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  • 151.
    Oates, T W H
    et al.
    Leibniz Institute Analyt Wissensch ISAS Berlin.
    Wormeester, H
    University of Twente.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Characterization of plasmonic effects in thin films and metamaterials using spectroscopic ellipsometry2011In: Progress in Surface Science, ISSN 0079-6816, E-ISSN 1878-4240, Vol. 86, no 11-12, p. 328-376Article, review/survey (Refereed)
    Abstract [en]

    In this article, spectroscopic ellipsometry studies of plasmon resonances at metal-dielectric interfaces of thin films are reviewed. We show how ellipsometry provides valuable non-invasive amplitude and phase information from which one can determine the effective dielectric functions, and how these relate to the material nanostructure and define exactly the plasmonic characteristics of the system. There are three related plasmons that are observable using spectroscopic ellipsometry; volume plasmon resonances, surface plasmon polaritons and particle plasmon resonances. We demonstrate that the established method of exploiting surface plasmon polaritons for chemical and biological sensing may be enhanced using the ellipsometric phase information and provide a comprehensive theoretical basis for the technique. We show how the particle and volume plasmon resonances in the ellipsometric spectra of nanoparticle films are directly related to size, surface coverage and constituent dielectric functions of the nanoparticles. The regularly observed splitting of the particle plasmon resonance is theoretically described using modified effective medium theories within the framework of ellipsometry. We demonstrate the wealth of information available from real-time in situ spectroscopic ellipsometry measurements of metal film deposition, including the evolution of the plasmon resonances and percolation events. Finally, we discuss how generalized and Mueller matrix ellipsometry hold great potential for characterizing plasmonic metamaterials and sub-wavelength hole arrays.

  • 152.
    Oates, Thomas W H
    et al.
    Leibniz Institute Analyt Wissensch ISAS Berlin.
    Ranjan, Mukesh
    Forschungszentrum Dresden Rossendorf eV.
    Facsko, Stefan
    Forschungszentrum Dresden Rossendorf eV.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Highly anisotropic effective dielectric functions of silver nanoparticle arrays2011In: OPTICS EXPRESS, ISSN 1094-4087, Vol. 19, no 3, p. 2014-2028Article in journal (Refereed)
    Abstract [en]

    Variable-angle and Mueller matrix spectroscopic ellipsometry are used to determine the effective dielectric tensors of random and aligned silver nanoparticles and nanorods thin films. Randomly arranged particles are uniaxially anisotropic while aligned particles are biaxially anisotropic, with the anisotropy predominantly at the plasmonic resonances. The strong resonances in nanorod arrays result in the real part of the effective in-plane permittivities being opposite in sign over a significant range in the visible, suggesting the potential to design materials that display tunable negative-refraction. A structural tilt in the particle arrays results in monoclinic dielectric properties.

  • 153.
    Persson, Nils-Krister
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Optical optimization of polyfluorene-fullerene blend photodiodes2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 97, no 3, p. 034503-1-034503-8Article in journal (Refereed)
    Abstract [en]

    Blends of polyfluorene-fullerenes are promising materials for polymer-based photovoltaic devices (PPVD). Using spectroscopic ellipsometry we deduce the dielectric function for the blend of the fullerene derivative [6,6]-phenyl-C 61-butyric acid methyl ester (PCBM) and the alternating polyfluorene copolymer, poly [2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1', 3'-benzothiadiazole)] DiO-PFDTBT (4:1 by weight), for the wavelength interval 250-1300 nm. n reaches above 2 and saturates to 1.9 for high wavelengths. Absorption starts at 720 nm (1.72 eV) and reaches a crest around 550 nm (2.25 eV). The spin coating introduces anisotropy in the blend, manifested in birefringence as well as in dichroism. The dielectric function for the blend versus its constituents is not additive. There are indications that the constituents lost their dielectric identity, as screening cannot explain the experimental data. Simulations of optical absorption inside a PPVD are performed for both monochromatic and polychromatic light, using an air mass 1.5 distributed solar irradiation. The model allows calculation of absorbed energies in absolute values in all layers within the device. An optimization is carried out with respect to the layer thicknesses. From a purely optical perspective there is no gain of optical absorbance in including an additional layer of acceptor. Spatially resolved energy dissipation within the device is presented for polychromatic light. Estimates for quantum efficiencies are derived. Experimental and theoretical results for reflectance are compared.

  • 154.
    Poksinski, Michal
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    In situ monitoring of metal surfaces exposed to milk using total internal reflection ellipsometry2003In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 94, no 3, p. 247-252Article in journal (Refereed)
    Abstract [en]

    A technique combining ellipsometry with total internal reflection is presented. The method is called total internal reflection ellipsometry (TIRE) and is suitable for monitoring of internal surfaces which opens new possibilities for measuring adsorption on metal surfaces in opaque liquids. Results from measurements of adsorption of milk and subsequent cleaning with sodium hydroxide on metal surfaces are given. These include studies on gold, iron, and chromium surfaces. A schematic design of the instrument used in TIRE is included. The main advantages of the system are non-invasive probing, fast response, and high sensitivity. The method has potential for applications in monitoring of internal surfaces of pipelines in industrial processes.

  • 155.
    Poksinski, Michal
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Protein monolayers monitored by internal reflection ellipsometry2004In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 455-456, p. 716-721Article in journal (Refereed)
    Abstract [en]

    Total internal reflection ellipsometry (TIRE) in spectroscopic mode in the wavelength range 400–1200 nm is employed in situ at a solid/liquid interface for investigation of protein adsorption on thin semitransparent gold films. In this configuration, the surface plasmon resonance phenomenon gives a large enhancement of the thin film sensitivity. Adsorption of a monolayer of the protein ferritin is monitored kinetically in situ and results in a change in the ellipsometric parameter Δ of more than 90° compared to 3° in similar ellipsometric measurements on gold substrates. This large sensitivity demonstrates a potential for sensor applications. The ferritin layer optical function is modeled with a Cauchy dispersion model resulting in a layer thickness of 9.2 nm, in good agreement with the dimension of the ferritin molecules. A transition layer between the protein film and the gold layer is necessary to introduce in the model to account for interactions between the protein layer and the gold film. The large sensitivity of TIRE for thin layers opens up a pathway to analyze in detail the structure of thin protein layers provided that a further development of the experimental setup and the model for the protein layer is carried out.

  • 156.
    Poksinski, Michal
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Total internal reflection ellipsometry: design of experimental setupManuscript (preprint) (Other academic)
    Abstract [en]

    A design of an experimental setup for total internal reflection ellipsometry is presented and possible component types are described and discussed. Advantages and drawbacks of selected designs based on selection of different components are discussed briefly and examples of applications are given.

  • 157.
    Poksinski, Michal
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Total internal reflection ellipsometry: thickness sensitivity in the pm-range for protein adsorptionManuscript (preprint) (Other academic)
    Abstract [en]

    Total internal reflection ellipsometry (TIRE) is used to study adsorption of human serum albumin and fibrinogen on thin gold films. TIRE shows very high sensitivity for protein mono-layers adsorbed on metal surfaces when surface plasmon resonance effects are ut ilised. The measured data, expressed in ellipsometric angles ψ and Δ are of several orders of magnitude larger in comparison to those from similar experiments performed with traditional ellipsometry. TIRE opens a new path for precise studies of organic layers adsorbed on metal surfaces, with a potential for resolving the adsorbed layer micro-structure.

  • 158.
    Poksinski, Michal
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Total internal reflection ellipsometry: ultrahigh sensitivity for protein adsorption on metal surfaces2007In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 32, no 10, p. 1308-1310Article in journal (Refereed)
    Abstract [en]

    Total internal reflection ellipsometry (TIRE) is used to study adsorption of human serum albumin and fibrinogen on thin gold films. TIRE shows very high sensitivity for protein monolayers adsorbed on metal surfaces when surface plasmon resonance effects are utilized. The measured data, expressed in ellipsometric angles ψ and Δ are of several orders of magnitude larger in comparison with those from similar experiments performed with traditional ellipsometry. TIRE in spectral mode opens a new path for precise studies of organic layers adsorbed on metal surfaces, with a potential for resolving the adsorbed layer microstructure.

  • 159.
    Poksinski, Michal
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Dzuho, Hasan
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Copper corrosion monitoring with total internal reflection ellipsometry2003In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, no 11, p. B536-B539Article in journal (Refereed)
    Abstract [en]

    A technique for in situ monitoring of changes on surfaces of semitransparent thin films is presented. This technique combines ellipsometry and total internal reflection and is called total internal reflection ellipsometry. It utilizes the high surface sensitivity of ellipsometry and can be applied to detect and quantify very small changes on thin film surfaces. One example on an application is corrosion monitoring. The main advantage in comparison to ordinary ellipsometry is that measurements are done from the “back side” of the sample and thus the probe beam does not propagate through and will not be influenced by the media reacting with the surface. An overview of total internal reflection ellipsometry and results from corrosion monitoring on thin copper films are presented.

  • 160.
    Poksinski, Michal
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Dzuho, Hasan
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Järrhed, Jan-Ove
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Total internal reflection ellipsometry2000In: Eurosensors XIV: The 14th European Conference on Solid-State Transducers : Book of Abstracts / [ed] R. de Reus, S. Bouwstra, MIC , 2000, p. 239-242Conference paper (Refereed)
    Abstract [en]

    A new measurement technique combining ellipsometry and total internal reflection is presented. This technique is called total internal reflection ellipsometry and opens new possibilities for measuring adsorption on metalsurfaces. Very promising results from protein adsorption on a gold surface are presented. Also a schematic design of the instrument used in total internal reflection ellipsometry is included. The main advantage compared to normal ellipsometry is that measurements can be done in opaque ambients because of total internal reflection.

  • 161.
    Rantzer, Annika
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hjörvarsson, B.
    Department of Materials Science, Royal Institute of Technology, Stockholm, Sweden.
    Bakker, J.W.P.
    Faculty of Applied Physics, University of Twente, The Netherlands.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Optical properties of intrinsic and doped a-Si:H films grown by d.c. magnetron sputter deposition2001In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 394, no 1-2, p. 255-262Article in journal (Refereed)
    Abstract [en]

    Thin films of intrinsic, B- and P-doped a-Si:H were grown by d.c. magnetron sputter deposition. The doping was accomplished by doped targets and co-sputtering Si and B4C. Spectroscopic ellipsometry was used for optical characterization and multiple sample analysis was applied to extract the dielectric functions of intrinsic films with 8–10 at.% hydrogen content, boron doped films with 2.2 at.% hydrogen and phosphorous-doped films with hydrogen contents of 10–15 at.%. One of the phosphorous-doped films was micro-crystalline. Hydrogen content was determined by nuclear reaction analysis. From the obtained optical properties the absorption and the optical gap were studied addressing p–i–n diode applications. The optical gaps for intrinsic a-Si:H material were 1.88±0.03 eV as determined by Tauc analysis and 1.45±0.06 eV by applying Cody analysis.

  • 162.
    Rantzer, Annika
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Hjörvarsson, B.
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Persson, Per O. A.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Kim, H.
    IBM TJ Watson Research Center, Yorktown Heights, NY, USA.
    Greene, J. E.
    Department of Materials Science and Frederick Seitz Materials Research Laboratory, University of Illinois, USA.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Sputter-deposited a-Si:H for p-i-n photodiodesManuscript (preprint) (Other academic)
    Abstract [en]

    DC magnetron sputter deposition is explored as an alternative for fabricating vertically integrated sensor systems in the form of p-i-n diodes of hydrogenated amorphous silican deposited on CMOS integrated circuit substrates in a post-processing step. We focus here on dopant oncorporation and surface morphological evolution during synthesis of the p-i-n diode sensor structures. The Doping was accomplished using doped targets in a mixed H2/Ar environment. Incorporated P concetrations range from 2.62 to 4.8 x 1019 cm-3 with corresponding conductivities, σ, up to 1.4 x10-5 ohm-1cm-1. B contentrations are between 2.79 and 6.7 X 1020 cm-3 with σ = 4 x 10-5 to 4 x 10-2 ohm-1cm-1. The results of the dopant incorporation are in agreement with reported molecular dynamics simulations. The best intrinsic films have a light to dark conductivity ratio of 102 for white light at an intensity of 10 W/m2. The dark conductivity is a 8 x 10-9 ohm-1cm-1. We conclude that dc magnetron sputter deposition is a good candidate for future device fabrication.

  • 163.
    Rehammar, R
    et al.
    Chalmers.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Fernandez-Dominguez, A I
    University of London Imperial College of Science, Technology and Medicine.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Kinaret, J M
    Chalmers.
    Maier, S A
    University of London Imperial College of Science, Technology and Medicine.
    Campbell, E E B
    University of Edinburgh.
    Optical properties of carbon nanofiber photonic crystals2010In: NANOTECHNOLOGY, ISSN 0957-4484, Vol. 21, no 46, p. 465203-Article in journal (Refereed)
    Abstract [en]

    Carbon nanofibers (CNFs) are used as components of planar photonic crystals. Square and rectangular lattices and random patterns of vertically aligned CNFs were fabricated and their properties studied using ellipsometry. We show that detailed information such as symmetry directions and the band structure of these novel materials can be extracted from considerations of the polarization state in the specular beam. The refractive index of the individual nanofibers was found to be n(CNF) = 4.1.

  • 164.
    Rehammar, Robert
    et al.
    Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden.
    Ghavanini, Farzan Alavian
    Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Kinaret, Jari
    Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden.
    Enoksson, Peter
    Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Campbell, Eleanor
    University of Edinburgh, Scotland.
    Electromechanically Tunable Carbon Nanofiber Photonic Crystal2013In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 13, no 2, p. 397-401Article in journal (Refereed)
    Abstract [en]

    We demonstrate an electrically tunable 2D photonic crystal array constructed from vertically alignedcarbon nanofibers. The nanofibers are actuated by applying a voltage between adjacent carbon nanofiberpairs grown directly on metal electrodes, thus dynamically changing the form factor of the photoniccrystal lattice. The change in optical properties is characterised using optical diffraction andellipsometry. The experimental results are shown to be in agreement with theoretical predictions andprovide a proof-of-principle for rapidly switchable photonic crystals operating in the visible that can befabricated using standard nanolithography techniques combined with plasma CVD growth of thenanofibers.

  • 165.
    Rehammar, Robert
    et al.
    Chalmers University of Technology, Gothenburg, Sweden.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Lassesson, Andreas
    Göteborg University, Gothenburg, Sweden.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Kinaret, Jari
    Chalmers University of Technology, Gothenburg, Sweden.
    Campbell, Eleanor
    Edinburgh University, UK.
    Carbon nanofiber-based photonic crystals – fabrication, diffraction and ellipsometry investigations2011In: Carbon-Based Electronic Devices - Processing, Performance and Reliability / [ed] M. Chhowalla, R.R. Keller, M. Meyyappan, W.J. Ready, Materials Research Society, 2011, Vol. 1283, p. 28-33Conference paper (Refereed)
    Abstract [en]

    Carbon nanofibers were used as building blocks for two-dimensional photonic crystal slabs. Electron beam lithography and chemical vapor deposition were used to fabricate regular arrays and random patterns of nanofibers. The optical properties of the samples were investigated using a diffraction measurement setup, as well as reflection ellipsometry. We find that carbon nanofiber regularity has a strong effect on both diffractive and specular optical properties. This shows that ellipsometry can be a valuable tool to study properties of carbon nanofiber arrays. It also shows that carbon nanofibers provide an interesting candidate as building blocks for nanostructured optical components.

  • 166.
    Schmidt, Daniel
    et al.
    Department of Electrical Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA.
    Müller, Christian
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Hofmann, Tino
    Department of Electrical Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Schubert, Eva
    Department of Electrical Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA.
    Schubert, Mathias
    Department of Electrical Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA.
    Optical properties of hybrid titanium chevron sculptured thin films coated with a semiconducting polymer2011In: THIN SOLID FILMS, ISSN 0040-6090, Vol. 519, no 9, p. 2645-2649Article in journal (Refereed)
    Abstract [en]

    Optical and structural properties of a hybrid metallic chevron sculptured thin film from titanium coated with the semiconducting polymer poly(3-dodecylthiophene) (P3DDT) are reported. The nanostructured thin film with two subsequent layers of oppositely slanted nanocolumns was fabricated by glancing angle deposition and coated with P3DDT by a spin-cast process. Spectroscopic generalized ellipsometry is employed to determine geometrical structure properties and the anisotropic optical constants of the coated and uncoated film in the spectral range from 400 to 1700 nm. The nanostructured thin films before and after hybridization show highly anisotropic optical properties. The complex refractive indices along major polarizability directions of the hybridized chevrons are increased in the entire investigated spectral range with respect to the as-deposited chevrons. Changes in birefringence and dichroism upon polymer infiltration are observed.

  • 167.
    Schubert, Mattias
    et al.
    Faculty of Physics and Geosciences, Inst. of Experimental Physics II University of Leipzig.
    Bundesmann, C.
    Faculty of Physics and Geosciences, Inst. of Experimental Physics II University of Leipzig.
    Jacopic, G.
    Institut für Nanostrukturierte Materialien und Photonik JOANNEUM Research Forschungsgesellschaft mbH.
    Maresch, H.
    Institut für Nanostrukturierte Materialien und Photonik JOANNEUM Research Forschungsgesellschaft mbH.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Infrared dielectric function and vibrational modes of pentacene thin films2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 84, no 2, p. 200-202Article in journal (Refereed)
  • 168.
    Schubert, Mattias
    et al.
    Inst for Experimental Physics II University of Leipzig.
    Bundesmann, C.
    Inst for Experimental Physics University of Leipzig.
    Jacopic, G.
    JOANNEUM Research Forschungsgesellschaft mbH, Austria.
    Maresch, H.
    JOANNEUM Research Forschungsgesellschaft Mbh, Austria.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Persson, Nils-Krister
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Infrared ellipsometry characterization of conducting thin organic films2004In: Elsevier Science, ISSN 1626-3200, Vol. 455-456, p. 295-300Article in journal (Refereed)
  • 169.
    Schubert, Mattias
    et al.
    Fakultät für Physik und Geowissenschaften Institut für Experimentelle Physik II, Leipzig.
    Bundesmann, C.
    Fakultät für Physik und Geowissenschaften Institut für Experimentelle Physik II, Leipzig.
    v. Wenckstern, H.
    Fakultät für Physik und Geowissenschaften Istitut für Experimentelle Physik II, Leipzig.
    Jakopic, G.
    Institut für Nanostrukturierte Materialien und Photonik JOHANNEUM Research Forschungsgesellschaft mbH.
    Haase, A.
    Institut für Nanostrukturierte Materialien und Photonik JOANNEUM Research Forschungsgesellschaft mbH.
    Persson, Nils-Krister
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Carrier redistribution in organic/inorganic (poly(3,4-ethylenedioxy thiophene/poly(styrenesulfonate)polymer)-Si) heterojunction determined from infrared ellipsometry2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 84, p. 1311-1313Article in journal (Refereed)
  • 170.
    Souxa Dantas, Nilton
    et al.
    Dept of Materials Science and Engineering, Royal Institute of Technology, Sweden.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Nzulu, Gabriel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    de Olivera Rappl, Paulo Henrique
    Instituto Nacional de Pesquisas Espaciais, Brazil.
    Ferreira da Silva, Antonio
    Instituto de Fisica Universidade Federal da Bahia, Brazil.
    Persson, Clas
    Dept of Materials Science and Engineering, Royal Institute of Technology, Sweden.
    Optical characterization of rocksalt Pb1-xSnxTe alloys2008In: physica status solidi (a): Applications and Materials Science, ISSN 1862-6300, Vol. 205, no 4, p. 837-840Article in journal (Refereed)
    Abstract [en]

    The optical properties in terms of dielectric function ε(hSω)= ε1(hSω)+iε2(hSω)of rocksalt pb 1-xsnx Te alloyes (0≤x≤1)are investigated experimentally by spectroscopic ellipsometry and theoretically by first-principles electronic band structure calculation. We find a strong optical response in the 0.5-2.0 eV region arising from optical absorption around the LW-line of the Brillouin zone. The response peak of the imaginary part of the dielectric functions at E = 1.6-1.8 eV shifts towards lower energies for high Sn compositions as a consequence of narrower W-point band-gap Eg(W) for the Sn-rich alloys, ©2008 WILEY-VCH Verlag GmbH & Co. KGaA.

  • 171.
    Tazawa, M.
    et al.
    National Institute of Advanced Industrial Science and Technology Japan.
    Xu, G.
    National Institute of Advanced Industrial Science and Technology Japan.
    Jin, P.
    National Institute of Advanced Industrial Science and Technology Japan.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    A memory application of light reflection from anisotropic microstructured thin films2004In: Elsevier Science, ISSN 1626-3200, Vol. 455-456, p. 824-827Article in journal (Refereed)
  • 172.
    Tazawa, Masato
    et al.
    National Institute of Advanced Industrial Science and Technology, Shidami, Moriyama-ku, Nagoya .
    Kakiuchida, Hiroshi
    National Institute of Advanced Industrial Science and Technology, Shidami, Moriyama-ku, Nagoya .
    Xu, Gang
    National Institute of Advanced Industrial Science and Technology, Shidami, Moriyama-ku, Nagoya .
    Jin, Ping
    National Institute of Advanced Industrial Science and Technology, Shidami, Moriyama-ku, Nagoya .
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Optical constants of vacuum evaporated SiO film and an application2006In: Journal of Electroceramics, ISSN 1385-3449, E-ISSN 1573-8663, Vol. 16, no 4, p. 511-515Article in journal (Refereed)
    Abstract [en]

    Silicon monoxide films were deposited on silver films on glass substrates and studied by infrared ellipsometry to determine the optical properties in the infrared wavelength range from 1.3 to 40 micrometers. The thicknesses of silicon monoxide and aluminum films were designed to 1 micrometer and 200 nanometers, respectively. The ellipsometric measurements were carried out by using a spectro-ellipsometer attached with an FT-IR. The imaginary part of the refractive index shows a high absorption region which is centered at 10 micrometers, whereas in other wavelength regions it shows rather low absorption. The resultant optical properties of silicon monoxide film are compared with published data. As an application, the spectral reflectance of spectral selective panel heating surface is calculated.

  • 173.
    Tulldahl, Michael
    et al.
    IFM Tillämpad optik Linköpings universitet.
    Steinvall, K. Ove
    Swedish defence Research Agency Linköping.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Simulation of sea surface wave influence on small target detection with airborne laser depth sounding2004Article in journal (Refereed)
    Abstract [en]

    A theoretical model for simulation of airborne depth-sounding lidar is presented with the purpose of analyzing the influence from water surface waves on the ability to detect 1-m3 targets placed on the sea bottom. Although water clarity is the main limitation, sea surface waves can significantly affect the detectability. The detection probability for a target at a 9-m depth can be above 90% at 1-m/s wind and below 80% at 6-m/s wind for the same water clarity. The simulation model contains both numerical and analytical components. Simulated data are compared with measured data and give realistic results for bottom depths between 3 and 10 m. © 2004 Optical Society of America.

  • 174.
    Tumenas, S
    et al.
    Institute for Semiconductor Physics, Vilnius .
    Karpus, V
    Institute for Semiconductor Physics, Vilnius .
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Assmus, W
    Goethe University Frankfurt.
    Optical conductivity of fci-ZnMgRE quasicrystals2011In: THIN SOLID FILMS, ISSN 0040-6090, Vol. 519, no 9, p. 2951-2954Article in journal (Refereed)
    Abstract [en]

    The results of room-temperature spectroscopic ellipsometry study of single-grain face-centred icosahedral (fci) ZnMgY, ZnMgHo, and ZnMgEr quasicrystals in the spectral range of 0.1-6.5 eV are presented. Analysis of the optical conductivity spectra, carried out within a framework of the band structure hypothesis, reveals that an optical response of the fci-ZnMgRE quasicrystals is determined by a superposition of the intraband Drude-type contribution and that of the interband optical transitions across a pseudogap. The deduced parameters of the fci-ZnMgRE electron energy spectrum are close to their values determined previously from an analysis of the fci-ZnMgRE photoemission data.

  • 175.
    Tumenas, S
    et al.
    Institute for Semiconductor Physics, Vilnius, Lithuania .
    Kasalynas, I
    Institute for Semiconductor Physics, Vilnius, Lithuania .
    Karpus, V
    Institute for Semiconductor Physics, Vilnius, Lithuania .
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Infrared Reflectance Kramers--Kronig Analysis by Anchor-Window Technique2011In: ACTA PHYSICA POLONICA A, ISSN 0587-4246, Vol. 119, no 2, p. 140-142Article in journal (Refereed)
    Abstract [en]

    An algorithm for the Kramers-Kronig analysis of the reflectivity spectra, based on an anchor-window technique is presented. The high-frequency asymptote, required for the Kramers-Kronig analysis, is determined by minimizing differences between the Kramers Kronig-deduced optical constants of a system under investigation and known optical constants measured in a small anchor-window. The algorithm is illustrated by applying it for a reconstruction of the optical conductivity sigma(omega) of the fci-ZnMgRE quasicrystals in the spectral range of 0.01-6.5 eV from the experimental IR Fourier-transform reflectivity data and the experimental spectral ellipsometry VIS-UV data. The reliability of the suggested Kramers-Kronig analysis technique is confirmed by independent infrared spectral ellipsometry sigma(omega) measurements for fci-ZnMgRE.

  • 176.
    Tumėnas, Saulius
    et al.
    Center for Physical Sciences and Technology, Vilnius.
    Karpus, Vytas
    Center for Physical Sciences and Technology, Vilnius.
    Kondrotas, R
    Center for Physical Sciences and Technology, Vilnius.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Spectroscopic Ellipsometry Study of Monocrystalline Zn2013Conference paper (Other academic)
  • 177.
    Tumėnas, Saulius
    et al.
    Center for Physical Sciences and Technology, Vilnius, Lithuania.
    Karpus, Vytautas
    Center for Physical Sciences and Technology, Vilnius, Lithuania.
    Bertulis, Klemensas
    Center for Physical Sciences and Technology, Vilnius, Lithuania.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Dielectric function and refractiveindex of GaBixAs1-x(x = 0.035, 0.052, 0.075)2012In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, no 7, p. 1633-1635Article in journal (Refereed)
    Abstract [en]

    MBE grown GaBiAs epitaxial layers with Bi content of3.5 %, 5.2 %, and 7.5 %, sandwiched between GaAs,have been investigated by spectroscopic ellipsometry inthe infrared and absorption threshold spectral regions.The real and imaginary parts of the dielectric function ofGaBiAs indicate bandgap Eg and spin-orbit splitting Δ0+values close to literature data. The refractive index ofGaBiAs in the IR region 0.2–0.8 eV exceeds that ofGaAs by ca. 0.8 %, 2.3 %, and 3.6 %, for Bi content3.5 %, 5.2 %, and 7.5 %, respectively.

  • 178.
    Valyukh, I.
    et al.
    Dalarna University.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Chiginov, V.
    Hong Kong University of Science and Technology.
    UV-induced in-plane anistropy in layers of mixtures of the azo-dyes SD1/SD2 characterized by spectroscopic ellipsometry2007In: 4th International Conference on Spectroscopic Ellipsometry,2007, Linköping: Linköpings universitet , 2007, p. 217-Conference paper (Refereed)
  • 179.
    Valyukh, I
    et al.
    Dalarna University.
    Green, S
    Uppsala University.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Niklasson, G A
    Uppsala University.
    Wackelgard, E
    Dalarna University.
    Granqvist, C G
    Uppsala University.
    Spectroscopic ellipsometry characterization of electrochromic tungsten oxide and nickel oxide thin films made by sputter deposition2010In: SOLAR ENERGY MATERIALS AND SOLAR CELLS, ISSN 0927-0248, Vol. 94, no 5, p. 724-732Article in journal (Refereed)
    Abstract [en]

    Electrochromic films of tungsten oxide and nickel oxide were made by reactive dc magnetron sputtering and were characterized by X-ray diffraction, Rutherford backscattering spectrometry, scanning electron microscopy, and atomic force microscopy. The optical properties were investigated in detail by spectroscopic ellipsometry and spectrophotometry, using a multiple-sample approach. The W-oxide film was modeled as a homogeneous isotropic layer, whereas the Ni-oxide film was modeled as an anisotropic layer with the optical axis perpendicular to the surface. Parametric models of the two layers were then used to derive complex refractive index in the 300-1700 nm range, film thickness, and surface roughness. A band gap of 3.15 eV was found for the W-oxide film, using a Tauc-Lorentz parameterization. For the Ni-oxide film, taken to have direct optical transitions, band gaps along the optical axis, perpendicular to it, and in an isotropic intermediate layer at the bottom of the film were found to be 3.95, 3.97, and 3.63 eV, respectively. Parameterization for the Ni oxide was made by use of the Lorentz model.

  • 180.
    Valyukh, Iryna
    et al.
    Dalarna University, Borlänge, Sweden.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Chigrinov, Vladimir
    Hong Kong University of Science and Technology, Kowloon, Hong Kong .
    Valyukh, Sergiy
    Hong Kong University of Science and Technology, Kowloon, Hong Kong .
    Characterization of the Photo-Alignment Material SD-1/SDA-2 with Spectroscopic Ellipsometry2007In: 14th  International Display Workshops, 2007, 2007, p. 391-394Conference paper (Other academic)
    Abstract [en]

    Variable angle spectroscopic ellipsometry (VASE) is applied for investigation of the azo-dye SD-1/SDA-2 which are used for photoalignment of liquid crystals. The azo-dye was spin coated on silicon substrates. Samples as prepared as well as samples illuminated with polarized UV light were studied. The measured optical constants were modelled with an ensemble of the Lorentz oscillators. The results confirm the reorientation mechanism of the photo-induced order formation in the azo-dye films under the action of polarized light, and also show that there exist some photochemical processes.

  • 181.
    Valyukh, Iryna
    et al.
    Dalarna University, Borlänge, Sweden.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Chigrinov, Vladimir
    Hong Kong University of Science and Technology, Hong Kong.
    Valyukh, Sergiy
    Hong Kong University of Science and Technology, Hong Kong.
    UV-induced in-plane anisotropy in layers of mixture of the azo-dyes SD-1/SDA-2 characterized by spectroscopic ellipsometry2008In: Physica Status Solidi. C, Current topics in solid state physics: Special Issue: 4th International Conference on Spectroscopic Ellipsometry (ICSE4), Weinheim, Germany: Wiley-VCH Verlagsgesellschaft, 2008, Vol. 5, no 5, p. 1274-1277Conference paper (Refereed)
    Abstract [en]

    The optical properties of the azo-dyes SD-1/SDA-2, which are used for photoaligning of liquid crystals (LCs), are investigated with Variable Angle Spectroscopic Ellipsometry (VASE). Films of mixture of SD-1/SDA-2 are deposited by spin coating on silicon wafers. The estimated thickness is approximately 10 nm. To achieve photo-induced anisotropy, one of the samples is illuminated during 15 minutes with linearly polarized UV light followed by thermal stabilization during 1 hour at 150 °C. VASE measurements are performed in the wavelength range 200–1350 nm at several angles of incidence and at different sample orientations. Dielectric functions of azo-dye films without/with polarized UV light illumination were modelled using an ensemble of Lorentz oscillators. The results confirm the diffusion model proposed recently for explanation of the formation of the photo-induced order in azo-dye films under the action of polarized light. Refractive indices, their wavelength dispersion and thicknesses of films of SD-1/SDA-2 are reported here.

  • 182.
    Valyukh, Iryna
    et al.
    Dalarna University, Borlänge.
    Green, S.
    Uppsala University, The Ångström Laboratory.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Niklasson, G.A.
    Uppsala University, The Ångström Laboratory.
    Wäckelgård, Ewa
    Uppsala University, The Ångström Laboratory.
    Granqvist, C.G.
    Uppsala University, The Ångström Laboratory.
    Optical Properties of Amorphous Tungsten Osice Films Deposited by Reactive DC magnetron sputtering2009Conference paper (Other academic)
  • 183.
    Valyukh, Iryna
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Green, S V
    Uppsala University, Sweden .
    Granqvist, C G
    Uppsala University, Sweden .
    Gunnarsson, K
    Uppsala University, Sweden .
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Niklasson, G A
    Uppsala University, Sweden .
    Ellipsometrically determined optical properties of nickel-containing tungsten oxide thin films: Nanostructure inferred from effective medium theory2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 4, p. 044308-Article in journal (Refereed)
    Abstract [en]

    Films of NixW1-x oxide with 0.05 andlt;= x andlt;= 0.53 were produced by reactive dc magnetron co-sputtering onto Si. Such films have documented electrochromism. Spectroscopic ellipsometry was used to extract accurate data on the dielectric function in the photon range 0.062 to 5.62 eV. The results for 0.62 to 5.62 eV were compared with computations from the Bruggeman effective medium theory applied to two nanostructural models: one representing a random mixture of structural entities characterized by the dielectric functions of WO3 and NiWO4 and the other describing a random mixture of WO3 and NiO. Unambiguous evidence was found in favor of the former model, and hence the films are composed of nanosized tungsten oxide and nickel tungstate. This agrees excellently with an earlier investigation of ours on NixW1-x oxide films, where nanostructure was inferred from Raman spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffraction.

  • 184.
    Valyukh, Iryna
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Green, S V
    Uppsala University.
    Granqvist, C G
    Uppsala University.
    Niklasson, G A
    Uppsala University.
    Valyukh, Sergiy
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Optical properties of thin films of mixed Ni-W oxide made by reactive DC magnetron sputtering2011In: THIN SOLID FILMS, ISSN 0040-6090, Vol. 519, no 9, p. 2914-2918Article in journal (Refereed)
    Abstract [en]

    Thin films of NixW1-x oxides with x = 0.05, 0.19, 0.43 and 0.90 were studied. Films with thicknesses in the range 125-250 nm were deposited on silicon wafers at room temperature by reactive DC magnetron co-sputtering from targets of Ni and W. The films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectroscopic ellipsometry (SE). XRD spectra and SEM micrographs showed that all films were amorphous and possessed a columnar structure. The ellipsometric angles psi and Delta of as-deposited films were measured by a rotating analyzer ellipsometer in the UV-visible-near infrared range (0.63-6.18 eV) and by an infrared Fourier transform rotating compensator ellipsometer in the 500-5200 cm(-1) wavenumber range. SE measurements were performed at angles of incidence of from 50 degrees to 70 degrees. Parametric models were used to extract thicknesses of the thin films and overlayers of NixW1-x oxide at different compositions, band gaps and optical constants. Features in the optical spectra of the NixW1-x oxides were compared with previous data on tungsten oxide, nickel oxide and nickel tungstate.

  • 185.
    Valyukh, Iryna
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Jiao, Z.
    Nanyang Technological University, Singapore.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Sun, X. W.
    Nanyang Technological University, Singapore.
    Optical Properties of Hydrated Tungsten Trioxide 3WO3ˑH2O 2014In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 571, p. 644-647Article in journal (Refereed)
    Abstract [en]

    Spectroscopic ellipsometry was used to determine the optical properties of plate-like hydrated tungsten trioxide (3WO3·H2O) films in the energy range 300–4000 cm− 1. Films with different thicknesses were deposited on glass substrates pre-coated with fluorine-doped tin oxide via an efficient and simple hydrothermal method. Parametric models were used to extract thicknesses and optical constants of the thin films. The WO3 was found to be more hydrated for thicker films. Moreover, the nano-plates are larger in thicker films, which leads to a decrease of the transmission due to an increase of the scattering. Features in the obtained dielectric functions of the 3WO3·H2O thin films were compared with the earlier published optical spectra of WO3 and its hydrates ½WO3·H2O and WO3·H2O.

  • 186.
    Valyukh, Iryna
    et al.
    Dalarna University, Borlänge, Sweden .
    Valyukh, Sergiy
    Swedish LCD Center AB, Borlänge, Sweden .
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Chigrinov, Vladimir
    Hong Kong University of Science and Technology, Kowloon, Hong Kong .
    Characteristic functions for uniformly twisted birefringent media2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 102, no 6Article in journal (Refereed)
    Abstract [en]

    We present two functions for characterization of birefringent media with application to twisted nematic liquid crystal (LC) cells in the field off state. The first function is for reflective LC cells and the second is for transmissive LC cells. Based on the Stockes formalism, it is shown that these functions describe the ability of a layer of the twisted birefringent medium to change polarization of the output light and are invariant to the layer orientation. The characteristic functions are found in simple procedures and can be used for simultaneous determination of retardation, its wavelength dispersion, and twist angle, as well as for solving optimization problems. © 2007 American Institute of Physics.

  • 187.
    Valyukh, Sergiy
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Light Scattering and Colour Generation in exoskeletons of Jewelled Beetle2012In: Photonics Global Conference, 2012Conference paper (Other academic)
  • 188.
    Valyukh, Sergiy
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Simulation of light scattering from exoskeletons of scarab beetles2016In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 24, no 6, p. 5794-5808Article in journal (Refereed)
    Abstract [en]

    An approach for simulation of light scattering from beetles exhibiting structural colors originating from periodic helicoidal structures is presented. Slight irregularities of the periodic structure in the exoskeleton of the beetles are considered as a major cause of light scattering. Two sources of scattering are taken into account: surface roughness and volume non-uniformity. The Kirchhoff approximation is applied to simulate the effect of surface roughness. To describe volume non-uniformity, the whole structure is modeled as a set of domains distributed in space in different orientations. Each domain is modeled as an ideal uniformly twisted uniaxial medium and differs from each other by the pitch. Distributions of the domain parameters are assumed to be Gaussian. The analysis is performed using the Mueller matrix formalism which, in addition to spectral and spatial characteristics, also provides polarization properties of the scattered light. (C) 2016 Optical Society of America

  • 189.
    Valyukh, Sergiy
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Åkerlind, Christina
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Simulation of light scattering from biological helicoidal structures2012In: 7th Workshop Ellipsometry, 2012, p. 90-Conference paper (Other academic)
  • 190.
    Valyukh, Sergiy
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Chigrinov, V.
    Hong Kong University of Science and Technology, Peoples R China .
    Kwok, H. S.
    Hong Kong University of Science and Technology, Peoples R China .
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    On liquid crystal diffractive optical elements utilizing inhomogeneous alignment2012In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, no 14, p. 15209-15221Article in journal (Refereed)
    Abstract [en]

    Formation of a desired liquid crystal (LC) director distribution by the use of inhomogeneous anchoring and pre-tilt angle for electrically controlled diffractive optical elements (DOE) is studied. Such LC DOE can have high periodicity and diffraction efficiency. At the same time they are free of constructive regularities, e. g. a periodic arrangement of the electrodes or thickness deviations, which have undesired impact on diffractive characteristics of LC DOE of other types. We focus on evaluation of potential functional abilities of LC DOE with inhomogeneous alignment. The reasons causing restriction of the LC DOE diffraction efficiency and periodicity are considered. Approaches for improvement of characteristics of the LC DOE are discussed.

  • 191.
    Valyukh, Sergiy
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Valyukh, Iryna
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Chigrinov, V
    Hong Kong University of Science and Technology.
    Kwok, H S
    Hong Kong University of Science and Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Liquid crystal light deflecting devices based on nonuniform anchoring2010In: APPLIED PHYSICS LETTERS, ISSN 0003-6951, Vol. 97, no 23, p. 231120-Article in journal (Refereed)
    Abstract [en]

    Tunable liquid crystal light deflecting devices based on nonuniform anchoring energy are proposed. These devices have uniform thicknesses of the layers they are composed of, and beam deviation is controlled with a uniform electrical field. Potential applicability of such an approach in beam deflectors and active lenses is investigated. It is shown that the approach is a competitive alternative to liquid crystal light deflecting devices, in which the needed spatial distribution of liquid crystal molecules is achieved either due to nonuniform thickness or due to generation of nonuniform electrical field.

  • 192.
    Wang, Guoliang
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Modification of vapor sensitivity in ellipsometric gas sensing by copper deposition in porous silicon2002In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 85, no 1-2, p. 95-103Article in journal (Refereed)
    Abstract [en]

    The sensitivities of porous silicon layers modified by copper deposition to low vapor concentrations of methanol, ethanol and 2-propanol are studied with spectroscopic ellipsometry. The porous silicon layers are prepared with electrochemical etching in hydrofluoric acid, and copper deposition is done in aqueous CuSO4. The ellipsometric vapor sensitivities, in terms of the ellipsometric spectral shifts due to gas exposures, of these samples and their oxides are studied and compared. It is shown that ellipsometric vapor sensitivities of porous silicon layers to alcohols are improved by copper deposition. It is also found that the oxidation of copper deposited in porous silicon layers shows improved selectivity to methanol. © 2002 Elsevier Science B.V. All rights reserved.

  • 193.
    Wang, Guoliang
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Return-path ellipsometry in gas sensing2003In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 15, p. 216-220Article in journal (Refereed)
  • 194.
    Wang, Guoliang
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Jansson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    An optical gas sensor based on ellipsometric readout2003In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 3, no 6, p. 739-743Article in journal (Refereed)
    Abstract [en]

    A gas sensor system based on ellipsometric readout is presented. It includes a gas chamber and a compact null ellipsometer operated in off-null mode. Small, low-cost optical components are used to demonstrate that this advanced methodology can be implemented in simplified instrumentation. The off-null ellipsometric sensing principle and transducer mechanisms of the sensing layers, as well as the instrumentation, are described. The application of the sensor system is exampled with experimental results on low-concentration alcoholic gases (methanol, ethanol, and 2-propanol) using porous silicon as a sensing layer. Optimization of the optics of the sensor system, improvement of sensitivity or alteration of selectivity by modification of sensing layers, and multisensing by using several ellipsometric units in parallel are discussed.

  • 195.
    Wang, Guoliang
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Jansson, Roger
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Optimization of azimuth angle settings in polarizer-compensator-sample-analyzer off-null ellipsometry2003In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 42, no 1, p. 38-44Article in journal (Refereed)
    Abstract [en]

    The dependence of the azimuth angle settings on the change in off-null intensity of a polarizer-.compensator-sample-analyzer ellipsometer owing to changes in sample properties is studied. First, a closed-form expression for the relationship between azimuth angles that fulfill the null condition is presented. An approximation for the off-null light intensity near null that is valid for small changes of the p- and s-reflection coefficients of an isotropic sample is then derived. This approximation shows that the intensity change near the null can be described by changes in the ellipsometric parameters tan q, and Delta only. Expressions for finding the azimuth angle that gives the maximum possible intensity change for a given change in the sample parameters are also derived. The importance of optimization of azimuth angle settings for different samples is investigated and found to depend on tan psi. Numerical and experimental results chosen from the investigation of gas sensors based on porous silicon are included to verify the approximations as well as the optimization. (C) 2003 Optical Society of America.

  • 196.
    Wang, Guoliang
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Jansson, Roger
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Optimization of off-null ellipsometry in sensor applications2004Article in journal (Refereed)
    Abstract [en]

    The optimization of azimuth angle settings of a polarizer-compensator-sample-analyzer off-null ellipsometric sensor system to obtain maximum intensity changes with respect to changes in the properties of a sensing layer, with and without considering changes in a reflectance, is studied. Optimal conditions in the two cases are derived analytically under the assumption that linear relationships exist among the changes in the parameters of the sensing layer. The validity of these optimal conditions is verified by numerical examples. The advantage of using ellipsometry compared with reflectometry to readout sensing information for some sensing samples is also discussed. © 2004 Optical Society of America.

  • 197.
    Wiklund, Henrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    A FEM-based application for numerical calculations of ellipsometric data2008In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 205, no 4, p. 945-948Article in journal (Refereed)
    Abstract [en]

    For modeling of advanced optical structures there is a need for stronger and more flexible modeling tools. Our aim is to develop and verify an application tool for calculations based on the Finite Element Method (FEM) of optical structures. To be able to understand which effects in the results that arises from limitations in the model, we begin by verifying the application tool for the most basic surface structures and gradually increase the complexity of the structures.

  • 198.
    Wingqvist, Gunilla
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Tasnadi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Zukauskaite, Agne
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Increased electromechanical coupling in w-ScxAl1-xN2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 11, p. 112902-Article in journal (Refereed)
    Abstract [en]

    AlN is challenged as the material choice in important thin film electroacoustic devices for modern wireless communication applications. We present the promise of superior electromechanical coupling (kt2), in w−ScxAl1−xN by studying its dielectric properties. w−ScxAl1−xN (0≤x≤0.3) thin films grown by dual reactive magnetron sputtering exhibited low dielectric losses along with minor increased dielectric constant (ε). Ellipsometry measurements of the high frequency ε showed good agreement with density function perturbation calculations. Our data show that kt2 will improve from 7% to 10% by alloying AlN with up to 20 mol % ScN.

     

  • 199.
    Wongmanerod, C.
    et al.
    Department of Physics, Fac. Sci., Chulalongkorn U., Bangkok, Thailand.
    Zangooie, S.
    Department of Electrical Engineering, Ctr. Microlectron. Optical Mat. R., Lincoln, NE 68588-0511, United States.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Determination of pore size distribution and surface area of thin porous silicon layers by spectroscopic ellipsometry2001In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 172, no 1-2, p. 117-125Article in journal (Refereed)
    Abstract [en]

    A non-destructive method for investigation of pore size distribution and surface area of porous silicon is presented. Adsorption and desorption isotherms of water in thin films of porous silicon are analyzed using variable angle of incidence spectroscopic ellipsometry. The analysis is based on multilayer optical models and the Bruggeman effective medium approximation. Pore size distribution and surface area are extracted from the isotherms employing the Wheeler theory combined with the Kelvin and Cohan equations. Good agreement is obtained between the calculated pore size distribution and estimations made by scanning electron microscopy. The evaluated specific surface area for the porous layers presented here is approximately 180 m2/cm3, which is in good agreement with the value reported in the literature.

  • 200.
    Wronkowska, A A
    et al.
    University of Technology and Life Science, Bydgoszcz.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Firszt, F
    Nicholas Copernicus University.
    Legowski, S
    Nicholas Copernicus University.
    Wronkowski, A
    University of Technology and Life Science, Bydgoszcz.
    Skowronski, L
    University of Technology and Life Science, Bydgoszcz.
    Optical spectra of Zn1-xBexTe mixed crystals determined by IR-VIS-UV ellipsometry and photoluminescence measurements2011In: THIN SOLID FILMS, ISSN 0040-6090, Vol. 519, no 9, p. 2795-2800Article in journal (Refereed)
    Abstract [en]

    Spectroscopic ellipsometry in the photon energy range from 0.04 eV to 6.50 eV is used for investigation of the optical response of Zn1-xBxTe crystals grown by a high-pressure Bridgman method in the composition range x andlt;= 0.12. Infrared spectra display absorption bands centred between 411 cm(-1) and 420 cm(-1) associated with BeTe-type optical phonon modes. The positions of the transverse-optical and longitudinal-optical phonon modes have been found by modelling the line shape of the complex dielectric functions, (epsilon) over tilde and Im(-(epsilon) over tilde (-1)), using a classical damped Lorentzian oscillator approach. Ellipsometric measurements in the VIS-UV range allow determination of the fundamental energy-gap (E-0) and the higher threshold energies (E-1, E-1 + Delta(1), E-2) originating from the band edge and spin-orbit splitting critical points. We have found that the Be content x = 0.12 causes an increase of the fundamental energy gap about 0.15 eV at room temperature when compared to the E-0 = 2.23 eV of ZnTe crystal at the same temperature. Photoluminescence spectra were measured in the temperature range from 30 K to room temperature. Luminescence at temperature Tandgt;200 K is very weak. The peak positions of the exciton emission lines agree well with the E-0 band-gaps derived from ellipsometric data if corrected for their temperature dependence.

12345 151 - 200 of 217
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