostructure thin films were produced using pulsed laser ablation of pie-shaped ZnO-SnO{sub 2} oxides target, and their structural and field effect electronic transport properties were investigated as a function of the thickness of the ZnO and SnO{sub 2} layers. The films have an amorphous multilayered heterostructure composed of the periodic stacking of the ZnO and SnO{sub 2} layers. The field effect electronic properties of amorphous multilayered ZnO-SnO{sub 2} heterostructure thin film transistors (TFTs) are highly dependent on the thickness of the ZnO and SnO{sub 2} layers. The highest electron mobility of 37 cm{sup 2}/V s, a low subthreshold swing of a 0.19 V/decade, a threshold voltage of 0.13 V, and a high drain current on-to-off ratio of ∼10{sup 10} obtained for the amorphous multilayered ZnO(1.5 nm)-SnO{sub 2}(1.5 nm) heterostructure TFTs. These results are presumed to be due to the unique electronic structure of an amorphous multilayered ZnO-SnO{sub 2} heterostructure film consisting of ZnO, SnO{sub 2}, and ZnO-SnO{sub 2} interface layers.

  5. Flat or curved thin optical display panel

    DOEpatents

    Veligdan, J.T.

    1995-01-10

    An optical panel includes a plurality of waveguides stacked together, with each waveguide having a first end and an opposite second end. The first ends collectively define a first face, and the second ends collectively define a second face of the panel. The second face is disposed at an acute face angle relative to the waveguides to provide a panel which is relatively thin compared to the height of the second face. In an exemplary embodiment for use in a projection TV, the first face is substantially smaller in height than the second face and receives a TV image, with the second face defining a screen for viewing the image enlarged. 7 figures.

  6. Robust, Thin Optical Films for Extreme Environments

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The environment of space presents scientists and engineers with the challenges of a harsh, unforgiving laboratory in which to conduct their scientific research. Solar astronomy and X-ray astronomy are two of the more challenging areas into which NASA scientists delve, as the optics for this high-tech work must be extremely sensitive and accurate, yet also be able to withstand the battering dished out by radiation, extreme temperature swings, and flying debris. Recent NASA work on this rugged equipment has led to the development of a strong, thin film for both space and laboratory use.

  7. Optical conductivity of topological insulator thin films

    SciTech Connect

    Li, L. L.; Xu, W.; Peeters, F. M.

    2015-05-07

    We present a detailed theoretical study on the optoelectronic properties of topological insulator thin film (TITFs). The k·p approach is employed to calculate the energy spectra and wave functions for both the bulk and surface states in the TITF. With these obtained results, the optical conductivities induced by different electronic transitions among the bulk and surface states are evaluated using the energy-balance equation derived from the Boltzmann equation. We find that for Bi{sub 2}Se{sub 3}-based TITFs, three characteristic regimes for the optical absorption can be observed. (i) In the low radiation frequency regime (photon energy ℏω<200 meV), the free-carrier absorption takes place due to intraband electronic transitions. An optical absorption window can be observed. (ii) In the intermediate radiation frequency regime (200<ℏω<300 meV), the optical absorption is induced mainly by interband electronic transitions from surface states in the valance band to surface states in the conduction band and an universal value σ{sub 0}=e{sup 2}/(8ℏ) for the optical conductivity can be obtained. (iii) In the high radiation frequency regime (ℏω>300 meV), the optical absorption can be achieved via interband electronic transitions from bulk and surface states in the valance band to bulk and surface states in the conduction band. A strong absorption peak can be observed. These interesting findings indicate that optical measurements can be applied to identify the energy regimes of bulk and surface states in the TITF.

  8. Analysis on vertical directional couplers with long range surface plasmons for multilayer optical routing

    NASA Astrophysics Data System (ADS)

    Alam, B.; Veroli, A.; Benedetti, A.

    2016-08-01

    A structure featuring vertical directional coupling of long-range surface plasmon polaritons between strip waveguides at λ = 1.55 μm is investigated with the aim of producing efficient elements that enable optical multilayer routing for 3D photonics. We have introduced a practical computational method to calculate the interaction on the bent part. This method allows us both to assess the importance of the interaction in the bent part and to control it by a suitable choice of the fabrication parameters that helps also to restrain effects due to fabrication issues. The scheme adopted here allows to reduce the insertion losses compared with other planar and multilayer devices.

  9. Coordinated Multi-layer Multi-domain Optical Network (COMMON) for Large-Scale Science Applications (COMMON)

    SciTech Connect

    Vokkarane, Vinod

    2013-09-01

    We intend to implement a Coordinated Multi-layer Multi-domain Optical Network (COMMON) Framework for Large-scale Science Applications. In the COMMON project, specific problems to be addressed include 1) anycast/multicast/manycast request provisioning, 2) deployable OSCARS enhancements, 3) multi-layer, multi-domain quality of service (QoS), and 4) multi-layer, multidomain path survivability. In what follows, we outline the progress in the above categories (Year 1, 2, and 3 deliverables).

  10. Ultra-short-period W/B4C multilayers for x-ray optics-microstructure limits on reflectivity

    SciTech Connect

    Walton, Christopher Charles

    1997-12-01

    Multilayer thin films are used as Bragg reflectors for soft x-rays in the energy range 50eV < E < 1000eV in many x-ray optics applications such as x-ray microscopes and telescopes, reducing optics for extreme ultraviolet (EUV) lithography, and x-ray polarizers and phase retarders. Applications often depend critically on reflectivity, which has not been systematically characterized for multilayer periods below 20Å. For this study, W/B4C multilayers were fabricated by magnetron sputtering on Si(111), with periods from 48Å to as little as 4.7Å. The x-ray reflectivity measured at λ = 1.54Å and at 45° incidence (289 eV < E < 860 eV) was found to decrease sharply for multilayer periods less than 15-20Å. Examination by high-resolution transmission electron microscopy (HRTEM) showed an expansion of the thickness of the W-rich layers of 30-40% from the nominal values, consistent with intermixture of the two materials during sputter growth, and discontinuous W-rich layers for multilayer periods below about 15Å. The experimental data for the specular reflectivity in the hard and soft x-ray regimes and the diffuse scattering fit well to a model of multilayer roughness. The model is expressed as a power-law dependence of roughness on spatial frequency. Analysis of small-angle scattering in transmission from multilayers grown on freestanding Si3N4 membranes confirms the onset of discontinuity at periods between 14Å and 22Å. Spectroscopy studies by x-ray absorption (NEXAFS) and electron energy loss (EELS) at the boron K-edge (188eV) are consistent with changes in the average boron bonding environment, as the multilayer period decreases and the W-rich layers are increasingly thin and dispersed. A discrete W-rich phase is present for periods at least as small as 6.3Å.

  11. Multilayer coatings for optics in the extreme ultraviolet

    NASA Astrophysics Data System (ADS)

    Larruquert, Juan I.; Vidal-Dasilva, Manuela; García-Cortés, Sergio; Rodríguez-de Marcos, Luis; Fernández-Perea, Mónica; Aznárez, José A.; Méndez, José A.

    2011-02-01

    The strong absorption of materials in the extreme ultraviolet (EUV) above ~50 nm has precluded the development of efficient coatings. The development of novel coatings with improved EUV performance is presented. An extensive research was performed on the search and characterization of new materials with low absorption or high reflectance. Lanthanide series was found to be a source of materials with relatively low absorption in this range, where most materials in nature present a strong absorption. Other materials, such as SiO and B, have been found to have interesting properties for applications on EUV coatings. As a result, novel multilayers based on Yb, Al, and SiO have been developed with narrowband performance in the 50-92 nm range. In some cases, the difficulty of developing narrowband coatings in the EUV can be overcome by designing multilayers that address specific purposes, such as maximizing and/or minimizing the reflectance at two or more wavelengths or bands. In this direction, we are working towards the development of coatings that combine a relatively high reflectance in a desired EUV band with a low reflectance in another band, for applications in which the presence of the latter radiation may mask a weak EUV radiation source.

  12. Thermal stability of exchange-biased NiFe/FeMn multilayered thin films

    NASA Astrophysics Data System (ADS)

    Chen, H. Y.; Phuoc, Nguyen N.; Ong, C. K.

    2012-09-01

    A systematic study of the effect of ferromagnetic thickness on magnetic and microwave properties of exchange-biased NiFe/FeMn multilayered thin films was carried out with regards to thermal stability. The temperature-dependent microwave characteristics of the films were obtained from the near-field microwave microscopy technique and analysed based on Landau-Lifshitz-Gilbert equation. The complex microwave permeability spectra of the magnetic thin films up to 5 GHz in the temperature range from room temperature to 420 K were measured. It was found that thicker ferromagnetic layers helped to reduce the dependence of the magnetic properties on temperature, leading to better thermal stability. The saturation magnetization MS, dynamic magnetic anisotropy field HKdyn, and ferromagnetic resonance frequency fFMR were found to decrease with temperature, while the effective damping coefficient αeff was increased with temperature. We also investigate the rotational magnetic anisotropy field HKrot with temperature which gives a measure of the rotatable magnetization of the antiferromagnetic layers and its thermal stability.

  13. A uniform porous multilayer-junction thin film for enhanced gas-sensing performance.

    PubMed

    Zhang, Ping-Ping; Zhang, Hui; Sun, Xu-Hui

    2016-01-21

    Highly-uniform In2O3/CuO bilayer and multilayer porous thin films were successfully fabricated using a self-assembled soft template and a simple sputtering deposition technique. The sensor based on the In2O3/CuO bilayer porous thin film shows obviously improved sensing performance to ethanol at a lower working temperature, compared to its single layer counterpart sensors. The response of the In2O3/CuO bilayer sensors exhibit nearly 3 and 5 times higher performance than those of the single layer In2O3 and CuO porous film sensors over the same ethanol concentration, respectively. The sensing mechanism based on the p-n hetero-junction, which contributed to the enhanced sensing performance, was also experimentally confirmed by a control experiment in which an SiO2 insulation layer was inserted between the In2O3 and CuO layers to break the p-n junction. In addition, the sensing performance can be further enhanced by increasing the number of In2O3/CuO junction layers. The facile process can be easily extended to the fabrication of other semiconductor oxide gas sensors for practical sensing applications.

  14. Proof of Concept Thin Films and Multilayers Toward Enhanced Field Gradients in SRF Cavities

    SciTech Connect

    Lukaszew, R A; Beringer, D; Roach, W M; Eremeev, G V; Valente-Feliciano, A-M; Reece, C E; Xi, X

    2013-09-01

    Due to the very shallow penetration depth of the RF fields, SRF properties are inherently a surface phenomenon involving a material thickness of less than 1 micron thus opening up the possibility of using thin film coatings to achieve a desired performance. The challenge has been to understand the dependence of the SRF properties on the detailed characteristics of real surfaces and then to employ appropriate techniques to tailor these surface properties for greatest benefit. Our aim is to achieve gradients >100 MV/m and no simple material is known to be capable of sustaining this performance. A theoretical framework has been proposed which could yield such behavior [1] and it requires creation of thin film layered structures. I will present our systematic studies on such proof-of-principle samples. Our overarching goal has been to build a basic understanding of key nano-scale film growth parameters for materials that show promise for SRF cavity multilayer coatings and to demonstrate the ability to elevate the barrier for vortex entry in such layered structures above the bulk value of Hc1 for type-II superconductors and thus to sustain higher accelerating fields.

  15. Sound transmission through finite lightweight multilayered structures with thin air layers.

    PubMed

    Dijckmans, A; Vermeir, G; Lauriks, W

    2010-12-01

    The sound transmission loss (STL) of finite lightweight multilayered structures with thin air layers is studied in this paper. Two types of models are used to describe the vibro-acoustic behavior of these structures. Standard transfer matrix method assumes infinite layers and represents the plane wave propagation in the layers. A wave based model describes the direct sound transmission through a rectangular structure placed between two reverberant rooms. Full vibro-acoustic coupling between rooms, plates, and air cavities is taken into account. Comparison with double glazing measurements shows that this effect of vibro-acoustic coupling is important in lightweight double walls. For infinite structures, structural damping has no significant influence on STL below the coincidence frequency. In this frequency region, the non-resonant transmission or so-called mass-law behavior dominates sound transmission. Modal simulations suggest a large influence of structural damping on STL. This is confirmed by experiments with double fiberboard partitions and sandwich structures. The results show that for thin air layers, the damping induced by friction and viscous effects at the air gap surfaces can largely influence and improve the sound transmission characteristics.

  16. Ferromagnetic resonance linewidth and damping in perpendicular-anisotropy magnetic multilayers thin films

    NASA Astrophysics Data System (ADS)

    Beaujour, Jean-Marc

    2010-03-01

    Transition metal ferromagnetic films with perpendicular magnetic anisotropy (PMA) have ferromagnetic resonance (FMR) linewidths that are one order of magnitude larger than soft magnetic materials, such as pure iron (Fe) and permalloy (NiFe) thin films. We have conducted systematic studies of a variety of thin film materials with perpendicular magnetic anisotropy to investigate the origin of the enhanced FMR linewidths, including Ni/Co and CoFeB/Co/Ni multilayers. In Ni/Co multilayers the PMA was systematically reduced by irradiation with Helium ions, leading to a transition from out-of-plane to in-plane easy axis with increasing He ion fluence [1,2]. The FMR linewidth depends linearly on frequency for perpendicular applied fields and increases significantly when the magnetization is rotated into the film plane with an applied in-plane magnetic field. Irradiation of the film with Helium ions decreases the PMA and the distribution of PMA parameters, leading to a large reduction in the FMR linewidth for in-plane magnetization. These results suggest that fluctuations in the PMA lead to a large two magnon scattering contribution to the linewidth for in-plane magnetization and establish that the Gilbert damping is enhanced in such materials (α˜0.04, compared to α˜0.002 for pure Fe) [2]. We compare these results to those on CoFeB/Co/Ni and published results on other thin film materials with PMA [e.g., Ref. 3]. [1] D. Stanescu et al., J. Appl. Phys. 103, 07B529 (2008). [2] J-M. L. Beaujour, D. Ravelosona, I. Tudosa, E. Fullerton, and A. D. Kent, Phys. Rev. B RC 80, 180415 (2009). [3] N. Mo, J. Hohlfeld, M. ulIslam, C. S. Brown, E. Girt, P. Krivosik, W. Tong, A. Rebel, and C. E. Patton, Appl. Phys. Lett. 92, 022506 (2008). *Research done in collaboration with: A. D. Kent, New York University, D. Ravelosona, Institut d'Electronique Fondamentale, UMR CNRS 8622, Universit'e Paris Sud, E. E. Fullerton, Center for Magnetic Recording Research, UCSD, and supported by NSF

  17. Thin Film Multilayer Conductor/Ferroelectric Tunable Microwave Components for Communication Applications

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Romanofsky, Robert R.; VanKeuls, Frederick W.; Mueller, Carl H.; Treece, Randolph E.; Rivkin, Tania V.

    1997-01-01

    High Temperature Superconductor/Ferroelectric (HTS/FE ) thin film multilayered structures deposited onto dielectric substrates are currently being investigated for use in low loss, tunable microwave components for satellite and ground based communications. The main goal for this technology is to achieve maximum tunability while keeping the microwave losses as low as possible, so as to avoid performance degradation when replacing conventional technology (e.g., filters and oscillators) with HTS/FE components. Therefore, for HTS/FE components to be successfully integrated into current working systems, full optimization of the material and electrical properties of the ferroelectric films, without degrading those of the HTS film; is required. Hence, aspects such as the appropriate type of ferroelectric and optimization of the deposition conditions (e.g., deposition temperature) should be carefully considered. The tunability range as well as the microwave losses of the desired varactor (i.e., tunable component) are also dependent on the geometry chosen (e.g., parallel plate capacitor, interdigital capacitor, coplanar waveguide, etc.). In addition, the performance of the circuit is dependent on the location of the varactor in the circuit and the biasing circuitry. In this paper, we will present our results on the study of the SrTiO3/YBa2Cu3O(7-delta)/LaAl03 (STO/YBCO/LAO) and the Ba(x)Sr(1-x)TiO3/YBa2Cu3O(7-delta)/LaAl03(BSTO/YBCO/ILAO) HTS/FE multilayered structures. We have observed that the amount of variation of the dielectric constant upon the application of a dc electric field is closely related to the microstructure of the film. The largest tuning of the STO/YBCO/LAO structure corresponded to single-phased, epitaxial STO films deposited at 800 C and with a thickness of 500 nm. Higher temperatures resulted in interfacial degradation and poor film quality, while lower deposition temperatures resulted in films with lower dielectric constants, lower tunabilities, and

  18. Collaboration of the NASA Glenn Research Center and Rolls-Royce Developed Thin Film Multilayered Dielectrics for Harsh Environments

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Fralick, Gustave C.; Busfield, A. Rachel; Thomas, Valarie D.; Blaha, Charles A.

    2003-01-01

    The use of thin films to electrically insulate thin film sensors on engine components minimizes the intrusiveness of the sensors and allows a more accurate measurement of the environment. A variety of insulating films were investigated for preventing electrical shorting caused by insulator failure between the sensor and the component. By alternating layers of sputtered high-temperature ceramics, a sequence of insulating layers was devised that (1) prevents pinholes from forming completely through the insulator and (2) maintains high electrical resistivity at high temperatures. The total thickness is only a fraction of that needed for conventional insulating techniques. The Sensors and Electronics Technology Branch of the NASA Glenn Research Center has an in-house effort to develop thin film sensors for surface measurement in propulsion system research. Thin film sensors do not require special machining of the components on which they are mounted, and they are considerably thinner (less than 10 mm thick) than wire or foil sensors. The thin film sensors are thus much less disturbing to the operating environment and have a minimal impact on the physical characteristics of the supporting component. To further this research, NASA Glenn and Rolls-Royce (Derby, UK), with assistance from the Ohio Aerospace Institute (OAI) and the Akima Corporation, pursued a joint investigation using multilayered thin film dielectrics as a reliable insulator in harsh environments. The use of a multilayered scheme is thought to be promising for the fabrication of electrically insulating thin films. A major cause of conduction in thin film dielectrics is the presence of defects, such as pinholes, that propagate through the film to the underlying substrate surface. By alternating the insulating material, each new growth pattern would deviate from the previous one, eliminating direct pathways for conduction to the substrate. The film depositions and testing were conducted in the Instrument

  19. Phase Modulator with Terahertz Optical Bandwidth Formed by Multi-Layered Dielectric Stack

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S. (Inventor); Fork, Richard L. (Inventor)

    2005-01-01

    An optical phase modulator includes a bandpass multilayer stack, formed by a plurality of dielectric layers, preferably of GaAs and AlAs, and having a transmission function related to the refractive index of the layers of the stack, for receiving an optical input signal to be phase modulated. A phase modulator device produces a nonmechanical change in the refractive index of each layer of the stack by, e.g., the injection of free carrier, to provide shifting of the transmission function so as to produce phase modulation of the optical input signal and to thereby produce a phase modulated output signal.

  20. Spatially selective optical tuning of quantum dot thin film luminescence.

    PubMed

    Chen, Jixin; Chan, Yang-Hsiang; Yang, Tinglu; Wark, Stacey E; Son, Dong Hee; Batteas, James D

    2009-12-30

    Photolithographically generated patterns have been created on immobilized CdSe QD thin films by fine-tuning their optical properties (intensity and emission wavelength) postsynthetically. These optically modified QDs show enhanced selectivity for binding of different ligands, affording the ability to fabricate optically reconfigurable surfaces for display or sensing applications. The patterns may be readily generated with any typical optical lithographic approach.

  1. Flat or curved thin optical display panel

    DOEpatents

    Veligdan, James T.

    1995-01-10

    An optical panel 10 includes a plurality of waveguides 12 stacked together, with each waveguide 12 having a first end 12a and an opposite second end 12b. The first ends 12a collectively define a first face 16, and the second ends 12b collectively define a second face 18 of the panel 10. The second face 18 is disposed at an acute face angle relative to the waveguides 12 to provide a panel 10 which is relatively thin compared to the height of the second face. In an exemplary embodiment for use in a projection TV, the first face 16 is substantially smaller in height than the second face 18 and receives a TV image, with the second face 18 defining a screen for viewing the image enlarged.

  2. Thermal conductivities of thin, sputtered optical films

    SciTech Connect

    Henager, C.H. Jr.; Pawlewicz, W.T.

    1991-05-01

    The normal component of the thin film thermal conductivity has been measured for the first time for several advanced sputtered optical materials. Included are data for single layers of boron nitride (BN), aluminum nitride (AIN), silicon aluminum nitride (Si-Al-N), silicon aluminum oxynitride (Si-Al-O-N), silicon carbide (SiC), and for dielectric-enhanced metal reflectors of the form Al(SiO{sub 2}/Si{sub 3}N{sub 4}){sup n} and Al(Al{sub 2}O{sub 3}/AIN){sup n}. Sputtered films of more conventional materials like SiO{sub 2}, Al{sub 2}O{sub 3}, Ta{sub 2}O{sub 5}, Ti, and Si have also been measured. The data show that thin film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or very fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film/substrate interface contribution is presented.

  3. Photolithographically patterened thin-film multilayer devices of YBa sub 2 Cu sub 3 O sub 7-x

    SciTech Connect

    Kingston, J.J.; Wellstood, F.C.; Quan, D.; Clarke, J.

    1990-09-01

    We have fabricated thin-film YBa{sub 2}Cu{sub 3}O{sub 7-x}-SrTiO{sub 3}-YBa{sub 2}Cu{sub 3}O{sub 7-x} multilayer interconnect structures in which each in situ laser-deposited film is independently patterned by photolithography. In particular, we have constructed the two key components necessary for a superconducting multilayer interconnect technology, crossovers and window contacts. As a further demonstration of the technology, we have fabricated a thin-film flux transformer, suitable for use with a Superconducting QUantum Interference Device (SQUID), that includes a ten-turn input coil with 6{mu}m linewidth. Transport measurements showed that the critical temperature was 87K and the critical current was 135 {mu}A at 82K. 7 refs., 6 figs.

  4. Microstructure and Mechanical Properties of Thin-Multilayer Ti/Al Laminates Prepared by One-Step Explosive Bonding

    NASA Astrophysics Data System (ADS)

    Fan, Minyu; Yu, Weiwei; Wang, Wentao; Guo, XunZhong; Jin, Kai; Miao, Runjie; Hou, Wenqing; Kim, Naksoo; Tao, Jie

    2016-11-01

    Thin-multilayer Ti/Al laminates were prepared by one-step explosive bonding method to investigate the interface bonding and mechanical properties owing to their potential application in aerospace and auto industry. It was found that Ti/Al laminates prepared at the detonation velocity of 2100 m/s exhibited superior surface quality without any defects in comparison with other detonation velocities owing to the optimum explosive pressure and impact velocity. The interface morphologies and element distribution of Ti/Al laminates prepared at the detonation velocity of 2100 m/s were characterized by means of SEM and EDS. The results indicated that the linear and wavy bonding interface coexisted and element diffusion occurred in the interfacial zone. Furthermore, thin-multilayer Ti/Al laminates possessed high microhardness, excellent interlaminar shear and tensile properties.

  5. Microstructure and Mechanical Properties of Thin-Multilayer Ti/Al Laminates Prepared by One-Step Explosive Bonding

    NASA Astrophysics Data System (ADS)

    Fan, Minyu; Yu, Weiwei; Wang, Wentao; Guo, XunZhong; Jin, Kai; Miao, Runjie; Hou, Wenqing; Kim, Naksoo; Tao, Jie

    2017-01-01

    Thin-multilayer Ti/Al laminates were prepared by one-step explosive bonding method to investigate the interface bonding and mechanical properties owing to their potential application in aerospace and auto industry. It was found that Ti/Al laminates prepared at the detonation velocity of 2100 m/s exhibited superior surface quality without any defects in comparison with other detonation velocities owing to the optimum explosive pressure and impact velocity. The interface morphologies and element distribution of Ti/Al laminates prepared at the detonation velocity of 2100 m/s were characterized by means of SEM and EDS. The results indicated that the linear and wavy bonding interface coexisted and element diffusion occurred in the interfacial zone. Furthermore, thin-multilayer Ti/Al laminates possessed high microhardness, excellent interlaminar shear and tensile properties.

  6. Chiral magnetic conductivity and surface states of Weyl semimetals in topological insulator ultra-thin film multilayer.

    PubMed

    Owerre, S A

    2016-06-15

    We investigate an ultra-thin film of topological insulator (TI) multilayer as a model for a three-dimensional (3D) Weyl semimetal. We introduce tunneling parameters t S, [Formula: see text], and t D, where the former two parameters couple layers of the same thin film at small and large momenta, and the latter parameter couples neighbouring thin film layers along the z-direction. The Chern number is computed in each topological phase of the system and we find that for [Formula: see text], the tunneling parameter [Formula: see text] changes from positive to negative as the system transits from Weyl semi-metallic phase to insulating phases. We further study the chiral magnetic effect (CME) of the system in the presence of a time dependent magnetic field. We compute the low-temperature dependence of the chiral magnetic conductivity and show that it captures three distinct phases of the system separated by plateaus. Furthermore, we propose and study a 3D lattice model of Porphyrin thin film, an organic material known to support topological Frenkel exciton edge states. We show that this model exhibits a 3D Weyl semi-metallic phase and also supports a 2D Weyl semi-metallic phase. We further show that this model recovers that of 3D Weyl semimetal in topological insulator thin film multilayer. Thus, paving the way for simulating a 3D Weyl semimetal in topological insulator thin film multilayer. We obtain the surface states (Fermi arcs) in the 3D model and the chiral edge states in the 2D model and analyze their topological properties.

  7. Chiral magnetic conductivity and surface states of Weyl semimetals in topological insulator ultra-thin film multilayer

    NASA Astrophysics Data System (ADS)

    Owerre, S. A.

    2016-06-01

    We investigate an ultra-thin film of topological insulator (TI) multilayer as a model for a three-dimensional (3D) Weyl semimetal. We introduce tunneling parameters t S, {{t}\\bot} , and t D, where the former two parameters couple layers of the same thin film at small and large momenta, and the latter parameter couples neighbouring thin film layers along the z-direction. The Chern number is computed in each topological phase of the system and we find that for {{t}\\text{S}},{{t}\\text{D}}>0 , the tunneling parameter {{t}\\bot} changes from positive to negative as the system transits from Weyl semi-metallic phase to insulating phases. We further study the chiral magnetic effect (CME) of the system in the presence of a time dependent magnetic field. We compute the low-temperature dependence of the chiral magnetic conductivity and show that it captures three distinct phases of the system separated by plateaus. Furthermore, we propose and study a 3D lattice model of Porphyrin thin film, an organic material known to support topological Frenkel exciton edge states. We show that this model exhibits a 3D Weyl semi-metallic phase and also supports a 2D Weyl semi-metallic phase. We further show that this model recovers that of 3D Weyl semimetal in topological insulator thin film multilayer. Thus, paving the way for simulating a 3D Weyl semimetal in topological insulator thin film multilayer. We obtain the surface states (Fermi arcs) in the 3D model and the chiral edge states in the 2D model and analyze their topological properties.

  8. Nanointaglio fabrication of optical lipid multilayer diffraction gratings with applications in biosensing

    NASA Astrophysics Data System (ADS)

    Lowry, Troy Warren

    The dynamic self-organization of lipids in biological systems is a highly regulated process that enables the compartmentalization of living systems at microscopic and nanoscopic levels. Exploiting the self-organization and innate biofunctionality of lyotropic liquid crystalline phospholipids, a novel nanofabrication process called "nanointaglio" was invented in order to rapidly and scalably integrate lipid nanopatterns onto the surface. The work presented here focuses on using nanointaglio fabricated lipid diffraction micro- and nanopatterns for the development of new sensing and bioactivity studies. The lipids are patterned as diffraction gratings for sensor functionality. The lipid multilayer gratings operate as nanomechanical sensor elements that are capable of transducing molecular binding to fluid lipid multilayers into optical signals in a label free manner due to shape changes in the lipid nanostructures. To demonstrate the label free detection capabilities, lipid nanopatterns are shown to be suitable for the integration of chemically different lipid multilayer gratings into a sensor array capable of distinguishing vapors by means of an optical nose. Sensor arrays composed of six different lipid formulations are integrated onto a surface and their optical response to three different vapors (water, ethanol and acetone) in air as well as pH under water is monitored as a function of time. Principal component analysis of the array response results in distinct clustering, indicating the suitability of the arrays for distinguishing these analytes. Importantly, the nanointaglio process used is capable of producing lipid gratings out of different materials with sufficiently uniform heights for the fabrication of an optical nose. A second main application is demonstrated for the study of membrane binding proteins. Although in vitro methods for assaying the catalytic activity of individual enzymes are well established, quantitative methods for assaying the kinetics of

  9. X ray, extreme and far ultraviolet optical thin films for space applications

    NASA Technical Reports Server (NTRS)

    Zukic, Muamer; Torr, Douglas G.; Kim, Jongmin

    1993-01-01

    Far and extreme ultraviolet optical thin film filters find many uses in space astronomy, space astrophysics, and space aeronomy. Spacebased spectrographs are used for studying emission and absorption features of the earth, planets, sun, stars, and the interstellar medium. Most of these spectrographs use transmission or reflection filters. This requirement has prompted a search for selective filtering coatings with high throughput in the FUV and EUV spectral region. Important progress toward the development of thin film filters with improved efficiency and stability has been made in recent years. The goal for this field is the minimization of absorption to get high throughput and enhancement of wavelength selection. The Optical Aeronomy Laboratory (OAL) at the University of Alabama in Huntsville has recently developed the technology to determine optical constants of bulk and film materials for wavelengths extending from x-rays (0.1 nm) to the FUV (200 nm), and several materials have been identified that were used for designs of various optical devices which previously have been restricted to space application in the visible and near infrared. A new design concept called the Pi-multilayer was introduced and applied to the design of optical coatings for wavelengths extending from x-rays to the FUV. Section 3 of this report explains the Pi-multilayer approach and demonstrates its application for the design and fabrication of the FUV coatings. Two layer Pi-stacks have been utilized for the design of reflection filters in the EUV wavelength range from 70 - 100 nm. In order to eliminate losses due to the low reflection of the imaging optics and increase throughput and out-of-band rejection of the EUV instrumentation we introduced a self-filtering camera concept. In the FUV region, MgF2 and LiF crystals are known to be birefringent. Transmission polarizers and quarterwave retarders made of MgF2 or LiF crystals are commercially available but the performances are poor. New

  10. Optical properties of TiN thin films close to the superconductor-insulator transition.

    SciTech Connect

    Pfuner, F.; Degiorgi, L.; Baturina, T. I.; Vinokur, V. M.; Baklanov, M. R.; Materials Science Division; ETH Zurich; Inst. Semiconductor Physics; IMEC Kapeldreef

    2009-11-10

    We present the intrinsic optical properties over a broad spectral range of TiN thin films deposited on an Si/SiO{sub 2} substrate. We analyze the measured reflectivity spectra of the film-substrate multilayer structure within a well-establish procedure based on the Fresnel equation and extract the real part of the optical conductivity of TiN. We identify the metallic contribution as well as the finite energy excitations and disentangle the spectral weight distribution among them. The absorption spectrum of TiN bears some similarities with the electrodynamic response observed in the normal state of the high-temperature superconductors. Particularly, a mid-infrared feature in the optical conductivity is quite reminiscent of a pseudogap-like excitation.

  11. All-thin-film multilayered multiferroic structures with a slot-line for spin-electromagnetic wave devices

    SciTech Connect

    Nikitin, Andrey A.; Ustinov, Alexey B.; Semenov, Alexander A.; Kalinikos, Boris A.; Lähderanta, E.

    2014-03-03

    Spin-electromagnetic waves propagating in thin-film multilayered multiferroic structures containing a slot transmission line have been investigated both experimentally and theoretically. The thin-film structure was composed of a ferrite film, a ferroelectric film, and a slot-line. It was shown that the spectrum of the spin-electromagnetic wave was formed as a result of hybridization of the spin wave in the ferrite film with the electromagnetic wave in the slot-line and was electrically and magnetically tunable. For the experimental investigations, a microwave phase shifter based on the multiferroic structure has been fabricated. Performance characteristics are presented.

  12. Damping constant of Co/Pt multilayer thin-film media

    NASA Astrophysics Data System (ADS)

    Fujita, N.; Inaba, N.; Kirino, F.; Igarashi, S.; Koike, K.; Kato, H.

    Gilbert's damping constants, α, of Co( tCo)/Pt (1.4 nm) multilayer thin films are investigated by Q-band FMR analysis. α is calculated from the resonance width of the FMR spectrum. With decreasing tCo, the α value decreases from 0.034 ( tCo=8.7 nm) to 0.023 ( tCo=1.8 nm), and then increases to 0.037 ( tCo=1.0 nm). The decrease of α with tCo>1.8 nm is probably due to the eddy current loss effects. The increase of α with tCo<1.8 nm would be caused by the increase of the distortion between the Co and the Pt layers at the interface. When the magnetic field direction was changed from θ=90° (parallel to the specimen) to θ=0° (perpendicular to the specimen), the α of all the specimens increased, and a sharp step in α was observed around θ=40°, where the α has the maximum value.

  13. High Thermoelectric Power Factor Organic Thin Films through Combination of Nanotube Multilayer Assembly and Electrochemical Polymerization.

    PubMed

    Culebras, Mario; Cho, Chungyeon; Krecker, Michelle; Smith, Ryan; Song, Yixuan; Gómez, Clara M; Cantarero, Andrés; Grunlan, Jaime C

    2017-02-22

    In an effort to produce effective thermoelectric nanocomposites with multiwalled carbon nanotubes (MWCNT), layer-by-layer assembly was combined with electrochemical polymerization to create synergy that would produce a high power factor. Nanolayers of MWCNT stabilized with poly(diallyldimethylammonium chloride) or sodium deoxycholate were alternately deposited from water. Poly(3,4-ethylene dioxythiophene) [PEDOT] was then synthesized electrochemically by using this MWCNT-based multilayer thin film as the working electrode. Microscopic images show a homogeneous distribution of PEDOT around the MWCNT. The electrical resistance, conductivity (σ) and Seebeck coefficient (S) were measured before and after the PEDOT polymerization. A 30 bilayer MWCNT film (<1 μm thick) infused with PEDOT is shown to achieve a power factor (PF = S(2)σ) of 155 μW/m K(2), which is the highest value ever reported for a completely organic MWCNT-based material and competitive with lead telluride at room temperature. The ability of this MWCNT-PEDOT film to generate power was demonstrated with a cylindrical thermoelectric generator that produced 5.5 μW with a 30 K temperature differential. This unique nanocomposite, prepared from water with relatively inexpensive ingredients, should open up new opportunities to recycle waste heat in portable/wearable electronics and other applications where low weight and mechanical flexibility are needed.

  14. Very thin Fe/Ni modulation multilayer films under ion bombardment

    NASA Astrophysics Data System (ADS)

    Amaral, L.; Scorzelli, R. B.; Brückman, M. E.; Paesano, A.; Schmidt, J. E.; Shinjo, T.; Hosoito, N.

    1997-04-01

    We investigated the effect of noble gas irradiation (He, Ne, and Xe) on Fe-Ni multilayers with a very thin modulation and nominal composition in the Invar region Fe0.63Ni0.37. The evaluation of the formation/stability of the Fe-Ni phases formed under irradiation with different ions and doses was followed by conversion electron Mössbauer spectroscopy. The magnetic hysteresis curves were also obtained in order to correlate the hyperfine pattern with magnetic properties. The as-deposited sample reveals mainly the characteristic α-Fe while He- and Ne-irradiated samples clearly show a phase transformation with segregation of γ-FeNi phases with different Ni concentrations, a magnetic atomically ordered phase (˜50% Ni), and a nonmagnetic phase (⩽30% Ni). However, mixing with Ne is more effective than with He for similar doses. The results obtained with Xe showed a large distribution of hyperfine fields similarly to previous results reported for Kr [C. Tosello, F. Ferrari, R. Brand, W. Keune, G. Marest, M. A. El Khakani, J. Parellada, G. Principi, S. Lo Russo, V. Rigato, and S. Enzo, Nucl. Instrum. Methods B 80/81, 417 (1993)].

  15. Sensitivity study of multilayer thin-film bulk acoustic resonator for mass sensor application

    NASA Astrophysics Data System (ADS)

    Liu, Haiqiang; Li, Fang; Qin, Lifeng; Wang, Qing-Ming

    2016-10-01

    The sensitivity of multilayer thin-film bulk acoustic resonators (MTFBARs) used as mass sensors is investigated. MTFBAR sensors with the structure of a mass-sensitive layer/electrode layer/piezo layer/electrode layer were used. Two methods, one using electric impedance and the other displacement, were adopted for the determination of sensitivity. Simulation results show that the two methods agree well, and the characteristic acoustic impedance and thickness of the non-piezo layers strongly affect mass sensitivity. It was found that high acoustic impedance in the non-piezo layer is not helpful for sensitivity improvement. Sensitivity is improved by choosing an appropriate thickness for the low acoustic impedance non-piezo layer, and the maximum sensitivity can be obtained by choosing suitable thickness combinations for the layers. Moreover, it was found that MTFBAR quality factor and sensitivity are simultaneously improved by adopting a high-quality-factor non-piezo layer with low acoustic impedance for an air working environment, whereas a balance between quality factor and sensitivity is found through optimization of the non-piezo layers for a water working environment. These results can be used for the design and application of MTFBAR mass sensors.

  16. Magnetoelastic coupling in multilayered ferroelectric/ferromagnetic thin films: A quantitative evaluation

    NASA Astrophysics Data System (ADS)

    Chiolerio, A.; Quaglio, M.; Lamberti, A.; Celegato, F.; Balma, D.; Allia, P.

    2012-08-01

    The electrical control of magnetization in a thin film, achieved by means of magnetoelastic coupling between a ferroelectric and a ferromagnetic layer represents an attractive way to implement magnetic information storage and processing within logical architectures known as Magnetic Quantum Cellular Automata (MQCA). Such systems have been addressed as multiferroics. We exploited cost-effective techniques to realize multi-layered multiferroic systems, such as sol-gel deposition and RF sputtering, introducing a specific technique to control the crystal structure and film roughness effect on the magnetic domain wall motion and reconfiguration, induced by magnetoelastic coupling, by evaluating the 2-dimensional statistical properties of enhanced MFM matrices. A RF sputtered 50-nm-thick Co layer on a Si/SiO2/Si3N4/Ti/Pt/PbTiO3/Pb(Zr0.53Ti0.47)O3 substrate was realized, exploiting two differently engineered PZT nano-crystalline structures and the conditions leading to a favorable compromise in order to realize functional devices were elucidated.

  17. Nanostructured multilayered thin film barriers for Mg{sub 2}Si thermoelectric materials

    SciTech Connect

    Battiston, S.; Boldrini, S.; Fiameni, S.; Agresti, F.; Famengo, A.; Fabrizio, M.; Barison, S.

    2012-06-26

    The Mg{sub 2}Si-based alloys are promising candidates for thermoelectric energy conversion in the middle-high temperature range in order to replace lead compounds. The main advantages of silicide-based thermoelectrics are the nontoxicity and the abundance of their constituent elements in the earth crust. The drawback of such kind of materials is their oxygen sensitivity at high temperature that entails their use under vacuum or inert atmosphere. In order to limit the corrosion phenomena, nanostructured multilayered molybdenum silicide-based materials were deposited via RF magnetron sputtering onto stainless steel, alumina and silicon (100) to set up the deposition process and then onto Mg{sub 2}Si pellets. XRD, EDS, FE-SEM and electrical measurements at high temperature were carried out in order to obtain, respectively, the structural, compositional, morphological and electrical characterization of the deposited coatings. At the end, the mechanical behavior of the system thin film/Mg{sub 2}Si-substrate as a function of temperature and the barrier properties for oxygen protection after thermal treatment in air at high temperature were qualitatively evaluated by FE-SEM.

  18. Multilayer Optics for Ultra-high Resolution Solar Imaging in the EUV Region

    NASA Astrophysics Data System (ADS)

    Soufli, R.; Spiller, E.; Sommargren, G. E.; Bajt, S.; Folta, J. A.; Taylor, J. S.; Gullikson, E. M.

    2003-05-01

    Highly reflective multilayer-coated optics operating at near-normal incidence angles have been the enabling technology for solar imaging instruments in the extreme ultraviolet (EUV) energy range. Despite the advances made in recent years towards understanding of solar processes through missions such as TRACE, major unresolved questions in solar physics still remain, for instance on the subjects of coronal heating, eruptive flare and coronal wind initiation. Future generations of missions will need to study the physics of hot magnetized plasmas that occur in the corona on extremely small spatial and temporal scales, requiring imaging instruments with extremely high resolution and large fields of view. Proposals for future solar missions require optics with diameters up to 700 mm and system wavefront errors as low as 0.4 nm. Experimental results will be presented for normal-incidence, four-mirror and two-mirror EUV cameras operating around 13.4 nm. Mirror substrates were manufactured by commercial vendors and achieved figure errors around 0.25 nm rms, verified by phase-shifting, point-diffraction visible light interferometers developed at Lawrence Livermore Lab. The optics were multilayer-coated aligned and tested at facilities at Lawrence Livermore and Lawrence Berkeley National Labs. A large-scale DC-magnetron sputtering tool is used to coat the optics and can accommodate multiple optics up to 600 mm in diameter in a single deposition run. During multilayer deposition, a velocity modulation algorithm is applied in order to achieve extremely precise film thickness control. The deposited Mo/Si coatings demonstrate added figure errors below 0.05 nm rms. While these systems were constructed for EUV lithographic applications, the experimental results are immediately applicable to astronomical x-ray optics. Currently these are the only multilayer-coated EUV cameras worldwide meeting such stringent specifications, and have been implemented in the construction of the first

  19. Optical Properties of Thin Film Molecular Mixtures

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Shumway, Dean A.; Lyons, Valerie (Technical Monitor)

    2002-01-01

    Thin films composed of molecular mixtures of metal and dielectric are being considered for use as solar selective coatings for a variety of space power applications. By controlling the degree of molecular mixing, the solar selective coatings can be tailored to have the combined properties of high solar absorptance, alpha, and low infrared emittance, epsilon. On orbit, these combined properties would simultaneously maximize the amount of solar energy captured by the coating and minimize the amount of thermal energy radiated. Mini-satellites equipped with solar collectors coated with these cermet coatings may utilize the captured heat energy to power a heat engine to generate electricity, or to power a thermal bus that directs heat to remote regions of the spacecraft. Early work in this area identified the theoretical boundary conditions needed to operate a Carnot cycle in space, including the need for a solar concentrator, a solar selective coating at the heat inlet of the engine, and a radiator. A solar concentrator that can concentrate sunlight by a factor of 100 is ideal. At lower values, the temperature of the solar absorbing surface becomes too low for efficient heat engine operation, and at higher values, cavity type heat receivers become attractive. In designing the solar selective coating, the wavelength region yielding high solar absorptance must be separated from the wavelength region yielding low infrared emittance by establishing a sharp transition in optical properties. In particular, a sharp transition in reflectance is desired in the infrared to achieve the desired optical performance. For a heat engine operating at 450C, a sharp transition at 1.8 micrometers is desired. The radiator completes the heat flow through the Carnot cycle. Additional work has been done supporting the use of molecular mixtures for terrestrial applications. Sputter deposition provides a means to apply coatings to the tubes that carry a working fluid at the focus of trough

  20. Multilayer Phase-Only Diffraction Gratings: Fabrication andApplication to EUV Optics

    SciTech Connect

    Salmassi, Farhad; Gullikson, Eric M.; Anderson, Erik H.; Naulleau, Patrick P.

    2007-05-01

    The use of phase-only diffractive devices has long played an important role in advanced optical systems in varying fields. Such devices include gratings, diffractive and holographic optical elements, diffractive lenses, and phase-shift masks for advanced lithography. Extending such devices to the increasingly important regime of extreme ultraviolet (EUV) wavelengths, however, is not trivial. Here, we present an effective fabrication and etch process enabling high-resolution patterning of Mo/Si multilayers for use in EUV phase devices, providing another method for fabrication of high numerical aperture diffractive devices or high-resolution EUV phase shift masks.

  1. Temperature dependent magnetic coupling between ferromagnetic FeTaC layers in multilayer thin films

    NASA Astrophysics Data System (ADS)

    Singh, Akhilesh Kumar; Hsu, Jen-Hwa; Perumal, Alagarsamy

    2016-11-01

    We report systematic investigations on temperature dependent magnetic coupling between ferromagnetic FeTaC layers and resulting magnetic properties of multilayer structured [FeTaC (~67 nm)/Ta(x nm)]2/FeTaC(~67 nm)] thin films, which are fabricated directly on thermally oxidized Si substrate. As-deposited amorphous films are post annealed at different annealing temperatures (TA=200, 300 and 400 °C). Structural analyzes reveal that the films annealed at TA≤200 °C exhibit amorphous nature, while the films annealed above 200 °C show nucleation of nanocrystals at TA=300 °C and well-defined α-Fe nanocrystals with size of about 9 nm in amorphous matrix for 400 °C annealed films. Room temperature and temperature dependent magnetic hysteresis (M-H) loops reveal that magnetization reversal behaviors and magnetic properties are strongly depending on spacer layer thickness (x), TA and temperature. A large reduction in coercivity (HC) was observed for the films annealed at 200 °C and correlated to relaxation of stress quenched in during the film deposition. On the other hand, the films annealed at 300 °C exhibit unusual variation of HC(T), i.e., a broad minimum in HC(T) vs T curve. This is caused by change in magnetic coupling between ferromagnetic layers having different microstructure. In addition, the broad minimum in the HC(T) curve shifts from 150 K for x=1 film to 80 K for x=4 film. High-temperature thermomagnetization data show a strong (significant) variation of Curie temperature (TC) with TA (x). The multilayer films annealed at 200 °C exhibit low value of TC with a minimum of 350 K for x=4 film. But, the films annealed at 400 °C show largest TC with a maximum of 869 K for x=1 film. The observed results are discussed on the basis of variations in magnetic couplings between FeTaC layers, which are majorly driven by temperature, spacer layer thickness, annealing temperature and nature of interfaces.

  2. Blueshift of the optical band gap: Implications for the quantum confinement effect in a-Si:H/a-SiNx:H multilayers

    NASA Astrophysics Data System (ADS)

    Beaudoin, M.; Meunier, M.; Arsenault, C. J.

    1993-01-01

    Optical-absorption measurements are presented for multilayer structures of hydrogenated amorphous silicon and hydrogenated amorphous silicon nitride (a-Si:H/a-SiNx:H) produced by glow discharge. Small-angle x-ray-scattering measurements show that these multilayers are very periodic and confirm that the interfaces are abrupt. Optical band-gap measurements are presented for two sets of samples. Samples for the first set have constant barrier thickness and a fixed number of layer repeats while for the second set the composition and total thickness are kept constant. Even for very thin well layer thicknesses, no blueshift in the optical band gap is observed for the second set whereas the first set displays this effect quite well. This can be explained if the blueshift in the second set is due to an artifact of the Tauc law rather than quantum confinement effects as suggested by Collins and Huang [Phys. Rev. B 34, 2910 (1986)]. This interpretation is further supported by a Cody law [Solar Energy Mater. 8, 231 (1982)] analysis for which no blueshift in the optical band gap is observed for either set of samples. We conclude that optical band-gap measurements cannot be used as proof for the quantum confinement of carriers in these structures.

  3. Optical Properties of Thin Film Molecular Mixtures

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Shumway, Dean A.

    2003-01-01

    Thin films composed of molecular mixtures of metal and dielectric are being considered for use as solar selective coatings for a variety of space power applications. By controlling the degree of molecular mixing, the solar selective coatings can be tailored to have the combined properties of high solar absorptance, , and low infrared emittance, . On orbit, these combined properties would simultaneously maximize the amount of solar energy captured by the coating and minimize the amount of thermal energy radiated. Mini-satellites equipped with solar collectors coated with these cermet coatings may utilize the captured heat energy to power a heat engine to generate electricity, or to power a thermal bus that directs heat to remote regions of the spacecraft. Early work in this area identified the theoretical boundary conditions needed to operate a Carnot cycle in space, including the need for a solar concentrator, a solar selective coating at the heat inlet of the engine, and a radiator.1 A solar concentrator that can concentrate sunlight by a factor of 100 is ideal. At lower values, the temperature of the solar absorbing surface becomes too low for efficient heat engine operation, and at higher values, cavity type heat receivers become attractive. In designing the solar selective coating, the wavelength region yielding high solar absorptance must be separated from the wavelength region yielding low infrared emittance by establishing a sharp transition in optical properties. In particular, a sharp transition in reflectance is desired in the infrared to achieve the desired optical performance. For a heat engine operating at 450 C, a sharp transition at 1.8 micrometers is desired.2 The radiator completes the heat flow through the Carnot cycle.

  4. Multilayered phantoms with tunable optical properties for a better understanding of light/tissue interactions

    NASA Astrophysics Data System (ADS)

    Roig, Blandine; Koenig, Anne; Perraut, François; Piot, Olivier; Vignoud, Séverine; Lavaud, Jonathan; Manfait, Michel; Dinten, Jean-Marc

    2015-03-01

    Light/tissue interactions, like diffuse reflectance, endogenous fluorescence and Raman scattering, are a powerful means for providing skin diagnosis. Instrument calibration is an important step. We thus developed multilayered phantoms for calibration of optical systems. These phantoms mimic the optical properties of biological tissues such as skin. Our final objective is to better understand light/tissue interactions especially in the case of confocal Raman spectroscopy. The phantom preparation procedure is described, including the employed method to obtain a stratified object. PDMS was chosen as the bulk material. TiO2 was used as light scattering agent. Dye and ink were adopted to mimic, respectively, oxy-hemoglobin and melanin absorption spectra. By varying the amount of the incorporated components, we created a material with tunable optical properties. Monolayer and multilayered phantoms were designed to allow several characterization methods. Among them, we can name: X-ray tomography for structural information; Diffuse Reflectance Spectroscopy (DRS) with a homemade fibered bundle system for optical characterization; and Raman depth profiling with a commercial confocal Raman microscope for structural information and for our final objective. For each technique, the obtained results are presented and correlated when possible. A few words are said on our final objective. Raman depth profiles of the multilayered phantoms are distorted by elastic scattering. The signal attenuation through each single layer is directly dependent on its own scattering property. Therefore, determining the optical properties, obtained here with DRS, is crucial to properly correct Raman depth profiles. Thus, it would be permitted to consider quantitative studies on skin for drug permeation follow-up or hydration assessment, for instance.

  5. The effect of underlayers on the reversal of perpendicularly magnetized multilayer thin films for magnetic micro- and nanoparticles

    NASA Astrophysics Data System (ADS)

    Vemulkar, T.; Mansell, R.; Petit, D. C. M. C.; Cowburn, R. P.; Lesniak, M. S.

    2017-01-01

    Perpendicularly magnetized microparticles offer the ability to locally apply high torques on soft matter under an applied magnetic field. These particles are engineered to have a zero remanence magnetic configuration via synthetic antiferromagnetic coupling using a Ru coupling interlayer. The flexibility offered by the top down thin film fabrication process in a CoFeB/Pt perpendicular thin film is demonstrated by using the Pt interlayer thicknesses in a Pt/Ru/Pt antiferromagnetic coupling multilayer to tune the applied magnetic field value of the easy axis spin-flip transition to saturation and hence the field value at which the magnetic particles are magnetically activated via a distinct transition to saturation. The importance of a Ta buffer layer on the magnetic behavior of the stack is shown. While Au capping layers are desirable for biotechnology applications, we demonstrate that they can drastically change the nucleation and propagation of domains in the film, thereby altering the reversal behavior of the thin film. The effect of Au underlayers on a multilayer thin film composed of repeated motifs of a synthetic antiferromagnetic building block is also investigated.

  6. Optical tuning a dichroic multilayer for a high fluence laser application

    SciTech Connect

    R. Chow, Loomis, G.E.; Bibeau, C.; Molau, N.E.; Kanz, V.K.; Beach, R.J.

    1995-10-11

    We report on the design and successful fabrication of a dichroic multilayer stack using a procedure that allowed shifting from high reflectance to high transmittance within 89 rim and surviving high laser fluences. A design approach based on quarter-wave thick layers allowed the multilayer stack to be optically tuned in the last layers of the stack. In our case, this necessitated removing the samples from the coating chamber for a transmittance scan prior to depositing the last layers. This procedure is not commonly practiced due to thermal stress-induced failures in an oxide multilayer. However, D.J. Smith and co-workers reported that reactive e-beam evaporated hafnia from a Hf source produced laser-resistant coatings that had less coating stress compared to coatings evaporated from a HfO{sub 2} source. Tuned dichroic coatings were made that had high transmittance at 941 rim and high reflectance at 1030 nm. The coating was exposed for 5 minutes to a 100 kW/cm{sup 2} 1064 nm (180-ns pulsewidth, 10.7 kHz) laser beam and survived without microscopic damage. The same coating survived a 140 kW/cm{sup 2} of laser intensity without catastrophic damage before optical tuning were performed.

  7. Magneto-optical fingerprints of distinct graphene multilayers using the giant infrared Kerr effect

    PubMed Central

    Ellis, Chase T.; Stier, Andreas V.; Kim, Myoung-Hwan; Tischler, Joseph G.; Glaser, Evan R.; Myers-Ward, Rachael L.; Tedesco, Joseph L.; Eddy, Charles R.; Gaskill, D. Kurt; Cerne, John

    2013-01-01

    The remarkable electronic properties of graphene strongly depend on the thickness and geometry of graphene stacks. This wide range of electronic tunability is of fundamental interest and has many applications in newly proposed devices. Using the mid-infrared, magneto-optical Kerr effect, we detect and identify over 18 interband cyclotron resonances (CR) that are associated with ABA and ABC stacked multilayers as well as monolayers that coexist in graphene that is epitaxially grown on 4H-SiC. Moreover, the magnetic field and photon energy dependence of these features enable us to explore the band structure, electron-hole band asymmetries, and mechanisms that activate a CR response in the Kerr effect for various multilayers that coexist in a single sample. Surprisingly, we find that the magnitude of monolayer Kerr effect CRs is not temperature dependent. This unexpected result reveals new questions about the underlying physics that makes such an effect possible. PMID:24189548

  8. Fabrication of thromboresistant multilayer thin film on plasma treated poly (vinyl chloride) surface.

    PubMed

    Tan, Qinggang; Ji, Jian; Zhao, Feng; Fan, De-Zeng; Sun, Fu-Yu; Shen, Jia-Cong

    2005-07-01

    Layer-by-layer deposited anticoagulant multilayer films were prepared on ammonia plasma treated poly (vinyl chloride) (PVC). Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and contact angle results revealed the presence of -NH2 on the ammonia plasma treated PVC surfaces and the layer-by-layer self-assembly process. The stability of multilayer film was studied with the radio labeled method. The remainder bovine serum albumin (BSA) in cross-linked 5(heparin/BSA) multilayer films dipped in phosphate buffered saline (PBS, pH 7.4) was more than 90% in 40 days. The static platelet adhesion result indicated the anticoagulant multilayer films deposited on the plasma treated PVC reduced platelet adhesion drastically and no thrombus forming. The plasma recalcification time revealed that the multilayer modified surfaces greatly prolonged the plasma recalcification time. Such an easy processing and shape-independent method may have good potential for surface modification of cardiovascular devices.

  9. Structure-property relationships in the design, assembly and applications of polyelectrolyte multilayer thin films

    NASA Astrophysics Data System (ADS)

    Rmaile, Hassan H.

    Ultrathin films consisting of an alternating sequence of positively and negatively charged polyelectrolytes have been prepared by means of the electrostatic layer-by-layer sequential assembly technique. To augment their typical applications in the water treatment, personal care as well as the pulp and paper industry, the structure and the design of these polyelectrolytes were tailored synthetically to satisfy the requirements of different types of applications. Some were used for surface modifications, hydrophobic and hydrophilic coatings, corrosion protection, conducting and biocompatible surfaces. Others were found to be very efficient for membrane and chromatographic applications. The ease with which these multilayer coatings can be constructed, their robustness and stability make them very good candidates for industrial applications. The dissertation focuses mainly on the structure-property relationships of these polyelectrolytes and their corresponding thin films. Various polyelectrolytes were synthesized or modified in a strategic approach and gave novel and promising properties. Some of them exhibited permeabilities that were higher than any membranes reported in the literature. Also, some are potentially very useful for designing drug delivery systems such as tablets or encapsulations since they were shown to control the permeability of sample drugs and vitamins very efficiently based on their sensitivity to pH changes. Other synthesized polyelectrolytes proved to be very effective in preventing protein adsorption or promoting cell growth and differentiation. Some systems were very useful as robust stationary phases for simple chiral separations in capillary electrochromatography. Along with modifications and improvements, the approach might one day be applied commercially for chiral separations using high performance liquid chromatography and replace currently used stationary phases. Last but not least, the potential for these polyelectrolytes and their

  10. Chemical and phase distributions in a multilayered organic matter-Ag nanoparticle thin film system

    NASA Astrophysics Data System (ADS)

    Michel, F. M.; Levard, C.; Wang, Y.; Choi, Y.; Eng, P.; Brown, G. E.

    2010-12-01

    Rapid development of nanotechnologies raises concern regarding the environmental impact of nanoparticles on ecosystems. Among the types of nanoparticles currently in production, metallic silver is the most widely used in nanotechnology (1). Synthetic Ag nanoparticles (Ag-NPs) are most often used for their antimicrobial and antifungal properties that are, in part, explained by the release of highly toxic Ag+ species (2). While such properties are desirable in certain applied cases, the release of Ag-NPs and soluble Ag+ species to the environment is expected to impact biota as well as soil and water quality (3). With the production of Ag-NPs projected to increase (1), the amount of Ag-NPs that will be released to the environment through waste streams is also likely to increase. As such, a deeper understanding of the fundamental processes associated with Ag-NPs toxicity and reactivity is needed to evaluate their impact on the environment. We have studied the interaction during aging of poly-acrylic acid (PAA) and Ag-NPs with average particle sizes of 20 ±5 nm. The sample studied was composed of thin films of PAA and Ag-NPs deposited on a Si-wafer support. PAA served as a model compound and a simplified surrogate for exopolysaccharide, an organic substance produced through metabolic activity by most microorganisms. We applied a novel combination of long-period x-ray standing wave fluorescence yield (XSW-FY) spectroscopy, grazing-incidence x-ray diffraction (GI-XRD), and XRD-based standing wave profiles (XSW-XRD) to obtain chemical- and phase-specific information on this sample. After 24 hours, we observed the formation of AgCl(s) in the PAA film of the sample, which suggests oxidation and dissolution of a portion of the Ag-NPs during aging, resulting in the release of Ag+. In addition, we see partitioning of Cl and Br, both present initially in the PAA, to the intact Ag-NPs thin film. To our knowledge, this is the first application of this suite of techniques to this

  11. Biocatalytic polymer thin films: optimization of the multilayered architecture towards in situ synthesis of anti-proliferative drugs

    NASA Astrophysics Data System (ADS)

    Andreasen, Sidsel Ø.; Fejerskov, Betina; Zelikin, Alexander N.

    2014-03-01

    We report on the assembly of multi-layered polyelectrolyte thin films containing an immobilized enzyme to perform conversion of externally administered prodrugs and achieve delivery of the resulting therapeutics to adhering cells. Towards this goal, multi-layered coatings were assembled using poly(sodium styrene sulfonate) and poly(allylamine hydrochloride). Activity of the incorporated enzyme was quantified as a function of the assembly conditions, position of the enzyme within the multi-layered architecture, concentration of the enzyme in the adsorption solution, and concentration of the administered prodrug. Biocatalytic coatings exhibited sustained levels of enzymatic activity over at least one week of incubation in physiological buffers without signs of loss of activity of the enzyme. Developed enzyme-containing polymer films afforded zero-order release of the in situ synthesized cargo with kinetics of synthesis (nM per hour) covering at least 3 orders of magnitude. Internalization of the synthesized product by adhering cells was visualized using a fluorogenic enzyme substrate. Therapeutic utility of biocatalytic coatings was demonstrated using a myoblast cell line and a prodrug for the anti-proliferative agent, 5-fluorouridine. Taken together, this work presents a novel approach to delivery of small molecule drugs using multi-layered polymer thin films with utility in surface-mediated drug delivery, assembly of therapeutic implantable devices, and tissue engineering.We report on the assembly of multi-layered polyelectrolyte thin films containing an immobilized enzyme to perform conversion of externally administered prodrugs and achieve delivery of the resulting therapeutics to adhering cells. Towards this goal, multi-layered coatings were assembled using poly(sodium styrene sulfonate) and poly(allylamine hydrochloride). Activity of the incorporated enzyme was quantified as a function of the assembly conditions, position of the enzyme within the multi-layered

  12. Sensitivity analysis of multi-layered C-axis inclined zigzag zinc oxide thin-film resonators as viscosity sensors.

    PubMed

    Zhang, Haifeng; Bao, Yuanye

    2014-03-01

    This paper presents a theoretical analysis of a new zigzag C-axis inclined multi-layer ZnO thin-film bulk acoustic wave resonator (FBAR) as a viscosity sensor to monitor the lubrication performance of engine oil and other liquids. Free vibration and forced vibration for the FBAR loaded with liquids are analyzed. Equations necessary to calculate the sensitivity are derived. The numerical analysis shows that as the number of layers increases, the absolute sensitivity increases as well. The influences on the sensitivity of C-axis inclined angle, Q-factor, and thickness are also investigated. The results provide a foundation for further design of multi-layer FBAR viscosity sensors.

  13. Depositing highly adhesive optical thin films on acrylic substrates.

    PubMed

    Takahashi, Tomoaki; Harada, Toshinori; Murotani, Hiroshi; Matumoto, Shigeharu

    2014-02-01

    Optical thin films are used to control the reflectance and transmittance of optical components. However, conventional deposition technologies applicable to organic (plastic) substrates typically result in weak adhesion. We overcame this problem by using vacuum deposition in combination with sputtering to directly deposit a SiO2 optical thin film onto an acrylic resin substrate. We observed neither yellowing nor deformation. The hardness of the film is 2H as measured by the pencil hardness test, indicating successful modulation of optical properties without sacrificing substrate hardness.

  14. Analogy between generalized Coddington equations and thin optical element approximation.

    PubMed

    Golub, Michael A

    2009-05-01

    Local wavefront curvature transformations at an arbitrarily shaped optical surface are commonly determined by generalized Coddington equations that are developed here via a local thin optical element approximation. Eikonal distributions of the incident and refracted beams are calculated and related by an eikonal transfer function of a local thin optical element located in close proximity to a given point at a tangent plane of an optical surface. Main coefficients and terms involved in the generalized Coddington equations are derived and explained as a local nonparaxial generalization for the customary paraxial wavefront transformations.

  15. Optical sensors and multisensor arrays containing thin film electroluminescent devices

    DOEpatents

    Aylott, Jonathan W.; Chen-Esterlit, Zoe; Friedl, Jon H.; Kopelman, Raoul; Savvateev, Vadim N.; Shinar, Joseph

    2001-12-18

    Optical sensor, probe and array devices for detecting chemical biological, and physical analytes. The devices include an analyte-sensitive layer optically coupled to a thin film electroluminescent layer which activates the analyte-sensitive layer to provide an optical response. The optical response varies depending upon the presence of an analyte and is detected by a photodetector and analyzed to determine the properties of the analyte.

  16. Magneto-optical activity in organic thin film materials

    NASA Astrophysics Data System (ADS)

    Vleugels, Rick; de Vega, Laura; Brullot, Ward; Verbiest, Thierry; Gómez-Lor, Berta; Gutierrez-Puebla, Enrique; Hennrich, Gunther

    2016-12-01

    A series of CF3-capped phenylacetylenes with varying symmetry is obtained by a conventional palladium-catalyzed cross-coupling protocol. The phenylacetylene targets form thin films both, liquid crystalline (LC) and crystalline in nature depending on their molecular structure. The magneto-optical activity of the resulting organic material is extraordinarily high as proved by Faraday rotation spectroscopy on thin film devices.

  17. Experimental demonstration of a Fresnel-reflection based optical fiber biosensor coated with polyelectrolyte multilayers

    NASA Astrophysics Data System (ADS)

    Yu, Wenjie; Lang, Tingting

    2014-11-01

    We report that the end facet of an optical fiber can be coated with polyelectrolyte multilayers (PEM) of polycation (diallyldimethyl ammonium chloride) and polyanion (styrenesulfonate sodium salt) (PDDA+PSS)n (n is the number of bilayers), which functions effectively as a Fresnel-reflection based biosensor. The experimental setup includes a broadband light source, a 3dB coupler, and an optical spectrum analyzer. Biotin and streptavidin are deposited onto the multilayers-coated end facet sequentially. The light intensity change due to variation of external refractive index is monitored. When the concentrations of streptavidin changes from 0.1mg/ml to 1mg/ml, a linear relationship between the concentration of streptavidin and the reflected optical power at the wavelength of 1530nm is observed. The sensitivity increases from -1.6262×10-3 dB/ppm to -4.7852 ×10-3 dB/ppm, when the number of PEM increases from 1 to 2. Then we confirm the optimized numbers of bilayers of PEM are 5 through experiment. Selectivity and repeatability of our proposed optical fiber biosensor are verified. When bovine serum albumin (BSA) is added instead of streptavidin, the obtained spectra overlaps with that of biotin's. The final end facet coated with PEM and biotin-streptavidin can be cleaned using microwave vibration or aqua regia. The microwave vibration method is utilized due to security concern. The optical spectra changes back to the initial one of the optical fiber in air. In conclusion, a Fresnel-reflection based optical fiber biosensor with good sensitivity, selectivity and repeatability is proposed. This biosensor has the advantages of simple structure, low cost and reliability.

  18. Optimal structure of light trapping in thin-film solar cells: dielectric nanoparticles or multilayer antireflection coatings?

    PubMed

    Zhao, Yongxiang; Chen, Fei; Shen, Qiang; Zhang, Lianmeng

    2014-08-10

    Recent research has found an alternative way to enhance light trapping of thin-film solar cells by using dielectric nanoparticles deposited on the cell surface. To improve the performance of light trapping, a systematic study on the influence of dielectric nanoparticles on enhancement efficiency is performed in this paper. We prove that the optimal dielectric nanoparticles are substantially equivalent to the multilayer antireflection coatings (ARCs) with a "low-high-low" dielectric constant profile. Moreover, it is demonstrated that the use of a simple two-layer SiO2/SiC ARC can reach 34.15% enhancement, which has exceeded the ideal limit of 32% of nanoparticles structure including plasmonic Ag nanoparticles, dielectric SiC, and TiO2 nanoparticles. That means the optimal multilayer ARCs structure is obviously superior to the optimal dielectric nanoparticles structure, and the deposition of a simple two-layer SiO2/SiC structure on top of a thin-film silicon solar cell can significantly enhance photoelectron generation and hence, result in superior performance of thin-film solar cells.

  19. Analysis of Oxidation State of Multilayered Catalyst Thin Films for Carbon Nanotube Growth Using Plasma-Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Okita, Atsushi; Ozeki, Atsushi; Suda, Yoshiyuki; Nakamura, Junji; Oda, Akinori; Bhattacharyya, Krishnendu; Sugawara, Hirotake; Sakai, Yosuke

    2006-10-01

    We synthesized vertically aligned carbon nanotubes (CNTs) using multilayered catalyst thin films (Fe/Al2O3 and Al2O3/Fe/Al2O3) by RF (13.56 MHz) CH4/H2/Ar plasma-enhanced chemical vapor deposition. Pretreatment of the catalyst is crucial for CNT growth. In this paper, we analyzed the effect of catalyst reduction on CNT growth. Catalyst thin films on substrates were reduced by H2 plasma pretreatment at 550 °C to form nanometer-sized catalyst particles. The multilayered thin films were analyzed; the chemical composition and oxidation state by X-ray photoelectron spectroscopy (XPS) and the surface morphology by scanning electron microscopy (SEM). The Fe 2p peak of the XPS spectra showed that FexOy in the as-deposited catalyst was effectively reduced to Fe by a pretreatment of duration 4 min. Using this catalyst, we obtained CNTs with an average diameter of 10.7 nm and an average length of 5.3 μm. However, pretreatment longer than 4 min resulted in shorter CNTs and the Fe peak was shifted from Fe to Fe3O4. These transitions (Fe2O3→Fe3O4→Fe→Fe3O4) can be explained by the enthalpy of the oxides. This result indicates the presence of an optimum ratio between Fe and FexOy to maximize the CNT lengths.

  20. A standard model eye with micro scale multilayer structure for ophthalmic optical coherence tomography equipment

    NASA Astrophysics Data System (ADS)

    Cao, Zhenggang; Ding, Zengqian; Hu, Zhixiong; Wen, Tao; Qiao, Wen; Liu, Wenli

    2016-10-01

    Optical coherence tomography (OCT) has been widely applied in diagnosis of eye diseases during the last 20 years. Differing from traditional two-dimension imaging technologies, OCT could also provide cross-sectional information of target tissues simultaneously and precisely. As well known, axial resolution is one of the most critical parameters impacting the OCT image quality, which determines whether an accurate diagnosis could be obtained. Therefore, it is important to evaluate the axial resolution of an OCT equipment. Phantoms always play an important role in the standardization and validation process. Here, a standard model eye with micro-scale multilayer structure was custom designed and manufactured. Mimicking a real human eye, analyzing the physical characteristic of layer structures of retina and cornea in-depth, appropriate materials were selected by testing the scattering coefficient of PDMS phantoms with difference concentration of TiO2 or BaSO4 particles. An artificial retina and cornea with multilayer-films which have a thickness of 10 to 60 micrometers for each layer were fabricated using spin coating technology. Considering key parameters of the standard model eye need to be traceable as well as accurate, the optical refractive index and layer structure thicknesses of phantoms were verified by utilizing Thickness Monitoring System. Consequently, a standard OCT model eye was obtained after the retinal or corneal phantom was embedded into a water-filled model eye which has been fabricated by 3D printing technology to simulate ocular dispersion and emmetropic refraction. The eye model was manufactured with a transparent resin to simulate realistic ophthalmic testing environment, and most key optical elements including cornea, lens and vitreous body were realized. By investigating with a research and a clinical OCT system respectively, the OCT model eye was demonstrated with similar physical properties as natural eye, and the multilayer film measurement

  1. Multilayer optics for monochromatic high-resolution x-ray imaging mircoscopes

    NASA Astrophysics Data System (ADS)

    Troussel, Ph.; Do, A.; Gontier, D.; Dennetiere, D.; Høghøj, P.; Hedacq, S.

    2015-08-01

    Within the framework of its researches on Inertial Confinement Fusion (ICF), the "Commissariat à l'Énergie Atomique et aux Énergies Alternatives" (CEA) studies and designs advanced X-ray diagnostics in order to probe dense plasmas produced by Laser facilities. The final goal for those diagnostics is to be used during experiments on the Laser Megajoules french facility (LMJ) at Bordeaux. We present two types of advanced monochromatic High Resolution X-ray Imaging microscopes (HRXI) who have high spatial resolution capability (3-6 μm) and high efficiency. The first microscope so-called MERSSIX consists of two toroïdals mirrors mounted into a Wolter type geometry and working at grazing incidence. Non-periodic multilayer (depth graded) mirrors were developed with special coatings designed to provide broadband X-ray reflectance in the 1 - 22 keV energy range. Associated to this Wolter microscope a potential monochromatic third mirror coated with a multilayer stack can be used for monochromatic application in that range. The second microscope is composed of a transmission gold Fresnel Phase Zone Plate (FPZP) and a narrow bandwidth multilayer mirror. We present an experimental study with X-ray plasma-source and a complete characterization of the X-ray optics on the synchrotron radiation facility BESSY II. Potentialities (a few μspatial resolution monochromatic images) and complementarity of these two monochromatic HRXI are discussed. The design of the MLs for each microscope is detailed.

  2. The magnetic and chemical structural property of the epitaxially-grown multilayered thin film

    NASA Astrophysics Data System (ADS)

    Lee, Hwachol

    L10 FePt- and Fe-related alloys such as FePtRh, FeRh and FeRhPd have been studied for the high magnetocrystalline anisotropy and magnetic phase transition property for the future application. In this work, the thin film structural and magnetic property is investigated for the selected FePtRh and FeRhPd alloys. The compositionally-modulated L10 FePtRh multilayered structure is grown epitaxially on a-plane Al2O3 with Cr and Pt buffer layer at 600degC growth temperature by DC sputtering technique and examined for the structural, interfacial and magnetic property. For the epitaxially grown L10 [Fe50Pt45Rh5 (FM) (10nm) / Fe50Pt25Rh25 (AFM) (20nm)]x8 superlattice, the magnetically and chemically sharp interface formation between layers was observed in X-ray diffraction, transmission electron microscopy and polarized neutron reflectivity measurements with the negligible exchange bias at room and a slight coupling effect at lower temperature regime. For FeRhPd, the magnetic phase transition of epitaxially-grown 111-oriented Fe46Rh48Pd6 thin film is studied. The applied Rhodium buffer layer on a-plane Al2O3 (11 20) at 600degC shows the extraordinarily high quality of epitaxial film in (111) orientation, where two broad and coherent peak in rocking curve, and Laue oscillations are observed. The epitaxially-grown Pd-doped FeRh on Pt (111) grown at 600degC, 700degC exhibits the co-existing stable L10 (111) and B2 (110) structures and magnetic phase transition around 300degC. On the other hand, the partially-ordered FeRhPd structure grown at 400degC, 500degC shows background high ferromagnetic state over 5K˜350K temperature. For the reduced thickness of Fe46Rh48Pd 6, the ferromagnetic state becomes dominant with a reduced portion of the film undergoing a magnetic phase transition. For some epitaxial FeRhPd film, the spin-glass-like disordered state is also observed in field dependent SQUID measurement. For the tri-layered FeRhPd with thin Pt spacer, the background

  3. Investigation of multilayer domains in large-scale CVD monolayer graphene by optical imaging

    NASA Astrophysics Data System (ADS)

    Yu, Yuanfang; Li, Zhenzhen; Wang, Wenhui; Guo, Xitao; Jiang, Jie; Nan, Haiyan; Ni, Zhenhua

    2017-03-01

    CVD graphene is a promising candidate for optoelectronic applications due to its high quality and high yield. However, multi-layer domains could inevitably form at the nucleation centers during the growth. Here, we propose an optical imaging technique to precisely identify the multilayer domains and also the ratio of their coverage in large-scale CVD monolayer graphene. We have also shown that the stacking disorder in twisted bilayer graphene as well as the impurities on the graphene surface could be distinguished by optical imaging. Finally, we investigated the effects of bilayer domains on the optical and electrical properties of CVD graphene, and found that the carrier mobility of CVD graphene is seriously limited by scattering from bilayer domains. Our results could be useful for guiding future optoelectronic applications of large-scale CVD graphene. Project supported by the National Natural Science Foundation of China (Nos. 61422503, 61376104), the Open Research Funds of Key Laboratory of MEMS of Ministry of Education (SEU, China), and the Fundamental Research Funds for the Central Universities.

  4. AND/R: Advanced neutron diffractometer/reflectometer for investigation of thin films and multilayers for the life sciences

    SciTech Connect

    Dura, Joseph A.; Pierce, Donald J.; Majkrzak, Charles F.; Maliszewskyj, Nicholas C.; McGillivray, Duncan J.; Loesche, Mathias; O'Donovan, Kevin V.; Mihailescu, Mihaela; Perez-Salas, Ursula; Worcester, David L.; White, Stephen H.

    2006-07-15

    An elastic neutron scattering instrument, the advanced neutron diffractometer/reflectometer (AND/R), has recently been commissioned at the National Institute of Standards and Technology Center for Neutron Research. The AND/R is the centerpiece of the Cold Neutrons for Biology and Technology partnership, which is dedicated to the structural characterization of thin films and multilayers of biological interest. The instrument is capable of measuring both specular and nonspecular reflectivity, as well as crystalline or semicrystalline diffraction at wave-vector transfers up to approximately 2.20 A{sup -1}. A detailed description of this flexible instrument and its performance characteristics in various operating modes are given.

  5. Design of a superluminal ring laser gyroscope using multilayer optical coatings with huge group delay.

    PubMed

    Qu, Tianliang; Yang, Kaiyong; Han, Xiang; Wu, Suyong; Huang, Yun; Luo, Hui

    2014-11-18

    We propose and analyze a superluminal ring laser gyroscope (RLG) using multilayer optical coatings with huge group delay (GD). This GD assisted superluminal RLG can measure the absolute rotation with a giant sensitivity-enhancement factor of ~10(3); while, the broadband FWHM of the enhancement factor can reach 20 MHz. This superluminal RLG is based on a traditional RLG with minimal re-engineering, and beneficial for miniaturization according to theoretical calculation. The idea of using GD coatings as a fast-light medium will shed lights on the design and application of fast-light sensors.

  6. Design of a superluminal ring laser gyroscope using multilayer optical coatings with huge group delay

    PubMed Central

    Qu, Tianliang; Yang, Kaiyong; Han, Xiang; Wu, Suyong; Huang, Yun; Luo, Hui

    2014-01-01

    We propose and analyze a superluminal ring laser gyroscope (RLG) using multilayer optical coatings with huge group delay (GD). This GD assisted superluminal RLG can measure the absolute rotation with a giant sensitivity-enhancement factor of ~103; while, the broadband FWHM of the enhancement factor can reach 20 MHz. This superluminal RLG is based on a traditional RLG with minimal re-engineering, and beneficial for miniaturization according to theoretical calculation. The idea of using GD coatings as a fast-light medium will shed lights on the design and application of fast-light sensors. PMID:25403698

  7. Optimizing the sensitivity of porous thin film optical sensors

    NASA Astrophysics Data System (ADS)

    Mackay, Tom G.

    2012-10-01

    We considered a porous thin film as a platform for optical sensing. It is envisaged that the porous thin filmbecomes infiltrated by a fluid containing an agent to be sensed. The basis for detection of this agent to besensed is provided by changes in the optical properties of the infiltrated porous thin film. Provided that thepore sizes are much smaller than the wavelengths involved, the infiltrated porous thin film may be regardedas a homogenized composite material. Using the well-established Bruggeman homogenization formalism, thesensitivity of such an optical sensor was investigated theoretically. The sensitivity was considered in relation tothe optical properties of the porous thin film and the infiltrating fluid, the porosity of the thin film, and theshape of the pores. For the case of an isotropic dielectric porous thin film of relative permittivity ɛa and anisotropic dielectric fluid of relative permittivity ɛb, the sensitivity was found to be maximized if: (i) the contrast between ɛa and ɛb was maximized; (ii) mid-range values of porosity were used; (iii) the regime 0 < ɛb < 1 with ɛa » 1 pertained, for example; and (iv) pores which have elongated spheroidal shapes were incorporated.

  8. The structural, magnetic and microwave properties of spherical and flake shaped carbonyl iron particles as thin multilayer microwave absorbers

    NASA Astrophysics Data System (ADS)

    Khani, Omid; Shoushtari, Morteza Zargar; Ackland, Karl; Stamenov, Plamen

    2017-04-01

    An increase in microwave permeability is a prerequisite for reducing the thickness of radar absorber coatings. The aim of this paper is to increase the magnetic loss of commercial carbonyl iron particles for fabricating wideband microwave absorbers with a multilayer structure. For this purpose, carbonyl iron particles were milled and their static and dynamic magnetic properties were studied before and after milling. A distinct morphological change from spherical to flake-like particles is measured with increased milling time, whereas no distinct changes in magnetic properties are measured with increased milling time. The imaginary part of the permeability (μ״) of the milled carbonyl iron particles increased from 1.23 to 1.88 and showed a very broad peak over the entire frequency range 1-18 GHz. The experimental results were modeled using the Rousselle effective medium theory (EMT) in the Neo formulation. The theoretical predictions showed good agreement with the experimental results. Two layer absorbers were designed according to the measured microwave parameters and the multilayer design. The results revealed that a thin multilayer with a thickness of 1.75 mm can effectively absorb microwaves in both the entire X and Ku frequency bands. The results suggest that microwave absorbers with excellent absorption properties could be mass-produced, using commercial carbonyl iron particles.

  9. Accurate calculation and Matlab based fast realization of merit function's Hesse matrix for the design of multilayer optical coating

    NASA Astrophysics Data System (ADS)

    Wu, Su-Yong; Long, Xing-Wu; Yang, Kai-Yong

    2009-09-01

    To improve the current status of home multilayer optical coating design with low speed and poor efficiency when a large layer number occurs, the accurate calculation and fast realization of merit function’s gradient and Hesse matrix is pointed out. Based on the matrix method to calculate the spectral properties of multilayer optical coating, an analytic model is established theoretically. And the corresponding accurate and fast computation is successfully achieved by programming with Matlab. Theoretical and simulated results indicate that this model is mathematically strict and accurate, and its maximal precision can reach floating-point operations in the computer, with short time and fast speed. Thus it is very suitable to improve the optimal search speed and efficiency of local optimization methods based on the derivatives of merit function. It has outstanding performance in multilayer optical coating design with a large layer number.

  10. General Strategy for Broadband Coherent Perfect Absorption and Multi-wavelength All-optical Switching Based on Epsilon-Near-Zero Multilayer Films

    PubMed Central

    Kim, Tae Young; Badsha, Md. Alamgir; Yoon, Junho; Lee, Seon Young; Jun, Young Chul; Hwangbo, Chang Kwon

    2016-01-01

    We propose a general, easy-to-implement scheme for broadband coherent perfect absorption (CPA) using epsilon-near-zero (ENZ) multilayer films. Specifically, we employ indium tin oxide (ITO) as a tunable ENZ material, and theoretically investigate CPA in the near-infrared region. We first derive general CPA conditions using the scattering matrix and the admittance matching methods. Then, by combining these two methods, we extract analytic expressions for all relevant parameters for CPA. Based on this theoretical framework, we proceed to study ENZ CPA in a single layer ITO film and apply it to all-optical switching. Finally, using an ITO multilayer of different ENZ wavelengths, we implement broadband ENZ CPA structures and investigate multi-wavelength all-optical switching in the technologically important telecommunication window. In our design, the admittance matching diagram was employed to graphically extract not only the structural parameters (the film thicknesses and incident angles), but also the input beam parameters (the irradiance ratio and phase difference between two input beams). We find that the multi-wavelength all-optical switching in our broadband ENZ CPA system can be fully controlled by the phase difference between two input beams. The simple but general design principles and analyses in this work can be widely used in various thin-film devices. PMID:26965195

  11. General Strategy for Broadband Coherent Perfect Absorption and Multi-wavelength All-optical Switching Based on Epsilon-Near-Zero Multilayer Films

    NASA Astrophysics Data System (ADS)

    Kim, Tae Young; Badsha, Md. Alamgir; Yoon, Junho; Lee, Seon Young; Jun, Young Chul; Hwangbo, Chang Kwon

    2016-03-01

    We propose a general, easy-to-implement scheme for broadband coherent perfect absorption (CPA) using epsilon-near-zero (ENZ) multilayer films. Specifically, we employ indium tin oxide (ITO) as a tunable ENZ material, and theoretically investigate CPA in the near-infrared region. We first derive general CPA conditions using the scattering matrix and the admittance matching methods. Then, by combining these two methods, we extract analytic expressions for all relevant parameters for CPA. Based on this theoretical framework, we proceed to study ENZ CPA in a single layer ITO film and apply it to all-optical switching. Finally, using an ITO multilayer of different ENZ wavelengths, we implement broadband ENZ CPA structures and investigate multi-wavelength all-optical switching in the technologically important telecommunication window. In our design, the admittance matching diagram was employed to graphically extract not only the structural parameters (the film thicknesses and incident angles), but also the input beam parameters (the irradiance ratio and phase difference between two input beams). We find that the multi-wavelength all-optical switching in our broadband ENZ CPA system can be fully controlled by the phase difference between two input beams. The simple but general design principles and analyses in this work can be widely used in various thin-film devices.

  12. Structural, magnetic, and magneto-optical properties of nanocrystalline face centered cubic Co70Cr30/Pt multilayers with perpendicular magnetic anisotropy.

    PubMed

    Papaioannou, E Th; Angelakeris, M; Poulopoulos, P; Tsiaoussis, I; Rüdt, C; Fumagalli, P; Flevaris, N K

    2007-12-01

    Co70Cr30 alloyed layers are combined with extremely thin Pt layers in order to produce novel face-centered-cubic multilayered films to be considered as a potential perpendicular magnetic recording medium. The films were grown on Si, glass and polyimide substrates by e-beam evaporation at a temperature slightly higher than room temperature. The multilayered structure of the films was verified by X-ray diffraction experiments. Plane-view transmission electron microscopy images have revealed the formation of very small grains in the range of 7-9 nm. Hysteresis loops as a function of temperature were recorded via the magneto-optic Kerr effect in the polar geometry configuration. The system exhibits perpendicular magnetic anisotropy, which enhances with decreasing temperature. Hysteresis loops with a squareness of 1 and a coercivity of 1.45 kOe were obtained at 10 K. Furthermore, complete magneto-optic spectra of the films are recorded, showing a strong magneto-optic enhancement in the ultraviolet region at around 4.5 eV.

  13. Electrodeposited Multilayer Solar Cell Materials^*

    NASA Astrophysics Data System (ADS)

    Friedfeld, R.; Raffaelle, R. P.; Mantovani, J. G.

    1996-03-01

    We have been investigating the synthesis of electrochemically deposited multilayer structures based on the Cu_xIn_2-xSe2 system for use in thin film solar cells. Electrochemical deposition is a cost- effective alternative for producing these solar cell materials. Cu_xIn_2-xSe2 is one of the most promising thin film solar cell materials, due to its ideal optical and electrical properties. The interest in multilayer structures is due to their proposed use in increasing thin film solar cell efficiency. We present our attempts at synthesizing nanoscale multilayer thin films based on the Cu_xIn_2-xSe2 system using various solutions and techniques. We have characterized the composition, structure, and optical properties of these films using energy dispersive spectroscopy, x-ray diffraction, scanning tunneling microscopy, and optical spectroscopy. * This work was supported by the Southeastern University Research Association in collaboration with Oak Ridge National Laboratory and the Florida Solar Energy Center.

  14. Anisotropy of the optical and magneto-optical response of Au/Co/Au/Cu multilayers grown on vicinal Si (111) surfaces

    NASA Astrophysics Data System (ADS)

    Cheikh-Rouhou, W.; Sampaio, L. C.; Bartenlian, B.; Beauvillain, P.; Brun, A.; Ferré, J.; Georges, P.; Jamet, J.-P.; Mathet, V.; Stupakewicz, A.

    2002-05-01

    The optical and magneto-optical second harmonic reflectivity response of Au/Co/Au/Cu multilayers grown on vicinal Si (111) substrates has been studied. These azimuthal optical non-linear experiments check the uniaxial character of the crystallinity of the Au buffer layer and the magnetic behavior of the ultrathin Co films in the metallic multilayer. They clearly show the strong dependence of the growth parameters and the misorientation of the vicinal surface on the SHG reflectivity signals. This uniaxial behavior is also correlated to linear MOKE experiments on the magnetic anisotropy with an easy magnetization axis parallel to the step edges.

  15. Multilayer Markov Random Field models for change detection in optical remote sensing images

    NASA Astrophysics Data System (ADS)

    Benedek, Csaba; Shadaydeh, Maha; Kato, Zoltan; Szirányi, Tamás; Zerubia, Josiane

    2015-09-01

    In this paper, we give a comparative study on three Multilayer Markov Random Field (MRF) based solutions proposed for change detection in optical remote sensing images, called Multicue MRF, Conditional Mixed Markov model, and Fusion MRF. Our purposes are twofold. On one hand, we highlight the significance of the focused model family and we set them against various state-of-the-art approaches through a thematic analysis and quantitative tests. We discuss the advantages and drawbacks of class comparison vs. direct approaches, usage of training data, various targeted application fields and different ways of Ground Truth generation, meantime informing the Reader in which roles the Multilayer MRFs can be efficiently applied. On the other hand we also emphasize the differences between the three focused models at various levels, considering the model structures, feature extraction, layer interpretation, change concept definition, parameter tuning and performance. We provide qualitative and quantitative comparison results using principally a publicly available change detection database which contains aerial image pairs and Ground Truth change masks. We conclude that the discussed models are competitive against alternative state-of-the-art solutions, if one uses them as pre-processing filters in multitemporal optical image analysis. In addition, they cover together a large range of applications, considering the different usage options of the three approaches.

  16. Optical response of cylindrical multilayers in the context of hydrodynamic convection-diffusion model

    NASA Astrophysics Data System (ADS)

    Dong, Tianyu; Shi, Yi; Lu, Lizhen; Chen, Feng; Ma, Xikui; Mittra, Raj

    2016-09-01

    In this work, we generalize the cascading scattering matrix algorithm for calculating the optical response of concentric multilayered structures comprised of either plasmonic metal or dielectric, within the framework of hydrodynamic convection-diffusion model of electrodynamics. Two additional boundary conditions, namely, the continuity of first order pressure of free electron density and the continuity of normal components of free charge velocity, respectively, are adopted in order to handle the behaviour at interfaces involving metals. Scattering matrices at interfaces can be readily obtained and cascaded to obtain the modal coefficients in each layer by expanding electromagnetic waves in harmonic modes with cylindrical vector wave functions. We have validated the proposed method by analyzing the optical responses of several configurations of nanostructures, including a bi-metallic nanocylinder and a hyperlens. We found that nonlocal effects can be important for small structures, when the characteristic size is comparable to the Fermi wavelength. The proposed method shows its capability and flexibility to solve hybrid metal-dielectric multilayer structures even when the number of layers is large. Although we have discussed our method in the context of the retarded radiation regime, it can be applied in quasi-static scenarios without any difficulties. Furthermore, it may be extended to solve similar problems in other areas of physics, such as acoustics.

  17. Investigation of optical properties of Cu/Ni multilayer nanowires embedded in etched ion-track template

    NASA Astrophysics Data System (ADS)

    Xie, Lu; Yao, Huijun; Duan, Jinglai; Chen, Yonghui; Lyu, Shuangbao; Maaz, Khan; Mo, Dan; Liu, Jie; Sun, Youmei; Hou, Mingdong

    2016-12-01

    For understanding the interaction between light and noble/magnetism multilayer nanowires, Cu/Ni multilayer nanowires are fabricated by a multi-potential step deposition technique in etched ion-track polycarbonate template. The component and the corresponding layer thickness of multilayer nanowire are confirmed by TEM and EDS line-scan analysis. By tailoring the nanowire diameter, the Cu layer thickness and the periodicity of the nanowire, the extinction spectral of nanowire arrays exhibit an extra sensitivity to the change of structural parameters. The resonance wavelength caused by surface plasmon resonance increases obviously with increasing the nanowire diameter, the Cu layer thickness and the periodicity. The observations in our work can be explained by the "impurity effect" and coupled effect and can also be optimized for developing optical devices based on multilayer nanowires.

  18. Skyrmions in thin-film multilayers with interfacially-induced Dzyaloshinskii-Moriya interaction observed by MFM

    NASA Astrophysics Data System (ADS)

    Bacani, Mirko; Marioni, Miguel A.; Schwenk, Johannes; Romer, Sara; Zhao, Xue; Guiller, Alexandre; Hug, Hans J.

    By proper selection of interfaces in thin-film multilayers one can separately engineer the anisotropy, magnetization and Dzyaloshinskii-Moriya interaction (DMI), which is useful in the design of skyrmion materials. We use high-sensitivity, high-resolution magnetic force microscopy (MFM) in various applied magnetic fields to image the micromagnetic structures in multilayers based on symmetric-interface stacks of Pt/Co/Pt and asymmetric ones of Pt/Co/Ir. The former have domain sizes of several microns, whereas the latter show considerably smaller domain sizes. These are (246 +/-40) nm independently of the demagnetization process used. We attribute the lower domain size to a net DMI. The calculated DMI in the asymmetric case is too small to support a skyrmion phase, but isolated skyrmions can exist. MFM experiments reveal skyrmions with a diameter below 50 nm, when the field is reduced from positive saturation. In negative fields these skyrmions are either incorporated into expanding domains or burst into a larger domain. Local DMI constants estimated from the bursting fields agree well with the average DMI constant. Our work demonstrates that MFM can detect skyrmions in thin films, and can help accelerate research in this field.

  19. Thermal analysis of thin multi-layer metal films during femtosecond laser heating

    NASA Astrophysics Data System (ADS)

    Karakas, A.; Tunc, M.; Camdali, Ü.

    2010-12-01

    Multi-layer metals films are widely used in modern engineering applications such as gold-coated metal mirrors used in high power laser systems. A transient heat flux model is derived to analyze multi-layer metal films under laser heating. The two separate system composed of electrons and the lattice is considered to take into account the electron-lattice interaction. The present model predicted the effects of underlying chromium's thermal properties on temperature rise of the top gold layer. The effects of two adjacent and different metals with different electron-lattice coupling factors are analyzed for the heating mechanism of different lattices. The derived transient model combined with the two different conservation equations for the lattice and electrons are applied for the ultra short-pulse laser heating of a multi-layer film composed of gold and chromium.

  20. Electro-optical backplane demonstrator with integrated multimode gradient-index thin glass waveguide panel

    NASA Astrophysics Data System (ADS)

    Schröder, Henning; Brusberg, Lars; Pitwon, Richard; Whalley, Simon; Wang, Kai; Miller, Allen; Herbst, Christian; Weber, Daniel; Lang, Klaus-Dieter

    2015-03-01

    Optical interconnects for data transmission at board level offer increased energy efficiency, system density, and bandwidth scalability compared to purely copper driven systems. We present recent results on manufacturing of electrooptical printed circuit board (PCB) with integrated planar glass waveguides. The graded index multi-mode waveguides are patterned inside commercially available thin-glass panels by performing a specific ion-exchange process. The glass waveguide panel is embedded within the layer stack-up of a PCB using proven industrial processes. This paper describes the design, manufacture, assembly and characterization of the first electro-optical backplane demonstrator based on integrated planar glass waveguides. The electro-optical backplane in question is created by laminating the glass waveguide panel into a conventional multi-layer electronic printed circuit board stack-up. High precision ferrule mounts are automatically assembled, which will enable MT compliant connectors to be plugged accurately to the embedded waveguide interfaces on the glass panel edges. The demonstration platform comprises a standardized sub-rack chassis and five pluggable test cards each housing optical engines and pluggable optical connectors. The test cards support a variety of different data interfaces and can support data rates of up to 32 Gb/s per channel.

  1. Optical diffraction analysis of petrographic thin sections.

    PubMed

    Power, P C; Pincus, H J

    1974-10-18

    Diffraction patterns that are highly reproducible, of useful quality, and consistent with the input generating them can be easily obtained with a microscope system. The input can be either a reduced photograph or a thin section. With two exceptions, the relationships between a thin section and its diffraction pattern produced by a petrographic microscope are the same as the relationships between a photographic input and its diffraction pattern produced by a conventional ODA system. The exceptions are that the diffraction patterns generated directly by the thin sections may be asymmetrical or, if the thin section is sufficiently heterogeneous, may be smeared. The microscope system is generally more useful than a conventional ODA system for the analysis of microfabric in thin sections. One can readily use the microscope system to analyze elements of widely varying spatial frequency simply by changing the objectives. The diffraction patterns can be magnified by changing to a higherpower ocular. In most cases the microscope-generated diffraction pattern transmits the useful spatial information in the thin section more completely than the conventionally produced diffraction pattern; the photographic inputs for the conventionally produced diffraction pattern emphasize lower-frequency spatial information. This property, combined with the microscope system's better response to twinning, makes the microscope more sensitive to commonly used microfabric elements. For the analysis of thin sections, a conventional ODA system is superior to the microscope system in only three cases. First, if one wants to analyze the entire thin section at one time, a conventional system must be used with a photographic input of the thin section. Second, if the thin section is extremely heterogeneous (crystallographically or mineralogically), the microscope-generated diffraction pattern may exhibit gross smearing even with the highestpower objectives available. Finally, the thin section may

  2. Coastal thin layer dynamics: Consequences to biology and optics

    NASA Astrophysics Data System (ADS)

    Sullivan, James M.; Donaghay, Percy L.; Rines, Jan E. B.

    2010-01-01

    Thin layers are fine-scale structures with high concentrations of organisms or particles occurring over very small vertical scales (a few meters or less), but with large horizontal scales, often extending for many kilometers. Because of their small vertical scales, thin layers are traditionally under sampled, but when proper measurement techniques are used, thin layers have been found to be ubiquitous in stratified oceans. A multi-investigator, interdisciplinary study of thin layers was sponsored by the US Office of Naval Research under a research initiative termed: Layered Organization in the Coastal Ocean (LOCO). The goal of this program was to understand the properties of coastal thin layers and the interacting physical, chemical, biological and optical processes responsible for their formation, maintenance and dissipation. As part of this program, fine-scale vertical profiles (cm resolution) of biological, physical and chemical properties were made hourly over periods spanning 1-3 weeks during three summers in Monterey Bay, California USA. The vertical profiles were made using arrays of moored autonomous profilers. In total, these profilers made ~2000 individual vertical profiles and provided a unique view of phytoplankton thin layer spatial-temporal dynamics. The autonomous profiler data were supplemented with high-resolution ship-based profiling and discrete water sampling for identifications of organisms. Persistent phytoplankton thin layers were observed during each year in Monterey Bay; however, each year had very different biological and physical dynamics. During 2002, thin layers were dominated by the non-motile and potentially toxic diatom genus Pseudo-nitzschia; during 2005, thin layers were dominated by the highly motile dinoflagellate species Akashiwo sanguinea; and during 2006, a more complex phytoplankton assemblage was present, but thin layers of the toxic dinoflagellate species Alexandrium catenella frequently occurred. The variability in the

  3. Preparation and Characterization of Multilayer Capacitor with SrTiO3 Thin Films by Aerosol Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Wang, Shuqiang; Kawase, Akihiro; Ogawa, Hirotaka

    2006-09-01

    The deposition of crystalline and amorphous STO (SrTiO3) thin films by aerosol chemical vapor deposition (ASCVD) was investigated. The crystalline STO thin film exhibited a higher dielectric constant of approximately 160 and a dielectric loss (\\tanδ) of 3.5% (at 1 kHz). In contrast, the amorphous STO thin films with dielectric constants of 20-65 showed a smaller dielectric loss below 1% and much lower leakage currents of 10-8-10-6 A/cm2 at up to ± 30 VDC. On the basis of these results, a thin-film multilayer ceramic capacitor (MLCC) with ten amorphous STO dielectric layers and Pt electrodes of 160 and 120 nm thicknesses, respectively, was prepared at a processing temperature of 600 °C, showing a capacitance density of higher than 900 nF/cm2 (effective electrode area: 2× 2 mm2), a dielectric loss of 0.1% at 1 kHz and a leakage current of 10-7 A/cm2 at ± 5 VDC.

  4. Optical thin-film technology: past, present, future

    NASA Astrophysics Data System (ADS)

    Strickland, William P.

    1990-12-01

    The evolution of the vacuum coating industry is reviewed. Vacuum science progressed slowly until the late nineteenth century due to an incomplete understanding of vacuum and lack of applications. Edison's invention of the light bulb launched the vacuum industry and increased developmentof improved vacuum systems. The thin film optical coating industry arose from the needs of the German and U.S. military efforts during World War II. The author presents his experience in thin film coating from 1939 to the present.

  5. Nanocavity enhancement for ultra-thin film optical absorber.

    PubMed

    Song, Haomin; Guo, Luqing; Liu, Zhejun; Liu, Kai; Zeng, Xie; Ji, Dengxin; Zhang, Nan; Hu, Haifeng; Jiang, Suhua; Gan, Qiaoqiang

    2014-05-01

    A fundamental strategy is developed to enhance the light-matter interaction of ultra-thin films based on a strong interference effect in planar nanocavities, and overcome the limitation between the optical absorption and film thickness of energy harvesting/conversion materials. This principle is quite general and is applied to explore the spectrally tunable absorption enhancement of various ultra-thin absorptive materials including 2D atomic monolayers.

  6. Polydimethylsiloxane thin film characterization using all-optical photoacoustic mechanism.

    PubMed

    Zou, Xiaotian; Wu, Nan; Tian, Ye; Zhang, Yang; Wang, Xingwei

    2013-09-01

    This paper presents a nondestructive ultrasound testing method for characterization of the resonant frequencies of polydimethylsiloxane (PDMS) thin film by using a miniature fiber optic photoacoustic (PA) probe. The PA probe was fabricated with an optical fiber and a synthesized gold nanocomposite. During the experiment, a cured PDMS thin film with a thickness of 220 μm was immersed into a water medium using a custom-designed holder to clamp the film. An acoustic pulse was generated by the PA probe and propagated through the water media to excite the fixed film. A fiber optic pressure sensor based on the Fabry-Perot principle was used to collect the excited acoustic signals on the other side of the film. The acquired response of the acoustic pulse was used to compute the resonant frequencies of the PDMS thin film based on a deconvolution method.

  7. Assembly of luminescent ordered multilayer thin-films based on oppositely-charged MMT and magnetic NiFe-LDHs nanosheets with ultra-long lifetimes

    NASA Astrophysics Data System (ADS)

    Liu, Meitang; Wang, Tianlei; Ma, Hongwen; Fu, Yu; Hu, Kunran; Guan, Chao

    2014-11-01

    In this present report, luminescent ordered multilayer thin films (OMFs) based on oppositely-charged inorganic nanosheets and the different oppositely-charged chromophores were fabricated via layer-by-layer assembly method. Exfoliated layered double hydroxides (LDHs) and montmorillonite (MMT) nanosheets with opposite charges can be expected to provide a pseudo electronic microenvironment (PEM) which has not been declared in previous literatures, and transition metal-bearing LDHs nanosheets can offer an additional ferromagnetic effect (FME) for the chromophores at the same time. Surprisingly, the luminescent lifetimes of those OMFs with PEM and FME are significantly prolonged compared with that of the pristine chromophores, even much longer than those of OMFs without oppositely-charged and ferromagnetic architecture. Therefore, it is highly expected that the PEM and FME formed by oppositely-charged and transition metal-bearing inorganic nanosheets have remarkable influence on obtaining better optical property, which suggests a new potential way to manipulate, control and develop the novel light-emitting materials and optical devices.

  8. Assembly of luminescent ordered multilayer thin-films based on oppositely-charged MMT and magnetic NiFe-LDHs nanosheets with ultra-long lifetimes.

    PubMed

    Liu, Meitang; Wang, Tianlei; Ma, Hongwen; Fu, Yu; Hu, Kunran; Guan, Chao

    2014-11-21

    In this present report, luminescent ordered multilayer thin films (OMFs) based on oppositely-charged inorganic nanosheets and the different oppositely-charged chromophores were fabricated via layer-by-layer assembly method. Exfoliated layered double hydroxides (LDHs) and montmorillonite (MMT) nanosheets with opposite charges can be expected to provide a pseudo electronic microenvironment (PEM) which has not been declared in previous literatures, and transition metal-bearing LDHs nanosheets can offer an additional ferromagnetic effect (FME) for the chromophores at the same time. Surprisingly, the luminescent lifetimes of those OMFs with PEM and FME are significantly prolonged compared with that of the pristine chromophores, even much longer than those of OMFs without oppositely-charged and ferromagnetic architecture. Therefore, it is highly expected that the PEM and FME formed by oppositely-charged and transition metal-bearing inorganic nanosheets have remarkable influence on obtaining better optical property, which suggests a new potential way to manipulate, control and develop the novel light-emitting materials and optical devices.

  9. Composite surface-plasmon-polariton waves guided by a thin metal layer sandwiched between a homogeneous isotropic dielectric material and a periodically multilayered isotropic dielectric material

    NASA Astrophysics Data System (ADS)

    Chiadini, Francesco; Fiumara, Vincenzo; Scaglione, Antonio; Lakhtakia, Akhlesh

    2015-01-01

    Multiple p- and s-polarized compound surface-plasmon-polariton (SPP) waves at a fixed frequency can be guided by a structure consisting of a metal layer sandwiched between a homogeneous isotropic dielectric (HID) material and a periodic multilayered isotropic dielectric (PMLID) material. For any thickness of the metal layer, at least one compound SPP wave must exist. It possesses the p-polarization state, and is strongly bound to the metal/HID interface when the metal thickness is large but to both metal/dielectric interfaces when the metal thickness is small. When the metal layer vanishes, this compound SPP wave transmutes into a Tamm wave. Additional compound SPP waves exist, depending on the thickness of the metal layer, the relative permittivity of the HID material, and the period and composition of the PMLID material. Some of these are p-polarized, the others are s-polarized. All of them differ in phase speed, attenuation rate, and field profile, even though all are excitable at the same frequency. The multiplicity and dependence of the number of compound SPP waves on the relative permittivity of the HID material when the metal layer is thin could be useful for optical sensing applications and intrachip plasmonic optical communication.

  10. Thin Hydrogel Films for Optical Biosensor Applications

    PubMed Central

    Mateescu, Anca; Wang, Yi; Dostalek, Jakub; Jonas, Ulrich

    2012-01-01

    Hydrogel materials consisting of water-swollen polymer networks exhibit a large number of specific properties highly attractive for a variety of optical biosensor applications. This properties profile embraces the aqueous swelling medium as the basis of biocompatibility, non-fouling behavior, and being not cell toxic, while providing high optical quality and transparency. The present review focuses on some of the most interesting aspects of surface-attached hydrogel films as active binding matrices in optical biosensors based on surface plasmon resonance and optical waveguide mode spectroscopy. In particular, the chemical nature, specific properties, and applications of such hydrogel surface architectures for highly sensitive affinity biosensors based on evanescent wave optics are discussed. The specific class of responsive hydrogel systems, which can change their physical state in response to externally applied stimuli, have found large interest as sophisticated materials that provide a complex behavior to hydrogel-based sensing devices. PMID:24957962

  11. Ferroelectric properties of multi-layer LiTaO 3 thin films with Ta IIO 5 buffer

    NASA Astrophysics Data System (ADS)

    Zhang, De-Yin; Peng, Wei-Dong; Li, Jin-Hua; Li, Kun; Huang, Da-Gui

    2007-12-01

    The new sol-gel derived multi-layer LiTaO 3 thin films with Ta IIO 5 buffer layer were prepared on Pt/Ti/SiO2/Si substrate using lithium ethoxide and tantalum ethoxide as starting materials. The sol of Ta IIO 5 was firstly covered on the substrate by spin coating at 6500rpm for 50s and then a rapid annealing at 650°C for 2min to form an about 20nm thick Ta IIO 5 buffer layer. Multi-layer LiTaO 3 thin films were made over Ta IIO 5 buffer by repeated spin coating at 4000rpm for 30s and then a rapid annealing process at 700°C for 3min. The spectrum of XRD show the crystalline orientation of thin film type Ta IIO 5 is different compared to powder type Ta IIO 5. The SEM micrograph of the cross section shows the prepared sample is uniform, smooth and crack-free on the surface and the thickness of LiTaO 3 thin film is 0.341μm. The ferroelectric hysteresis loop and leakage current of the prepared sample have been measured using Al/LiTaO 3/Ta IIO 5/Pt structure electrode by a ferroelectric material analyzer PLC-100. The remanent polarization and coercive field of the prepared sample polarized at 13V were 3.4μC/cm2 and 185kV/cm respectively. The leakage current of the prepared sample was 2.66x10 -7A at 71.43kV/cm .Experimental results show the prepared sample of LiTaO 3 thin film with Ta IIO 5 buffer has good ferroelectric properties. Ta IIO 5 buffer introduction between LiTaO 3 thin film and Pt substrate can effectively decrease the leakage current and improve the properties of uncooled LiTaO 3 infrared device.

  12. Epitaxial growth and magnetic properties of ultraviolet transparent Ga2O3/(Ga1−xFex)2O3 multilayer thin films

    PubMed Central

    Guo, Daoyou; An, Yuehua; Cui, Wei; Zhi, Yusong; Zhao, Xiaolong; Lei, Ming; Li, Linghong; Li, Peigang; Wu, Zhenping; Tang, Weihua

    2016-01-01

    Multilayer thin films based on the ferromagnetic and ultraviolet transparent semiconductors may be interesting because their magnetic/electronic/photonic properties can be manipulated by the high energy photons. Herein, the Ga2O3/(Ga1−xFex)2O3 multilayer epitaxial thin films were obtained by alternating depositing of wide band gap Ga2O3 layer and Fe ultrathin layer due to inter diffusion between two layers at high temperature using the laser molecular beam epitaxy technique. The multilayer films exhibits a preferred growth orientation of crystal plane, and the crystal lattice expands as Fe replaces Ga site. Fe ions with a mixed valence of Fe2+ and Fe3+ are stratified distributed in the film and exhibit obvious agglomerated areas. The multilayer films only show a sharp absorption edge at about 250 nm, indicating a high transparency for ultraviolet light. What’s more, the Ga2O3/(Ga1−xFex)2O3 multilayer epitaxial thin films also exhibits room temperature ferromagnetism deriving from the Fe doping Ga2O3. PMID:27121446

  13. Epitaxial growth and magnetic properties of ultraviolet transparent Ga2O3/(Ga1-xFex)2O3 multilayer thin films

    NASA Astrophysics Data System (ADS)

    Guo, Daoyou; An, Yuehua; Cui, Wei; Zhi, Yusong; Zhao, Xiaolong; Lei, Ming; Li, Linghong; Li, Peigang; Wu, Zhenping; Tang, Weihua

    2016-04-01

    Multilayer thin films based on the ferromagnetic and ultraviolet transparent semiconductors may be interesting because their magnetic/electronic/photonic properties can be manipulated by the high energy photons. Herein, the Ga2O3/(Ga1-xFex)2O3 multilayer epitaxial thin films were obtained by alternating depositing of wide band gap Ga2O3 layer and Fe ultrathin layer due to inter diffusion between two layers at high temperature using the laser molecular beam epitaxy technique. The multilayer films exhibits a preferred growth orientation of crystal plane, and the crystal lattice expands as Fe replaces Ga site. Fe ions with a mixed valence of Fe2+ and Fe3+ are stratified distributed in the film and exhibit obvious agglomerated areas. The multilayer films only show a sharp absorption edge at about 250 nm, indicating a high transparency for ultraviolet light. What’s more, the Ga2O3/(Ga1-xFex)2O3 multilayer epitaxial thin films also exhibits room temperature ferromagnetism deriving from the Fe doping Ga2O3.

  14. Threshold response using modulated continuous wave illumination for multilayer 3D optical data storage

    NASA Astrophysics Data System (ADS)

    Saini, A.; Christenson, C. W.; Khattab, T. A.; Wang, R.; Twieg, R. J.; Singer, K. D.

    2017-01-01

    In order to achieve a high capacity 3D optical data storage medium, a nonlinear or threshold writing process is necessary to localize data in the axial dimension. To this end, commercial multilayer discs use thermal ablation of metal films or phase change materials to realize such a threshold process. This paper addresses a threshold writing mechanism relevant to recently reported fluorescence-based data storage in dye-doped co-extruded multilayer films. To gain understanding of the essential physics, single layer spun coat films were used so that the data is easily accessible by analytical techniques. Data were written by attenuating the fluorescence using nanosecond-range exposure times from a 488 nm continuous wave laser overlapping with the single photon absorption spectrum. The threshold writing process was studied over a range of exposure times and intensities, and with different fluorescent dyes. It was found that all of the dyes have a common temperature threshold where fluorescence begins to attenuate, and the physical nature of the thermal process was investigated.

  15. Amorphous Si waveguides with high-quality stacked gratings for multi-layer Si optical circuits

    NASA Astrophysics Data System (ADS)

    Tokushige, H.; Endo, T.; Saiki, K.; Hiidome, K.; Kitamura, S.; Katsuyama, T.; Tokuda, M.; Takagi, H.; Morita, M.; Ito, Y.; Tsutsui, K.; Wada, Y.; Ikeda, N.; Sugimoto, Y.

    2014-11-01

    To realize a stacked multi-layer silicon-based photonic device, a waveguide with a stacked grating was fabricated by using amorphous Si (a-Si) material, which is suitable for constructing layered structures. The fabrication method was based on forming a flat a-Si layer on a non-flat structure by using only spin-on-glass (SOG) coating technique. The a-Si grating was precisely constructed on the a-Si waveguide with gold alignment marks for electron beam lithography. Transmitted and reflected light power dependence on the grating period, wavelength, and polarization was systematically measured and compared with the designed dependence. As a result, the reflected light power exhibited a characteristic peak structure at a particular wavelength. Remarkable transverse electric/transverse magnetic (TE/TM) mode dependence was also observed. Furthermore, the measured and the designed properties were in excellent agreement with each other. Consequently, the designed structure was well reproduced in the actual stacked structure based on the a-Si material. These results pave the way for novel a-Si based integrated photonic devices such as polarization selectors and wavelength filters, indicating that a-Si is an excellent material for implementing Si-based multi-layer optical circuits.

  16. Tungsten-carbon multilayers for x-ray optics prepared by ArF excimer-laser-induced chemical vapor deposition

    SciTech Connect

    Mutoh, K.; Yamada, Y.; Iwabuchi, T.; Miyata, T. )

    1990-08-01

    The authors have studied the characteristics of tungsten (W) and carbon (C) thin films, and W/C multilayers prepared by ArF excimer-laser-induced chemical vapor deposition using tungsten hexafluoride and benzene gases. Amorphous W and C films with very smooth surfaces were obtained at substrate temperatures of 100--200 {degree}C and 100--300 {degree}C, respectively. In small-angle x-ray scattering measurements for the multilayers deposited at 200 {degree}C, a first order of multilayer reflections were clearly observed. Furthermore, Auger electron spectroscopy showed that W and C layers in the multilayers were periodically deposited.

  17. Tungsten-carbon multilayers for x-ray optics prepared by ArF excimer-laser-induced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Mutoh, Katsuhiko; Yamada, Yuka; Iwabuchi, Takashi; Miyata, Takeo

    1990-08-01

    The authors have studied the characteristics of tungsten (W) and carbon (C) thin films, and W/C multilayers prepared by ArF excimer-laser-induced chemical vapor deposition using tungsten hexafluoride and benzene gases. Amorphous W and C films with very smooth surfaces were obtained at substrate temperatures of 100-200 °C and 100-300 °C, respectively. In small-angle x-ray scattering measurements for the multilayers deposited at 200 °C, a first order of multilayer reflections were clearly observed. Furthermore, Auger electron spectroscopy showed that W and C layers in the multilayers were periodically deposited.

  18. ZrO2 Layer Thickness Dependent Electrical and Dielectric Properties of BST/ZrO2/BST Multilayer Thin Films

    SciTech Connect

    Sahoo, S. K.; Misra, D.; Agrawal, D. C.; Mohapatra, Y. N.

    2011-01-01

    Recently, high K materials play an important role in microelectronic devices such as capacitors, memory devices, and microwave devices. Now a days ferroelectric barium strontium titanate [Ba{sub x}Sr{sub 1-x}TiO{sub 3}, (BST)] thin film is being actively investigated for applications in dynamic random access memories (DRAM), field effect transistor (FET), and tunable devices because of its properties such as high dielectric constant, low leakage current, low dielectric loss, and high dielectric breakdown strength. Several approaches have been used to optimize the dielectric and electrical properties of BST thin films such as doping, graded compositions, and multilayer structures. We have found that inserting a ZrO{sub 2} layer in between two BST layers results in a significant reduction in dielectric constant, loss tangent, and leakage current in the multilayer thin films. Also it is shown that the properties of multilayer structure are found to depend strongly on the sublayer thicknesses. In this work the effect of ZrO{sub 2} layer thickness on the dielectric, ferroelectric as well as electrical properties of BST/ZrO{sub 2}/BST multilayer structure is studied. The multilayer Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3}/ZrO{sub 2}/Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} film is deposited by a sol-gel process on the platinized Si substrate. The thickness of the middle ZrO{sub 2} layer is varied while keeping the top and bottom BST layer thickness as fixed. It is observed that the dielectric constant, dielectric loss tangent, and leakage current of the multilayer films reduce with the increase of ZrO{sub 2} layer thickness and hence suitable for memory device applications. The ferroelectric properties of the multilayer film also decrease with the ZrO{sub 2} layer thickness.

  19. The investigation of thermal properties on multilayer Sb2Te3/Au thermoelectric material system with ultra-thin Au interlayers

    NASA Astrophysics Data System (ADS)

    Zhang, Haiming; Ye, Fengjie; Hu, Yangsen; Liu, Jun; Zhang, Yan; Wu, Yigui; Hu, Zhiyu

    2016-01-01

    The manipulation of heat transport across multilayer thin films with metal-semicounductor interfaces is of great interest for thermoelectric material optimization. Here we fabricated Sb2Te3/Au multilayer films with different Au thickness by magnetron sputtering. We demonstrated that the thermal conductivity of the system can be facilely manipulated by simply changing the Au layer thickness, where an optimal thickness (5 nm) value exists with the lowest thermal conductivity (˜0.44 Wm-1K-1, 44% of the pure Sb2Te3 thin film thermal conductivity). It has been proved that the decreased thermal conductivity was mainly attributed to the strong electron-phonon coupling in a metal-nonmetal multilayered system with Au layer thickness larger than 5 nm, where the Two Temperature Model (TTM) predicts the experimental data perfectly. It was also proposed that the grain boundary effect may dominiate the phonon scattering when the Au layer is in a discountinuous form (<5 nm).

  20. Diffusion barrier properties of single- and multilayered quasi-amorphous tantalum nitride thin films against copper penetration

    NASA Astrophysics Data System (ADS)

    Chen, G. S.; Chen, S. T.

    2000-06-01

    Tantalum-related thin films containing different amounts of nitrogen are sputter deposited at different argon-to-nitrogen flow rate ratios on (100) silicon substrates. Using x-ray diffractometry, transmission electron microscopy, composition and resistivity analyses, and bending-beam stress measurement technique, this work examines the impact of varying the nitrogen flow rate, particularly on the crystal structure, composition, resistivity, and residual intrinsic stress of the deposited Ta2N thin films. With an adequate amount of controlled, reactive nitrogen in the sputtering gas, thin films of the tantalum nitride of nominal formula Ta2N are predominantly amorphous and can exist over a range of nitrogen concentrations slightly deviated from stoichiometry. The single-layered quasi-amorphous Ta2N (a-Ta2N) thin films yield intrinsic compressive stresses in the range 3-5 GPa. In addition, the use of the 40-nm-thick a-Ta2N thin films with different nitrogen atomic concentrations (33% and 36%) and layering designs as diffusion barriers between silicon and copper are also evaluated. When subjected to high-temperature annealing, the single-layered a-Ta2N barrier layers degrade primarily by an amorphous-to-crystalline transition of the barrier layers. Crystallization of the single-layered stoichiometric a-Ta2N (Ta67N33) diffusion barriers occurs at temperatures as low as 450 °C. Doing so allows copper to preferentially penetrate through the grain boundaries or thermal-induced microcracks of the crystallized barriers and react with silicon, sequentially forming {111}-facetted pyramidal Cu3Si precipitates and TaSi2 Overdoping nitrogen into the amorphous matrix can dramatically increase the crystallization temperature to 600 °C. This temperature increase slows down the inward diffusion of copper and delays the formation of both silicides. The nitrogen overdoped Ta2N (Ta64N36) diffusion barriers can thus be significantly enhanced so as to yield a failure temperature 100

  1. Optical memory device structure using vertical interference from digital thin films

    NASA Astrophysics Data System (ADS)

    Chi, Robert Chih-Jen

    2001-10-01

    The objective of this dissertation research was to create a high-density optical memory device. From an engineering point of view, to create a promising durable optical memory device with high density requires a simple, efficient, effective storage method. This need led to the concept of creating a three-dimensional memory by storage of many bits data in a single physical location. Unlike conventional multi-layer 3D structure, this was accomplished in a single layer structure using a dielectric thin film. The resulting digital thin-film (DTF) structure was investigated in order to prove and demonstrate that the vertical interference properties of micro-scale Fabry-Perot filters array can be used as the basis for optical data storage cells. Optical memory devices are conventionally fabricated by laser beam processing. In this work, a Ga+ focused ion beam was used to ``write'' data on a SiO2 film grown on Si as proof of concept and demonstration of this DTF structure. The use of FIB milling has the advantage of creating smaller data storage elements and higher data density since the ion beam can be focused into a much smaller spot size than that of lasers. The FIB-written data creates a sub-micron structure with multiple bit capacity per physical location and can be read by far-field optical detection methods. A bit density of 5 Gbit in 2 which is roughly double the current storage density of a DVD has been obtained. The extended lifetime of data stored on a robust material such as SiO2/Si produces a data storage option with excellent survival under harsh environment such as high temperature, radiation, etc.

  2. Magnetization reversal and magnetic anisotropy in patterned Co/Pd multilayer thin films

    SciTech Connect

    Smith, Darren; Parekh, Vishal; E, Chunsheng; Litvinov, Dmitri; Zhang Shishan; Donner, Wolfgang; Lee, T. Randall; Khizroev, Sakhrat

    2008-01-15

    (Co/Pd){sub N} multilayers exhibit high vertical magnetic anisotropy and have been extensively explored as recording medium candidates for high density magnetic recording applications. In this work (Co/Pd){sub N} multilayers are deposited by magnetron sputtering and patterned into large periodic arrays of 200 nm islands to enable controlled domain wall injection for quantitative comparison of magnetic anisotropy energies. Magnetic properties are correlated with x-ray photoelectron spectroscopy data, an approach commonly used to probe the binding energies and valence band positions. Confirming theoretical predictions, it is demonstrated that the degree of d-shell hybridization at Co/Pd interfaces directly correlated with the magnitude of magnetic anisotropy.

  3. Microstructural and chemical characterization of the inconel/ti(n) thin film and multilayer system.

    PubMed

    Diehl, P E; Pew, H K; Madsen, D W; Leavitt, J A; Smith, D J

    1995-01-01

    Single layer and multilayer films of titanium and Inconel 600 (76 at.% Ni, 16 at.% Cr, 8 at.% Fe) have been prepared by sputtering in argon/nitrogen atmospheres, with nitrogen partial pressures ranging from 0% to 40%. The microstructure and chemistry of the sputtered films were characterized using transmission/high-resolution electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, electron probe microanalysis, and ion beam analysis with MeV helium beams. The microstructure depended on deposition power and individual layer thickness, as well as the sputtering atmosphere composition. Metal nitrides were formed in single layers of both materials whereas, for multilayers, nitrogen was preferentially incorporated into the titanium layer.

  4. Defect Interactions at Metal/Ceramic Interfaces in Thin Film Multilayers

    SciTech Connect

    Misra, Amit

    2012-06-14

    Summary of metal-ceramic multilayer deformation: (1) In nanolayered Al/TiN, Al layers grow in a twin orientation with the underlying TiN/Al layers favored by N-terminated TiN layers; (2) The shear strength of Al/TiN interface varies significantly depending on whether the interface is Ti or N terminated; (3) 2 nm Al - 2 TiN multilayers exhibit unusual mechanical properties as revealed by compression testing - (a) High maximum flow strength of 4.5 GPa, which is significantly higher than hardness (6 GPa) divided by a factor of 3, (b) Extraordinarily high strain hardening rates in Al nanolayers (16-35 GPa, {approx} E/2 to E/4), (c) Co-deformability of the TiN nanolayers with Al (confirmed by TEM on nanoindents) to plastic strains in excess of 5%.

  5. Grating-assisted vertical couplers for signal routing in multilayer integrated optical networks

    NASA Astrophysics Data System (ADS)

    Calò, Giovanna; Petruzzelli, Vincenzo

    2017-03-01

    Grating-assisted vertical couplers, which behave as add-drop filters, are proposed for wavelength routing of the signal among the different layers of on-chip multilayer optical networks. The device implements a 2×2 wavelength router which can be assembled into higher-order three-dimensional matrices. In particular, simple design criteria are found through a rapid and efficient optimization approach based on the mode analysis and demonstrated by the Finite Difference Time Domain (FDTD) simulations. The proposed numerical method is valid either for in-plane or for vertical grating-assisted couplers and it requires negligible computational effort. Different configurations of grating-assisted vertical couplers are designed and their spectral behavior is analyzed by the FDTD. The proposed devices achieve low values of the crosstalk between the different ports (below -20 dB) and of the input reflection (below -15 dB).

  6. Nonlocal optical effects on the Goos-Hänchen shifts at multilayered hyperbolic metamaterials

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Wei; Bian, Tingting; Chiang, Hai-Pang; Leung, P. T.

    2016-02-01

    The lateral beam shift of light incident on a multilayered hyperbolic metamaterial (HMM) is investigated using a theoretical model which emphasizes the nonlocal optical response of the indefinite material. By applying an effective local response theory formulated recently in the literature, it is found that nonlocal effects only affect p polarized light in this Goos-Hänchen (GH) shift of the incident beam; leading to a blue-shifted peak for positive shifts at high frequencies and red-shifted dip for negative shifts at low frequencies in the GH shift spectrum. An account for the observed phenomenon is given by referring to the ‘Brewster condition’ for the reflected wave from the HMM. This observation thus provides a relatively direct probe for the nonlocal response of the HMM.

  7. Nanocomposite thin films for optical temperature sensing

    DOEpatents

    Ohodnicki, Jr., Paul R.; Brown, Thomas D.; Buric, Michael P.; Matranga, Christopher

    2017-02-14

    The disclosure relates to an optical method for temperature sensing utilizing a temperature sensing material. In an embodiment the gas stream, liquid, or solid has a temperature greater than about 500.degree. C. The temperature sensing material is comprised of metallic nanoparticles dispersed in a dielectric matrix. The metallic nanoparticles have an electronic conductivity greater than approximately 10.sup.-1 S/cm at the temperature of the temperature sensing material. The dielectric matrix has an electronic conductivity at least two orders of magnitude less than the dispersed metallic nanoparticles at the temperature of the temperature sensing material. In some embodiments, the chemical composition of a gas stream or liquid is simultaneously monitored by optical signal shifts through multiple or broadband wavelength interrogation approaches. In some embodiments, the dielectric matrix provides additional functionality due to a temperature dependent band-edge, an optimized chemical sensing response, or an optimized refractive index of the temperature sensing material for integration with optical waveguides.

  8. Improving the surface structure of high quality Sr2FeMoO6 thin films for multilayer structures

    NASA Astrophysics Data System (ADS)

    Angervo, I.; Saloaro, M.; Tikkanen, J.; Huhtinen, H.; Paturi, P.

    2017-02-01

    Two sets of Sr2FeMoO6 thin films were prepared with pulsed laser deposition and the effect of the laser fluence and the deposition temperature was investigated. The Sr2FeMoO6 thin films showed clear evidence of impurity phases when the laser fluence was altered. Phase pure films resulted through the whole temperature range between 900 °C and 1050 °C when a proper laser fluence was used. Films fabricated at lower deposition temperatures resulted with smaller surface roughnesses around 5 nm, higher Curie temperatures and with relatively high saturation magnetization values. The Curie temperature was determined from the minimum of the first order derivative and results showed the highest values of 350 K and above. The films with the highest Curie temperature reached zero magnetization above 400 K. The results indicate that both high microstructural and high magnetic quality Sr2FeMoO6 thin films can be obtained with a deposition temperature between 900 °C and 950 °C. This provides better fabrication parameters for the upcoming SFMO multilayer structures.

  9. Characterization of r.f. sputtered thin Mo, W and Si films as precursors to multilayer X-ray mirrors

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, D.; Joseph, D.; Poswal, A. K.

    2006-08-01

    Single layers of Mo, W and Si thin films have been deposited by r.f. sputtering on float glass and c-Si substrates kept at room temperature. The films have been characterised by grazing incidence X-ray reflectometry (GIXR), X-ray transmission (XRT), Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM) and phase modulated spectroscopic ellipsometry (SE) studies. The thickness values obtained from the GIXR measurements have been used to calibrate the in situ thickness monitors. The surface roughness of the thin layers have also been determined from the GIXR measurements. The atomic mass density in the films have been obtained from the RBS measurements while X-ray absorption has been estimated from the XRT measurements. The surface morphology of the films has been investigated by the AFM micrographs. The Si thin films have also been characterized by the SE technique. The characterization of the samples by these complementary techniques have been very useful in optimizing the process parameters to obtain good quality layers as precursors to the fabrication of the multilayer X-ray mirrors based on Mo/Si and W/Si structures.

  10. Investigation of solar cell performance using multilayer thin film structure (SiO2/Si3N4) and grating

    NASA Astrophysics Data System (ADS)

    Dubey, R. S.; Jhansirani, K.; Singh, Shyam

    Thin film silicon solar cells are the better choice due to their low cost as compared to the crystalline solar cells. However, thin film silicon solar cells are suffering from a problem of weak absorption of incident light and hence, light trapping mechanism is essential for the harvesting of maximum solar radiation. In this paper, we present the performance of solar cell using an efficient back reflector composed of multilayer thin film (SiO2/Si3N4) and a diffraction grating. The use of a back reflector showed enhanced light absorption due to the folding of unabsorbed light coming to it after crossing the active region in a wide wavelength range. Further, the effect of active layer thickness and grating height were also discussed for the optimal performance of the solar cell. In the case of magnetic transverse mode, a relative enhancement in cell efficiency about 79 and 21% respectively have been observed with respect to a planar and SC4 solar cells.

  11. Tailoring the emissive properties of photocathodes through materials engineering: Ultra-thin multilayers

    NASA Astrophysics Data System (ADS)

    Velázquez, Daniel; Seibert, Rachel; Ganegoda, Hasitha; Olive, Daniel; Rice, Amy; Logan, Kevin; Yusof, Zikri; Spentzouris, Linda; Terry, Jeff

    2016-01-01

    We report on an experimental verification that emission properties of photocathodes can be manipulated through the engineering of the surface electronic structure. Ultrathin multilayered MgO/Ag(0 0 1)/MgO films were grown by pulsed laser deposition, tuning the thickness n of the flanking MgO layers to 0, 2, 3, and 4 monolayers. We observed an increase in quantum efficiency and simultaneous decrease in work function with layer thickness. The scale and trend direction of measurements are in good but not excellent agreement with theory. Angle resolved photoemission data for the multilayered sample n = 3 showed that the emission profile has a metallic-like momentum dispersion. Deviations from theoretical predictions [K. Németh et al., PRL 104, 046801 (2010)] are attributed to imperfections of real surfaces in contrast with the ideal surfaces of the calculation. Photoemissive properties of cathodes are critical for electron beam applications such as photoinjectors for Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). An ideal photoemitter has a high quantum efficiency, low work function, low intrinsic emittance and long lifetime. It has been demonstrated here that emission properties may be systematically tailored by control of layer thickness in ultrathin multilayered structures. The reproducibility of the emission parameters under specific growth conditions is excellent, even though the interfaces themselves have varying degrees of roughness.

  12. Effect of Al2O3 encapsulation on multilayer MoSe2 thin-film transistors

    NASA Astrophysics Data System (ADS)

    Lee, Hyun Ah; Yeoul Kim, Seong; Kim, Jiyoung; Choi, Woong

    2017-03-01

    We report the effect of Al2O3 encapsulation on the device performance of multilayer MoSe2 thin-film transistors based on statistical investigation of 29 devices with a SiO2 bottom-gate dielectric. On average, Al2O3 encapsulation by atomic layer deposition increased the field-effect mobility from 10.1 cm2 V‑1 s‑1 to 14.8 cm2 V‑1 s‑1, decreased the on/off-current ratio from 8.5  ×  105 to 2.3  ×  105 and negatively shifted the threshold voltage from  ‑1.1 V to  ‑8.1 V. Calculation based on the Y-function method indicated that the enhancement of intrinsic carrier mobility occurred independently of the reduction of contact resistance after Al2O3 encapsulation. Furthermore, contrary to previous reports in the literature, we observe a negligible effect of thermal annealing on contact resistance and carrier mobility during the atomic layer deposition of Al2O3. These results demonstrate that Al2O3 encapsulation is a useful method for improving the carrier mobility of multilayer MoSe2 transistors, providing important implications on the application of MoSe2 and other 2D materials into high-performance transistors.

  13. Enhanced carrier mobility of multilayer MoS2 thin-film transistors by Al2O3 encapsulation

    NASA Astrophysics Data System (ADS)

    Kim, Seong Yeoul; Park, Seonyoung; Choi, Woong

    2016-10-01

    We report the effect of Al2O3 encapsulation on the carrier mobility and contact resistance of multilayer MoS2 thin-film transistors by statistically investigating 70 devices with SiO2 bottom-gate dielectric. After Al2O3 encapsulation by atomic layer deposition, calculation based on Y-function method indicates that the enhancement of carrier mobility from 24.3 cm2 V-1 s-1 to 41.2 cm2 V-1 s-1 occurs independently from the reduction of contact resistance from 276 kΩ.μm to 118 kΩ.μm. Furthermore, contrary to the previous literature, we observe a negligible effect of thermal annealing on contact resistance and carrier mobility during the atomic layer deposition of Al2O3. These results demonstrate that Al2O3 encapsulation is a useful method of improving the carrier mobility of multilayer MoS2 transistors, providing important implications on the application of MoS2 and other two-dimensional materials into high-performance transistors.

  14. Structural and optical properties of nanoscale Galinobisuitite thin films.

    PubMed

    Abd-Elkader, Omar H; Deraz, N M

    2014-01-27

    Galinobisuitite thin films of (Bi2S3)(PbS) were prepared using the chemical bath deposition technique (CBD). Thin films were prepared by a modified chemical deposition process by allowing the triethanolamine (TEA) complex of Bi(3+) and Pb(2+) to react with S(2)- ions, which are released slowly by the dissociation of the thiourea (TU) solution. The films are polycrystalline and the average crystallite size is 35 nm. The composition of the films was measured using the atomic absorption spectroscopy (AAS) technique. The films are very adherent to the substrates. The crystal structure of Galinobisuitite thin films was calculated by using the X-ray diffraction (XRD) technique. The surface morphology and roughness of the films were studied using scanning electron microscopes (SEM), transmission electron microscopes (TEM) and stylus profilers respectively. The optical band gaps of the films were estimated from optical measurements.

  15. Structural and Optical Properties of Nanoscale Galinobisuitite Thin Films

    PubMed Central

    Abd-Elkader, Omar H.; Deraz, N. M.

    2014-01-01

    Galinobisuitite thin films of (Bi2S3)(PbS) were prepared using the chemical bath deposition technique (CBD). Thin films were prepared by a modified chemical deposition process by allowing the triethanolamine (TEA) complex of Bi3+ and Pb2+ to react with S2− ions, which are released slowly by the dissociation of the thiourea (TU) solution. The films are polycrystalline and the average crystallite size is 35 nm. The composition of the films was measured using the atomic absorption spectroscopy (AAS) technique. The films are very adherent to the substrates. The crystal structure of Galinobisuitite thin films was calculated by using the X-ray diffraction (XRD) technique. The surface morphology and roughness of the films were studied using scanning electron microscopes (SEM), transmission electron microscopes (TEM) and stylus profilers respectively. The optical band gaps of the films were estimated from optical measurements. PMID:24473136

  16. Maskless deposition technique for the physical vapor deposition of thin film and multilayer coatings with subnanometer precision and accuracy

    DOEpatents

    Vernon, Stephen P.; Ceglio, Natale M.

    2000-01-01

    The invention is a method for the production of axially symmetric, graded and ungraded thickness thin film and multilayer coatings that avoids the use of apertures or masks to tailor the deposition profile. A motional averaging scheme permits the deposition of uniform thickness coatings independent of the substrate radius. Coating uniformity results from an exact cancellation of substrate radius dependent terms, which occurs when the substrate moves at constant velocity. If the substrate is allowed to accelerate over the source, arbitrary coating profiles can be generated through appropriate selection and control of the substrate center of mass equation of motion. The radial symmetry of the coating profile is an artifact produced by orbiting the substrate about its center of mass; other distributions are obtained by selecting another rotation axis. Consequently there is a direct mapping between the coating thickness and substrate equation of motion which can be used to tailor the coating profile without the use of masks and apertures.

  17. Characterization of thin-film multilayers using magnetization curves and modeling of low-angle X-ray diffraction data

    SciTech Connect

    Lane, M.; Chaiken, A.; Michel, R.P.

    1994-12-01

    We have characterized thin-film multilayers grown by ion-beam sputtering using magnetization curves and modeling of low-angle x-ray diffraction data. In our films, we use ferromagnetic layer = Co, Fe, and NiFe and spacer layer = Si, Ge, FeSi{sub 2}, and CoSi{sub 2}. We have studied the effects of (1) deposition conditions; (2) thickness of layers; (3) different layer materials; and (4) annealing. We find higher magnetization in films grown at 1000V rather than 500V and in films with spacer layers of 50{angstrom} rather than 100{angstrom}. We find higher coercivity in films with cobalt grown on germanium rather than silicon, metal grown on gold underlayers rather than on glass substrates, and when using thinner spacer layers. Finally, modeling reveals that films grown with disilicide layers are more thermally stable than films grown with silicon spacer layers.

  18. Strain rate sensitivity and activation volume of Cu/Ni metallic multilayer thin films measured via micropillar compression

    NASA Astrophysics Data System (ADS)

    Carpenter, J. S.; Misra, A.; Uchic, M. D.; Anderson, P. M.

    2012-07-01

    Micropillar compression testing with repeated jumps in strain rate is used to circumvent inherent difficulties associated with nanoindentation and tensile testing of free-standing films. Application to sputtered 21 nm/21 nm Cu/Ni multilayer thin films with a cube-on-cube texture reveals an average strain rate sensitivity (m = 0.014) and activation volume (V = 17 b3), comparable to nanocrystalline face-centered cubic metals. Yet, m increases by ˜50% and V decreases by 70% with increasing strain, opposite to trends reported for nanotwinned Cu. The large, strain-dependent shifts in m and V are dependent on the underlying misfit dislocation structure of Cu/Ni interfaces.

  19. All-optical diode action in asymmetric nonlinear photonic multilayers with perfect transmission resonances

    SciTech Connect

    Zhukovsky, Sergei V.; Smirnov, Andrey G.

    2011-02-15

    Light propagation in asymmetric Kerr-nonlinear multilayers with perfect transmission resonances is theoretically investigated. It is found that hybrid Fabry-Perot-resonator-photonic-crystal structures of the type (BA){sup k}(AB){sup k}(AABB){sup m} exhibit both pronounced unidirectionality (due to strong spatial asymmetry of the resonant mode) and high transmission (due to the existence of a perfect transmission resonance). This results in nonlinear optical diode action with low reflection losses without need for a pumping beam or input pulse modulation. By slightly perturbing the perfect transmission resonance condition, the operating regime of the optical diode can be tuned, with a tradeoff between minimizing the reflection losses and maximizing the frequency bandwidth where unidirectional transmission exists. Optical diode action is demonstrated in direct numerical simulation, showing >92% transmittance in one direction and about 22% in the other. The effect of perfect transmission resonance restoration induced by nonlinearity was observed analytically and numerically. The proposed geometry is shown to have advantages over previously reported designs based on photonic quasicrystals.

  20. Optical theory of partially coherent thin-film energy-absorbing structures for power detectors and imaging arrays.

    PubMed

    Withington, Stafford; Thomas, Christopher N

    2009-06-01

    Free-space power detectors often have energy absorbing structures comprising multilayer systems of patterned thin films. We show that for any system of interacting resistive films, the expectation value of the absorbed power is given by the contraction of two tensor fields: one describes the spatial state of coherence of the incoming radiation, the other the state of coherence to which the detector is sensitive. Equivalently, the natural modes of the optical field scatter power into the natural modes of the detector. We describe a procedure for determining the amplitude, phase, and polarization patterns of a detector's optical modes and their relative responsivities. The procedure gives the state of coherence of the currents flowing in the system and leads to important conceptual insights into the way the pixels of an imaging array interact and extract information from an optical field.

  1. Oriented niobate ferroelectric thin films for electrical and optical devices

    DOEpatents

    Wessels, Bruce W.; Nystrom, Michael J.

    2001-01-01

    Sr.sub.x Ba.sub.1-x Nb.sub.2 O.sub.6, where x is greater than 0.25 and less than 0.75, and KNbO.sub.3 ferroelectric thin films metalorganic chemical vapor deposited on amorphous or cyrstalline substrate surfaces to provide a crystal axis of the film exhibiting a high dielectric susceptibility, electro-optic coefficient, and/or nonlinear optic coefficient oriented preferentially in a direction relative to a crystalline or amorphous substrate surface. Such films can be used in electronic, electro-optic, and frequency doubling components.

  2. System for measuring optical admittance of a thin film stack

    NASA Astrophysics Data System (ADS)

    Chen, Sheng-Hui; Wu, Kai; Kuo, Chien-Cheng; Ma, Sheng-Ju; Lee, Cheng-Chung

    2009-07-01

    A new method based on the polarization interferometer structure has been applied to measure the optical admittance, the refractive index and thickness of a thin film. The structure is a vibration insensitive optical system. There is one Twyman-Green interferometer part to induce a phase difference and one Fizeau interferometer part to induce the interference in the system. The intensities coming from four different polarizers were measured at the same time to prevent mechanical vibration influence. Using the polarization interferometer, the optical admittance, the refractive index and thickness of a single layer of Ta2O5 thin film has been measured. The measurement results were compared with the results obtained by ellipsometer. The results meet reasonable values in both refractive index and thickness.

  3. Morphological Evolution of Multilayer Ni/NiO Thin Film Electrodes during Lithiation

    SciTech Connect

    Evmenenko, Guennadi; Fister, Timothy T.; Buchholz, D. Bruce; Li, Qianqian; Chen, Kan-Sheng; Wu, Jinsong; Dravid, Vinayak P.; Hersam, Mark C.; Fenter, Paul; Bedzyk, Michael J.

    2016-08-10

    Oxide conversion reactions in lithium ion batteries are challenged by substantial irreversibility associated with significant volume change during the phase separation of an oxide into lithia and metal species (e.g., NiO + 2Li(+) + 2e(-) -> Ni + Li2O). We demonstrate that the confinement of nanometer-scale NiO layers within a Ni/NiO multilayer electrode can direct lithium transport and reactivity, leading to coherent expansion of the multilayer. The morphological changes accompanying lithiation were tracked in real-time by in-operando X-ray reflectivity (XRR) and ex situ cross-sectional transmission electron microscopy on well-defined periodic Ni/NiO multilayers grown by pulsed-laser deposition. Comparison of pristine and lithiated structures reveals that the nm-thick nickel layers help initiate the conversion process at the interface and then provide an architecture that confines the lithiation to the individual oxide layers. XRR data reveal that the lithiation process starts at the top and progressed through the electrode stack, layer by layer resulting in a purely vertical expansion. Longer term cycling showed significant reversible capacity (similar to 800 mA h g(-1) after similar to 100 cycles), which we attribute to a combination of the intrinsic bulk lithiation capacity of the NiO and additional interfacial lithiation capacity. These observations provide new insight into the role of metal/metal oxide interfaces in controlling lithium ion conversion reactions by defining the relationships between morphological changes and film architecture during reaction.

  4. Orientational tomography of optical axes directions distributions of multilayer biological tissues birefringent polycrystalline networks

    NASA Astrophysics Data System (ADS)

    Zabolotna, Natalia I.; Dovhaliuk, Rostyslav Y.

    2013-09-01

    We present a novel measurement method of optic axes orientation distribution which uses a relatively simple measurement setup. The principal difference of our method from other well-known methods lies in direct approach for measuring the orientation of optical axis of polycrystalline networks biological crystals. Our test polarimetry setup consists of HeNe laser, quarter wave plate, two linear polarizers and a CCD camera. We also propose a methodology for processing of measured optic axes orientation distribution which consists of evaluation of statistical, correlational and spectral moments. Such processing of obtained data can be used to classify particular tissue sample as "healthy" or "pathological". For our experiment we use thin layers of histological section of normal and muscular dystrophy tissue sections. It is shown that the difference between mentioned moments` values of normal and pathological samples can be quite noticeable with relative difference up to 6.26.

  5. Sputter deposition of ZnS:Mn/SrS:Ce multilayer stacks for use as white phosphor thin film electroluminscent panels

    SciTech Connect

    Ruffner, J.A.; Tuenge, R.T.; Sun, Sey-Shing

    1995-07-01

    Sputter deposition of ZnS:Mn/SrS:Ce multilayered broad-band ``white`` emission thin film electroluminescent (TFEL) stacks has been investigated. To date, deposition of these multilayers has been limited to vacuum evaporation techniques and atomic layer epitaxy, both of which require two different substrate temperatures for growth of high quality ZnS and SrS. This repeated thermal cycling during multilayer deposition can induce stress, defects, and interdiffusion with adversely affect EL performance. Sputter deposition of ZnS and SrS produces high quality TFELs for a wider range of substrate temperatures. Both materials can be sputter deposited at a common temperature (300-350{degrees}C) which eliminates the need for thermal cycling and increases manufacturability. Luminance outputs from sputter deposited ZnS and SrS thin films are comparable to those from evaporated films, making sputtering an attractive alternative deposition technique for these materials. We report on the effects of sputter deposition parameters including chamber pressure, substrate temperature, and H2S process gas partial pressure on the resultant composition and morphology of ZnS:Mn and SrS:Ce thin films and multilayers. Their EL performance was evaluated and correlated to composition and morphology.

  6. Spectroscopic ellipsometry investigations of the optical properties of manganese doped bismuth vanadate thin films

    SciTech Connect

    Kumari, Neelam; Krupanidhi, S.B.; Varma, K.B.R.

    2010-04-15

    The optical properties of Bi{sub 2}V{sub 1-x}Mn{sub x}O{sub 5.5-x} {l_brace}x = 0.05, 0.1, 0.15 and 0.2 at.%{r_brace} thin films fabricated by pulsed laser deposition on platinized silicon substrates were studied in UV-visible spectral region (1.51-4.17 eV) using spectroscopic ellipsometry. The optical constants and thicknesses of these films have been obtained by fitting the ellipsometric data ({Psi} and {Delta}) using a multilayer four-phase model system and a relaxed Lorentz oscillator dispersion relation. The surface roughness and film thickness obtained by spectroscopic ellipsometry were found to be consistent with the results obtained by atomic force and scanning electron microscopy. The refractive index measured at 650 nm does not show any marginal increase with Mn content. Further, the extinction coefficient does not show much decrease with increasing Mn content. An increase in optical band gap energy from 2.52 to 2.77 eV with increasing Mn content from x = 0.05 to 0.15 was attributed to the increase in oxygen ion vacancy disorder.

  7. Optical monitoring of thin oil film thickness in extrusion processes

    NASA Astrophysics Data System (ADS)

    Bogdanowicz, Robert; Wroczyński, Piotr; Graczyk, Jan; Gnyba, Marcin

    2005-09-01

    We have used reflectance spectroscopy for the in-situ, non-invasive monitoring of a thin oil film thickness during extrusion process of ceramic paste in capillary rheometer. Investigated pastes are disperse solid liquid systems prepared from the silicone oil AK106 (Wacker) and ceramic powder AlOOH. The thin oil film, extracted from the extruded paste, appears on walls of the rheometer die. A borosilicate view-port-glass provides optical access to the thin film inside the die. Reflectance spectroscopy enables the thin film thickness measurements by wideband spectral analysis of light back reflected from the sample. This spectrum includes extremes, which results from interference between beams reflected from glass-oil boundary and oil-paste boundary. Position and intensity of this extremes were determined by thickness of the thin film as well as refractive indices of the oil and the paste. Optoelectronic system dedicated for process monitoring by means of reflectance spectroscopy had been designed and built. The system comprises tungsten halogen lamp and fiber optic spectrometer. Optical signals are transmitted through bifurcated fibers, focusing optics and the view-port-window. Spectroscopic monitoring was carried out in VIS-NIR range from 400 to 900 nm as a function of extrusion velocity (0.01-5mm/s) and paste particle granulation (5-20 μm). Computer calculation, performed using dedicated software, enables fast determination of thickness even for reflectance spectra interfered by high noise level. Fast development of ceramic components technology requires detailed description of complex rheometric processes. Monitoring of the most important process parameter - oil layer thickness - enables pre-determination of rheometric factors required for proper paste extrusion and accurate shape filling.

  8. Optical properties of thin nanosilicon films

    NASA Astrophysics Data System (ADS)

    Buchenko, Viktor V.; Rodionova, Tatiana V.; Sutyagina, Anastasia S.; Goloborodko, Andrey A.; Multian, Volodymyr V.; Uklein, Andrii V.; Gayvoronsky, Volodymyr Ya.

    2016-12-01

    Present paper is devoted to the investigation of the nanosilicon films internal structure effect on optical properties. Atomic force microscopy results reveal that the films with different thickness have fundamentally different grain size distribution (samples with the film thickness less than 50 nm have single-mode grain size distribution, while samples with the film thickness more than 50 nm have multi-mode distribution of grain size). The correlation between grain size of nanosilicon films, photoluminescence and scattering indicatrix was shown. Well-isolated vibronic structures were observed on the ultraviolet-visible photoluminescence spectrum from nanosilicon films with the thickness more than 10 nm. The photoluminescence spectra in the red range correlate with the nanosilicon grain size distribution due to the effect of the quantum confinement. However, due to the complex shape of the grains mathematical modeling of photoluminescence spectrum is complicated. Both scattering indicatrix and photoluminescence reveal the multi-mode grain size distribution of the films with thickness more than 50 nm. The comparative analysis of theoretical results of optical radiation scattering by nanosilicon films with experimental ones is illustrated. Mathematical modeling of the scattering indicatrix shows the correlation of average grain size from scattering and photoluminescence data.

  9. Reflectivity quenching of ESR multilayer polymer film reflector in optically bonded scintillator arrays

    NASA Astrophysics Data System (ADS)

    Loignon-Houle, Francis; Pepin, Catherine M.; Charlebois, Serge A.; Lecomte, Roger

    2017-04-01

    The 3M-ESR multilayer polymer film is a widely used reflector in scintillation detector arrays. As specified in the datasheet and confirmed experimentally by measurements in air, it is highly reflective (> 98 %) over the entire visible spectrum (400-1000 nm) for all angles of incidence. Despite these outstanding characteristics, it was previously found that light crosstalk between pixels in a bonded LYSO scintillator array with ESR reflector can be as high as ∼30-35%. This unexplained light crosstalk motivated further investigation of ESR optical performance. Analytical simulation of a multilayer structure emulating the ESR reflector showed that the film becomes highly transparent to incident light at large angles when surrounded on both sides by materials of refractive index higher than air. Monte Carlo simulations indicate that a considerable fraction (∼25-35%) of scintillation photons are incident at these leaking angles in high aspect ratio LYSO scintillation crystals. The film transparency was investigated experimentally by measuring the scintillation light transmission through the ESR film sandwiched between a scintillation crystal and a photodetector with or without layers of silicone grease. Strong light leakage, up to nearly 30%, was measured through the reflector when coated on both sides with silicone, thus elucidating the major cause of light crosstalk in bonded arrays. The reflector transparency was confirmed experimentally for angles of incidence larger than 60 ° using a custom designed setup allowing illumination of the bonded ESR film at selected grazing angles. The unsuspected ESR film transparency can be beneficial for detector arrays exploiting light sharing schemes, but it is highly detrimental for scintillator arrays designed for individual pixel readout.

  10. Possibilities Of Optically Non Linear Thin Films

    NASA Astrophysics Data System (ADS)

    De Micheli, Marc; Zyss, Joseph; Azema, Alain

    1983-11-01

    Efficient integrated frequency doubling devices transparent in the visible and near I.R. are demanded by a number of applications. The optimization of both wave interaction configurations and material intrinsic nonlinear susceptibility are successively discussed within this scope. Basic features such as power confinement, interaction length dependence, phase matching techniques, underlying the second harmonic generation conversion rate in bulk and waveguided structures are compared. Undoped Ga As film epitaxied over n+ doped Ga As substrate and TIPE Lithium Lobate waveguides exemplify the possibilities of non linear thin films. The higher non linear susceptibility of certain organic molecular single crys-tals should help raise the efficiency of doubling devices. We report the definition and bulk performances of two non linear organic crystals, namely POM (3-methyl-4 nitropyridine-1-oxyde) and MAP (methyl-(2,4-dinitropheny1)-aminopropanoate) with a figure of merit up to one order of magnitude above that of Li Nb 03. The combination of organic materials and waveguided configuration should lead to a new generation of non linear devices.

  11. Molecular dynamics simulation of nano-indentation on Ti-V multilayered thin films

    NASA Astrophysics Data System (ADS)

    Feng, Chao; Peng, Xianghe; Fu, Tao; Zhao, Yinbo; Huang, Cheng; Wang, Zhongchang

    2017-03-01

    We developed a second nearest-neighbor modified embedded-atom method potential for binary Ti-V system. The potential parameters were identified by fitting the lattice parameter, cohesive energy and elastic constants of CsCl-type TiV, and further validated by reproducing the fundamental physical and mechanical properties of Ti-V systems with other crystal structures. In addition, we also performed molecular dynamics simulations of nano-indentation processes of pure Ti film, pure V film, and two kinds of four-layer Ti-V films, V-Ti-V-Ti and Ti-V-Ti-V. We found that the indentation force-depth curve for the pure V film turns flat at an indentation depth of 2.8 nm, where a prismatic loop was observed. Such prismatic loop is not found in the V/Ti/V/Ti multilayer because the thickness of each layer is insufficient for the formation of such prismatic loops, which accounts for the increase of stress in the multilayer.

  12. Fast Industrial Inspection of Optical Thin Film Using Optical Coherence Tomography

    PubMed Central

    Shirazi, Muhammad Faizan; Park, Kibeom; Wijesinghe, Ruchire Eranga; Jeong, Hyosang; Han, Sangyeob; Kim, Pilun; Jeon, Mansik; Kim, Jeehyun

    2016-01-01

    An application of spectral domain optical coherence tomography (SD-OCT) was demonstrated for a fast industrial inspection of an optical thin film panel. An optical thin film sample similar to a liquid crystal display (LCD) panel was examined. Two identical SD-OCT systems were utilized for parallel scanning of a complete sample in half time. Dual OCT inspection heads were utilized for transverse (fast) scanning, while a stable linear motorized translational stage was used for lateral (slow) scanning. The cross-sectional and volumetric images of an optical thin film sample were acquired to detect the defects in glass and other layers that are difficult to observe using visual inspection methods. The rapid inspection enabled by this setup led to the early detection of product defects on the manufacturing line, resulting in a significant improvement in the quality assurance of industrial products. PMID:27690043

  13. Fast Industrial Inspection of Optical Thin Film Using Optical Coherence Tomography.

    PubMed

    Shirazi, Muhammad Faizan; Park, Kibeom; Wijesinghe, Ruchire Eranga; Jeong, Hyosang; Han, Sangyeob; Kim, Pilun; Jeon, Mansik; Kim, Jeehyun

    2016-09-28

    An application of spectral domain optical coherence tomography (SD-OCT) was demonstrated for a fast industrial inspection of an optical thin film panel. An optical thin film sample similar to a liquid crystal display (LCD) panel was examined. Two identical SD-OCT systems were utilized for parallel scanning of a complete sample in half time. Dual OCT inspection heads were utilized for transverse (fast) scanning, while a stable linear motorized translational stage was used for lateral (slow) scanning. The cross-sectional and volumetric images of an optical thin film sample were acquired to detect the defects in glass and other layers that are difficult to observe using visual inspection methods. The rapid inspection enabled by this setup led to the early detection of product defects on the manufacturing line, resulting in a significant improvement in the quality assurance of industrial products.

  14. Magneto-Optical Study of Lithographically Patterned Ferromagnetic Multilayer (Co/Pt)8 Micro-Channels

    NASA Astrophysics Data System (ADS)

    Bowers, Alexis; Samarth, Nitin; Kempinger, Susan; Fraleigh, Robert

    Controlled domain movement in magnetic structures has become promising for applications in magnetic memory systems and data processing. This study examines magnetic domain nucleation and propagation within a series of lithographically patterned Co/Pt micro-channels with perpendicular magnetic anisotropy (PMA). Magnetic domains are nucleated and then manipulated using out-of-plane sweep protocols and studied in situ using magneto-optical Kerr effect (MOKE) imaging. Co/Pt multilayers were fabricated with optical lithography and sputter deposition. Effects of channel width and annealing are presented. Annealing the Co/Pt after fabrication as a function of time and temperature resulted in increasing the coercivity of the unpatterned film, decreasing the coercivity of the micro-channels, and reducing the average domain size in both. Atomic force microscopy (AFM) characterization of the micro-channels showed non-uniform deposition near feature edges. MOKE imaging demonstrated that the feature edges had a much lower coercivity (70G) than the middle of the channel/pad (150G) or the unpatterned film (250G). We found that an oscillating field protocol to re-initialize soft domains near feature edges proved to be more effective than a traditional field sweep to initialize a domain wall in the channel. Once a domain wall was formed, we explored a combination of constant and pulsed field protocols to manipulate the domain wall. 2015 Penn State REU in Interdisciplinary Materials and Physics.

  15. Substrate material selection method for multilayer diffractive optics in a wide environmental temperature range.

    PubMed

    Piao, Mingxu; Cui, Qingfeng; Zhao, Chunzhu; Zhang, Bo; Mao, Shan; Zhao, Yuanming; Zhao, Lidong

    2017-04-01

    We present a substrate material selection method for multilayer diffractive optical elements (MLDOEs) to obtain high polychromatic integral diffraction efficiency (PIDE) in a wide environmental temperature range. The extended expressions of the surface relief heights for the MLDOEs are deduced with consideration of the influence of the environmental temperature. The PIDE difference Δη¯(λ) and PIDE change factor F are introduced to select a reasonable substrate material combination. A smaller value of Δη¯(λ) or F indicates a smaller decrease of the PIDE in a wide temperature range, and the corresponding substrate material combination is better. According to the deduced relation, double-layer and three-layer DOEs with different combinations are discussed. The results show that IRG26 and zinc sulfide is the best substrate material combination in the infrared waveband for double-layer DOEs, and polycarbonate is more reasonable than polymethyl methacrylate as the middle filling optical material for three-layer DOEs when the two substrate materials are the same.

  16. Optical properties of vanadium dioxide and vanadium pentoxide thin films.

    PubMed

    Chain, E E

    1991-07-01

    Several oxides of vanadium undergo a transition from a semiconductor or insulating state to a metal phase at a critical temperature. Vanadium dioxide undergoes this transition near 68 degrees C, while V(2)O(5) undergoes a similar phase transition near 257 degrees C. During the transition a change in oxide crystal structure is accompanied by large changes in electrical and optical behavior. Thin films of vanadium oxides are capable of reversibly switching from the semiconductor to the metallic state at high speeds and with high spatial resolution. Therefore, these oxides have potential use, particularly in thin film form, for a wide variety of applications involving thermally activated electronic or optical switching devices. Such films are of considerable technical interest because of applications in chemical sensors, energy-conserving coatings, transparent conductors, and switching materials. The numerous potential electronic, optical, and optoelectronic device applications which have been suggested have stimulated work on the preparation of thin films by a variety of techniques, including chemical vapor deposition, solgel, evaporation, and sputter deposition. This paper reviews the optical properties of vanadium oxide coatings and stresses the dependence of film properties on sample preparation and resultant film microstructure.

  17. Nanostructured multilayer thin films of multiwalled carbon nanotubes/gold nanoparticles/glutathione for the electrochemical detection of dopamine

    NASA Astrophysics Data System (ADS)

    Detsri, Ekarat; Rujipornsakul, Sirilak; Treetasayoot, Tanapong; Siriwattanamethanon, Pawarit

    2016-10-01

    In the present study, multiwalled carbon nanotubes (MWCNTs), gold nanoparticles (AuNPs), and glutathione (GSH) were used to fabricate multilayer nanoscale thin films. The composite thin films were fabricated by layer-by-layer technique as the films were constructed by the alternate deposition of cationic and anionic polyelectrolytes. The MWCNTs were modified via a noncovalent surface modification method using poly(diallydimethylammonium chloride) to form a cationic polyelectrolyte. An anionic polyelectrolyte was prepared by the chemical reduction of HAuCl4 using sodium citrate as both the stabilizing and reducing agent to form anionic AuNPs. GSH was used as an electrocatalyst toward the electro-oxidation of dopamine. The constructed composite electrode exhibits excellent electrocatalytic activity toward dopamine with a short response time and a wide linear range from 1 to 100 μmol/L. The limits of detection and quantitation of dopamine are (0.316 ± 0.081) μmol/L and (1.054 ± 0.081) μmol/L, respectively. The method is satisfactorily applied for the determination of dopamine in plasma and urine samples to obtain the recovery in the range from 97.90% to 105.00%.

  18. Optical limiting effects in nanostructured silicon carbide thin films

    SciTech Connect

    Borshch, A A; Starkov, V N; Volkov, V I; Rudenko, V I; Boyarchuk, A Yu; Semenov, A V

    2013-12-31

    We present the results of experiments on the interaction of nanosecond laser radiation at 532 and 1064 nm with nanostructured silicon carbide thin films of different polytypes. We have found the effect of optical intensity limiting at both wavelengths. The intensity of optical limiting at λ = 532 nm (I{sub cl} ∼ 10{sup 6} W cm{sup -2}) is shown to be an order of magnitude less than that at λ = 1064 nm (I{sub cl} ∼ 10{sup 7} W cm{sup -2}). We discuss the nature of the nonlinearity, leading to the optical limiting effect. We have proposed a method for determining the amount of linear and two-photon absorption in material media. (nonlinear optical phenomena)

  19. Thin Film Metal Coated Fiber Optic Hydrophone Probe

    PubMed Central

    Gopinath, R.; Arora, P.; Gandhi, G.; Daryoush, A.S.; El-Sherif, M.; Lewin, P.A.

    2010-01-01

    The purpose of this work was to improve on sensitivity performance of fiber sensor employed as Fiber Optic Hydrophone Probe (FOHP) by nano-scale thin film gold coating. The fiber is designed to provide a uniform and spatial averaging free response up to 100 MHz by etching down to an active diameter of about 9 μm. The sensitivity performance of straight cleaved (i.e. full size core and cladding) uncoated, tapered uncoated and tapered thin film gold coated fiber sensors were compared in the frequency range of 1.5 MHz to 20 MHz in the presence of acoustic pressure amplitude levels of up to 6 MPa. An unprecedented voltage sensitivity of −245 dB re 1V/uPa (560 mV/ MPa) was measured for thin film gold coated FOHP by optimizing the gold coating thickness. PMID:19881652

  20. Synthesis and Evaluation of Single Layer, Bilayer, and Multilayer Thermoelectric Thin Films

    DOE R&D Accomplishments Database

    Farmer, J. C.; Barbee, T. W. Jr.; Chapline, G. C. Jr.; Olsen, M. L.; Foreman, R. J.; Summers, L. J.; Dresselhaus, M. S.; Hicks, L. D.

    1995-01-20

    The relative efficiency of a thermoelectric material is measured in terms of a dimensionless figure of merit, ZT. Though all known thermoelectric materials are believed to have ZT{le}1, recent theoretical results predict that thermoelectric devices fabricated as two-dimensional quantum wells (2D QWs) or one-dimensional (ID) quantum wires could have ZT{ge}3. Multilayers with the dimensions of 2D QWs have been synthesized by alternately sputtering thermoelectric and barrier materials onto a moving single-crystal sapphire substrate from dual magnetrons. These materials have been used to test the thermoelectric quantum well concept and gain insight into relevant transport mechanisms. If successful, research could lead to thermoelectric devices that have efficiencies close to that of an ideal Carnot engine. Ultimately, such devices could be used to replace conventional heat engines and mechanical refrigeration systems.

  1. Electroluminescent behaviors in multilayer thin-film electroluminescent devices using 9,10-bisstyrylanthracene derivatives

    NASA Astrophysics Data System (ADS)

    Aminaka, Ei-Ichiro; Tsutsui, Tetsuo; Saito, Shogo

    1994-02-01

    Using nine 9,10-bisstyrylanthracene derivatives (BSA's) with different substituents as emission layer materials, multilayer electroluminescent (EL) devices were fabricated. Among nine BSA's, three BSA's were found to exhibit high EL performance. Four types of devices, a single-layer device with a BSA emission layer, two types of two-layer devices in which BSA emission layers were combined with a triphenylamine dimer as a hole transport layer or an oxadiazole derivative as an electron transport layer, and a three-layer device, were fabricated using the three BSA's. The relationships between the device structures and EL performances of these devices were studied. Ionization potential values in vacuum-deposited films of BSA's were measured. It was found that the introduction of an electron withdrawing group increased electron injection/transport capability, and that of electron donating groups increased hole injection/transport capability. The relative EL efficiencies of various devices were discussed in terms of the electronic nature of BSA's.

  2. Synthesis and evaluation of single layer, bilayer, and multilayer thermoelectric thin films

    SciTech Connect

    Farmer, J.C.; Barbee, T.W. Jr.; Chapline, G.C. Jr.; Olsen, M.L.; Foreman, R.J.; Summers, L.J.; Dresselhaus, M.S.; Hicks, L.D.

    1995-01-20

    The relative efficiency of a thermoelectric material is measured in terms of a dimensionless figure of merit, ZT. Though all known thermoelectric materials are believed to have ZT{le}1, recent theoretical results predict that thermoelectric devices fabricated as two-dimensional quantum wells (2D QWs) or one-dimensional (ID) quantum wires could have ZT{ge}3. Multilayers with the dimensions of 2D QWs have been synthesized by alternately sputtering thermoelectric and barrier materials onto a moving single-crystal sapphire substrate from dual magnetrons. These materials have been used to test the thermoelectric quantum well concept and gain insight into relevant transport mechanisms. If successful, research could lead to thermoelectric devices that have efficiencies close to that of an ideal Carnot engine. Ultimately, such devices could be used to replace conventional heat engines and mechanical refrigeration systems.

  3. Damage mechanisms of MoN/SiN multilayer optics for next-generation pulsed XUV light sources.

    PubMed

    Sobierajski, R; Bruijn, S; Khorsand, A R; Louis, E; van de Kruijs, R W E; Burian, T; Chalupsky, J; Cihelka, J; Gleeson, A; Grzonka, J; Gullikson, E M; Hajkova, V; Hau-Riege, S; Juha, L; Jurek, M; Klinger, D; Krzywinski, J; London, R; Pelka, J B; Płociński, T; Rasiński, M; Tiedtke, K; Toleikis, S; Vysin, L; Wabnitz, H; Bijkerk, F

    2011-01-03

    We investigated the damage mechanism of MoN/SiN multilayer XUV optics under two extreme conditions: thermal annealing and irradiation with single shot intense XUV pulses from the free-electron laser facility in Hamburg - FLASH. The damage was studied "post-mortem" by means of X-ray diffraction, interference-polarizing optical microscopy, atomic force microscopy, and scanning transmission electron microscopy. Although the timescale of the damage processes and the damage threshold temperatures were different (in the case of annealing it was the dissociation temperature of Mo2N and in the case of XUV irradiation it was the melting temperature of MoN) the main damage mechanism is very similar: molecular dissociation and the formation of N2, leading to bubbles inside the multilayer structure.

  4. Retrieval of Aerosol Optical Properties under Thin Cirrus from MODIS

    NASA Technical Reports Server (NTRS)

    Lee, Jaehwa; Hsu, Nai-Yung Christina; Bettenhausen, Corey; Sayer, Andrew Mark.

    2014-01-01

    Retrieval of aerosol optical properties using shortwave bands from passive satellite sensors, such as MODIS, is typically limited to cloud-free areas. However, if the clouds are thin enough (i.e. thin cirrus) such that the satellite-observed reflectance contains signals under the cirrus layer, and if the optical properties of this cirrus layer are known, the TOA reflectance can be corrected for the cirrus layer to be used for retrieving aerosol optical properties. To this end, we first correct the TOA reflectances in the aerosol bands (0.47, 0.55, 0.65, 0.86, 1.24, 1.63, and 2.12 micron for ocean algorithm and 0.412, 0.47, and 0.65 micron for deep blue algorithm) for the effects of thin cirrus using 1.38 micron reflectance and conversion factors that convert cirrus reflectance in 1.38 micron band to those in aerosol bands. It was found that the conversion factors can be calculated by using relationships between reflectances in 1.38 micron band and minimum reflectances in the aerosol bands (Gao et al., 2002). Refer to the example in the figure. Then, the cirrus-corrected reflectance can be calculated by subtracting the cirrus reflectance from the TOA reflectance in the optically thin case. A sensitivity study suggested that cloudy-sky TOA reflectances can be calculated with small errors in the form of simple linear addition of cirrus-only reflectances and clear-sky reflectances. In this study, we correct the cirrus signals up to TOA reflectance at 1.38 micron of 0.05 where the simple linear addition is valid without extensive radiative transfer simulations. When each scene passes the set of tests shown in the flowchart, the scene is corrected for cirrus contamination and passed into aerosol retrieval algorithms.

  5. Optically Thin Liquid Water Clouds: Their Importance and Our Challenge

    NASA Technical Reports Server (NTRS)

    Turner, D. D.; Vogelmann, A. M.; Austin, R. T.; Barnard, J. C.; Cady-Pereira, K.; Chiu, J. C.; Clough, S. A.; Flynn, C.; Khaiyer, M. M.; Liljegren, J.; Johnson, K.; Lin, B.; Long, C.; Marshak, A.; Matrosov, S. Y.; McFarlane, S. A.; Miller, M.; Min, Q.; Minnis, P.; O'Hirok, W.; Wang, Z.; Wiscombe, W.

    2006-01-01

    Many of the clouds important to the Earth's energy balance, from the tropics to the Arctic, are optically thin and contain liquid water. Longwave and shortwave radiative fluxes are very sensitive to small perturbations of the cloud liquid water path (LWP) when the liquid water path is small (i.e., < g/sq m) and, thus, the radiative properties of these clouds must be well understood to capture them correctly in climate models. We review the importance of these thin clouds to the Earth's energy balance, and explain the difficulties in observing them. In particular, because these clouds are optically thin, potentially mixed-phase, and often (i.e., have large 3-D variability), it is challenging to retrieve their microphysical properties accurately. We describe a retrieval algorithm intercomparison that was conducted to evaluate the issues involved. The intercomparison included eighteen different algorithms to evaluate their retrieved LWP, optical depth, and effective radii. Surprisingly, evaluation of the simplest case, a single-layer overcast cloud, revealed that huge discrepancies exist among the various techniques, even among different algorithms that are in the same general classification. This suggests that, despite considerable advances that have occurred in the field, much more work must be done, and we discuss potential avenues for future work.

  6. Multilayer silver nanoparticles embedded in graded-index dielectric layers

    NASA Astrophysics Data System (ADS)

    Shokeen, Poonam; Jain, Amit; Gupta, Vinay; Kapoor, Avinashi

    2017-04-01

    A pulsed laser deposited SiO2/Ag/ZnO/Ag/TiO2 multilayer structure is studied to enhance the light trapping capability of thin-film solar cell. Structural and optical properties of structure are studied with scanning electron microscopy, x-ray diffraction, photoluminescence and UV-visible spectroscopy. Proposed geometry improves the extinction spectra and quenches photoluminescence in comparison to TiO2/Ag and SiO2/Ag/ZnO geometry. Finite-difference time-domain (FDTD) simulations indicate a promising effect of the proposed geometries on thin-film solar cells. Twofold enhancement in total quantum efficiency of an optimized multilayer plasmonic graded-index thin-film solar cell is observed in comparison to the pristine solar cell. Results suggest a more concerted study of multilayer plasmonic nanostructures with graded-index anti-reflection coatings to improve the performance of thin-film photovoltaic devices.

  7. Efficient multi-keV x-ray source generated by nanosecond laser pulse irradiated multi-layer thin foils target

    SciTech Connect

    Tu, Shao-yong; Hu, Guang-yue Zhao, Bin; Zheng, Jian; Miao, Wen-yong; Yuan, Yong-teng; Zhan, Xia-yu; Hou, Li-fei; Jiang, Shao-en; Ding, Yong-kun

    2014-04-15

    A new target configuration is proposed to generate efficient multi-keV x-ray source using multiple thin foils as x-ray emitters. The target was constructed with several layers of thin foils, which were placed with a specific, optimized spacing. The thin foils are burned though one by one by a nanosecond-long laser pulse, which produced a very large, hot, underdense plasma. One-dimensional radiation hydrodynamic simulations show that the emission region and the multi-keV x-ray flux generated by multi-layer thin foil target are similar to that of the low-density gas or foam target, which is currently a bright multi-keV x-ray source generated by laser heating. Detailed analysis of a range of foil thicknesses showed that a layer-thickness of 0.1 μm is thin enough to generate an efficient multi-keV x-ray source. Additionally, this type of target can be easily manufactured, compared with the complex techniques for fabrication of low-density foam targets. Our preliminary experimental results also verified that the size of multi-keV x-ray emission region could be enhanced significantly by using a multi-layer Ti thin foil target.

  8. Maximized reliability with minimal cross-layer cutset under arbitrary link failure probability in multilayer optical networks

    NASA Astrophysics Data System (ADS)

    Zhao, Yongli; Chen, Bowen; Zhang, Jie

    2016-09-01

    We investigate the maximized cross-layer reliability under arbitrary link failure probability in multilayer optical networks. A concept of minimal cross-layer cutset is first defined and a reliability model with arbitrary physical link failure probability is built in the multilayer optical networks. In order to reduce the scale of cutset enumeration, we introduce two metrics to estimate cross-layer reliability, i.e., the minimum cross-layer node reliability and the minimum cross-layer edge reliability (MCER). Furthermore, we develop two linear programming (LP) models and two heuristic algorithms to maximize the cross-layer reliability of multilayer optical networks, i.e., the minimum shared-risk mapping algorithm and the least shared failure probability algorithm. Simulation results show that: (i) the cross-layer reliability of the two proposed algorithms is close to the LP solutions under logical networks with different sizes, which achieves better results in terms of additional resources utilization compared with the shortest path algorithm; (ii) less difference between the results of our proposed algorithms and the results of the shortest path algorithm is accompanied by a small standard deviation of failure probability distribution. Moreover, the superiority of our proposed algorithms becomes more remarkable with the increasing of the standard deviation.

  9. Wideband dynamic behavioral modeling of reflective semiconductor optical amplifiers using a tapped-delay multilayer perceptron.

    PubMed

    Liu, Zhansheng; Violas, Manuel Alberto; Carvalho, Nuno Borges

    2013-02-11

    In this paper, we propose a wideband dynamic behavioral model for a bulk reflective semiconductor optical amplifier (RSOA) used as a modulator in colorless radio over fiber (RoF) systems using a tapped-delay multilayer perceptron (TDMLP). 64 quadrature amplitude modulation (QAM) signals with 20 Msymbol/s were used to train, validate and test the model. Nonlinear distortion and dynamic effects induced by the RSOA modulator are demonstrated. The parameters of the model such as the number of nodes in the hidden layer and memory depth were optimized to ensure the generality and accuracy. The normalized mean square error (NMSE) is used as a figure of merit. The NMSE was up to -44.33 dB when the number of nodes in the hidden layer and memory depth were set to 20 and 3, respectively. The TDMLP model can accurately approximate to the dynamic characteristics of the RSOA modulator. The dynamic AM-AM and dynamic AM-PM distortions of the RSOA modulator are drawn. The results show that the single hidden layer TDMLP can provide accurate approximation for behaviors of the RSOA modulator.

  10. Development of x-ray multilayer telescope optics for XTP mission

    NASA Astrophysics Data System (ADS)

    Shen, Zhengxiang; Wang, Xiaoqiang; Wang, Kun; Ma, Bin; Huang, Qiushi; Zhang, Zhong; Wang, Haifeng; Dai, Ying; He, Pengfei; Wang, Zhanshan

    2016-07-01

    The X-ray Timing and Polarization (XTP) satellite is dedicated to study black hole, neutron star and magnetar and then get more information in the physics under extreme gravity, density and magnetism. With an effective area of about 1 square meter and angular resolution of 1 arcminute, XTP is expected to make the most sensitive temporal and polarization observations with good energy resolution in 1-30 keV. Large collecting areas are obtained by tightly nesting layers of grazing incidence mirrors in a conical approximation Wolter-I design. The segmented mirrors that form these layers are formed by thermally slumping glass substrates coated with depth-graded W/Si multilayers for enhanced reflectivity in higher energy region. In order to force the overall shape of the nominally cylindrical substrates to the appropriate conic form, an over-constraint method was used to assemble the mirrors to a telescope. We will present performance on the XTP optics and report the current status of the telescope.

  11. Automated multilayer segmentation and characterization in 3D spectral-domain optical coherence tomography images

    NASA Astrophysics Data System (ADS)

    Hu, Zhihong; Wu, Xiaodong; Hariri, Amirhossein; Sadda, SriniVas R.

    2013-03-01

    Spectral-domain optical coherence tomography (SD-OCT) is a 3-D imaging technique, allowing direct visualization of retinal morphology and architecture. The various layers of the retina may be affected differentially by various diseases. In this study, an automated graph-based multilayer approach was developed to sequentially segment eleven retinal surfaces including the inner retinal bands to the outer retinal bands in normal SD-OCT volume scans at three different stages. For stage 1, the four most detectable and/or distinct surfaces were identified in the four-times-downsampled images and were used as a priori positional information to limit the graph search for other surfaces at stage 2. Eleven surfaces were then detected in the two-times-downsampled images at stage 2, and refined in the original image space at stage 3 using the graph search integrating the estimated morphological shape models. Twenty macular SD-OCT (Heidelberg Spectralis) volume scans from 20 normal subjects (one eye per subject) were used in this study. The overall mean and absolute mean differences in border positions between the automated and manual segmentation for all 11 segmented surfaces were -0.20 +/- 0.53 voxels (-0.76 +/- 2.06 μm) and 0.82 +/- 0.64 voxels (3.19 +/- 2.46 μm). Intensity and thickness properties in the resultant retinal layers were investigated. This investigation in normal subjects may provide a comparative reference for subsequent investigations in eyes with disease.

  12. Construction and Calibration of Optically Efficient LCD-based Multi-Layer Light Field Displays

    NASA Astrophysics Data System (ADS)

    Hirsch, Matthew; Lanman, Douglas; Wetzstein, Gordon; Raskar, Ramesh

    2013-02-01

    Near-term commercial multi-view displays currently employ ray-based 3D or 4D light field techniques. Conventional approaches to ray-based display typically include lens arrays or heuristic barrier patterns combined with integral interlaced views on a display screen such as an LCD panel. Recent work has placed an emphasis on the co-design of optics and image formation algorithms to achieve increased frame rates, brighter images, and wider fields-of-view using optimization-in-the-loop and novel arrangements of commodity LCD panels. In this paper we examine the construction and calibration methods of computational, multi-layer LCD light field displays. We present several experimental configurations that are simple to build and can be tuned to sufficient precision to achieve a research quality light field display. We also present an analysis of moiré interference in these displays, and guidelines for diffuser placement and display alignment to reduce the effects of moiré. We describe a technique using the moiré magnifier to fine-tune the alignment of the LCD layers.

  13. Fabrication of Optical Multilayer Devices from Porous Silicon Coatings with Closed Porosity by Magnetron Sputtering.

    PubMed

    Caballero-Hernández, Jaime; Godinho, Vanda; Lacroix, Bertrand; Jiménez de Haro, Maria C; Jamon, Damien; Fernández, Asunción

    2015-07-01

    The fabrication of single-material photonic-multilayer devices is explored using a new methodology to produce porous silicon layers by magnetron sputtering. Our bottom-up methodology produces highly stable amorphous porous silicon films with a controlled refractive index using magnetron sputtering and incorporating a large amount of deposition gas inside the closed pores. The influence of the substrate bias on the formation of the closed porosity was explored here for the first time when He was used as the deposition gas. We successfully simulated, designed, and characterized Bragg reflectors and an optical microcavity that integrates these porous layers. The sharp interfaces between the dense and porous layers combined with the adequate control of the refractive index and thickness allowed for excellent agreement between the simulation and the experiments. The versatility of the magnetron sputtering technique allowed for the preparation of these structures for a wide range of substrates such as polymers while also taking advantage of the oblique angle deposition to prepare Bragg reflectors with a controlled lateral gradient in the stop band wavelengths.

  14. Highly Conductive Graphene and Polyelectrolyte Multilayer Thin Films Produced From Aqueous Suspension.

    PubMed

    Stevens, Bart; Guin, Tyler; Sarwar, Owais; John, Alyssa; Paton, Keith R; Coleman, Jonathan N; Grunlan, Jaime C

    2016-09-27

    Rapid, large-scale exfoliation of graphene in water has expanded its potential for use outside niche applications. This work focuses on utilizing aqueous graphene dispersions to form thin films using layer-by-layer processing, which is an effective method to produce large-area coatings from water-based solutions of polyelectrolytes. When layered with polyethyleneimine, graphene flakes stabilized with cholate are shown to be capable of producing films thinner than 100 nm. High surface coverage of graphene flakes results in electrical conductivity up to 5500 S m(-1) . With the relative ease of processing, the safe, cost effective nature of the ingredients, and the scalability of the deposition method, this system should be industrially attractive for producing thin conductive films for a variety of electronic and antistatic applications.

  15. "Shrink-to-fit" superhydrophobicity: thermally-induced microscale wrinkling of thin hydrophobic multilayers fabricated on flexible shrink-wrap substrates.

    PubMed

    Manna, Uttam; Carter, Matthew C D; Lynn, David M

    2013-06-11

    An approach to the design of flexible superhydrophobic surfaces based on thermally induced wrinkling of thin, hydrophobic polymer multilayers on heat-shrinkable polymer films is reported. This approach exploits shrinking processes common to "heat-shrink" plastics, and can thus be used to create "shrink-to-fit" superhydrophobic coatings on complex surfaces, manipulate the dimensions and densities of patterned features, and promote heat-activated repair of full-thickness defects.

  16. Optoelectronic Nanocomposite Materials for Thin Film Photovoltaics

    DTIC Science & Technology

    2012-06-01

    CdTe and ZnO single-phase thin films , nanocomposite films ...for the CdTe -ZnO thin film system under these conditions. c. Optical Absorption The films produced in the present study consistently exhibited...optical absorbance spectra collected from CdTe -ZnO multilayer nanocomposite thin films . The effect of CdTe layer thickness used per deposition cycle

  17. Sensitivity and Response of Polyvinyl Alcohol/Tin Oxide Nanocomposite Multilayer Thin Film Sensors.

    PubMed

    Sriram, G; Dhineshbabu, N R; Nithyavathy, N; Saminathan, K; Kaler, K V I S; Rajendran, V

    2016-01-01

    Nanocrystalline Tin Oxide (SnO₂) is Non-Stoichiometric in Nature with Functional Properties Suitable for gas sensing. In this study, SnO₂nanoparticles were prepared by the sol-gel technique, which were then characterised using X-ray diffraction. The nanoparticles showed tetragonal structure with an average crystallite size of 18 nm. The stretching and vibration modes of SnO₂were confirmed using Fourier transform infrared spectroscopy. The size of SnO₂ nanoparticles was determined using particle size analyser, which was found be 60 ± 10 nm on average. The surface morphology of the nanoparticles was investigated using scanning electron microscope, which showed irregular-sized agglomerated SnO₂nanostructures. In addition, primary particle size was evaluated using high-resolution transmission electron microscopy, which was found to be 50 nm on average. The polyvinyl alcohol/SnO₂ composite thin film was prepared on a glass substrate using spin-coating method. The values of band gap energy and electrical conductance of 13-layer thin film were found to be 2.96 eV and 0.0505 mho, respectively. Sulfur dioxide (SO₂) was suitably tailored to verify the sensor response over a concentration range of 10-70 ppm at room temperature. The performance, response, and recovery time of sensors were increased by increasing the layers of the thin film.

  18. High-frequency magnetoimpedance in multilayer thin films with longitudinal and transverse anisotropy

    NASA Astrophysics Data System (ADS)

    de Cos, D.; Lepalovskij, V. N.; Kurlyandskaya, G. V.; García-Arribas, A.; Barandiarán, J. M.

    Giant magnetoimpedance (GMI) effect in NiFe (150 nm)/Cu (500 nm)/NiFe (150 nm) multilayers with longitudinal and transverse induced magnetic anisotropy was studied at frequencies of 300 kHz-3 GHz. Several sensitive elements were built in a single "chip" configuration. At low and intermediate frequencies the GMI displays a single peak at zero-field for samples with longitudinal and two peaks for the samples with transverse anisotropy. Above 500 MHz the observed behaviour in both cases can be explained by the apparition of the ferromagnetic resonance (FMR). Regarding the performance of the sample, the maximum GMI sensitivity values achieved in case of longitunal anisotropy are 6%/Oe from the single peak to the saturation field at 500 MHz (quasistatic regime), and 12%/Oe from the FMR peaks to zero-field at 1.12 GHz (dynamic regime). Sensitivity values achieved in case of transverse anisotropy are 31%/Oe from the single peak to the saturation field at 70 MHz and 17%/Oe from the FMR peaks to zero-field at 0.8 GHz. Small variations of GMI ratio and field sensitivity for different sensitive elements built in a single "chip" confirm the possibility to use this design for multi-analyte detector construction.

  19. Enhanced soft magnetic properties in stress free amorphous FeTaC/Ta multilayer thin films

    NASA Astrophysics Data System (ADS)

    Singh, Akhilesh Kr.; Perumal, A.

    2013-02-01

    We report the enhanced soft magnetic properties of FeTaC film at higher thicknesses (200 nm) using [FeTaC(y)/Ta(x)]n = 2/FeTaC(y) multilayer structured films prepared on thermally oxidized Si substrates. As-made films and post annealed films at 250 °C exhibited amorphous structure. The room temperature coercivity decreased from 10 Oe for the as-made film to 0.03 Oe for the post annealed film. Also, the field necessary to saturate the M-H loop decreased largely with annealing. Interestingly, the temperature dependent magnetic data of the annealed films showed not only a narrow M-H loop as compared to the as-made films, but also exhibited a multi-step magnetization reversal process at T<60 K. The observed results are discussed on the basis of release of stress accumulated during the deposition process, with the post annealing process and the topological coupling between the magnetic layers.

  20. Unusual ZFC and FC magnetic behavior in thin Co multi-layered structure

    NASA Astrophysics Data System (ADS)

    Ben-Dor, Oren; Yochelis, Shira; Felner, Israel; Paltiel, Yossi

    2017-04-01

    The observation of unusual magnetic phenomena in a Ni -based magnetic memory device ([4] O. Ben-Dor et al., 2013) encouraged us to conduct a systematic research on Co based multi-layered structure which contains a α-helix L polyalanine (AHPA-L) organic compound. The constant Co thickness is 7 nm and AHPA-L was also replaced by non-chiral 1-Decanethiol organic molecules. Both organic compounds were chemisorbed on gold by a thiol group. The dc magnetic field (H) was applied parallel and perpendicular to the surface layers. The perpendicular direction is the easy magnetization axis and along this orientation only, the zero-field-cooled (ZFC) plots exhibit a pronounced peak around 55-58 K. This peak is suppressed in the second ZFC and field-cooled (FC) runs performed shortly after the virgin ZFC one. Thus, around the peak position ZFC>FC a phenomenon seldom observed. This peak reappears after measuring the same material six months later. This behavior appears in layers with the non-chiral 1-Decanethiol and it is very similar to that obtained in sulfur doped amorphous carbon. The peak origin and the peculiar ZFC>FC case are qualitatively explained.

  1. Optically thin hybrid cavity for terahertz photo-conductive detectors

    NASA Astrophysics Data System (ADS)

    Thompson, R. J.; Siday, T.; Glass, S.; Luk, T. S.; Reno, J. L.; Brener, I.; Mitrofanov, O.

    2017-01-01

    The efficiency of photoconductive (PC) devices, including terahertz detectors, is constrained by the bulk optical constants of PC materials. Here, we show that optical absorption in a PC layer can be modified substantially within a hybrid cavity containing nanoantennas and a Distributed Bragg Reflector. We find that a hybrid cavity, consisting of a GaAs PC layer of just 50 nm, can be used to absorb >75% of incident photons by trapping the light within the cavity. We provide an intuitive model, which describes the dependence of the optimum operation wavelength on the cavity thickness. We also find that the nanoantenna size is a critical parameter, small variations of which lead to both wavelength shifting and reduced absorption in the cavity, suggesting that impedance matching is key for achieving efficient absorption in the optically thin hybrid cavities.

  2. Application of measurement configuration optimization for accurate metrology of sub-wavelength dimensions in multilayer gratings using optical scatterometry.

    PubMed

    Zhu, Jinlong; Shi, Yating; Goddard, Lynford L; Liu, Shiyuan

    2016-09-01

    Critical dimension measurement accuracy in optical scatterometry relies not only on the systematic noise level of instruments and the reliability of forward modeling algorithms, but also heavily on the measurement configuration. To construct a set of potentially high-accuracy configurations, we apply a general measurement configuration optimization method based on error propagation theory and singular value decomposition, by which the measurement accuracy is approximated as a function of a pseudo Jacobian with respect to the measurement configurations. Simulations and experiments for the optical metrology of a sub-wavelength deep-etched multilayer grating establish the feasibility of the proposed method.

  3. First-principles determination of the in-plane interface magnetocrystalline anisotropy in (110) Co thin films and multilayers.

    NASA Astrophysics Data System (ADS)

    Kim, Miyoung; Zhong, Lieping; Freeman, A. J.

    1996-03-01

    In order to investigate possible in-plane magnetocrystalline anisotropy (MCA) in transition metal thin films, we have carried out first principles MCA calculations for fcc Co (110) in various environments: a free standing Co monolayer and Co/Cu multilayers. The full potential linearized augmented-plane-wave (FLAPW) method [1] was used to obtain semi-relativistic self-consistent charge densities within the local density approximation. Spin-orbit coupling was treated in a second variational manner and our newly developed state tracking and torque methods were adopted to accurately determine the MCA energy. We found a large in-plane anisotropy of the magnetocrystalline energy in the (110) orientation and a strong dependence of the in-plane MCA behavior on the structure. The calculated results and mechanism involved in the in-plane MCA are presented and discussed. Supported by the ONR (Grant No.N00014-94-1-0030) [1] E. Wimmer, H. Krakauer, M. Weinert and A. J. Freeman, Phys. Rev. B 24, 864 (1981)

  4. Influence of cellulose nanocrystals concentration and ionic strength on the elaboration of cellulose nanocrystals-xyloglucan multilayered thin films.

    PubMed

    Dammak, Abir; Moreau, Céline; Azzam, Firas; Jean, Bruno; Cousin, Fabrice; Cathala, Bernard

    2015-12-15

    The effect of the variation of CNC concentration on the growth pattern of CNC-XG films is investigated. We found that a transition in the growth slope occurs at a CNC concentration of roughly 3-4gL(-1). A close effect can be obtained by the increase of the ionic strength of the CNC suspensions, suggesting that electrostatic interactions are involved. Static light scattering investigation of CNC dispersions at increasing concentrations demonstrated that the particle-particle interactions change as the CNC concentration increases. Neutron Reflectivity (NR) was used to probe the internal structure of the films. The increase of the CNC concentration as well as the increase of the ionic strength in the CNC suspension were found to induce a densification of the adsorbed CNC layers, even though the mechanisms are not strictly identical in both cases. Small changes in these parameters provide a straightforward way of controlling the architecture of CNC-based multilayered thin films and, as a result, their functional properties.

  5. Oxidation of nano-multilayered AlTiSiN thin films between 600 and 1000 degrees C in air.

    PubMed

    Lee, Jae Chun; Kim, Sun Kyu; Nguyen, Thuan Dinh; Lee, Dong Bok

    2011-07-01

    Multilayered AlTiSiN films with a composition of 32.0Al-12.4Ti-4.9Si-50.7N (at.%) were deposited on a steel substrate in a nitrogen atmosphere by cathodic arc plasma deposition. The films consisted of crystalline approximately 8 nm-thick AISiN nanolayers that originated from the Al-Si target and approximately 3 nm-thick TiN nanolayers that originated from the Ti target. Their oxidation characteristics were studied between 600 and 1000 degrees C for up to 20 h in air. They displayed good oxidation resistance due to the formation of a thin, dense Al2O3 surface scale below which an (Al2O3, TiO2, SiO2)-intermixed inner scale existed. They oxidized slower than TiN films because protective Al2O3-rich scales formed on the surface. However, they oxidized faster than CrN films because impure Al2O3 scale formed on the AlTiSiN film. Their oxidation progressed primarily by the outward diffusion of nitrogen and substrate elements, combined with the inward transport of oxygen that gradually reacted with Al, Ti, and Si in the film.

  6. Layer-by-Layer assembled hybrid multilayer thin film electrodes based on transparent cellulose nanofibers paper for flexible supercapacitors applications

    NASA Astrophysics Data System (ADS)

    Wang, Xi; Gao, Kezheng; Shao, Ziqiang; Peng, Xiaoqing; Wu, Xue; Wang, Feijun

    2014-03-01

    Cellulose nanofibers (CNFs) paper with low thermal expansion and electrolyte absorption properties is considered to be a good potential substrate for supercapacitors. Unlike traditional substrates, such as glass or plastic, CNFs paper saves surfaces pretreatment when Layer-by-Layer (LbL) assembly method is used. In this study, negatively charged graphene oxide (GO) nanosheets and poly(3,4-ethylenedioxythiophene: poly(styrene sulfonate)) (PEDOT:PSS) nanoparticles are deposited onto CNFs paper with positively charged polyaniline (PANI) nanowires as agents to prepare multilayer thin film electrodes, respectively. Due to the different nanostructures of reduced graphene oxide (RGO) and PEDOT:PSS, the microstructures of the electrodes are distinguishing. Our work demonstrate that CNFs paper/PANI/RGO electrode provides a more effective pathway for ion transport facilitation compared with CNFs paper/PANI/PEDOT:PSS electrode. The supercapacitor fabricated by CNFs/[PANI-RGO]8 (S-PG-8) exhibits an excellent areal capacitance of 5.86 mF cm-2 at a current density of 0.0043 mA cm-2, and at the same current density the areal capacitance of the supercapacitor fabricated by CNFs/[PANI-PEDOT:PSS]8 (S-PP-8) is 4.22 mF cm-2. S-PG-8 also exhibits good cyclic stability. This study provides a novel method using CNFs as substrate to prepare hybrid electrodes with diverse microstructures that are promising for future flexible supercapacitors.

  7. Coating Thin Mirror Segments for Lightweight X-ray Optics

    NASA Technical Reports Server (NTRS)

    Chan, Kai-Wing; Sharpe, Marton V.; Zhang, William; Kolosc, Linette; Hong, Melinda; McClelland, Ryan; Hohl, Bruce R.; Saha, Timo; Mazzarellam, James

    2013-01-01

    Next generations lightweight, high resolution, high throughput optics for x-ray astronomy requires integration of very thin mirror segments into a lightweight telescope housing without distortion. Thin glass substrates with linear dimension of 200 mm and thickness as small as 0.4 mm can now be fabricated to a precision of a few arc-seconds for grazing incidence optics. Subsequent implementation requires a distortion-free deposition of metals such as iridium or platinum. These depositions, however, generally have high coating stresses that cause mirror distortion. In this paper, we discuss the coating stress on these thin glass mirrors and the effort to eliminate their induced distortion. It is shown that balancing the coating distortion either by coating films with tensile and compressive stresses, or on both sides of the mirrors is not sufficient. Heating the mirror in a moderately high temperature turns out to relax the coated films reasonably well to a precision of about a second of arc and therefore provide a practical solution to the coating problem.

  8. Multilayer films with sharp, stable interfaces for use in EUV and soft X-ray application

    DOEpatents

    Barbee, Jr., Troy W.; Bajt, Sasa

    2002-01-01

    The reflectivity and thermal stability of Mo/Si (molybdenum/silicon) multilayer films, used in soft x-ray and extreme ultraviolet region, is enhanced by deposition of a thin layer of boron carbide (e.g., B.sub.4 C) between alternating layers of Mo and Si. The invention is useful for reflective coatings for soft X-ray and extreme ultraviolet optics, multilayer for masks, coatings for other wavelengths and multilayers for masks that are more thermally stable than pure Mo/Si multilayers

  9. Flux Pinning Effects of Y2O3 Nanoparticulate Dispersions in Multilayered YBCO Thin Films

    DTIC Science & Technology

    2012-02-01

    substrates with a Y2O3 nanoparticulate pseudo-layer thickness ranging from 0.2 to 1.4 nm , and YBCO layer thickness varying from 7 to 50 nm . Scanning...with a Y2O3 nanoparticulate pseudo-layer thickness ranging from 0.2 to 1.4 nm , and YBCO layer thickness varying from 7 to 50 nm . Scanning electron...2.0 nm [3,4] compared to about 0.7 nm for Y2O3.4. Conclusion The use of Y2O3 nanoparticulates showed potential as flux pinning centers in YBCO thin

  10. Second-order nonlinear optical characteristics of nanoscale self-assembled multilayer organic films

    NASA Astrophysics Data System (ADS)

    Neyman, Patrick J.

    Ionically self-assembled monolayer (ISAM) films are typically an assemblage of oppositely charged polymers built layer by layer through Coulombic attraction utilizing an environmentally friendly process to form ordered structures that are uniform, molecularly smooth and physically robust. ISAM films have been shown to be capable of the noncentrosymmetric order requisite for a second-order nonlinear optical response with excellent temporal and thermal stability. However, such films fabricated with a nonlinear optical (NLO) polyanion result in significant cancellation of the chromophore orientations. This cancellation occurs by two mechanisms: competitive orientation due to the ionic bonding of the polymer chromophore with the subsequent polycation layer, and random orientation of the chromophores within the bulk of each polyanion layer. A reduction in film thickness accompanied by an increase in net polar ordering is one possible avenue to obtain the second-order susceptibility chi (2) necessary for practical application in electro-optic devices. In this thesis, we discuss the structural characteristics of ISAM films and explore a novel approach to obtain the desired characteristics for nonlinear optical response. This approach involves a hybrid covalent/ionic self-assembly technique which affords improved net dipole alignment and concentration of monomer chromophores in the film. This technique yields a substantial increase in chi(2) due to the preferential chromophore orientation being locked in place by a covalent bond to the preceding polycation layer. The films fabricated in this manner yield a chi(2) (56 x 10-9 esu) that substantially exceeds that of any known polymer-polymer ISAM film (˜0.3 x 10-9 esu). This covalent-hybrid ionically self-assembled multilayer (CHISAM) technique is demonstrated to result in films suitable for electro-optic devices, with measured electro-optic coefficient (14 pm/V) comparable to that of the inorganic crystal lithium niobate

  11. Optical and structural properties of zinc iodine thin films

    NASA Astrophysics Data System (ADS)

    Kariper, İ. A.

    2015-06-01

    Zinc iodide (ZnI2) crystalline thin film is produced with chemical bath deposition on substrates (commercial glass). The pH of chemical bath is scanned with controlled potassium hydroxide. Some properties of films changed with pH and changes of pH were analyzed. The pH values are scanned at 6.01-6.29. Transmittance, absorption, optical band gap and refractive index are investigated by UV/Vis. spectrum. The hexagonal and tetragonal form in structural properties in XRD at pH: 6.01 were seen. The pH of bath was up to 6.01, KZnI3ṡ2H2O (orthorhombic), KZnI3ṡ(H2O)2 (orthorhombic), ZnI2 (tetragonal) and ZnI2 (hexagonal) forms were observed in XRD patterns. The structural and optical properties of ZnI2 thin films analyzed at different pH. SEM analysis studied for surface analysis in films. The SEM analyses were agreed with XRD patterns. The optical band gap increased with pH between 3.4 and 3.6 eV. The film thickness changed with pH at 108-345 nm. Also refractive index and transmission generally increased with pH.

  12. Optical transmission in thin films of vanadium compounds

    NASA Astrophysics Data System (ADS)

    Karimov, Kh. S.; Mahroof-Tahir, M.; Saleem, M.; Ahmad, N.; Rashid, A.

    2014-07-01

    Thin films of five vanadium compounds/composite: (1) VO2(3-fl) (3-fl = 3-Hydroxyflavone), (2) VO(pbd)2 (pbd = 1-Phenyl-1, 3-butadione), (3) VO(dbm)2 (dbm = Dibenzoylmethane), (4) VPc (Vanadyl Phthalocyanine) and (5) V2O5-PEPC (V2O5- poly-N-epoxypropylcarbazole composite), were deposited by the drop-casting method from the solution in benzene. The transmittance—irradiance relationships were investigated and the transmission in the visible spectrum and optical images were obtained as well. It was found that the transmittance of the VO2(3-fl), VO(pbd)2, VO(dbm)2 and VPc, was practically independent of the irradiance; whereas the transmittance of V2O5-PEPC decreased by 4% for thin and 9% for thick films with an increase of the irradiance.

  13. Microstructure, Optical and Photocatalytic Properties of TiO₂ Thin Films Prepared by Chelating-Agent Assisted Sol-Gel Method.

    PubMed

    Matĕjová, Lenka; Cieslarová, Monika; Matĕj, Zdenĕk; Danis, Stanislav; Peikertová, Pavlína; Sihor, Marcel; Lang, Jaroslav; Matĕjka, Vlastimil

    2016-01-01

    Single and multilayer TiO₂ thin films coated on two types of soda-lime glass substrates (microscope slides and cylinders) were prepared by a chelating agent-assisted sol-gel method, using ethyl acetoacetate as a chelating agent, dip-coating and calcination at 500 °C for 2 h in air. Phase composition, microstructural, morphological and optical properties of thin films were comprehensively investigated by using XRF, advanced XRD analysis, Raman and UV-vis spectroscopy and AFM. It was found out that the thickness of thin films increases linearly with increasing number of deposited layers, indicating a good adhesion of the titania solution to a glass substrate as well as to a previously calcined layer. 1 layer film crystallized to anatase-TiO₂(B) mixture with minor/negligible amount of nanosized brookite, 2-4 layers films crystallized to anatase-brookite-TiO₂(B) mixture. In contrast to other multilayers films, 4 layers film was highly inhomogeneous. The different phase composition of thin films was clarified based on the crystallization via titanate/s and metastable monoclinic TiO₂(B) as a consequence of several phenomena; the diffusion of Na⁺ ions from a soda-lime glass substrate, acidic conditions and repeated thermal treatment. The multilayer films were in average highly transparent (80-95%) in the visible light region with the sharp absorption edge in the UV light region. Additionally, the photocatalytic properties of selected multilayer films were compared in AO7 photodegradation. Photocatalytic experiments showed that thicker 4 layers film of tricrystalline anatase-brookite-TiO₂(B) phase mixture was similarly active as thinner 3 layers film of similar phase composition, which may be a consequence of the inhomogeneity of the thicker film.

  14. Optical figuring specifications for thin shells to be used in adaptive telescope mirrors

    NASA Astrophysics Data System (ADS)

    Riccardi, A.

    2006-06-01

    The present work describes the guidelines to define the optical figuring specifications for optical manufacturing of thin shells in terms of figuring error power spectrum (and related rms vs scale distributon) to be used in adaptive optics correctors with force actuators like Deformable Secondary Mirrors (DSM). In particular the numerical example for a thin shell for a VLT DSM is considered.

  15. Plasmonic multilayer nanoparticles enhanced photocurrent in thin film hydrogenated amorphous silicon solar cells

    NASA Astrophysics Data System (ADS)

    Ho, Chung-I.; Yeh, Dan-Ju; Su, Vin-Cent; Yang, Chieh-Hung; Yang, Po-Chuan; Pu, Ming-Yi; Kuan, Chieh-Hsiung; Cheng, I.-Chun; Lee, Si-Chen

    2012-07-01

    A plasmonic-structure incorporated double layer of Au nanoparticles embedded in the transparent conducting oxide at the back-reflector of the hydrogenated amorphous silicon (a-Si:H) solar cells is demonstrated. These devices exhibit an increase of energy conversion efficiency of 18.4% and short-circuit current density of 9.8% while improving fill-factor and without sacrificing open-circuit voltage. The increase in photocurrent is correlated with the enhanced optical absorption in the cell, with improved optical-path-length by a factor of 7 at the wavelength of 800 nm, due to enhanced diffuse scattering of light through resonant plasmon excitations within Au nanoparticles. In addition to enhanced scattering, applying high-work-function Au nanoparticles can improve the work function match at TCO/a-Si:H interface.

  16. Enhancement of crystallinity and optical properties of bilayer TiO2/ZnO thin films prepared by atomic layer deposition.

    PubMed

    Hussin, Rosniza; Choy, Kwang-Leong; Hou, Xianghui

    2011-09-01

    Bilayer and multilayer thin films are becoming increasingly important in the development of faster, smaller and more efficient electronic and optoelectronic devices. One of the motivations of applying bilayer or multilayer structures is to modify the optical properties of materials. Atomic layer deposition (ALD) is a variant of Chemical Vapour Deposition that can produce uniform and conformal thin films with well controlled nanostructures. In this study, we have demonstrated new findings of the use of ALD fabricated bilayer TiO2/ZnO thin films with enhanced crystallinity and optical properties. TiO2 films have been deposited at 300 degrees C for 1000 (51 nm in thickness) or 3000 (161 nm in thickness) deposition cycles onto glass and Si substrates. ZnO films are subsequently deposited on the TiO2 layers at 280 degrees C for 500 deposition cycles (55 nm). The crystallinity and optical properties of the TiO2/ZnO thin films have been analysed by X-ray diffraction, photoluminescence, UV-Vis spectroscopy, Atomic Force Microscopy and Scanning Electron Microscopy. XRD diffraction pattern confirmed the presence of ZnO with wutrtize crystal structure and TiO2 with anatase structure. It shows that the crystallinity of the TiO2 films has been improved with the deposition of ZnO. The intensity of UV luminescence has increased by almost 30% for TiO2/ZnO bilayer as compared to the single layer TiO2. The possible mechanism for the enhancement of the optical properties of bilayer TiO2/ZnO thin films will be discussed.

  17. Transparent ambipolar organic thin film transistors based on multilayer transparent source-drain electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Nan; Hu, Yongsheng; Lin, Jie; Li, Yantao; Liu, Xingyuan

    2016-08-01

    A fabrication method for transparent ambipolar organic thin film transistors with transparent Sb2O3/Ag/Sb2O3 (SAS) source and drain electrodes has been developed. A pentacene/N,N'-ditridecylperylene-3,4,9,10-tetracarboxylic di-imide (PTCDI-C13) bilayer heterojunction is used as the active semiconductor. The electrodes are deposited by room temperature electron beam evaporation. The devices are fabricated without damaging the active layers. The SAS electrodes have high transmittance (82.5%) and low sheet resistance (8 Ω/sq). High performance devices with hole and electron mobilities of 0.3 cm2/V s and 0.027 cm2/V s, respectively, and average visible range transmittance of 72% were obtained. These transistors have potential for transparent logic integrated circuit applications.

  18. Theoretical model for thin ferroelectric films and the multilayer structures based on them

    SciTech Connect

    Starkov, A. S. Pakhomov, O. V.; Starkov, I. A.

    2013-06-15

    A modified Weiss mean-field theory is used to study the dependence of the properties of a thin ferroelectric film on its thickness. The possibility of introducing gradient terms into the thermodynamic potential is analyzed using the calculus of variations. An integral equation is introduced to generalize the well-known Langevin equation to the case of the boundaries of a ferroelectric. An analysis of this equation leads to the existence of a transition layer at the interface between ferroelectrics or a ferroelectric and a dielectric. The permittivity of this layer is shown to depend on the electric field direction even if the ferroelectrics in contact are homogeneous. The results obtained in terms of the Weiss model are compared with the results of the models based on the correlation effect and the presence of a dielectric layer at the boundary of a ferroelectric and with experimental data.

  19. Structural and optical properties of molybdenum trioxide thin films

    SciTech Connect

    Bhatia, Shally; Khanna, Atul

    2015-06-24

    Thermal evaporation technique was used to prepare thin films of MoO{sub 3}. X-ray diffraction measurements found that as-deposited films of MoO{sub 3} were amorphous which crystallized to orthorhombic phase on annealing at 623K for 1h in air. The optical band gap of the films decreases from 3.1eV to 1.7eV upon crystallization. Short range structure of the as deposited films and annealed films were studied by Raman spectroscopy and it consisted of MoO{sub 6} units.

  20. The optically thin C III spectrum - Line and multiplet intensities

    NASA Astrophysics Data System (ADS)

    Bhatia, A. K.; Kastner, S. O.

    1993-05-01

    C III line/multiplet intensities expected under optically thin conditions are presented over the density/ temperature ranges 4.0 - 12.0 and 4.6 - 5.0 (40,000 - l00,000 K). These improved values are obtained from a hybrid level/term calculation which makes use of the most recently available atomic data and extends the treatment down to lower densities than were achieved with our previous term representation. Some illustrative applications are given, including a brief description of the importance of the present data for interpretation of the strong C III line emission from carbon Wolf-Rayet stars.

  1. The optically thin C III spectrum - Line and multiplet intensities

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Kastner, S. O.

    1993-01-01

    C III line/multiplet intensities expected under optically thin conditions are presented over the density/ temperature ranges 4.0 - 12.0 and 4.6 - 5.0 (40,000 - l00,000 K). These improved values are obtained from a hybrid level/term calculation which makes use of the most recently available atomic data and extends the treatment down to lower densities than were achieved with our previous term representation. Some illustrative applications are given, including a brief description of the importance of the present data for interpretation of the strong C III line emission from carbon Wolf-Rayet stars.

  2. Characterization of nodular and thermal defects in hafnia/silica multilayer coatings using optical, photothermal, and atomic force microscopy

    SciTech Connect

    Stolz, C.J.; Yoshiyama, J.M.; Salleo, A.; Wu, Z.L.; Green, J.; Krupka, R.

    1997-12-24

    Multilayer coatings manufactured from metallic hafnium and silica sources by reactive electron beam deposition, are being developed for high fluence optics in a fusion laser with a wavelength of 1053 nm and a 3 ns pulse length. Damage threshold studies have revealed a correlation between laser damage and nodular defects, but interestingly laser damage is also present in nodule-free regions. Photothermal studies of optical coatings reveal the existence of defects with strong optical absorption in nodule-free regions of the coating. A variety of microscopic techniques were employed to characterize the effects for a better understanding of the thermal properties of nodular defects and role of thermal defects in laser damage. Photothermal microscopy, utilizing the surface thermal lensing technique, was used to map the thermal characteristics of 3 mm x 3 mm areas of the coatings. High resolution subaperture scans, with a 1 pm step size and a 3 um pump beam diameter, W= conducted on the defects to characterize their photothermal properties. Optical and atomic force microscopy was used to visually identify defects and characterize their topography. The defects were then irradiated to determine the role of nodular and thermal defects in limiting the damage threshold of the multilayer.

  3. Multiscale roughness in optical multilayers: atomic force microscopy and light scattering.

    PubMed

    Deumié, C; Richier, R; Dumas, P; Amra, C

    1996-10-01

    We have previously shown that macroscopic roughness spectra measured with light scattering at visible wavelengths were perfectly extrapolated at high spatial frequencies by microscopic roughness spectra measured with atomic force microscopy [Europhys. Lett. 22, 717 (1993); Proc. SPIE 2253, 614 (1994)]. These results have been confirmed by numerous experiments [Proc. SPIE 2253, 614 (1994)] and allow us today to characterize thin films microstructure from a macroscopic to a microscopic scale. In the first step the comparison of light scattering and atomic force microscopy is completed by optical measurements at UV wavelengths that allow us to superimpose (and no longer extrapolate) the spectra measured by the two techniques. In the second step we extract multiscale parameters that describe the action of thin-film coatings on substrate roughness in all bandwidths. The results obviously depend on materials and substrates and deposition techniques. Electron-beam evaporation, ion-assisted deposition, and ion plating are compared, and the conclusions are discussed in regard to the deposition parameters. Finally, special attention is given to the limits and performances of the two characterization techniques (light scattering and atomic force microscopy) that may be sensitive to different phenomena.

  4. Preservation of the morphology of a self-encapsulated thin titania film in a functional multilayer stack: an X-ray scattering study.

    PubMed

    Perlich, Jan; Memesa, Mine; Diethert, Alexander; Metwalli, Ezzeldin; Wang, Weinan; Roth, Stephan V; Timmann, Andreas; Gutmann, Jochen S; Müller-Buschbaum, Peter

    2009-03-23

    Tailoring of the titania morphology is achieved by the combination of a triblock copolymer, acting as structure-directing agent, and a sol-gel chemistry enabling the incorporation of the provided inorganic material (titania) into the selected phase of the triblock copolymer. Spin-coating of the solution on FTO-coated glass, followed by plasma etching and calcination of the thin film results in the formation of self-encapsulated crystalline titania nanostructures. The fabricated nanostructures are coated stepwise with dye, conductive polymers and gold forming a functional multilayer stack. An advanced small-angle scattering technique probing the sample with X-ray synchrotron radiation under grazing incidence (GISAXS) is employed for the characterization of the preparation route, as scattering allows accessing the structure inside the multilayers. The tailored titania morphology is preserved during the preparation route towards the functional multilayer stack of a photovoltaic demonstration cell. Two clearly distinguishable structures originate from the substrate and the titania templated by the triblock copolymer; hence the other layers induce no additional structures. Therefore, this investigation provides the evidence that the effort spent to tailor the morphology is justified by the preservation of the self-encapsulated titania morphology that is created by the structure-directing agent throughout the functional multilayer stack build-up.

  5. Structural and optical properties of distyrylbenzene derivative thin films

    NASA Astrophysics Data System (ADS)

    Ni, J. P.; Ueda, Y.; Hanada, T.; Takada, N.; Ichino, Y.; Yoshida, Y.; Tanigaki, N.; Yase, K.; Wang, D. K.; Wang, F. S.

    1999-12-01

    In order to understand the relationship between the molecular orientation and optical properties of oligophenylenevinylene film, oriented thin films of 1,4-di(p-methoxystyryl)benzene (DSB-1) and 1,4-di(p-methoxystyryl)-2,5-dimethoxybenzene (DSB-2) were fabricated on a potassium bromide (KBr) (001) surface by the vacuum-evaporation method. The structures and optical properties of DSB films have been investigated by transmission electron microscopy (TEM), atomic force microscopy (AFM) and polarized photoluminescence (PL) spectroscopy, respectively. DSB-1 molecules orient obliquely and/or parallel to the substrate surface depending on the substrate temperature. On the other hand, DSB-2 molecules tend to grow epitaxially with the molecular plane parallel to the substrate surface. The anisotropic molecular orientations represent the polarized PL. The epitaxial growth and molecular orientations observed by TEM and AFM at the local and microscopic scale are confirmed by polarized PL measurement on a macroscopic scale.

  6. Theoretical model for a thin cylindrical film optical fiber fluorosensor

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O.; Rogowski, Robert S.

    1992-01-01

    The analytical treatment of power efficiency (P(eff) is undertaken for the case of a positively guiding optical fiber with a thin-film source distributed in the core-cladding interface. The approach adopts the exact solution of the cylindrical optical fiber with an infinite cladding to account for differences between the indices of refraction of the core and the cladding. The excitation of low-loss leaky modes by the cladding is ignored, and only the injection by the evanescent field is considered. The formulas permit the analysis of the power-injection efficiency of fibers with arbitrary differences in indices of refraction. P(eff) does not always increase with V number, but rather varies slightly with wavelength and fiber-core radius and varies significantly with the difference in the indices of refraction. The theoretical results of the work are of interest for designing an atomic-O chemical sensor based on evanescent-wave coupling.

  7. Perpendicular magnetic tunnel junctions based on thin CoFeB free layer and Co-based multilayer synthetic antiferromagnet pinned layers

    NASA Astrophysics Data System (ADS)

    Natarajarathinam, A.; Zhu, R.; Visscher, P. B.; Gupta, S.

    2012-04-01

    We have previously reported on fully perpendicular Co/Pd multilayer (ML)-based CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs). However, Co/Pd ML-based MTJs have rarely exhibited tunneling magnetoresistance (TMR) ratios greater than 10%. This has been attributed to the inability to pull a sufficiently thick CoFeB layer perpendicular on top of MgO, as well as the incomplete bcc templating of CoFeB from MgO owing to the adjacent fcc Co/Pd MLs. Other researchers have used amorphous thin Ta bridge layers to transition between the bcc and fcc layers. Thin CoFeB with various seed or capping layers have also shown fully perpendicular anisotropy, and thus have gained interest in use as a free layer. Here we report on fully perpendicular MTJs of this type, with a thin CoFeB free layer and a Co/Pd ML-based SAF pinned layer with a thin amorphous Ta bridge layer to transition from bcc CoFeB to the fcc multilayers. The experimentally measured M-H loops show excellent agreement with micromagnetic simulations. Current-in-plane tunneling measurements indicated TMR values of nearly 40% for fully perpendicular stacks annealed at 150 °C for 2 h. Annealing at higher temperatures degraded the magnetoresistance for these Co/Pd ML based SAF pinned MTJs.

  8. Method for high-precision multi-layered thin film deposition for deep and extreme ultraviolet mirrors

    DOEpatents

    Ruffner, J.A.

    1999-06-15

    A method for coating (flat or non-flat) optical substrates with high-reflectivity multi-layer coatings for use at Deep Ultra-Violet (DUV) and Extreme Ultra-Violet (EUV) wavelengths. The method results in a product with minimum feature sizes of less than 0.10 [micro]m for the shortest wavelength (13.4 nm). The present invention employs a computer-based modeling and deposition method to enable lateral and vertical thickness control by scanning the position of the substrate with respect to the sputter target during deposition. The thickness profile of the sputter targets is modeled before deposition and then an appropriate scanning algorithm is implemented to produce any desired, radially-symmetric thickness profile. The present invention offers the ability to predict and achieve a wide range of thickness profiles on flat or figured substrates, i.e., account for 1/R[sup 2] factor in a model, and the ability to predict and accommodate changes in deposition rate as a result of plasma geometry, i.e., over figured substrates. 15 figs.

  9. Method for high-precision multi-layered thin film deposition for deep and extreme ultraviolet mirrors

    DOEpatents

    Ruffner, Judith Alison

    1999-01-01

    A method for coating (flat or non-flat) optical substrates with high-reflectivity multi-layer coatings for use at Deep Ultra-Violet ("DUV") and Extreme Ultra-Violet ("EUV") wavelengths. The method results in a product with minimum feature sizes of less than 0.10-.mu.m for the shortest wavelength (13.4-nm). The present invention employs a computer-based modeling and deposition method to enable lateral and vertical thickness control by scanning the position of the substrate with respect to the sputter target during deposition. The thickness profile of the sputter targets is modeled before deposition and then an appropriate scanning algorithm is implemented to produce any desired, radially-symmetric thickness profile. The present invention offers the ability to predict and achieve a wide range of thickness profiles on flat or figured substrates, i.e., account for 1/R.sup.2 factor in a model, and the ability to predict and accommodate changes in deposition rate as a result of plasma geometry, i.e., over figured substrates.

  10. Laser interference metallurgy: A new method for periodic surface microstructure design on multilayered metallic thin films

    NASA Astrophysics Data System (ADS)

    Lasagni, A.; Holzapfel, C.; Weirich, T.; Mücklich, F.

    2007-07-01

    Methods for micro- and nanostructuring are essential for functionalization of materials surfaces. In particular, photon-assisted methods for synthesis of functional surfaces have been intensively investigated in the last years. In this study, a new method for surface modification and production of long-range order periodical structures called "laser interference metallurgy" is explored. A metallic thin film sample consisting of three layers composed of Fe, Cu and Al (from top to bottom) on a glass substrate was irradiated with an interference pattern using a Nd:YAG laser (wavelength of 355 nm, 10 ns of pulse duration). For the interference pattern, a configuration producing a line-type energy distribution was chosen. The laser fluence was high enough to melt the aluminium and copper layers at the interference maxima but the iron layer remained in the solid state. Thus, diffusive and convective exchange occurred between aluminium and copper at the energy maxima positions leading to periodical alloy formation with a long-range order. Because it remained in solid state, the iron layer at the top acted as a protective layer effectively preventing removal of the molten layers. The interaction of the different layers was characterized using FIB, TEM and EDX in STEM mode.

  11. Indentation and overall compression behavior of multilayered thin-film composites. Effect of undulating layer geometry

    SciTech Connect

    Jamison, Ryan D.; Shen, Y. -L.

    2015-03-19

    Two finite element models are used to investigate the behavior of aluminum/silicon carbide thin-film layered composites with imperfect internal geometry when subjected to various loadings. In both models, undulating layers are represented by regular waveforms with various amplitudes, wavelengths, and phase offsets. First, uniaxial compressive loading of the composite is considered. The modulus and stress/strain response of the composite is sensitive to both loading direction and frequency of the undulation. Second, the nanoindentation response of the composite is investigated. The derived hardness and modulus are shown to be sensitive to the presence of undulating layers and the relative size of the indenter to the undulation. Undulating layers create bands of tensile and compressive stress in the indentation direction that are significantly different from the flat layers. The amount of equivalent plastic strain in the Al layers is increased by the presence of undulating layers. The correlations between the two forms of loading, and the implications to composite property measurement are carefully examined in this study.

  12. A vibrating reed apparatus to measure the natural frequency of multilayered thin films

    NASA Astrophysics Data System (ADS)

    Gamboa, F.; López, A.; Avilés, F.; Corona, J. E.; Oliva, A. I.

    2016-04-01

    An apparatus for measuring the natural frequency of sub-micrometric layered films in cantilever beam configuration is presented. The instrument comprises a specially designed test rig with a sample holder, an electronic excitation source, a vibration sensor and an automated software for the excitation and data recollection. The beam is excited by means of an air pulse and the oscillation amplitude of its free end is measured through a laser diode-photosensor arrangement. The instrument provides a very low uncertainty (˜1 mHz, for frequencies of the order of tens Hz) for repeated sequential tests and the major source of uncertainty (˜0.2 Hz, corresponding to a coefficient of variation of 0.18%) arises from the difficulty of placing the sample in an exactly identical location upon clamping. This high sensitivity renders the capability of measuring very small frequency shifts upon deposition of sub-micrometric films over thicker substrates. In order to assess the reliability of the apparatus, cantilever beams of 125 μm thick neat Kapton (substrate) and thin layered films of Au/Kapton and Al/Au/Kapton of 200-250 nm film thickness were fabricated and their natural frequency and damping factor were measured. Calculations of the natural frequency of such beams by finite element analysis further support the accuracy of the experimental measurements.

  13. Indentation and overall compression behavior of multilayered thin-film composites. Effect of undulating layer geometry

    DOE PAGES

    Jamison, Ryan D.; Shen, Y. -L.

    2015-03-19

    Two finite element models are used to investigate the behavior of aluminum/silicon carbide thin-film layered composites with imperfect internal geometry when subjected to various loadings. In both models, undulating layers are represented by regular waveforms with various amplitudes, wavelengths, and phase offsets. First, uniaxial compressive loading of the composite is considered. The modulus and stress/strain response of the composite is sensitive to both loading direction and frequency of the undulation. Second, the nanoindentation response of the composite is investigated. The derived hardness and modulus are shown to be sensitive to the presence of undulating layers and the relative size ofmore » the indenter to the undulation. Undulating layers create bands of tensile and compressive stress in the indentation direction that are significantly different from the flat layers. The amount of equivalent plastic strain in the Al layers is increased by the presence of undulating layers. The correlations between the two forms of loading, and the implications to composite property measurement are carefully examined in this study.« less

  14. Toward air-stable multilayer phosphorene thin-films and transistors.

    PubMed

    Kim, Joon-Seok; Liu, Yingnan; Zhu, Weinan; Kim, Seohee; Wu, Di; Tao, Li; Dodabalapur, Ananth; Lai, Keji; Akinwande, Deji

    2015-03-11

    Few-layer black phosphorus (BP), also known as phosphorene, is poised to be the most attractive graphene analogue owing to its high mobility approaching that of graphene, and its thickness-tunable band gap that can be as large as that of molybdenum disulfide. In essence, phosphorene represents the much sought after high-mobility, large direct band gap two-dimensional layered crystal that is ideal for optoelectronics and flexible devices. However, its instability in air is of paramount concern for practical applications. Here, we demonstrate air-stable BP devices with dielectric and hydrophobic encapsulation. Microscopy, spectroscopy, and transport techniques were employed to elucidate the aging mechanism, which can initiate from the BP surface for bare samples, or edges for samples with thin dielectric coating, highlighting the ineffectiveness of conventional scaled dielectrics. Our months-long studies indicate that a double layer capping of Al2O3 and hydrophobic fluoropolymer affords BP devices and transistors with indefinite air-stability for the first time, overcoming a critical material challenge for applied research and development.

  15. Multilayer crack-free hybrid coatings for functional devices

    NASA Astrophysics Data System (ADS)

    Islam, Shumaila; Bidin, Noriah; Riaz, Saira; Naseem, Shahzad; Marsin Sanagi, Mohd.; Imran, M.

    2016-04-01

    Porous acid catalyzed TiO2 single, SiO2-TiO2 hybrid, and TiO2/SiO2-TiO2/SiO2 multilayer coatings are synthesized and characterized for optical and electro-optical applications. The reflection value is reasonably reduced from the surface of the glass by integrating sol-gel based spin-coated single and multilayer thin films. Structurally, the films show uniform, crack-free, and porous nanofilms with good surface roughness of below 10 nm, which has potential for optical applications. Wide range tunability of refractive index (2.83 to 1.59) with more than 78% optical transparency is observed. The multilayered reflection profile is observed around 0.18%, so these coatings are desirable for optochemical functional devices.

  16. Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications

    NASA Astrophysics Data System (ADS)

    Skuza, J. R.; Scott, D. W.; Mundle, R. M.; Pradhan, A. K.

    2016-02-01

    We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5–10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT.

  17. Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications.

    PubMed

    Skuza, J R; Scott, D W; Mundle, R M; Pradhan, A K

    2016-02-17

    We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5-10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT.

  18. Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications

    PubMed Central

    Skuza, J. R.; Scott, D. W.; Mundle, R. M.; Pradhan, A. K.

    2016-01-01

    We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5–10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT. PMID:26884225

  19. Optically Thin Metallic Films for High-Radiative-Efficiency Plasmonics.

    PubMed

    Yang, Yi; Zhen, Bo; Hsu, Chia Wei; Miller, Owen D; Joannopoulos, John D; Soljačić, Marin

    2016-07-13

    Plasmonics enables deep-subwavelength concentration of light and has become important for fundamental studies as well as real-life applications. Two major existing platforms of plasmonics are metallic nanoparticles and metallic films. Metallic nanoparticles allow efficient coupling to far field radiation, yet their synthesis typically leads to poor material quality. Metallic films offer substantially higher quality materials, but their coupling to radiation is typically jeopardized due to the large momentum mismatch with free space. Here, we propose and theoretically investigate optically thin metallic films as an ideal platform for high-radiative-efficiency plasmonics. For far-field scattering, adding a thin high-quality metallic substrate enables a higher quality factor while maintaining the localization and tunability that the nanoparticle provides. For near-field spontaneous emission, a thin metallic substrate, of high quality or not, greatly improves the field overlap between the emitter environment and propagating surface plasmons, enabling high-Purcell (total enhancement >10(4)), high-quantum-yield (>50%) spontaneous emission, even as the gap size vanishes (3-5 nm). The enhancement has almost spatially independent efficiency and does not suffer from quenching effects that commonly exist in previous structures.

  20. Direct absorption measurements in thin rods and optical fibers

    NASA Astrophysics Data System (ADS)

    Mühlig, Christian; Bublitz, Simon; Lorenz, Martin

    2015-11-01

    We report on the first realization of direct absorption measurements in thin rods and optical fibers using the laser induced deflection (LID) technique. Typically, along the fiber processing chain more or less technology steps are able to introduce additional losses to the starting material. After the final processing, the fibers are commonly characterized regarding losses using the so-called cut-back technique in combination with spectrometers. This, however, only serves for a total loss determination. For optimization of the fiber processing, it would be of great interest to not only distinguish between different loss mechanisms but also have a better understanding of possible causes. For measuring the absorption losses along the fiber processing, a particular concept for the LID technique is introduced and requirements, calibration procedure as well as first results are presented. It allows to measure thin rods, e.g. during preform manufacturing, as well as optical fibers. In addition, the results show the prospects to also apply the new concept to topics like characterizing unwanted absorption after fiber splicing or Bragg grating inscription.

  1. Optical and Structural Properties of Thin Film Composites.

    NASA Astrophysics Data System (ADS)

    Gibson, Ursula Jane

    This work describes the optical and structural characterization of metal-insulator and bimetallic composite films. Included are experimental details, theoretical descriptions of these systems, and a correlation of the optical response and microstructure of these thin film systems. The films were made by simultaneous or sequential evaporation of the constituents onto either amorphous or single crystal substrates. Two reflectance and one transmittance measurements were combined and inverted to determine the intrinsic optical constants of these materials over the wavelength range 0.2 to 3.0 microns. The metal insulator systems studied were Au-Al(,2)O(,3) and Au-MgO. The optical behavior and transport properties of these materials were measured, and correlated with their disparate microstructures. The optical behavior was compared to the predictions of three effective medium theories, labelled as the Maxwell-Garnett, Bruggeman Self-Consistent and Probabilistic Growth theories. The differing topological assumptions which form the bases of these theories were correlated with microscopic examination of the morphologies of the films, and it was found that the simple theories adequately predicted the optical response of the composites. Bimetallic systems were also studied, to investigate the extension of the Bruggeman theory to symmetric composites of immiscible metal constituents. It was found that the theory adequately predicts the behavior of films which display the symmetric morphology assumed by the theory. Studies of non-symmetric composites, and anisotropic systems (such as epitaxial layered materials (ELMs), showed that the symmetric morphology is necessary in order to model these systems with the Bruggeman theory.

  2. Multilayer stress field interference in sandstone and mudstone thin interbed reservoir

    NASA Astrophysics Data System (ADS)

    Guo, Jian-Chun; Luo, Bo; Zhu, Hai-Yan; Yuan, Shu-Hang; Deng, Yan; Duan, You-Jing; Duan, Wei-Gang; Chen, Li

    2016-10-01

    General fracturing and separate layer fracturing play an important role in sandstone and mudstone thin interbed (SMTI) reservoirs, where one of the main issues is to control the excessive height growth of fracturing. The fracture propagation at the interface depends on the induced stress produced by the hydraulic fracturing construction. This paper employed a poroelastic coupled damage element with the cohesive zone method (CZM) to establish a 2D fracture quasi-static propagation model. A parametric study was performed under different fracture height, fracture width, pumping rate, fluid viscosity, in situ stress, elastic modulus and tensile strength with this model. General fracturing and separate layer fracturing are compared with each other through fracture morphology and induced stress. The simulation results show that the absolute value of induced stress increases with the decrease in matrix stress near the fracture tip. As a result, the propagation of the fractures is much easier due to the weakened degree of compression. The growth of fracture height and width, the increase in pumping rate and the excessively large or small value of fluid viscosity lead to larger induced stress on the interface. Higher in situ stress, lower elastic modulus, and higher tensile strength of the interlayers can control the excessive height growth of fracturing. The simulated results also show that the fractures are more likely to be overlapped with each other in general fracturing compared to that in separate-layer fracturing. Results of the simulations suggest that lower pumping rates, the proper value of fluid viscosity, separate layer fracturing and interlayers with higher in situ stress, lower elastic modulus and higher tensile strength tend to limit fracture height. Finally, the proposed model was applied to a practical oil field case to verify its effectiveness.

  3. 2-1/2-D electromagnetic modeling of nodular defects in high-power multilayer optical coatings

    SciTech Connect

    Molau, N.E.; Brand, H.R.; Kozlowski, M.R.; Shang, C.C.

    1996-07-01

    Advances in the design and production of high damage threshold optical coatings for use in mirrors and polarizers have been driven by the design requirements of high-power laser systems such as the proposed 1.8-MJ National Ignition Facility (NIF) and the prototype 12- kJ Beamlet laser system. The present design of the NIF will include 192 polarizers and more than 1100 mirrors. Currently, the material system of choice for high-power multilayer optical coatings with high damage threshold applications near 1.06 {mu}m are e-beam deposited HfO{sub 2}/Si0{sub 2} coatings. However, the optical performance and laser damage thresholds of these coatings are limited by micron-scale defects and insufficient control over layer thickness. In this report, we will discuss the results of our 2-1/2-D finite-element time- domain (FDTD) EM modeling effort for rotationally-symmetric nodular defects in multilayer dielectric HR coatings. We have added a new diagnostic to the 2-1/2-D FDTD EM code, AMOS, that enables us to calculate the peak steady-state electric fields throughout a 2-D planar region containing a 2-D r-z cross-section of the axisymmetric nodular defect and surrounding multilayer dielectric stack. We have also generated a series of design curves to identify the range of loss tangents for Si0{sub 2} and HfO{sub 2} consistent with the experimentally determined power loss of the HR coatings. In addition, we have developed several methods to provide coupling between the EM results and the thermal-mechanical simulation effort.

  4. Mode-locking of Er-doped fiber laser using a multilayer MoS2 thin film as a saturable absorber in both anomalous and normal dispersion regimes.

    PubMed

    Khazaeizhad, Reza; Kassani, Sahar Hosseinzadeh; Jeong, Hwanseong; Yeom, Dong-Il; Oh, Kyunghwan

    2014-09-22

    Application of a multilayer Molybdenum Disulfide (MoS2) thin film as a saturable absorber was experimentally demonstrated by realizing a stable and robust passive mode-locked fiber laser via the evanescent field interaction between the light and the film. The MoS2 film was grown by chemical vapor deposition, and was then transferred to a side polished fiber by a lift-off method. Intensity-dependent optical transmission through the MoS2 thin film on side polished fiber was experimentally observed showing efficient saturable absorption characteristics. Using erbium doped fiber as an optical gain medium, we built an all-fiber ring cavity, where the MoS2 film on the side polished fiber was inserted as a saturable absorber. Stable dissipative soliton pulse trains were successfully generated in the normal dispersion regime with a spectral bandwidth of 23.2 nm and the pulse width of 4.98 ps. By adjusting the total dispersion in the cavity, we also obtained soliton pulses with a width of 637 fs in the anomalous dispersion regime near the lasing wavelength λ = 1.55 μm. Detailed and systematic experimental comparisons were made for stable mode locking of an all-fiber laser cavity in both the normal and anomalous regimes.

  5. Quantitative analysis of electron energy loss spectra and modelling of optical properties of multilayer systems for extreme ultraviolet radiation regime

    SciTech Connect

    Gusenleitner, S.; Hauschild, D.; Reinert, F.; Handick, E.

    2014-03-28

    Ruthenium capped multilayer coatings for use in the extreme ultraviolet (EUV) radiation regime have manifold applications in science and industry. Although the Ru cap shall protect the reflecting multilayers, the surface of the heterostructures suffers from contamination issues and surface degradation. In order to get a better understanding of the effects of these impurities on the optical parameters, reflection electron energy loss spectroscopy (REELS) measurements of contaminated and H cleaned Ru multilayer coatings were taken at various primary electron beam energies. Experiments conducted at low primary beam energies between 100 eV and 1000 eV are very surface sensitive due to the short inelastic mean free path of the electrons in this energy range. Therefore, influences of the surface condition on the above mentioned characteristics can be appraised. In this paper, it can be shown that carbon and oxide impurities on the mirror surface decrease the transmission of the Ru cap by about 0.75% and the overall reflectance of the device is impaired as the main share of the non-transmitted EUV light is absorbed in the contamination layer.

  6. Magnetic layer thickness dependence of all-optical magnetization switching in GdFeCo thin films

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Hiroki; El Moussaoui, Souliman; Terashita, Shinnosuke; Ueda, Ryohei; Tsukamoto, Arata

    2016-07-01

    To clarify the relationship between all-optical magnetization switching (AOS) and nonlocal and nonadiabatic energy dissipation process, we focus on the contribution from energy dissipation in the depth direction. Differently designed structure dependence of created magnetic domain is observed from the reversal phenomenon, AOS, or multidomains by thermomagnetic nucleation (TMN) in GdFeCo multilayer thin films. TMN depends on the shared absorbed energy throughout the continuous metallic volume. On the other hand, AOS critically depends on nonadiabatic energy dissipation process with the electron system in sub-picoseconds. Furthermore, the laser fluence dependence of AOS-created domain sizes indicates that the value of irradiated laser fluence threshold per magnetic domain volume is almost constant. However, a lower laser irradiation fluence below 1-2 mW has a larger value and thickness dependence. From these results, we suggest that AOS depends on energy dissipation from the incident surface in the depth direction for a few picoseconds.

  7. Deposition and characterization of titania-silica optical multilayers by asymmetric bipolar pulsed dc sputtering of oxide targets

    NASA Astrophysics Data System (ADS)

    Sagdeo, P. R.; Shinde, D. D.; Misal, J. S.; Kamble, N. M.; Tokas, R. B.; Biswas, A.; Poswal, A. K.; Thakur, S.; Bhattacharyya, D.; Sahoo, N. K.; Sabharwal, S. C.

    2010-02-01

    Titania-silica (TiO2/SiO2) optical multilayer structures have been conventionally deposited by reactive sputtering of metallic targets. In order to overcome the problems of arcing, target poisoning and low deposition rates encountered there, the application of oxide targets was investigated in this work with asymmetric bipolar pulsed dc magnetron sputtering. In order to evaluate the usefulness of this deposition methodology, an electric field optimized Fabry Perot mirror for He-Cd laser (λ = 441.6 nm) spectroscopy was deposited and characterized. For comparison, this mirror was also deposited by the reactive electron beam (EB) evaporation technique. The mirrors developed by the two complementary techniques were investigated for their microstructural and optical reflection properties invoking atomic force microscopy, ellipsometry, grazing incidence reflectometry and spectrophotometry. From these measurements the layer geometry, optical constants, mass density, topography, surface and interface roughness and disorder parameters were evaluated. The microstructural properties and spectral functional characteristics of the pulsed dc sputtered multilayer mirror were found to be distinctively superior to the EB deposited mirror. The knowledge gathered during this study has been utilized to develop a 21-layer high-pass edge filter for radio photoluminescence dosimetry.

  8. The hard magnetic properties and microstructure evolution of the multilayer [NdFeBNbCu/FeBSi]ṡn thin films

    NASA Astrophysics Data System (ADS)

    Chiriac, H.; Grigoras, M.; Lupu, N.; Urse, M.; Buta, V.

    2008-04-01

    The influence of the thickness of constituent layers and annealing conditions for multilayer [NdFeBNbCu/FeBSi]ṡn thin films on the magnetic properties and microstructure is reported. The Nb-Cu combination inhibits the grain growth and promotes the formation of nucleation sites. The FeSiB layer insertion leads to a slight increase in the Curie temperature and to a rectangular hysteresis loop. As compared to Ta /NdFeBNbCu (540nm)/Ta single layer, the Ta /[NdFeBNbCu(180nm)/FeBSi(15nm)]ṡ3/Ta multilayer nanocomposite films exhibit very good magnetic properties such as squareness Mr/Ms of about 0.92, maximum energy product of about 397kJ/m3, and an increase in the Curie temperature of about 17°C due to stratification by using FeBSi film as space layer.

  9. Optical properties analysis of Ta-doped TiO2 thin films on LaAlO3 substrates

    NASA Astrophysics Data System (ADS)

    Nurfani, Eka; Sutjahja, Inge M.; Winata, Toto; Rusydi, Andrivo; Darma, Yudi

    2015-09-01

    We study optical properties of Ta-doped TiO2 thin film on LaAlO3 substrate using spectroscopy ellipsometry (SE) analysis at energy range of 0.5 - 6.5 eV. Room temperature SE data for Ψ (amplitude ratio) and Δ (phase difference) between p- and s- polarized light waves are taken with multiple incident angles at several spots on the samples. Here, absorption coefficient has been extracted from SE measurements at photon incident angle of 70° for different Ta concentration (0.01, 0.4, and 5 at. %). Multilayer modelling is performed which takes into account reflections at each interface through Fresnel coefficients to obtain reasonably well the fitting of Ψ and Δ data simultaneously. As the results, we estimate that film thickness increases by increasing Ta concentration accompanied by the formation of a new electronic structure. By increasing Ta impurities, the blueshift of absorption coefficient (α) peaks is observable. This result indicates that TiO2 thin film becomes optically resistive by introducing Ta doping. Schematic model of interband transition inTiO2:Ta will be proposed base on obtained optical properties. This study enables us to predict the role of Ta doping on the electronic and optical band structures of TiO2 thin film. Due to a processing error by AIP Publishing, an incorrect version of the above article was published on 30 September 2015 that omitted the name of author Toto Winata. AIP Publishing apologizes for this error. All online versions of the article were corrected on 7 October 2015. The author names and affiliations appear correctly above.

  10. An analytical approach to estimating aberrations in curved multilayer optics for hard x-rays: 1. Derivation of caustic shapes.

    PubMed

    Guigay, J-P; Morawe, Ch; Mocella, V; Ferrero, C

    2008-08-04

    An analytical approach has been developed to derive aberration effects in parabolic and elliptic multilayer optics with weak interaction between photons and matter. The method is based on geometrical ray tracing including refraction effects up to the first order of the refractive index decrement delta. In the parabolic case, the derivation leads to simple parametric equations for the caustic shape. In the elliptic case, the analytical results more involved, but can be well approximated by the parabolic solution. Both geometries are compared with regard to the fundamental impact on their focusing properties.

  11. State-of-the-art thin film X-ray optics for synchrotrons and FEL sources

    NASA Astrophysics Data System (ADS)

    Hertlein, Frank; Wiesmann, Jörg; Michaelsen, Carsten; Störmer, Michael; Seifert, Andreas

    2007-05-01

    Selected aspects of simulation, preparation and characterization of total reflection and multilayer X-ray optics will be discussed. The best multilayer is found by calculating the optical properties of the coating. Sophisticated improvements in deposition technology allow the precise realization of the specified parameters when manufacturing the X-ray optics. The quality of the shape of the substrate for the optics is measured with the aid of profilometry. X-ray reflectometry measures both film thickness as well as their lateral gradient. Last but not least we will be showing results of the development of carbon coatings as total reflection mirrors for FEL (free electron laser) sources. Over the past years we have developed optimized optics for the XUV range up to 200 eV. First FEL irradiation tests have shown that carbon coatings offer high reflectivity > 95%, high radiation stability, good uniformity in thickness and roughness. An optimized coating of two stripes for different beam energies was produced especially for a tomography beamline, where a Ru/C multilayer was chosen for energies between 10 and 22 keV and a W/Si multilayer for energies between 22 and 45 keV.

  12. An Atmospheric Radiation Measurement Value-Added Product to Retrieve Optically Thin Cloud Visible Optical Depth using Micropulse Lidar

    SciTech Connect

    Lo, C; Comstock, JM; Flynn, C

    2006-10-01

    The purpose of the Micropulse Lidar (MPL) Cloud Optical Depth (MPLCOD) Value-Added Product (VAP) is to retrieve the visible (short-wave) cloud optical depth for optically thin clouds using MPL. The advantage of using the MPL to derive optical depth is that lidar is able to detect optically thin cloud layers that may not be detected by millimeter cloud radar or radiometric techniques. The disadvantage of using lidar to derive optical depth is that the lidar signal becomes attenuation limited when τ approaches 3 (this value can vary depending on instrument specifications). As a result, the lidar will not detect optically thin clouds if an optically thick cloud obstructs the lidar beam.

  13. Multilayer Thin Film Polarizer Design for Far Ultraviolet using Induced Transmission and Absorption Technique

    NASA Technical Reports Server (NTRS)

    Kim, Jongmin; Zukic, Muamer; Wilson, Michele M.; Park, Jung Ho; Torr, Douglas G.

    1994-01-01

    Good theoretical designs of far ultraviolet polarizers have been reported using a MgF2/Al/MgF2 three layer structure on a thick Al layer as a substrate. The thicknesses were determined to induce transmission and absorption of p-polarized light. In these designs Al optical constants were used from films produced in ultrahigh vacuum (UHV: 10(exp -10) torr). Reflectance values for polarizers fabricated in a conventional high vacuum (p approx. 10(exp -6 torr)) using the UHV design parameters differed dramatically from the design predictions. Al is a highly reactive material and is oxidized even in a high vacuum chamber. In order to solve the problem other metals have been studied. It is found that a larger reflectance difference is closely related to higher amplitude and larger phase difference of Fresnel reflection coefficients between two polarizations at the boundary of MgF2/metal. It is also found that for one material a larger angle of incidence from the surface normal brings larger amplitude and phase difference. Be and Mo are found good materials to replace Al. Polarizers designed for 121.6 nm with Be at 60 deg and with Mo at 70 deg are shown as examples.

  14. Giant magnetoimpedance effect in a thin-film multilayer meander-like sensor

    NASA Astrophysics Data System (ADS)

    Vilela, G. L. S.; Monsalve, J. G.; Rodrigues, A. R.; Azevedo, A.; Machado, F. L. A.

    2017-03-01

    A meander-like magnetic sensing element based on the giant magnetoimpedance (GMI) effect was prepared by using optical lithography and sputtering deposition techniques. The structure of the sensing element consists of layers of Permalloy (Py = Ni81Fe19), titanium (Ti), and copper (Cu) with composition [Py(100 nm)/Ti(6 nm)]4/Cu(400 nm)/[Py(100 nm)/Ti(6 nm)]4. The GMI was investigated at room temperature under applied magnetic fields (H) varying in the range of ±4.0 kOe in both longitudinal and transversal geometries. The amplitude Iac and frequency f of the ac electrical current were varied in the range of 0.35-6.50 mA and 0.1-20 MHz, respectively. The overall dc electrical resistance of the sensing element was found to be 45.6 Ω. The sensing element yielded a GMI of 53.5% for H ≃ 5.0 Oe and f = 7.0 MHz, and the corresponding maximum average sensitivity of about 5 Ω/Oe. The sensing element was used for measuring the local Earth magnetic field ( H l o c a l = 0.26 ± 0.03 Oe) yielding a value close to the one measured by using a Hall sensor probe ( = 0.23 ± 0.01 Oe). GMI sensors are being used in applications such as accelerometers, magnetometers, biomagnetism, magnetic compasses, traffic control, non-destructive analysis, and virus and cancer cell detection.

  15. Multifunctional Hybrid Multilayer Gate Dielectrics with Tunable Surface Energy for Ultralow-Power Organic and Amorphous Oxide Thin-Film Transistors.

    PubMed

    Byun, Hye-Ran; You, Eun-Ah; Ha, Young-Geun

    2017-03-01

    For large-area, printable, and flexible electronic applications using advanced semiconductors, novel dielectric materials with excellent capacitance, insulating property, thermal stability, and mechanical flexibility need to be developed to achieve high-performance, ultralow-voltage operation of thin-film transistors (TFTs). In this work, we first report on the facile fabrication of multifunctional hybrid multilayer gate dielectrics with tunable surface energy via a low-temperature solution-process to produce ultralow-voltage organic and amorphous oxide TFTs. The hybrid multilayer dielectric materials are constructed by iteratively stacking bifunctional phosphonic acid-based self-assembled monolayers combined with ultrathin high-k oxide layers. The nanoscopic thickness-controllable hybrid dielectrics exhibit the superior capacitance (up to 970 nF/cm(2)), insulating property (leakage current densities <10(-7) A/cm(2)), and thermal stability (up to 300 °C) as well as smooth surfaces (root-mean-square roughness <0.35 nm). In addition, the surface energy of the hybrid multilayer dielectrics are easily changed by switching between mono- and bifunctional phosphonic acid-based self-assembled monolayers for compatible fabrication with both organic and amorphous oxide semiconductors. Consequently, the hybrid multilayer dielectrics integrated into TFTs reveal their excellent dielectric functions to achieve high-performance, ultralow-voltage operation (< ± 2 V) for both organic and amorphous oxide TFTs. Because of the easily tunable surface energy, the multifunctional hybrid multilayer dielectrics can also be adapted for various organic and inorganic semiconductors, and metal gates in other device configurations, thus allowing diverse advanced electronic applications including ultralow-power and large-area electronic devices.

  16. Structure and Optical Properties of Nanocrystalline Hafnium Oxide Thin Films (PostPrint)

    DTIC Science & Technology

    2014-09-01

    AFRL-RX-WP-JA-2014-0214 STRUCTURE AND OPTICAL PROPERTIES OF NANOCRYSTALLINE HAFNIUM OXIDE THIN FILMS (POSTPRINT) Neil R. Murphy AFRL...OPTICAL PROPERTIES OF NANOCRYSTALLINE HAFNIUM OXIDE THIN FILMS (POSTPRINT) 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...microstructure and optical constants is established. 15. SUBJECT TERMS hafnium oxide , sputter-deposition, structure, XRR, optical properties

  17. Feasibility of Ultra-Thin Fiber-Optic Dosimeters for Radiotherapy Dosimetry.

    PubMed

    Lee, Bongsoo; Kwon, Guwon; Shin, Sang Hun; Kim, Jaeseok; Yoo, Wook Jae; Ji, Young Hoon; Jang, Kyoung Won

    2015-11-17

    In this study, prototype ultra-thin fiber-optic dosimeters were fabricated using organic scintillators, wavelength shifting fibers, and plastic optical fibers. The sensor probes of the ultra-thin fiber-optic dosimeters consisted of very thin organic scintillators with thicknesses of 100, 150 and 200 μm. These types of sensors cannot only be used to measure skin or surface doses but also provide depth dose measurements with high spatial resolution. With the ultra-thin fiber-optic dosimeters, surface doses for gamma rays generated from a Co-60 therapy machine were measured. Additionally, percentage depth doses in the build-up regions were obtained by using the ultra-thin fiber-optic dosimeters, and the results were compared with those of external beam therapy films and a conventional fiber-optic dosimeter.

  18. Feasibility of Ultra-Thin Fiber-Optic Dosimeters for Radiotherapy Dosimetry

    PubMed Central

    Lee, Bongsoo; Kwon, Guwon; Shin, Sang Hun; Kim, Jaeseok; Yoo, Wook Jae; Ji, Young Hoon; Jang, Kyoung Won

    2015-01-01

    In this study, prototype ultra-thin fiber-optic dosimeters were fabricated using organic scintillators, wavelength shifting fibers, and plastic optical fibers. The sensor probes of the ultra-thin fiber-optic dosimeters consisted of very thin organic scintillators with thicknesses of 100, 150 and 200 μm. These types of sensors cannot only be used to measure skin or surface doses but also provide depth dose measurements with high spatial resolution. With the ultra-thin fiber-optic dosimeters, surface doses for gamma rays generated from a Co-60 therapy machine were measured. Additionally, percentage depth doses in the build-up regions were obtained by using the ultra-thin fiber-optic dosimeters, and the results were compared with those of external beam therapy films and a conventional fiber-optic dosimeter. PMID:26593917

  19. High-efficiency diffractive x-ray optics from sectioned multilayers

    SciTech Connect

    Kang, H C; Stephenson, G B; Liu, C; Conley, R; Macrander, A T; Maser, J; Bajt, S; Chapman, H N

    2004-12-14

    We investigate the diffraction properties of sectioned multilayers in Laue (transmission) geometry, at hard x-ray energies (9.5 and 19.5 keV). Two samples are studied, a 200 period W/Si multilayer of 29 nm d-spacing, and a 2020 period Mo/Si multilayer of 7 nm d-spacing, with cross-section depths ranging from 2 to 17 {micro}m. Rocking curves across the Bragg reflections exhibit well-defined interference fringes originating from the depth of the sample. Efficiencies as high as 70% were obtained. This exceeds the theoretical limit for standard zone plates operating in the multi-beam regime, demonstrating that all of the intensity can be directed into a single diffraction order in small-period structures.

  20. Thin-film fiber optic hydrogen and temperature sensor system

    DOEpatents

    Nave, S.E.

    1998-07-21

    The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiber optic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences. 3 figs.

  1. Investigations of the structural, morphological and electrical properties of multilayer ZnO/TiO2 thin films, deposited by sol-gel technique

    NASA Astrophysics Data System (ADS)

    Khan, M. I.; Bhatti, K. A.; Qindeel, Rabia; Bousiakou, Leda G.; Alonizan, Norah; Fazal-e-Aleem

    Investigations of the structural, morphological and electrical properties of multilayer ZnO/TiO2 thin films deposited by sol-gel technique on glass substrate. Sol-gel is a technique in which compound is dissolved in a liquid in order to bring it back as a solid in a controlled manner. TiO2 solution was obtained by dissolving 0.4 g of TiO2 nano powder in 5 ml ethanol and 5 ml diethylene glycol. ZnO solution was obtained by dissolving 0.88 g zinc acetate in 20 ml of 2-methoxyethanol. X-ray diffraction (XRD) (PW 3050/60 PANalytical X'Pert PRO diffractometer) results showed that the crystallinity is improved when the number of ZnO/TiO2 layers increased. Also it shows the three phases (rutile, anatase and brookite) of TiO2. Surface morphology measured by scanning electron microscopy (SEM) (Quanta 250 fei) revealed that Crakes are present on the surface of ZnO/TiO2 thin films which are decreased when the number of ZnO/TiO2 layers increased. Four point probe (KIETHLEY instrument) technique used to investigate the electrical properties of ZnO/TiO2 showed the average resistivity decreased by increasing the number of ZnO/TiO2 layers. These results indicated that the multilayer thin films improved the quality of film crystallinity and electrical properties as compared to single layer.

  2. Piezoelectric and Dielectric Properties of Multilayered BaTiO3/(Ba,Ca)TiO3/CaTiO3 Thin Films.

    PubMed

    Zhu, Xiao Na; Gao, Ting Ting; Xu, Xing; Liang, Wei Zheng; Lin, Yuan; Chen, Chonglin; Chen, Xiang Ming

    2016-08-31

    Highly oriented multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films were fabricated on Nb-doped (001) SrTiO3 (Nb:STO) substrates by pulsed laser deposition. The configurations of multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films are designed with the thickness ratio of 1:1:1 and 2:1:1 and total thickness ∼300 nm. Microstructural characterization by X-ray diffraction indicates that the as-deposited thin films are highly c-axis oriented and large in-plane strain is determined in BaTiO3 and CaTiO3 layers. Piezoresponse force microscopy (PFM) studies reveal an intense in-plane polarization component, whereas the out-of-plane shows inferior phase contrast. The optimized combination is found to be the BaTiO3-(Ba0.85Ca0.15)TiO3-CaTiO3 structure with combination ratio 2:1:1, which displays the largest domain switching amplitude under DC electric field, the largest room-temperature dielectric constant ∼646, a small dielectric loss of 0.03, and the largest dielectric tunability of ∼50% at 400 kV/cm. These results suggest that the enhanced dielectric and tunability performance are greatly associated with the large in-plane polarization component and domain switching.

  3. Optical study of thin-film photovoltaic cells with apparent optical path length

    NASA Astrophysics Data System (ADS)

    Cho, Changsoon; Jeong, Seonju; Lee, Jung-Yong

    2016-09-01

    Extending the insufficient optical path length (OPL) in thin-film photovoltaic cells (PVs) is the key to achieving a high power conversion efficiency (PCE) in devices. Here, we introduce the apparent OPL (AOPL) as a figure of merit for light absorbing capability in thin-film PVs. The optical characteristics such as the structural effects and angular responses in thin-film PVs were analyzed in terms of the AOPL. Although the Lambertian scattering surface yields a broadband absorption enhancement in thin-film PVs, the enhancement is not as effective as in thick-film PVs. On the other hand, nanophotonic schemes are introduced as an approach to increasing the single-pass AOPL by inducing surface plasmon resonance. The scheme using periodic metal gratings is proved to increase the AOPL in a narrow wavelength range and specific polarization, overcoming the Yablonovitch limit. The AOPL calculation can be also adopted in the experimental analysis and a maximum AOPL of 4.15d (where d is the active layer thickness) is exhibited in the absorption band edge region of PTB7:PC70BM-based polymer PVs.

  4. Optical constants and nonlinear calculations of fluorescein/FTO thin film optical system

    NASA Astrophysics Data System (ADS)

    Zahran, H. Y.; Iqbal, Javed; Yahia, I. S.

    2016-11-01

    The organic thin films of fluorescein dye were deposited on fluorine-doped tin oxide glass substrate by using low-cost spin coating technique. The surface of the deposited film was characterized by using AFM and X-ray diffraction spectroscopy, which shows that the film is uniform and amorphous. The spectrophotometric study was carried out at the wavelength range of 300-2500 nm. The spectral dependences of the linear refractive index and absorption index were found to decrease as the wavelength was increased. Tauc's plot study revealed that the film shows the direct transition and energy band gap values were found 1.75 eV and 3.55 eV for the thin film and the substrate, respectively. Optical constants were found nearly the same in the higher energy domain (1.0-4.5 eV). Spectroscopic method was employed to study the nonlinear optical susceptibility χ (3). The deposited thin film is a promising optical system for new generation of optoelectronics.

  5. Controlling Optical Properties of Electrodes With Stacked Metallic Thin Films for Polymeric Light-Emitting Diodes and Displays

    NASA Astrophysics Data System (ADS)

    Wu, Elbert Hsing-En; Li, Sheng-Han; Chen, Chieh-Wei; Li, Gang; Xu, Zheng; Yang, Yang

    2005-09-01

    A semi-transparent metallic film and a high optical absorbing film were constructed with stacking metallic films. Both films were used as cathodes for polymeric light-emitting diodes (PLEDs). The semi-transparent film was made of gold/aluminum/gold thin multilayers with its optical transparency of the device reaches as high as ~70% in the visible region without capping layer, and the electrical sheet resistance reduces below 10 Omega/square. During illumination of the PLED, there was approximately 47% of light emitting from the top of the cathode surface, and 53% of light from the ITO side. The high optical absorbing film, also refer to as the black cathode, was constructed with four alternating layers of aluminum-silver, each aluminum or silver layer is 4 nm thick. The PLED with this black cathode demonstrated 126% enhancement of contrast under 1000 lx ambient illumination. The physical properties of these two cathodes were characterized by current-voltage measurement and atomic force microscopy. Ultraviolet-visible transmission spectroscopy and X-ray photoemission spectroscopy were also used to characterize the semi-transparent cathode and the black cathode respectively. For polymer light-emitting device,it is believed that morphology modification at each interface of the cathode plays a crucial role in determining the optical properties and conductivity of the over cathode.

  6. Maria Goeppert-Mayer Award Talk: Novel Magnetism and Transport in Complex Oxide Thin Films, Multilayers and Nanostructures

    NASA Astrophysics Data System (ADS)

    Suzuki, Yuri

    2005-03-01

    In epitaxial complex oxide systems, epitaxial strain, cation substitution and nanofabrication are just some ways in which their magnetic, electronic and optical properties may be tuned. In addition, their surfaces and interfaces provide a rich playground for the exploration of novel magnetic properties not found in the bulk constituents and the development of functional interfaces to be incorporated into technological applications. We have probed magnetism in complex oxide materials through studies of epitaxial oxide thin films, nanostructures and junction devices. With our ability to control oxide film growth as well as our expertise in nanofabrication, we have been able to study the effects of surfaces and interfaces on magnetism in ultra-thin magnetic oxide films and magnetic oxide nanostructures. For example, we have found that the nature of local magnetic structure in submicron islands of colossal magnetoresistance (CMR) material reveals the importance of shape anisotropy as well as magnetostriction in determining the micromagnetics in such small CMR structures. We have also studied epitaxial oxide trilayer junctions composed of magnetite (Fe3O4) and doped manganite (La0.7Sr0.3MnO3) in which we have confirmed the theoretically predicted negative spin polarization of Fe3O4. Transport through the barrier can be understood in terms of hopping transport through localized states that preserves electron spin information.

  7. Growth and optical properties of SrBi2Nb2O9 ferroelectric thin films using pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Yang, Pingxiong; Carroll, David L.; Ballato, John; Schwartz, Robert W.

    2003-06-01

    High quality SrBi2Nb2O9 ferroelectric thin films were fabricated on platinized silicon using pulsed laser deposition assisted with dc glow discharge plasma. Microstructure and ferroelectric properties of the films were characterized. Optical properties of the thin films were studied by spectroscopic ellipsometry and photoluminescence from the ultraviolet to the infrared region. Optical constants, n˜0.56 in the infrared region and n˜2.24 in the visible spectral region, were determined through multilayer analyses on their respective pseudodielectric functions. The band-gap energy is estimated to be 3.60 eV. A photoluminescence peak at 0.78 μm, whose intensity decreases with decreasing temperature, was observed when excited with subband-gap energy (2.41 eV). This emission process may involve intermediate defect states at the crystallite boundaries. A possible mechanism for the observed photoluminescence, a Nb4+-O- exciton in the NbO6 octahedron, is discussed.

  8. Magnetically soft, high-moment, high-resistivity thin films using discontinuous metal/native oxide multilayers

    NASA Astrophysics Data System (ADS)

    Beach, G. S. D.; Berkowitz, A. E.; Parker, F. T.; Smith, David J.

    2001-07-01

    Multilayers consisting of discontinuous metal layers with native oxide surfaces have been fabricated using CoxFe100-x alloys ranging in composition from pure Co to pure Fe. For the Fe-containing compositions, the composites are magnetically soft with resistivities in the range of 100 to 2000 μΩ cm. Mössbauer spectroscopy indicates a magnetically ordered Fe-oxide component, and the magnetic moment of the oxide phase for pure Fe/native oxide multilayers has been determined.

  9. Vanadium dioxide thin films for smart windows: optical design and performance improvement

    NASA Astrophysics Data System (ADS)

    He, Xinfeng; Gu, Congcong; Chen, Fei; Xu, Xiaofeng

    2013-12-01

    The high quality vanadium dioxide (VO2) thin films have been fabricated successfully on sapphire by a simple novel sputtering oxidation coupling (SOC) method. Transmittance spectra of vanadium dioxide film have been measured between 25 °C and 90 °C. The thin film samples exhibit a good insulator-metal transition near room temperature. The optical constants of VO2 thin film samples were derived by fitting the transmittance spectra using the Drude-Lorentz model. In order to improve the transition efficiency, the thin film thickness was optimized by the optical design. The calculated results with different thin film thickness show that VO2 thin film with 84 nm owns a maximums value of the transition efficiency. This research will promote VO2 thin film optical performance improvement for the smart windows.

  10. Magnetic and magneto-optical properties and domain structure of Co/Pd multilayers

    NASA Technical Reports Server (NTRS)

    Gadetsky, S.; Wu, Teho; Suzuki, T.; Mansuripur, M.

    1993-01-01

    The domain structure of Co/Pd(1.6/6.3 A)xN multilayers and its relation to the bulk magnetic properties of the samples were studied. The Co/Pd multilayers were deposited by rf and dc magnetron sputtering onto different substrates. It was found that magnetic and magnetooptical properties and domain structure of the multilayers were affected by total film thickness and substrate condition. Magnetization, coercivity, and anisotropy of the films decreased significantly as the film thickness dropped below 100 A. However, Kerr rotation angle had a maximum at the same thickness. The width of the domain structure increased with the decrease of the film thickness attaining the single domain state at N = 10. The initial curves in Co/Pd multilayers were found to depend on demagnetization process. The samples demagnetized by inplane field showed the largest difference between initial curves and the corresponding parts of the loops. Different domain structures were observed in the samples demagnetized by perpendicular and in-plane magnetic fields.

  11. HfO2/SiO2 multilayer based reflective and transmissive optics from the IR to the UV

    NASA Astrophysics Data System (ADS)

    Wang, Jue; Hart, Gary A.; Oudard, Jean Francois; Wamboldt, Leonard; Roy, Brian P.

    2016-05-01

    HfO2/SiO2 multilayer based reflective optics enable threat detection in the short-wave/middle-wave infrared and high power laser targeting capability in the near infrared. On the other hand, HfO2/SiO2 multilayer based transmissive optics empower early missile warning by taking advantage of the extremely low noise light detection in the deep-ultraviolet region where solar irradiation is strongly absorbed by the ozone layer of the earth's atmosphere. The former requires high laser damage resistance, whereas the latter needs a solar-blind property, i.e., high transmission of the radiation below 290 nm and strong suppression of the solar background from 300 nm above. The technical challenges in both cases are revealed. The spectral limits associated with the HfO2 and SiO2 films are discussed and design concepts are schematically illustrated. Spectral performances are realized for potential A and D and commercial applications.

  12. Optically transparent frequency selective surfaces on flexible thin plastic substrates

    SciTech Connect

    Dewani, Aliya A. O’Keefe, Steven G.; Thiel, David V.; Galehdar, Amir

    2015-02-15

    A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm), flexible transparent plastic substrate (relative permittivity 3.2). It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing) to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

  13. Optical and electrical properties of thin superconducting films

    NASA Technical Reports Server (NTRS)

    Covington, Billy C.; Jing, Feng Chen

    1990-01-01

    Infrared spectroscopic techniques can provide a vital probe of the superconducting energy gap which is one of the most fundamental physical properties of superconductors. Currently, the central questions regarding the optical properties of superconductors are how the energy gap can be measured by infrared techniques and at which frequency the gap exists. An effective infrared spectroscopic method to investigate the superconducting energy gap, Eg, was developed by using the Bomem DA 3.01 Fourier Transformation Spectrophotometer. The reflectivity of a superconducting thin film of YBaCuO deposited on SrTiO3 was measured. A shoulder was observed in the superconducting state reflectance R(sub S) at 480/cm. This gives a value of Eg/kT(sub c) = 7.83, where k is the Boltzmann constant and T(sub c) is the superconducting transition temperature, from which, it is suggested that YBaCuO is a very strong coupling superconductor.

  14. Ferroelectric Tungsten Bronze Bulk Crystals and Epitaxial Thin Films for Electro-Optic Device Applications

    DTIC Science & Technology

    1983-05-01

    23 FERROELECTRIC TUNGSTEN BRONZE BULK CRYSTALS AND EPITAXIAL THIN FILMS FOR ELECTRO-OPTIC DEVICE APPLICATIONS 10 CO O Semi-Annual Technical... THIN FILMS FOR ELECTRO-OPTIC DEVICE APPLICATIONS s TV^C or REPORT * pcmoo COVCHCO Semi-Annual Tec1! Rpt #1 for period 09/30/82-03/31/83...months, considerable progress has been made in several areas, including single crystal and thin film growth and characteriza- tion. The new

  15. Evaluation of space environmental effects on metals and optical thin films on EOIM-3

    NASA Technical Reports Server (NTRS)

    Vaughn, Jason A.; Linton, Roger C.; Finckenor, Miria M.; Kamenetzky, Rachel R.

    1995-01-01

    Metals and optical thin films exposed to the space environment on the Third Flight of the Evaluation of Oxygen Interactions with Materials (EOIM-3) payload, onboard Space Shuttle mission STS-46 were evaluated. The materials effects described in this paper include the effects of space exposure on various pure metals, optical thin films, and optical thin film metals. The changes induced by exposure to the space environment in the material properties were evaluated using bidirectional reflectance distribution function (BRDF), specular reflectance (250 nm to 2500 nm), ESCA, VUV reflectance (120 nm to 200 nm), ellipsometry, FTIR and optical properties. Using these analysis techniques gold optically thin film metal mirrors with nickel undercoats were observed to darken due to nickel diffusion through the gold to the surface. Also, thin film nickel mirrors formed nickel oxide due to exposure to both the atmosphere and space.

  16. The Effect of Viscous Air Damping on an Optically Actuated Multilayer MoS2 Nanomechanical Resonator Using Fabry-Perot Interference

    PubMed Central

    She, Yumei; Li, Cheng; Lan, Tian; Peng, Xiaobin; Liu, Qianwen; Fan, Shangchun

    2016-01-01

    We demonstrated a multilayer molybdenum disulfide (MoS2) nanomechanical resonator by using optical Fabry-Perot (F-P) interferometric excitation and detection. The thin circular MoS2 nanomembrane with an approximate 8-nm thickness was transferred onto the endface of a ferrule with an inner diameter of 125 μm, which created a low finesse F-P interferometer with a cavity length of 39.92 μm. The effects of temperature and viscous air damping on resonance behavior of the resonator were investigated in the range of −10–80 °C. Along with the optomechanical behavior of the resonator in air, the measured resonance frequencies ranged from 36 kHz to 73 kHz with an extremely low inflection point at 20 °C, which conformed reasonably to those solved by previously obtained thermal expansion coefficients of MoS2. Further, a maximum quality (Q) factor of 1.35 for the resonator was observed at 0 °C due to viscous dissipation, in relation to the lower Knudsen number of 0.0025~0.0034 in the tested temperature range. Moreover, measurements of Q factor revealed little dependence of Q on resonance frequency and temperature. These measurements shed light on the mechanisms behind viscous air damping in MoS2, graphene, and other 2D resonators. PMID:28335290

  17. Ultra-thin and low-power optical interconnect module based on a flexible optical printed circuit board

    NASA Astrophysics Data System (ADS)

    Hwang, Sung Hwan; Lee, Woo-Jin; Kim, Myoung Jin; Jung, Eun Joo; Kim, Gye Won; An, Jong Bae; Jung, Ki Young; Cha, Kyung Soon; Rho, Byung Sup

    2012-07-01

    We describe an ultra-thin and low-power optical interconnect module for mobile electronic devices such as mobile phones and notebooks. The module was fabricated by directly packaging optic and electronic components onto a thin and flexible optical printed circuit board having a size of 70×8×0.25 mm. The completed active module has features of thinness (0.5 mm), small size (7×5 mm), very low total power consumption (15.88 mW), and high data rate transmissions (2.5 Gbps).

  18. Linear and third-order nonlinear optical responses of multilayered Ag:Si3N4 nanocomposites.

    PubMed

    Toudert, J; Fernandez, H; Babonneau, D; Camelio, S; Girardeau, T; Solis, J

    2009-11-25

    The linear and third-order nonlinear responses of tailored Si3N4/Ag/Si3N4 trilayers and (Si3N4/Ag)n/Si3N4 multilayers grown by alternating ion-beam sputtering have been studied by combining complementary characterization techniques such as transmission electron microscopy, spectroscopic ellipsometry and degenerate four-wave mixing. The linear optical response dominated by the surface plasmon resonance of Ag nanoparticles has been measured over the whole visible range while the third-order nonlinear susceptibility has been probed at the surface plasmon resonance wavelength. Due to the weak in-plane interaction between Ag nanoparticles, the linear and nonlinear optical responses of the Si3N4/Ag/Si3N4 trilayers are mainly influenced by the size and shape of the nanoparticles. A maximum value of 1.1 x 10(-7) esu has been found at 635 nm for the effective third-order nonlinear susceptibility of the trilayer with the highest amount of silver. The linear optical response of the (Si3N4/Ag)n/Si3N4 multilayers is shown to be dominated by the surface plasmon resonance of isolated layers of weakly interacting nanoparticles at wavelengths shorter than 600 nm whereas a contribution due to vertical interactions has been shown for higher wavelengths. Below the vertical percolation threshold, their nonlinear optical response at the surface plasmon resonance wavelength is similar to the one of an isolated assembly of nanoparticles, and the effective third-order nonlinear susceptibility is slightly increased by decreasing the thickness of the Si3N4 spacer.

  19. Effects of channel structure consisting of ZnO/Al2O3 multilayers on thin-film transistors fabricated by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Cui, Guodong; Han, Dedong; Dong, Junchen; Cong, Yingying; Zhang, Xiaomi; Li, Huijin; Yu, Wen; Zhang, Shengdong; Zhang, Xing; Wang, Yi

    2017-04-01

    By applying a novel active layer comprising ZnO/Al2O3 multilayers, we have successfully fabricated fully transparent high-performance thin-film transistors (TFTs) with a bottom gate structure by atomic layer deposition (ALD) at low temperature. The effects of various ZnO/Al2O3 multilayers were studied to improve the morphological and electrical properties of the devices. We found that the ZnO/Al2O3 multilayers have a significant impact on the performance of the TFTs, and that the TFTs with the ZnO/15-cycle Al2O3/ZnO structure exhibit superior performance with a low threshold voltage (V TH) of 0.9 V, a high saturation mobility (μsat) of 145 cm2 V‑1 s‑1, a steep subthreshold swing (SS) of 162 mV/decade, and a high I on/I off ratio of 3.15 × 108. The enhanced electrical properties were explained by the improved crystalline nature of the channel layer and the passivation effect of the Al2O3 layer.

  20. Fabrication of multilayer TiO{sub 2} thin films for dye-sensitized solar cells with high conversion efficiency by electrophoresis deposition

    SciTech Connect

    Chang, Ho; Chen, Wei-An; Su, Hung-Ting; Chen, Sih-Li; David Huang, K.; Chien, Shu-Hua; Chen, Chih-Chieh

    2010-01-15

    This research coats a commercial TiO{sub 2} nanoparticle Degussa P25 with good roundness and size uniformity on an indium tin oxide (ITO) glass substrate and to be photoelectrical electrode by electrophoresis deposition. It combined with dye N719, electrolyte I{sup -}/ I{sub 3}{sup -} and counter-electrode of Pt layer to produce dye-sensitized solar cells (DSSCs). Through the electrophoretic technique, a multilayer film of an appropriate thickness is deposited in the suspension containing TiO{sub 2} nanoparticles and isopropanol. In this process, electric current, voltage, and the number of deposition cycles are well controlled to obtain a single TiO{sub 2} film of around 3.3 {mu}m thick. Stacking is then performed to obtain a multilayer-typed TiO{sub 2} film of around 12 {mu}m thick. As the sintering temperature reaches 400 C, the prepared multilayer TiO{sub 2} film with a good compactness can increase the dye adsorption capability of the thin film and enhance its adsorption percentage. In addition, the heat treatment will transfer a portion of the rutile crystalline into the anatase crystalline, resulting in better material properties for DSSCs application. DSSCs produced are exposed to metal halide lamp and their energy conversion efficiency is measured. The I-V curve of the produced DSSCs shows that it has an excellent energy conversion efficiency of 6.9%. (author)

  1. Investigation of local and nonlocal nonlinear optical refraction effect in IZO thin films

    NASA Astrophysics Data System (ADS)

    Htwe, Zin Maung; Zhang, Yun-Dong; Yao, Cheng-Bao; Li, Hui; Yuan, Ping

    2016-10-01

    We report the local and nonlocal nonlinear optical refraction properties of indium doped zinc oxide (IZO) thin films using closed aperture Z-scan technique. The Z-scan results show the films have positive nonlinear optical refraction properties. The nonlocal parameter m of samples is increased with indium. In both of local and nonlocal studies, the nonlinear optical refractions of thin films were increased with In contents and laser energy. This relation reveals the role of In composition in IZO affects on the nonlinear optical responses of the films. These results make the IZO thin films as the promising application in optoelectronics devices.

  2. Thin-film fiber optic hydrogen and temperature sensor system

    DOEpatents

    Nave, Stanley E.

    1998-01-01

    The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiberoptic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences.

  3. Layer-by-layer grown scalable redox-active ruthenium-based molecular multilayer thin films for electrochemical applications and beyond

    NASA Astrophysics Data System (ADS)

    Kaliginedi, Veerabhadrarao; Ozawa, Hiroaki; Kuzume, Akiyoshi; Maharajan, Sivarajakumar; Pobelov, Ilya V.; Kwon, Nam Hee; Mohos, Miklos; Broekmann, Peter; Fromm, Katharina M.; Haga, Masa-Aki; Wandlowski, Thomas

    2015-10-01

    Here we report the first study on the electrochemical energy storage application of a surface-immobilized ruthenium complex multilayer thin film with anion storage capability. We employed a novel dinuclear ruthenium complex with tetrapodal anchoring groups to build well-ordered redox-active multilayer coatings on an indium tin oxide (ITO) surface using a layer-by-layer self-assembly process. Cyclic voltammetry (CV), UV-Visible (UV-Vis) and Raman spectroscopy showed a linear increase of peak current, absorbance and Raman intensities, respectively with the number of layers. These results indicate the formation of well-ordered multilayers of the ruthenium complex on ITO, which is further supported by the X-ray photoelectron spectroscopy analysis. The thickness of the layers can be controlled with nanometer precision. In particular, the thickest layer studied (65 molecular layers and approx. 120 nm thick) demonstrated fast electrochemical oxidation/reduction, indicating a very low attenuation of the charge transfer within the multilayer. In situ-UV-Vis and resonance Raman spectroscopy results demonstrated the reversible electrochromic/redox behavior of the ruthenium complex multilayered films on ITO with respect to the electrode potential, which is an ideal prerequisite for e.g. smart electrochemical energy storage applications. Galvanostatic charge-discharge experiments demonstrated a pseudocapacitor behavior of the multilayer film with a good specific capacitance of 92.2 F g-1 at a current density of 10 μA cm-2 and an excellent cycling stability. As demonstrated in our prototypical experiments, the fine control of physicochemical properties at nanometer scale, relatively good stability of layers under ambient conditions makes the multilayer coatings of this type an excellent material for e.g. electrochemical energy storage, as interlayers in inverted bulk heterojunction solar cell applications and as functional components in molecular electronics applications

  4. Interface Properties of Atomic-Layer-Deposited Al2O3 Thin Films on Ultraviolet/Ozone-Treated Multilayer MoS2 Crystals.

    PubMed

    Park, Seonyoung; Kim, Seong Yeoul; Choi, Yura; Kim, Myungjun; Shin, Hyunjung; Kim, Jiyoung; Choi, Woong

    2016-05-11

    We report the interface properties of atomic-layer-deposited Al2O3 thin films on ultraviolet/ozone (UV/O3)-treated multilayer MoS2 crystals. The formation of S-O bonds on MoS2 after low-power UV/O3 treatment increased the surface energy, allowing the subsequent deposition of uniform Al2O3 thin films. The capacitance-voltage measurement of Au-Al2O3-MoS2 metal oxide semiconductor capacitors indicated n-type MoS2 with an electron density of ∼10(17) cm(-3) and a minimum interface trap density of ∼10(11) cm(-2) eV(-1). These results demonstrate the possibility of forming a high-quality Al2O3-MoS2 interface by proper UV/O3 treatment, providing important implications for their integration into field-effect transistors.

  5. Ordered organic-organic multilayer growth

    DOEpatents

    Forrest, Stephen R.; Lunt, Richard R.

    2016-04-05

    An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

  6. Ordered organic-organic multilayer growth

    DOEpatents

    Forrest, Stephen R; Lunt, Richard R

    2015-01-13

    An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

  7. High Energy Effects on Thermoelectric and Optical Properties of Si/Si+Sb Nanolayered Thin Films

    DTIC Science & Technology

    2013-04-01

    REPORT High Energy Effects on Thermoelectric and Optical Properties of Si/Si+Sb Nanolayered Thin Films 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: We...Energy Effects on Thermoelectric and Optical Properties of Si/Si+Sb Nanolayered Thin Films Report Title ABSTRACT We have prepared thermoelectric...the cross plane Seebeck coefficient and increase the cross plane electrical conductivity to increase the figure of merit. Some optical

  8. Investigation of multilayered polyelectrolyte thin films by means of refractive index measurements, FT-IR spectroscopy and SEM

    NASA Astrophysics Data System (ADS)

    Bodurov, I.; Vlaeva, I.; Exner, G.; Uzunova, Y.; Russev, S.; Pilicheva, B.; Viraneva, A.; Yovcheva, T.; Grancharova, Ts; Sotirov, S.; Marudova, M.

    2016-02-01

    Multilayered polyelectrolyte films are promising structures in the biomedical field. In order to meet the demands for biomedical applications, the structures have to be built from biocompatible and/or biodegradable, nontoxic starting materials, possessing some specific functional properties, depending on the particular application. In the present study, the multilayered polyelectrolyte films with potential use as buccal bioadhesive drug delivery systems were investigated. They were prepared via layer-by-layer deposition of successive nanolayers onto substrate. Three different biopolymers were used. The substrate, from poly(lactic acid), was solvent casted. After that, it was subjected to corona treatment, which ensures surface charge excess for the multilayer deposition. The nanolayers were prepared either from 0.01 g/L solutions of chitosan or 0.05 g/L xanthan. Acetate buffer (pH 4.5 and ionic strength 1 M) was used as a solvent. The substrate was dipped successively into one of the solutions, allowing formation of polyelectrolyte complexes of chitosan (polycation) and xanthan (polyanion). The substrates was treated in negative corona. The multilayered structures consisted of 8, 9, 14, 15 or 20 nanolayers. Number of techniques, such refractive index measurements, FT- IR spectroscopy and SEM morphology were employed in order to monitor the properties of the so prepared multilayered polyelectrolyte films.

  9. The impact of multilayer periodicity on texture, morphology, chemical stability and machining performance of titanium aluminum nitride/chromium nitride thin films

    NASA Astrophysics Data System (ADS)

    Delisle, Dale Andrew

    Multilayer thin films of TiAlN/CrN were deposited at varying bilayer periods (λ = 2, 4, 8 and 16 nm), along with a co-deposited (TiAlCr)N film and constituent TiAlN and CrN films, on both [111] silicon substrates and WC-4wt% Co inserts with an ISO SPGN 120308 geometry. The effects of periodicity on grain structure, texture, surface morphology, and roughness were examined, with characterization performed using electron microscopy, atomic force microscopy and x-ray diffraction analysis. An in-air constant temperature oxidation study was also performed at 650 thru 1050°C with stacked XRD line profiles and SEM used to identify the onset and extent of oxidation, respectively. Finally, dry high speed flank wear tool life experiments were completed against A2 tool steel, with the impact of the multilayer period reported in ISO standard wear vs. cutting time format. Machining results were connected back to the previously identified changes in structure. All films exhibited a rocksalt B1-type structure with a columnar morphology and lateral coarsening during film growth; which was more pronounced in the multilayer films with smaller bilayer periods. The surface morphology was found to be dependent on period; exhibiting sharp pyramidal surface features at λ = 2 nm and an increase in secondary faceting with increasing periodicity. Nearly rounded column tops result at λ = 16 nm. Surface roughness measurements showed an increasing roughness with decreasing bilayer period and pole figures revealed a small [111] texture component perpendicular to the sample surface in the 2 and 4 nm period films, with the distribution of [111] poles becoming nearly random for the films with larger periodicities (8 and 16 nm). Preferential [200] poles begin approximately 15° tilted away from the substrate normal while further increase in period results in a decrease in the off axis angle. The effect of multilayer period on the surface morphology is explained using an energetic argument

  10. Two-dimensional behavior in (YBa 2Cu 3O 7- δ) 24/(PrBa 2Cu 3O 7- δ) 2 multilayer thin films

    NASA Astrophysics Data System (ADS)

    Wang, Z. H.; Wang, S. J.; Chen, J. L.; Zhang, H.; Cao, X. W.

    1999-04-01

    We have measured the field and angular dependencies of the resistive broadening of epitaxial (YBa 2Cu 3O 7- δ) 24/(PrBa 2Cu 3O 7- δ) 2 multilayer thin film. The results show that in low measuring current density regime, the resistive broadening induced by magnetic field depends mainly on the orientation of applied magnetic field with respect to the c-axis rather than the macroscopic Lorentz force. The field dependence of the activation energy for H‖ c follows a logarithmic law, U∝ln H, similar to the results reported by Brunner et al. [O. Brunner, L. Antognazza, J.-M. Triscone, et al., Phys. Rev. Lett. 67 (1991) 1354.], suggesting a 2D character in the multilayer thin film. The angular dependence of the activation energy U and the characteristic temperature T* can be scaled by 2D model proposed by Kes et al. [P.H. Kes, J. Aarts, V.M. Vinokur, et al., Phys. Rev. Lett. 64 (1990) 267]. The phenomenon may be attributed to the flux lines that are cut by the insulating PrBCO layers when the applied magnetic field is tilted away from the ab-plane.

  11. Optical properties analysis of Ta-doped TiO{sub 2} thin films on LaAlO{sub 3} substrates

    SciTech Connect

    Nurfani, Eka; Sutjahja, Inge M.; Rusydi, Andrivo; Darma, Yudi

    2015-09-30

    We study optical properties of Ta-doped TiO{sub 2} thin film on LaAlO{sub 3} substrate using spectroscopy ellipsometry (SE) analysis at energy range of 0.5 – 6.5 eV. Room temperature SE data for Ψ (amplitude ratio) and Δ (phase difference) between p- and s- polarized light waves are taken with multiple incident angles at several spots on the samples. Here, absorption coefficient has been extracted from SE measurements at photon incident angle of 70° for different Ta concentration (0.01, 0.4, and 5 at. %). Multilayer modelling is performed which takes into account reflections at each interface through Fresnel coefficients to obtain reasonably well the fitting of Ψ and Δ data simultaneously. As the results, we estimate that film thickness increases by increasing Ta concentration accompanied by the formation of a new electronic structure. By increasing Ta impurities, the blueshift of absorption coefficient (α) peaks is observable. This result indicates that TiO{sub 2} thin film becomes optically resistive by introducing Ta doping. Schematic model of interband transition inTiO{sub 2}:Ta will be proposed base on obtained optical properties. This study enables us to predict the role of Ta doping on the electronic and optical band structures of TiO{sub 2} thin film.

  12. Magnetic-optical bifunctional CoPt3/Co multilayered nanowire arrays

    NASA Astrophysics Data System (ADS)

    Su, Yi-Kun; Yan, Zhi-Long; Wu, Xi-Ming; Liu, Huan; Ren, Xiao; Yang, Hai-Tao

    2015-10-01

    CoPt3/Co multilayered nanowire (NW) arrays are synthesized by pulsed electrodeposition into nanoporous anodic aluminum oxide (AAO) templates. The electrochemistry deposition parameters are determined by cyclic voltammetry to realize the well control of the ratio of Co to Pt and the length of every segment. The x-ray diffraction (XRD) patterns show that both Co and CoPt3 NWs exhibit face-centered cubic (fcc) structures. In the UV-visible absorption spectra, CoPt3/Co NW arrays show a red-shift with respect to pure CoPt3NWs. Compared with the pure Co nanowire arrays, the CoPt3/Co multilayered nanowire arrays show a weak shape anisotropy and well-modulated magnetic properties. CoPt3/Co multilayered nanowires are highly encouraging that new families of bimetallic nanosystems may be developed to meet the needs of nanomaterials in emerging multifunctional nanotechnologies. Project supported by the National Natural Science Foundation of China (Grant Nos. 51472165, 51471185, and 11274370).

  13. Technologies for manufacturing of high angular resolution multilayer coated optics for the New Hard X-ray Mission

    NASA Astrophysics Data System (ADS)

    Orlandi, A.; Basso, S.; Borghi, G.; Binda, R.; Citterio, O.; Grisoni, G.; Kools, J.; Marioni, F.; Missaglia, N.; Negri, B.; Negri, R.; Pareschi, G.; Raimondi, L.; Ritucci, A.; Salmaso, B.; Sironi, G.; Spiga, D.; Subranni, R.; Tagliaferri, G.; Valsecchi, G.; Vernani, D.

    2011-05-01

    In the frame of the technology development to be used for the Optical Payload of next future X-ray missions (such as e.g. New Hard X-ray Mission-ASI), a new set of manufacturing techniques were finalized by Media Lario Technologies (MLT), in collaboration with the Italian Space Agency (ASI) and the Brera Astronomical Observatory (INAF/OAB). The set of new technologies includes master manufacturing machines and processes, electroforming method, a vertical optical bench and metrology machines to support manufacturing and integration of mirrors. A magnetron sputtering PVD machine was upgraded and a Pt/C development study has been performed on the basis of the W/Si results obtained in the first phase of the study. New manufacturing technologies for highly accurate masters were developed and tested by mean of two full-size masters together with several dummies. A number of ultrathin Nickel-Cobalt focusing mirrors were manufactured via galvanic replication process from the masters and coated with Pt/C multilayer. Tests on substrate material, roughness and shape of the shell together with analysis on specimens were performed. Tests with AFM and XRR supported the development of the Pt/C multilayer which is the enabling technology for focusing high energy X-Rays. Several mirror shells were integrated into two demonstrator modules to assess the whole manufacturing process up to optical payload integration. The summary of the results from manufacturing and testing of specimens and mirror shells is reported in this paper together with a description of the technologies now available at MLT.

  14. Transparent thin-film characterization by using differential optical sectioning interference microscopy.

    PubMed

    Wang, Chun-Chieh; Lin, Jiunn-Yuan; Jian, Hung-Jhang; Lee, Chau-Hwang

    2007-10-20

    We propose an optical thin-film characterization technique, differential optical sectioning interference microscopy (DOSIM), for simultaneously measuring the refractive indices and thicknesses of transparent thin films with submicrometer lateral resolution. DOSIM obtains the depth and optical phase information of a thin film by using a dual-scan concept in differential optical sectioning microscopy combined with the Fabry-Perot interferometric effect and allows the solution of refractive index and thickness without the 2pi phase-wrapping ambiguity. Because DOSIM uses a microscope objective as the probe, its lateral resolution achieves the diffraction limit. As a demonstration, we measure the refractive indices and thicknesses of SiO2 thin films grown on Si substrate and indium-tin-oxide thin films grown on a glass substrate. We also compare the measurement results of DOSIM with those of a conventional ellipsometer and an atomic force microscope.

  15. Optical characterization of hydrogenated silicon thin films using interference technique

    NASA Astrophysics Data System (ADS)

    Globus, Tatiana; Ganguly, Gautam; Roca i Cabarrocas, Pere

    2000-08-01

    This work introduces an application of an "interference spectroscopy technique" (IST) for determination of absorption coefficient and refractive index spectra of amorphous silicon (a-Si:H) and related thin film materials. The technique is based on computer analysis of measurements of optical transmission and specular reflection (T & R) of thin films (including the films on substrates) over a wide range of the incident photon energies (0.5-2.8 eV) using carefully controlled spectrometer conditions. IST is used to investigate the absorption spectrum in the sub-gap energy range (0.8-1.6 eV) of intrinsic and phosphorous-doped a-Si:H, "polymorphous-Si:H," and microcrystalline silicon films. The enhanced sensitivity of the technique over conventional analysis of T & R data results from utilization of interference to obtain absorption coefficient values at the maxima of transmission. The factors limiting the accuracy of the calculated absorption coefficient are discussed in detail. Measurement on films of thickness ranging from 0.1 to 5 μm identifies that the sub-gap absorption in these films arises from the bulk rather than the surface. A set of samples prepared under widely different conditions that appear to have overlapping (α=20 cm-1) sub-gap absorption spectra measured using photo-thermal deflection spectroscopy (PDS), reveal significant differences (α=10 to 100 cm-1) using IST. Changes (factor of 2) in sub-gap absorption spectra due to light soaking are also clearly observable using IST.

  16. Optical and structural characterization of CeO2/B4C multilayers near boron K-edge energy

    NASA Astrophysics Data System (ADS)

    Sertsu, M. G.; Giglia, A.; Brose, S.; Comisso, A.; Wang, Z. S.; Juschkin, L.; Nicolosi, P.

    2015-05-01

    A search for novel materials for making multilayers of high reflectivity has been driven by the vigorous demand towards miniaturizing photonics. A typical consumer of high performance multilayers (MLs) is the extreme ultraviolet lithography (EUVL) based on the 13.5 nm laser produced plasma (LPP) source. To sustain "Moore's law" and print fine features below 10 nm on integrated circuits (IC), source of radiation for the EUVL has to shift towards even shorter wavelengths where 6.x nm wavelength seems to be immediate successor. However, the 6.x nm EUV lithography needs MLs of reflectivity performance above 70 % to support high volume manufacturing (HVM). It is clear that more work is required particularly on the development of MLs with high reflectance, stable to thermal heat and sufficient lifetime. In this work new MLs of B4C/CeO2 are deposited, analyzed and characterized for the first time. Combinations of X-ray reflectometry (XRR) and EUV reflectance measurements near resonance edge of boron are analyzed to derive structural and optical parameters of MLs. ML coatings of B4C/CeO2 MLs have shown similar reflectance performance with the leading candidate MLs around 6.x nm wavelength. Analysis shows that interlayer diffusion is a major reason for low reflectivity performance. Cross-sectional scanning electron microscopy (SEM) images of the MLs have proved formation of interlayer diffusion.

  17. Thin film technologies for optoelectronic components in fiber optic communication

    NASA Astrophysics Data System (ADS)

    Perinati, Agostino

    1998-02-01

    will grow at an annual average rate of 22 percent from 1.3 million fiber-km in 1995 to 3.5 million fiber-km in 2000. The worldwide components market-cable, transceivers and connectors - 6.1 billion in 1994, is forecasted to grow and show a 19 percent combined annual growth rate through the year 2000 when is predicted to reach 17.38 billion. Fiber-in-the-loop and widespread use of switched digital services will dominate this scenario being the fiber the best medium for transmitting multimedia services. As long as communication will partially replace transportation, multimedia services will push forward technology for systems and related components not only for higher performances but for lower cost too in order to get the consumers wanting to buy the new services. In the long distance transmission area (trunk network) higher integration of electronic and optoelectronic functions are required for transmitter and receiver in order to allow for higher system speed, moving from 2.5 Gb/s to 5, 10, 40 Gb/s; narrow band wavelength division multiplexing (WDM) filters are required for higher transmission capacity through multiwavelength technique and for optical amplifier. In the access area (distribution network) passive components as splitters, couplers, filters are needed together with optical amplifiers and transceivers for point-to-multipoint optical signal distribution: main issue in this area is the total cost to be paid by the customer for basic and new services. Multimedia services evolution, through fiber to the home and to the desktop approach, will be mainly affected by the availability of technologies suitable for component consistent integration, high yield manufacturing processes and final low cost. In this paper some of the optoelectronic components and related thin film technologies expected to mainly affect the fiber optic transmission evolution, either for long distance telecommunication systems or for subscriber network, are presented.

  18. Silicon-integrated thin-film structure for electro-optic applications

    DOEpatents

    McKee, Rodney A.; Walker, Frederick Joseph

    2000-01-01

    A crystalline thin-film structure suited for use in any of an number of electro-optic applications, such as a phase modulator or a component of an interferometer, includes a semiconductor substrate of silicon and a ferroelectric, optically-clear thin film of the perovskite BaTiO.sub.3 overlying the surface of the silicon substrate. The BaTiO.sub.3 thin film is characterized in that substantially all of the dipole moments associated with the ferroelectric film are arranged substantially parallel to the surface of the substrate to enhance the electro-optic qualities of the film.

  19. Ge2Sb2Te5/SnSe2 nanocomposite multilayer thin films for phase change memory application

    NASA Astrophysics Data System (ADS)

    Feng, Xiaoyi; Wen, Ting; Zhai, Jiwei; Lai, Tianshu; Wang, Changzhou; Song, Sannian; Song, Zhitang

    2014-10-01

    By nanocompositing Ge2Sb2Te5 and SnSe2, the electrical and thermal proprieties of Ge2Sb2Te5/SnSe2 multilayer films for phase change random access memory (PCRAM) are better than those of Ge2Sb2Te5 films. The crystallization temperature rises and can be controlled. The resistance gap can reach approximately five orders of magnitude to ensure high data reliability. The activity energy (Ea) is more than 2.60 eV and the temperature for 10 year data retention reach 110 °C. The analysis of both XRD patterns and TEM images confirmed the reversible phase change transition between amorphous and crystalline state in Ge2Sb2Te5/SnSe2 nanocomposite multilayer films. According to transient photoreflectance traces, the speed of crystallization process was about 33 ns. Among different Ge2Sb2Te5/SnSe2 multilayer films, the film constitute of [Ge2Sb2Te5 (4 nm)/SnSe2(10 nm)]7 showed better properties and was manufactured by CMOS technology to phase change memory (PCM) cells. This result revealed that the Ge2Sb2Te5/SnSe2 nanocomposite multilayer film is a promising phase change material.

  20. Nonlinear Optical Properties of Organic and Polymeric Thin Film Materials of Potential for Microgravity Processing Studies

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin; Frazier, Donald O.; Paley, Mark S.; Penn, Benjamin; Witherow, William K.; Bank, Curtis; Shields, Angela; Hicks, Rosline; Ashley, Paul R.

    1996-01-01

    In this paper, we will take a closer look at the state of the art of polydiacetylene, and metal-free phthalocyanine films, in view of the microgravity impact on their optical properties, their nonlinear optical properties and their potential advantages for integrated optics. These materials have many attractive features with regard to their use in integrated optical circuits and optical switching. Thin films of these materials processed in microgravity environment show enhanced optical quality and better molecular alignment than those processed in unit gravity. Our studies of these materials indicate that microgravity can play a major role in integrated optics technology. Polydiacetylene films are produced by UV irradiation of monomer solution through an optical window. This novel technique of forming polydiacetylene thin films has been modified for constructing sophisticated micro-structure integrated optical patterns using a pre-programmed UV-Laser beam. Wave guiding through these thin films by the prism coupler technique has been demonstrated. The third order nonlinear parameters of these films have been evaluated. Metal-free phthalocyanine films of good optical quality are processed in our laboratories by vapor deposition technique. Initial studies on these films indicate that they have excellent chemical, laser, and environmental stability. They have large nonlinear optical parameters and show intrinsic optical bistability. This bistability is essential for optical logic gates and optical switching applications. Waveguiding and device making investigations of these materials are underway.

  1. On the Nature and Extent of Optically Thin Marine low Clouds

    NASA Technical Reports Server (NTRS)

    Leahy, L. V.; Wood, R.; Charlson, R. J.; Hostetler, C. A.; Rogers, R. R.; Vaughan, M. A.; Winker, D. M.

    2012-01-01

    Macrophysical properties of optically thin marine low clouds over the nonpolar oceans (60 deg S-60 deg N) are measured using 2 years of full-resolution nighttime data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Optically thin clouds, defined as the subset of marine low clouds that do not fully attenuate the lidar signal, comprise almost half of the low clouds over the marine domain. Regionally, the fraction of low clouds that are optically thin (f(sub thin,cld)) exhibits a strong inverse relationship with the low-cloud cover, with maxima in the tropical trades (f(sub thin,cld) greater than 0.8) and minima in regions of persistent marine stratocumulus and in midlatitudes (f(sub thin,cld) less than 0.3). Domain-wide, a power law fit describes the cloud length distribution, with exponent beta = 2.03 +/- 0.06 (+/-95% confidence interval). On average, the fraction of a cloud that is optically thin decreases from approximately 1 for clouds smaller than 2 km to less than 0.3 for clouds larger than 30 km. This relationship is found to be independent of region, so that geographical variations in the cloud length distribution explain three quarters of the variance in f(sub thin,cld). Comparing collocated trade cumulus observations from CALIOP and the airborne High Spectral Resolution Lidar reveals that clouds with lengths smaller than are resolvable with CALIOP contribute approximately half of the low clouds in the region sampled. A bounded cascade model is constructed to match the observations from the trades. The model shows that the observed optically thin cloud behavior is consistent with a power law scaling of cloud optical depth and suggests that most optically thin clouds only partially fill the CALIOP footprint.

  2. Directional edge enhancement in optical tomography of thin phase objects.

    PubMed

    Meneses-Fabian, Cruz; Montes-Perez, Areli; Rodriguez-Zurita, Gustavo

    2011-01-31

    In this paper, we make a proposal to obtain the Hilbert-transform for each entry of the projection data leaving the slice of a thin phase object. These modified projections are stacked in such a way that they form a modified sinogram called Hilbert-sinogram. We prove that the inverse Radon-transform of this sinogram is the directional Hilbert-transform of the slice function, and the reconstructed image is the directional edge enhancement of the distribution function on the slice. The Hilbert-transform is implemented by a 4f optical Fourier-transform correlator and a spatial filter consisting of a phase step of π radians. One important feature of this proposal is to perform a turn of 180° in the spatial filter at a certain value of the projection angle within the range [0°, 360°]. The desired direction of enhancement can be chosen by the proper selection of such turning angle. We present both the mathematical modeling and numerical results.

  3. Optical waveguide spectrometer based on thin-film glass plates.

    PubMed

    Qi, Zhi-Mei; Matsuda, Naoki; Yoshida, Takamitsu; Asano, Hajime; Takatsu, Akiko; Kato, Kenji

    2002-11-15

    Commercially available thin-film glass plates have been successfully used for optical waveguide spectroscopy of chemical and biological films adsorbed upon the plates' surfaces. A 50-mum -thick glass plate was placed in contact with two parallel strips of silicone rubber supported on a slide glass. The plate area between the rubber strips served as the waveguiding region, eliminating the negative effect of the substrate on absorbance sensitivity. We coupled white light into the waveguide by focusing the light from a xenon lamp onto one end of a glass fiber and then inserting the other end into a glycerol drop overlaid upon the plate's surface. With a CCD detector, light at wavelengths as short as 360 nm was found to transmit out of the plate's end face. The propagation loss of the waveguide was measured to be

  4. Optical characterization of copper indium gallium diselenide thin films

    NASA Astrophysics Data System (ADS)

    Hebert, Damon

    Cu(In,Ga)Se2 (CIGS) and its alloys are the leading choice for thin film photovoltaic absorber layers due to their high performance in devices, low degradation, high optical absorption coefficient and high tolerance to off-stoichiometry and intrinsic defects. Film conductivity and recombination losses are controlled by intrinsic point defect concentrations, especially in the near-surface space-charge region of the heterojunction. Despite the amount of research already performed on CIGS alloys, their optoelectronic properties, defect chemistry and recombination mechanisms are still poorly understood. The focus of this dissertation is to optically characterize a selection of CIGS absorber layers fabricated by various techniques in order to better understand the radiative emission and defect physics. This work aims to identify the defects responsible for recombination and their relation to grain boundaries and band edge fluctuations, which limit device performance. This study used photoluminescence (PL) spectroscopy, photoluminescence excitation (PLE) spectroscopy, and cathodoluminescence (CL) to study radiative emissions from a variety of Cu-poor CIGS thin films. Three general types of CIGS films were analyzed. Polycrystalline layers deposited on Mo-coated soda lime glass, polycrystalline layers deposited on metal foil, and epitaxial films grown on (100) and (111) GaAs were analyzed in this work. This work concludes that the donor-acceptor pair recombination model used in most interpretations of CIGS emission should be replaced with a model that accounts for high compensation and band edge fluctuations, which is shown to be undoubtedly the case in Cu-poor CIGS. Within this model, the most commonly observed emissions were explained as free-to-bound types, specifically iii band-to-impurity (BI) and tail-to-impurity (TI) types. Band tail width was measured by PLE. A correlation was established between band tail width and device efficiency. CIGS absorber layers that

  5. Optical constants of SrF2 thin films in the 25-780-eV spectral range

    DOE PAGES

    Rodriguez-de Marcos, Luis; Larraguert, Juan I.; Aznarez, Jose A.; ...

    2013-04-08

    The transmittance and the optical constants of SrF2 thin films, a candidate material for multilayer coatings operating in the extreme ultraviolet and soft x-rays, have been determined in the spectral range of 25–780 eV, in most of which no experimental data were previously available. SrF2 films of various thicknesses were deposited by evaporation onto room-temperature, thin Al support films, and their transmittance was measured with synchrotron radiation. The transmittance as a function of film thickness was used to calculate the extinction coefficient k at each photon energy. A decrease in density with increasing SrF2 film thickness was observed. In themore » calculation of k, this effect was circumvented by fitting the transmittance versus the product of thickness and density. The real part of the refractive index of SrF2 films was calculated from k with Kramers-Krönig analysis, for which the measured spectral range was extended both to lower and to higher photon energies with data in the literature combined with interpolations and extrapolations. In conclusion, with the application of f- and inertial sum rules, the consistency of the compiled data was found to be excellent.« less

  6. Optical constants of SrF2 thin films in the 25-780-eV spectral range

    NASA Astrophysics Data System (ADS)

    Marcos, Luis Rodríguez-de; Larruquert, Juan I.; Aznárez, José A.; Fernández-Perea, Mónica; Soufli, Regina; Méndez, José A.; Baker, Sherry L.; Gullikson, Eric M.

    2013-04-01

    The transmittance and the optical constants of SrF2 thin films, a candidate material for multilayer coatings operating in the extreme ultraviolet and soft x-rays, have been determined in the spectral range of 25-780 eV, in most of which no experimental data were previously available. SrF2 films of various thicknesses were deposited by evaporation onto room-temperature, thin Al support films, and their transmittance was measured with synchrotron radiation. The transmittance as a function of film thickness was used to calculate the extinction coefficient k at each photon energy. A decrease in density with increasing SrF2 film thickness was observed. In the calculation of k, this effect was circumvented by fitting the transmittance versus the product of thickness and density. The real part of the refractive index of SrF2 films was calculated from k with Kramers-Krönig analysis, for which the measured spectral range was extended both to lower and to higher photon energies with data in the literature combined with interpolations and extrapolations. With the application of f- and inertial sum rules, the consistency of the compiled data was found to be excellent.

  7. Advances in short-wavelength x-ray multilayer optics: toward high-throughput multimirror systems for the wavelengths <10 nm

    NASA Astrophysics Data System (ADS)

    Artyukov, Igor A.; Bugayev, Yegor A.; Devizenko, Oleksandr Yu.; Feshchenko, Ruslan M.; Hatano, Tadashi; Kasyanov, Yuri S.; Kondratenko, Valeri V.; Uspenski, Yuri A.; Vinogradov, Alexander V.

    2007-09-01

    This paper presents novel approaches and techniques in development and application of multi-mirror X-ray optical systems operating in the spectral region of "carbon window" (λ ~ 4.5 nm). Two approaches for fabrication of the graded Co/C multilayer mirrors for Schwarzschild objective are presented. A pair of the spherical mirrors with Co/C multilayer coatings was tested in combination with scandium/carbon filters and laser produced plasma X-ray source for stereoimaging of low density materials at λ ~ 4.5 nm.

  8. Production of spectrally narrow soft-x-ray radiation through the use of broadband laser-produced plasma sources and multilayer-coated reflecting optics.

    PubMed

    Eligon, A M; Gruber, N; Silfvast, W T

    1995-08-01

    We describe a special filter design that produces spectrally narrow soft-x-ray radiation by using a broadband laser-produced plasma source and multilayer-coated reflecting optics. Calculations for the design were carried out at several laser-produced plasma-source temperatures and various multilayermirror combinations with and without a soft-x-ray filter. We determined that the best arrangement for a laser-produced plasma source consists of two multilayer mirrors and one soft-x-ray filter for each temperature investigated.

  9. Materials for and performance of multilayer lithography schemes

    NASA Astrophysics Data System (ADS)

    Weimer, Marc; Wang, Yubao; Neef, Charles J.; Claypool, James; Edwards, Kevin; Zu, Zhimin

    2007-03-01

    The 45-nm node will require the use of thinner photoresists, which necessitates the use of multilayer pattern transfer schemes. One common multilayer approach is the use of a silicon-rich anti-reflective hardmask (Si BARC) with a carbon-rich pattern transfer underlayer (spin-on carbon, or SOC). The combination of the two layers provides a highly planar platform for a thin resist, and provides a route to etch substrates due to the alternating plasma etch selectivities of the organic resist, inorganic Si BARC, and organic SOC. Yet such schemes will need to be optimized both for pattern transfer and optics. Optimizing optics under hyper-NA immersion conditions is more complicated than with standard (that is, NA<1) lithography. A rigorous calculation technique is used to evaluate and compare standard lithography to a hyper-NA case using a multilayer stack. An example of such a stack is shown to have reasonable lithographic performance.

  10. Multilayer Active Control For Structural Damping And Optical-Path Regulation

    NASA Technical Reports Server (NTRS)

    Rahman, Zahidul H.; Spanos, John T.; Fanson, James L.

    1995-01-01

    Two active-control concepts incorporated into system for suppression of vibrations in truss structure and regulation of length of optical path on structure to nanometer level. Optical-path-length-control subsystem contains two feedback control loops to obtain active damping in wide amplitude-and-frequency range. Concept described in more detail in number of previous articles, including "Stabilizing Optical-Path Length on a Vibrating Structure" (NPO-19040), "Controllable Optical Delay Line for Stellar Interferometry" (NPO-18686), "Test Bed for Control of Optical-Path Lengths" (NPO-18487).

  11. Effect of Thin Cirrus Clouds on Dust Optical Depth Retrievals From MODIS Observations

    NASA Technical Reports Server (NTRS)

    Feng, Qian; Hsu, N. Christina; Yang, Ping; Tsay, Si-Chee

    2011-01-01

    The effect of thin cirrus clouds in retrieving the dust optical depth from MODIS observations is investigated by using a simplified aerosol retrieval algorithm based on the principles of the Deep Blue aerosol property retrieval method. Specifically, the errors of the retrieved dust optical depth due to thin cirrus contamination are quantified through the comparison of two retrievals by assuming dust-only atmospheres and the counterparts with overlapping mineral dust and thin cirrus clouds. To account for the effect of the polarization state of radiation field on radiance simulation, a vector radiative transfer model is used to generate the lookup tables. In the forward radiative transfer simulations involved in generating the lookup tables, the Rayleigh scattering by atmospheric gaseous molecules and the reflection of the surface assumed to be Lambertian are fully taken into account. Additionally, the spheroid model is utilized to account for the nonsphericity of dust particles In computing their optical properties. For simplicity, the single-scattering albedo, scattering phase matrix, and optical depth are specified a priori for thin cirrus clouds assumed to consist of droxtal ice crystals. The present results indicate that the errors in the retrieved dust optical depths due to the contamination of thin cirrus clouds depend on the scattering angle, underlying surface reflectance, and dust optical depth. Under heavy dusty conditions, the absolute errors are comparable to the predescribed optical depths of thin cirrus clouds.

  12. Multilayer optics to be used as FEL fundamental suppressors for harmonics selection

    NASA Astrophysics Data System (ADS)

    Pelizzo, M. G.; Corso, A. J.; Monaco, G.; Nicolosi, P.; Suman, M.; Zuppella, P.; Cocco, D.

    2011-04-01

    Pump and probe experiments are one of the most attractive and powerful tools offered by a free electron laser facility. In these experiments it is fundamental to pump the system with a particular wavelength (usually the fundamental one) and to probe it with a second wavelength (e.g. higher emitted harmonics). Radiation emitted at the fundamental wavelength is 100 or more times the number of photons emitted in higher harmonics; selection of higher harmonics can be therefore critical. Multilayer (ML) mirrors that are able to provide high reflectivity peak at the desired harmonic wavelength while rejecting the fundamental have been designed and their application is foreseen to the FERMI@Elettra FEL beam transport system. The photon beam will be split into two and one of these will pass through a set of ML mirrors optimized for third harmonics selection; this scheme is also useable to realize a delay line in which the few nanosecond time delay will be controlled by changing the mirrors distance. A set of target wavelengths has been considered and multilayer structure materials have been selected. The MLs have been designed using a method based on the control of standing wave distribution at the fundamental and third harmonics wavelength, using a capping layer as a key element to achieve the willing rejection. Fabrication and test of such structures are foreseen.

  13. Optical and morphological characteristics of organic thin films for optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Zhong, Zhiyou; Sun, Fenglou

    2007-12-01

    Organic semiconductor thin films of tri-(8-hydroxyquinoline)-aluminum (Alq), 9,10-di-(2-naphthyl)-anthracene (ADN), and N,N'bis(naphthalen-1-yl)-N,N'bis(phenyl)-benzidine (NPB) for optoelectronic devices were deposited onto glass substrates by vacuum sublimation technique. The surface morphology and roughness of the thin film were characterized by means of atomic force microscopy (AFM). Experimental results indicate that all thin films present similar granular topography but different surface roughness. In addition, the optical transmittance spectra of thin films were measured by a double beam spectrophotometer and their corresponding optical properties were investigated. The complex refractive index and the optical band gap of thin films were obtained, respectively. Meanwhile, the dispersion behavior of the refractive index was studied in terms of Wemple-DiDomenico single oscillator model, and the oscillator parameters were achieved.

  14. Using fence post designs to speed the atomic layer deposition of optical thin films.

    PubMed

    Willey, Ronald R

    2008-05-01

    Atomic layer deposition (ALD) at this time is much slower than conventional optical thin-film deposition techniques. A more rapid ALD process for SiO(2) has been developed than for other ALD materials. A fence post design for optical thin films has thin layers of high-index posts standing above a broad low-index ground. If a design for ALD can be predominantly composed of SiO(2) layers with thin high-index layers, the deposition times can be correspondingly shortened, and it is shown that the required performance can still be nearly that of more conventional designs with high- and low-index layers of equal thickness. This combination makes the ALD benefits of conformal coating and precise thickness control more practical for optical thin-film applications.

  15. A Study of the Vertical Structure of Tropical (20 deg S-20 deg N) Optically Thin Clouds from SAGE II Observations

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Minnis, Patrick; McCormick, M. Patrick; Kent, Geoffrey S.; Yue, Glenn K.; Young, David F.; Skeens, Kristi M.

    1998-01-01

    The tropical cloud data obtained by the satellite instrument of the Stratospheric Aerosol and Gas Experiment (SAGE) II from October 1984 to May 1991 have been used to study cloud vertical distribution, including thickness and multilayer structure, and to estimate cloud optical depth. The results indicate that the SAGE-II-observed clouds are generally optically thin clouds, corresponding to a range of optical depth between approximately 8 x 10(exp -4) and 3 x 10(exp -1) with a mean of about 0.035. Two-thirds are classified as subvisual cirrus and one-third thin cirrus. Clouds between 2- to 3-km thick occur most frequently. Approximately 30% of the SAGE II cloud measurements are isolated single-layer clouds, while 65% are high clouds contiguous with an underlying opaque cloud that terminates the SAGE II profile. Thin clouds above detached opaque clouds at altitudes greater than 6.5 km occur less often. Only about 3% of the SAGE II single-layer clouds are located above the tropopause, while 58% of the cloud layers never reach the tropopause. More than one-third of the clouds appear at the tropopause. This study also shows that clouds occur more frequently and extend higher above the tropopause over the western Pacific than than over the eastern Pacific, especially during northern winter. The uncertainty of the derived results due to the SAGE II sampling constraints, data processing, and cloud characteristics is discussed.

  16. Exclusive examples of high-performance thin-film optical filters for fluorescence spectroscopy made by plasma-assisted reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lappschies, M.; Schallenberg, U.; Jakobs, S.

    2011-09-01

    For more than four decades band-pass filters are important components of microscopes used for the fluorescence spectroscopy. During all the time this special field of application has been one of the main drivers for research and development in thin-film optics, particularly for the thin-film design software and the coating technology. With a shortwave pass filter, a multi-notch filter, and a classical band-pass filter as examples of such filters provided for the latest generation of fluorescence microscopes we present the state-of-the-art in coating design and technology. Manufacturing these filters is a great challenge because the required spectral characteristics need necessarily multilayers with up to 300 layers and overall thicknesses up to 30 μm. In addition, the designs require also 3 to 5 nm as thinnest layers and all the layers are completely of non-quarterwave type. The filters were manufactured in a rapid-prototyping regime by a Leybold Helios plant using plasma-assisted reactive magnetron sputtering of thin films of different metal oxides. Designed and real spectra are compared and differences are discussed. Measurement results of other optical and non-optical characteristics as film stress, total integrated scattering, and micro roughness are presented.

  17. CO2 laser cutting of ultra thin (75 μm) glass based rigid optical solar reflector (OSR) for spacecraft application

    NASA Astrophysics Data System (ADS)

    Mishra, Shubham; Sridhara, N.; Mitra, Avijit; Yougandar, B.; Dash, Sarat Kumar; Agarwal, Sanjay; Dey, Arjun

    2017-03-01

    Present study reports for the first time laser cutting of multilayered coatings on both side of ultra thin (i.e., 75 μm) glass substrate based rigid optical solar reflector (OSR) for spacecraft thermal control application. The optimization of cutting parameters was carried out as a function of laser power, cutting speed and number of cutting passes and their effect on cutting edge quality. Systematic and in-detail microstructural characterizations were carried out by optical and scanning electron microscopy techniques to study the laser affected zone and cutting edge quality. Sheet resistance and water contact angle experiments were also conducted locally both prior and after laser cut to investigate the changes of electrical and surface properties, if any.

  18. Multiple spectrum analysis and evaluation for optical constants of HfO2 thin films

    NASA Astrophysics Data System (ADS)

    Liu, Dandan; Liu, Huasong; Jiang, Chenghui; Jiang, Yugang; Wang, Lishuan; Zhao, Zhihong; Ji, Yiqin

    2014-08-01

    HfO2 thin films were deposited on ZS1 silica by Ion Beam Sputtering (IBS) technique. Optical constants of HfO2 thin films were obtained by multiple spectrum analysis method, which combined the transmittance spectrum and ellipsometry spectrum of the film. The refractive index and extinction coiefficient of HfO2 thin films were evaluated by etching experiments of the film. The analysis spectral range was between 250nm and 850nm.

  19. Preparation, characterization, and infrared emissivity property of optically active polyurethane/TiO{sub 2}/SiO{sub 2} multilayered microspheres

    SciTech Connect

    Yang Yong; Zhou Yuming; Ge Jianhua; Wang Yongjuan; Zhu Yunxia

    2011-10-15

    Optically active polyurethane/titania/silica (LPU/TiO{sub 2}/SiO{sub 2}) multilayered core-shell composite microspheres were prepared by the combination of titania deposition on the surface of silica spheres and subsequent polymer grafting. LPU/TiO{sub 2}/SiO{sub 2} was characterized by FT-IR, UV-vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), SEM and TEM, and the infrared emissivity value (8-14 {mu}m) was investigated in addition. The results indicated that titania and polyurethane had been successfully coated onto the surfaces of silica microspheres. LPU/TiO{sub 2}/SiO{sub 2} exhibited clearly multilayered core-shell construction. The infrared emissivity values reduced along with the increase of covering layers thus proved that the interfacial interactions had direct influence on the infrared emissivity. Besides, LPU/TiO{sub 2}/SiO{sub 2} multilayered microspheres based on the optically active polyurethane took advantages of the orderly secondary structure and strengthened interfacial synergistic actions. Consequently, it possessed the lowest infrared emissivity value. - Graphical Abstract: Optically active polyurethane/titania/silica (LPU/TiO{sub 2}/SiO{sub 2}) multilayered core-shell composite microspheres were prepared by the combination of titania deposition on the surface of silica spheres and subsequent polymer grafting. Highlights: > Optically active polyurethane based on tyrosine was used for the modification of nanoparticles. > LPU/TiO{sub 2}/SiO{sub 2} multilayered core-shell microspheres were prepared and characterized. > Interfacial interactions and secondary structure affected the infrared emissivity of composite.

  20. Temperature induced CuInSe2 nanocrystal formation in the Cu2Se-In3Se2 multilayer thin films

    NASA Astrophysics Data System (ADS)

    A, Mohan; S, Rajesh

    2017-04-01

    The paper deals with the impact of annealing on Cu2Se-In3Se2 multilayer structure and discusses the quantum confinements. Thermal evaporation technique was used to prepare multilayer films over the glass substrates. The films were annealed at different temperatures (150 °C-350 °C) under vacuum atmosphere. The XRD pattern reveals that the films exhibit (112) peaks with CuInSe2 Chalcopyrite structure and upon annealing crystallinity improved. The grain size comes around 13-19 nm. The optical band gap value was found to be 2.21 to 2.09 eV and band gap splitting was observed for higher annealing temperatures. The increase in the band gap is related to quantum confinement effect. SEM image shows nano crystals spread over the entire surface for higher annealing temperatures. Optical absorption and PL spectra shows the blue shift during annealing. The HR-TEM shows the particle size in the nano range and which confirms the CuInSe2 nanocrystal formation. AFM image shows the rough surface with homogenous grains for the as deposited films and smooth surface for annealed films.

  1. Nonlinear optical parameters of nanocrystalline AZO thin film measured at different substrate temperatures

    NASA Astrophysics Data System (ADS)

    Jilani, Asim; Abdel-wahab, M. Sh; Al-ghamdi, Attieh A.; Dahlan, Ammar sadik; Yahia, I. S.

    2016-01-01

    The 2.2 wt% of aluminum (Al)-doped zinc oxide (AZO) transparent and preferential c-axis oriented thin films were prepared by using radio frequency (DC/RF) magnetron sputtering at different substrate temperature ranging from room temperature to 200 °C. For structural analysis, X-ray Diffraction (XRD) and Atomic Force Electron Microscope (AFM) was used for morphological studies. The optical parameters such as, optical energy gap, refractive index, extinction coefficient, dielectric loss, tangent loss, first and third order nonlinear optical properties of transparent films were investigated. High transmittance above 90% and highly homogeneous surface were observed in all samples. The substrate temperature plays an important role to get the best transparent conductive oxide thin films. The substrate temperature at 150 °C showed the growth of highly transparent AZO thin film. Energy gap increased with the increased in substrate temperature of Al doped thin films. Dielectric constant and loss were found to be photon energy dependent with substrate temperature. The change in substrate temperature of Al doped thin films also affect the non-liner optical properties of thin films. The value of χ(3) was found to be changed with the grain size of the thin films that directly affected by the substrate temperature of the pure and Al doped ZnO thin films.

  2. Domain size criterion for the observation of all-optical helicity-dependent switching in magnetic thin films

    NASA Astrophysics Data System (ADS)

    El Hadri, Mohammed Salah; Hehn, Michel; Pirro, Philipp; Lambert, Charles-Henri; Malinowski, Grégory; Fullerton, Eric E.; Mangin, Stéphane

    2016-08-01

    To understand the necessary condition for the observation of all-optical helicity-dependent switching (AO-HDS) of magnetization in thin films, we investigated ferromagnetic Co/Pt and Co/Ni multilayers as well as ferrimagnetic TbCo alloys as a function of magnetic layer compositions and thicknesses. We show that both ferro- and ferrimagnets with high saturation magnetization show AO-HDS if their magnetic thickness is strongly reduced below a material-dependent threshold thickness. By taking into account the demagnetizing energy and the domain wall energy, we are able to define a criterion to predict whether AO-HDS or thermal demagnetization (TD) will be observed. This criterion for the observation of AO-HDS is that the equilibrium size of magnetic domains forming during the cooling process should be larger than the laser spot size. From these results we anticipate that more magnetic materials are expected to show AO-HDS. However, the effect of the optical pulses' helicity is hidden by the formation of small magnetic domains during the cooling process.

  3. Harnessing second-order optical nonlinearities at interfaces in multilayer silicon-oxy-nitride waveguides

    NASA Astrophysics Data System (ADS)

    Logan, Dylan F.; Alamin Dow, Ali B.; Stepanov, Dmitri; Abolghasem, Payam; Kherani, Nazir P.; Helmy, Amr S.

    2013-02-01

    We demonstrate multi-layer silicon-oxy-nitride (SiON) waveguides as a platform for broadband tunable phase-matching of second-order nonlinear interactions arising at material interfaces. Second-harmonic generation (SHG) is measured with a 2 ps pulsed pump of 1515-1535 nm wavelength, where 6 nW power is generated by an average pump power of 30 mW in a 0.92 mm long device. The wavelength acceptance bandwidth of the SHG is as broad as 20 nm due to the low material dispersion of SiON waveguides. The waveguide structure provides a viable method for utilizing second order nonlinearity for light generation and manipulation in silicon photonic circuits.

  4. Novel optical super-resolution pattern with upright edges diffracted by a tiny thin aperture.

    PubMed

    Wu, Jiu Hui; Zhou, Kejiang

    2015-08-24

    In the past decade numerous efforts have been concentrated to achieve optical imaging resolution beyond the diffraction limit. In this letter a thin microcavity theory of near-field optics is proposed by using the power flow theorem firstly. According to this theory, the near-field optical diffraction from a tiny aperture whose diameter is less than one-tenth incident wavelength embedded in a thin conducting film is investigated by considering this tiny aperture as a thin nanocavity. It is very surprising that there exists a kind of novel super-resolution diffraction patterns showing resolution better than λ/80 (λ is the incident wavelength), which is revealed for the first time to our knowledge in this letter. The mechanism that has allowed the imaging with this kind of super-resolution patterns is due to the interaction between the incident wave and the thin nanocavity with a complex wavenumber. More precisely, these super-resolution patterns with discontinuous upright peaks are formed by one or three items of the integration series about the cylindrical waves according to our simulation results. This novel optical super-resolution with upright edges by using the thin microcavity theory presented in the study could have potential applications in the future semiconductor lithography process, nano-size laser-drilling technology, microscopy, optical storage, optical switch, and optical information processing.

  5. Multilayer Cloud Detection with the MODIS Near-Infrared Water Vapor Absorption Band

    NASA Technical Reports Server (NTRS)

    Wind, Galina; Platnick, Steven; King, Michael D.; Hubanks, Paul A,; Pavolonis, Michael J.; Heidinger, Andrew K.; Yang, Ping; Baum, Bryan A.

    2009-01-01

    Data Collection 5 processing for the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the NASA Earth Observing System EOS Terra and Aqua spacecraft includes an algorithm for detecting multilayered clouds in daytime. The main objective of this algorithm is to detect multilayered cloud scenes, specifically optically thin ice cloud overlying a lower-level water cloud, that presents difficulties for retrieving cloud effective radius using single layer plane-parallel cloud models. The algorithm uses the MODIS 0.94 micron water vapor band along with CO2 bands to obtain two above-cloud precipitable water retrievals, the difference of which, in conjunction with additional tests, provides a map of where multilayered clouds might potentially exist. The presence of a multilayered cloud results in a large difference in retrievals of above-cloud properties between the CO2 and the 0.94 micron methods. In this paper the MODIS multilayered cloud algorithm is described, results of using the algorithm over example scenes are shown, and global statistics for multilayered clouds as observed by MODIS are discussed. A theoretical study of the algorithm behavior for simulated multilayered clouds is also given. Results are compared to two other comparable passive imager methods. A set of standard cloudy atmospheric profiles developed during the course of this investigation is also presented. The results lead to the conclusion that the MODIS multilayer cloud detection algorithm has some skill in identifying multilayered clouds with different thermodynamic phases

  6. Ultrafast optical response of the Au-BaO thin film stimulated by femtosecond pulse laser

    NASA Astrophysics Data System (ADS)

    Wu, J. L.; Wang, C. M.; Zhang, G. M.

    1998-06-01

    The pump-probe method was applied to study the dependence of the transient optical transmissivity upon time delay for the Au-BaO composite thin film stimulated by a femtosecond pulsed laser. It was observed that the light absorption of the thin film increased rapidly and then resumed its initial value in several picoseconds. Optical relaxation is a process in which nonequilibrium electrons, excited by laser pulses and originating from Au ultrafine particles, return to the equilibrium state. In this article, the value of the electron-phonon coupling constant g of gold ultrafine particles in the composite thin film was calculated theoretically.

  7. All-optical diode with photonic multilayers based on asymmetric light localization

    NASA Astrophysics Data System (ADS)

    Jin, Li; Zhou, Jun; Yang, Mingyang; Xue, Chunhua; He, Miao

    2011-03-01

    An all-optical diode (AOD) with structure (AB)m(BA)n(BBAA)k is proposed based on asymmetric light localization, and its optical bistability are numerically investigated by the nonlinear transfer matrix method. Research results show that the behavior of the AOD strongly depends on the period number m, n, and k, the transmission direction of the AOD is related to the values of m and n, while k affects the transmission contrast of the AOD. It is a significant reference for the design of all-optical signal processing devices.

  8. Nonlinear optical characterization of ZnS thin film synthesized by chemical spray pyrolysis method

    NASA Astrophysics Data System (ADS)

    G, Sreeja V.; V, Sabitha P.; Anila, E. I.; R, Reshmi; John, Manu Punnan; Radhakrishnan, P.

    2014-10-01

    ZnS thin film was prepared by Chemical Spray Pyrolysis (CSP) method. The sample was characterized by X-ray diffraction method and Z scan technique. XRD pattern showed that ZnS thin film has hexagonal structure with an average size of about 5.6nm. The nonlinear optical properties of ZnS thin film was studied by open aperture Z-Scan technique using Q-switched Nd-Yag Laser at 532nm. The Z-scan plot showed that the investigated ZnS thin film has saturable absorption behavior. The nonlinear absorption coefficient and saturation intensity were also estimated.

  9. Nonlinear optical characterization of ZnS thin film synthesized by chemical spray pyrolysis method

    SciTech Connect

    G, Sreeja V; Anila, E. I. R, Reshmi John, Manu Punnan; V, Sabitha P; Radhakrishnan, P.

    2014-10-15

    ZnS thin film was prepared by Chemical Spray Pyrolysis (CSP) method. The sample was characterized by X-ray diffraction method and Z scan technique. XRD pattern showed that ZnS thin film has hexagonal structure with an average size of about 5.6nm. The nonlinear optical properties of ZnS thin film was studied by open aperture Z-Scan technique using Q-switched Nd-Yag Laser at 532nm. The Z-scan plot showed that the investigated ZnS thin film has saturable absorption behavior. The nonlinear absorption coefficient and saturation intensity were also estimated.

  10. Improvement of optical properties of TiO2 thin film treated with electron beam.

    PubMed

    Shin, Joong-Hyeok; Lee, Byung Cheol; Woo, Hee-Gweon; Hwang, Kwang Ha; Jun, Jin

    2013-03-01

    Nanocrystalline titanium dioxide (TiO2) thin films on silicon wafer substrates were prepared by sol-gel spin coating process. The prepared thin films were treated with electron beam (1.1 MeV, 300 kGy) at air atmosphere. The effects of electron-beam (EB) irradiation on the structural and optical properties of the TiO2 thin films were investigated. The structures of all the TiO2 thin films by XRD analysis showed an anatase phase, and the phase remained unchanged within the investigating range of EB treatment. The thickness of the titania thin film decreased slightly with EB treatment whereas the porosity increased. The EB treatment of TiO2 thin film can increase the proportion of Ti3+ in Ti2p at the thin film surface. The optical transmittance of the film in the wavelength ranges of above 380 nm increased after the EB treatment while its refractive index decreased with increasing EB dose. Therefore, improvement of the optical properties could be due to the change in both surface chemistry and morphology of the TiO2 thin films affected by EB irradiation.

  11. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, Michael D.; Britten, Jerald A.; Nguyen, Hoang T.; Boyd, Robert; Shore, Bruce W.

    1999-01-01

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

  12. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, M.D.; Britten, J.A.; Nguyen, H.T.; Boyd, R.; Shore, B.W.

    1999-05-25

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described. 7 figs.

  13. Fabrication of optical multilayer for two-color phase plate in super-resolution microscope

    SciTech Connect

    Iketaki, Yoshinori; Kitagawa, Katsuichi; Hidaka, Kohjiro; Kato, Naoki; Hirabayashi, Akira; Bokor, Nandor

    2014-07-15

    In super-resolution microscopy based on fluorescence depletion, the two-color phase plate (TPP) is an indispensable optical element, which can independently control the phase shifts for two beams of different color, i.e., the pump and erase beams. By controlling a phase shift of the erase beam through the TPP, the erase beam can be modulated into a doughnut shape, while the pump beam maintains the initial Gaussian shape. To obtain a reliable optical multiplayer (ML) for the TPP, we designed a ML with only two optical layers by performing numerical optimization. The measured phase shifts generated by the fabricated ML using interferometry correspond to the design values. The beam profiles in the focal plane are also consistent with theoretical results. Although the fabricated ML consists of only two optical layers, the ML can provide a suitable phase modulation function for the TPP in a practical super-resolution microscope.

  14. Fabrication of optical multilayer for two-color phase plate in super-resolution microscope.

    PubMed

    Iketaki, Yoshinori; Kitagawa, Katsuichi; Hidaka, Kohjiro; Kato, Naoki; Hirabayashi, Akira; Bokor, Nandor

    2014-07-01

    In super-resolution microscopy based on fluorescence depletion, the two-color phase plate (TPP) is an indispensable optical element, which can independently control the phase shifts for two beams of different color, i.e., the pump and erase beams. By controlling a phase shift of the erase beam through the TPP, the erase beam can be modulated into a doughnut shape, while the pump beam maintains the initial Gaussian shape. To obtain a reliable optical multiplayer (ML) for the TPP, we designed a ML with only two optical layers by performing numerical optimization. The measured phase shifts generated by the fabricated ML using interferometry correspond to the design values. The beam profiles in the focal plane are also consistent with theoretical results. Although the fabricated ML consists of only two optical layers, the ML can provide a suitable phase modulation function for the TPP in a practical super-resolution microscope.

  15. Surface plasmon resonance based fiber optic detection of chlorine utilizing polyvinylpyrolidone supported zinc oxide thin films.

    PubMed

    Tabassum, Rana; Gupta, Banshi D

    2015-03-21

    A highly sensitive chlorine sensor for an aqueous medium is fabricated using an optical fiber surface plasmon resonance (OFSPR) system. An OFSPR-based chlorine sensor is designed with a multilayer-type platform by zinc oxide (ZnO) and polyvinylpyrollidone (PVP) film morphology manipulations. Among all the methodologies of transduction reported in the field of solid state chemical and biochemical sensing, our attention is focused on the Kretschmann configuration optical fiber sensing technique using the mechanism of surface plasmon resonance. The optical fiber surface plasmon resonance (SPR) chlorine sensor is developed using a multimode optical fiber with the PVP-supported ZnO film deposited over a silver-coated unclad core of the fiber. A spectral interrogation mode of operation is used to characterize the sensor. In an Ag/ZnO/PVP multilayer system, the absorption of chlorine in the vicinity of the sensing region is performed by the PVP layer and the zinc oxide layer enhances the shift in resonance wavelength. It is, experimentally, demonstrated that the SPR wavelength shifts nonlinearly towards the red side of the visible region with an increase in the chlorine concentration in an aqueous medium while the sensitivity of the sensor decreases linearly with an increase in the chlorine concentration. As the proposed sensor utilizes an optical fiber, it possesses the additional advantages of fiber such as less signal degradation, less susceptibility to electromagnetic interference, possibility of remote sensing, probe miniaturization, probe re-usability, online monitoring, small size, light weight and low cost.

  16. Thin film technologies II; Proceedings of the Meeting, Innsbruck, Austria, Apr. 15-17, 1986

    NASA Astrophysics Data System (ADS)

    Jacobsson, J. Roland

    1986-01-01

    Papers are presented on automated optical coating processes and thin film production with an optical thickness monitoring system; the ultrasonic precision cleaning of optical components prior to and after vacuum coating; a wideband antireflection coating design by the random search approach; a computer-aided design of thin film optical coatings; subjective and objective methods for surface inspection; and micro/ultramicro hardness measurements with insulating films. Topics discussed include optical absorption in amorphous semiconductor films; the optical properties of thin silicide layers; laser damage to optical coatings; and light scattering and characterization of thin films; ion and photon-beam assisted deposition of thin films; and low temperature photo-CVD silicon nitride characterization. Consideration is given to the measurement of absorption in thin films using laser calorimetry; coherence loss due to thin film interface roughness; the performance of sputter deposited multilayer X-ray mirrors; and the stability of hard coating filters.

  17. Optically thin ice clouds in Arctic; Formation processes

    NASA Astrophysics Data System (ADS)

    Jouan, Caroline; Pelon, Jacques; Girard, Eric; Blanchet, Jean-Pierre; Wobrock, Wolfram; Gayet, Jean-Franćois; Schwarzenböck, Alfons; Gultepe, Ismail; Delanoë, Julien; Mioche, Guillaume

    2010-05-01

    Arctic ice cloud formation during winter is poorly understood mainly due to lack of observations and the remoteness of this region. Yet, their influence on Northern Hemisphere weather and climate is of paramount importance, and the modification of their properties, linked to aerosol-cloud interaction processes, needs to be better understood. Large concentration of aerosols in the Arctic during winter is associated to long-range transport of anthropogenic aerosols from the mid-latitudes to the Arctic. Observations show that sulphuric acid coats most of these aerosols. Laboratory and in-situ measurements show that at cold temperature (< -30°C), acidic coating lowers the freezing point and deactivates ice nuclei (IN). Therefore, the IN concentration is reduced in these regions and there is less competition for the same available moisture. As a result, large ice crystals form in relatively small concentrations. It is hypothesized that the observed low concentration of large ice crystals in thin ice clouds is linked to the acidification of aerosols. To check this, it is necessary to analyse cloud properties in the Arctic. Extensive measurements from ground-based sites and satellite remote sensing (CloudSat and CALIPSO) reveal the existence of two types of extended optically thin ice clouds (TICs) in the Arctic during the polar night and early spring. The first type (TIC-1) is seen only by the lidar, but not the radar, and is found in pristine environment whereas the second type (TIC-2) is detected by both sensors, and is associated with high concentration of aerosols, possibly anthropogenic. TIC-2 is characterized by a low concentration of ice crystals that are large enough to precipitate. To further investigate the interactions between TICs clouds and aerosols, in-situ, airborne and satellite measurements of specific cases observed during the POLARCAT and ISDAC field experiments are analyzed. These two field campaigns took place respectively over the North Slope of

  18. Optically thin ice clouds in Arctic : Formation processes

    NASA Astrophysics Data System (ADS)

    Jouan, C.; Girard, E.; Pelon, J.; Blanchet, J.; Wobrock, W.; Gultepe, I.; Gayet, J.; Delanoë, J.; Mioche, G.; Adam de Villiers, R.

    2010-12-01

    Arctic ice cloud formation during winter is poorly understood mainly due to lack of observations and the remoteness of this region. Their influence on Northern Hemisphere weather and climate is of paramount importance, and the modification of their properties, linked to aerosol-cloud interaction processes, needs to be better understood. Large concentration of aerosols in the Arctic during winter is associated to long-range transport of anthropogenic aerosols from the mid-latitudes to the Arctic. Observations show that sulphuric acid coats most of these aerosols. Laboratory and in-situ measurements show that at cold temperature (<-30°C), acidic coating lowers the freezing point and deactivates ice nuclei (IN). Therefore, the IN concentration is reduced in these regions and there is less competition for the same available moisture. As a result, large ice crystals form in relatively small concentrations. It is hypothesized that the observed low concentration of large ice crystals in thin ice clouds is linked to the acidification of aerosols. Extensive measurements from ground-based sites and satellite remote sensing (CloudSat and CALIPSO) reveal the existence of two types of extended optically thin ice clouds (TICs) in the Arctic during the polar night and early spring. The first type (TIC-1) is seen only by the lidar, but not the radar, and is found in pristine environment whereas the second type (TIC-2) is detected by both sensors, and is associated with high concentration of aerosols, possibly anthropogenic. TIC-2 is characterized by a low concentration of ice crystals that are large enough to precipitate. To further investigate the interactions between TICs clouds and aerosols, in-situ, airborne and satellite measurements of specific cases observed during the POLARCAT and ISDAC field experiments are analyzed. These two field campaigns took place respectively over the North Slope of Alaska and Northern part of Sweden in April 2008. Analysis of cloud type can be

  19. Automation Enhancement of Multilayer Laue Lenses

    SciTech Connect

    Lauer K. R.; Conley R.

    2010-12-01

    X-ray optics fabrication at Brookhaven National Laboratory has been facilitated by a new, state of the art magnetron sputtering physical deposition system. With its nine magnetron sputtering cathodes and substrate carrier that moves on a linear rail via a UHV brushless linear servo motor, the system is capable of accurately depositing the many thousands of layers necessary for multilayer Laue lenses. I have engineered a versatile and automated control program from scratch for the base system and many subsystems. Its main features include a custom scripting language, a fully customizable graphical user interface, wireless and remote control, and a terminal-based interface. This control system has already been successfully used in the creation of many types of x-ray optics, including several thousand layer multilayer Laue lenses.Before reaching the point at which a deposition can be run, stencil-like masks for the sputtering cathodes must be created to ensure the proper distribution of sputtered atoms. Quality of multilayer Laue lenses can also be difficult to measure, given the size of the thin film layers. I employ my knowledge of software and algorithms to further ease these previously painstaking processes with custom programs. Additionally, I will give an overview of an x-ray optic simulator package I helped develop during the summer of 2010. In the interest of keeping my software free and open, I have worked mostly with the multiplatform Python and the PyQt application framework, utilizing C and C++ where necessary.

  20. Optical band gap tuning of Sb-Se thin films for xerographic based applications

    NASA Astrophysics Data System (ADS)

    Kaur, Ramandeep; Singh, Palwinder; Singh, Kulwinder; Kumar, Akshay; Thakur, Anup

    2016-10-01

    In the present paper we have studied the effect of Sb addition on the optical band gap tuning of thermally evaporated SbxSe100-x (x = 0, 5, 20, 50 and 60) thin films. The structural investigations revealed that all thin films were amorphous in nature. Transmission spectrum was taken in the range 400-2500 nm shows that all films are highly transparent in the near infrared region. The fundamental absorption edge shifts towards longer wavelength with Sb incorporation. The optical band gap decreases with addition of antimony in a-Se thin films. A good correlation has been drawn between experimentally estimated and theoretically calculated optical band gap. The decrease in optical band gap of thin films has been explained using chemical bond approach and density of states model. Decrease in optical band gap with Sb addition increases the concentration of electron deep traps which increases the X-ray sensitivity of Sb-Se thin films. Thus by tuning the optical band gap of Sb-Se alloy, it could be utilized for xerographic based applications.