ICMCTF2006 Session C1: Recent Advances in Optical Thin Films

Tuesday, May 2, 2006 8:30 AM in Room Royal Palm 4-6

Tuesday Morning

Start	Invited?	Item
8:30 AM		C1-1 Colour Coatings with Tailored Properties Obtained by Magnetron Sputtering R. Domnick, M. Belzner, G. Bauer (identif GmbH, Germany) A multilayer, consisting of a mirror layer, a transparent distance layer, a semi-transparent metal layer and a protective layer shows strong colours and/or characteristic colour shift effects. The spectrum of possible colours is broad: ranging from purple, blue over green and yellow to red, including also intermediate colours - even black can be generated. Appropriate selection of materials allows the generation of either homogeneous colours or changing colours dependent on the viewing angle. Because these colours are physically based, divers materials can be used to create a specific colour. This enables the creation of functional colour coatings: One chooses the materials with the according layer properties (temperature, scratch or wear resistance, barrier properties, . . .) and generates the desired colours with them. This presentation discusses correlations between selected materials, coating conditions, and corresponding optical properties. To this end, functional coating examples were produced and analyzed by Optical Spectrometry, AFM, SEM, XPS, and other techniques. Results are shown and discussed.
8:50 AM		C1-2 Thickness Dependence of Optical Properties of TiO₂ Thin Films Prepared by PECVD A. Borras, A. Yanguas-Gil, J. Cotrino (Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Spain); T. Girardeau (Laboratoire de Metallurgie Physique de Poitiers, France); A.R. Gonzalez-Elipe (Instituto de Ciencina de Materiales de Sevilla (CSIC-Univ. Sevilla), Spain) TiO₂ thin films prepared by PECVD present an evolution of their refraction index as a function of their thickness. This inhomogeneity in optical parameters has been analysed as a function of different protocols of the plasma synthesis and correlated with the evolution of the microstructure of the thin films as observed by SEM and the assessment of their porosity by means of water adsorption isotherms with a quartz crystal monitor. The AFM analysis of the surface roughness and its modelling within the framework of the Dynamic Scale Theory provides some clues to understand the growth mechanism and the resulting evolution of refraction index through the thin film thickness.
9:10 AM		C1-3 Fabrication of Optical Elements with Better than λ/1000 Thickness Uniformity by Thin-Film Deposition Through a Multi-Aperture Mask J.W. Arkwright (CSIRO, Australia) A technique is presented for sub-nanometre correction of precision polished optical surfaces. The technique uses thin metallic masks with multiple apertures of varying widths to selectively occlude a beam of depositing species in an ion beam sputtering system. The masks are designed directly from measured surface profile maps of the optical surface, and are fabricated using well-established laser-cutting technology commonly used to fabricate solder masks for the semiconductor industry. The selective deposition has proved highly effective for fabrication of large-aperture Fabry-Perot filters and has resulted in optical uniformities of less then 0.3 nm rms over a clear aperture of 37.5 mm. This presentation will give details of the mask design, deposition technique, and results from recent surface-correction runs.
9:30 AM		C1-4 Azimuthal Birefringence in Oblique Thickness-Graded Coatings K. Robbie, C. Elliott, R.S. Dariani, C. Buzea (Queen's University, Canada) Atomic-scale shadowing is combined with macro-scale shadow masking to produce flat optical elements with extreme anisotropy, rotating in orientation around the substrate center. With the highest birefringence ever reported (0.4), these amorphous silicon films are promising optical elements for laser mirrors and new optical devices. Using a technique that merges the concepts of serial bideposition, glancing angle deposition, and graded-thickness masking, we demonstrate a new class of coatings where both the magnitude and orientation of local birefringence can be specified to vary with location on the substrate. Characterization by spectroscopic ellipsometry and scanning electron microscopy reveals an atomic-scale anisotropic morphology that yields anomalously large birefringence at visible and near-infrared wavelengths.
9:50 AM	Invited	C1-5 Micro-Filter Array for Hyperspectral Imaging D. Shiekh (Surface Optics Corporation) A multi-spectral filter is being developed for hyper spectral camera system, which utilizes a lithographic technique to create an array of microscopic narrow-band spectral filters. Each filter is approximately 50 square microns in size and the filter array is placed in register to a silicon detector array to allow discrete spectral information to be separated from an image. The filters are comprised of standard optical coating materials, which are deposited between lithographic iterations. A complete array consists of 16 different optical filters repeated many times over a 1 square centimeter area. The optical coating techniques and the lithographic techniques used to manufacture the filter array are discussed in the forthcoming paragraphs.
10:30 AM		C1-7 Visible-Light Photocatalyst of Carbon-Doped-Titanium Oxide Films by Dual-Cathode Co-Sputtering S.H. Wang, T.K. Chen, P.C. Huang, M.S. Wong (National Dong Hwa University, Taiwan) Carbon-doped titanium oxide (TiO_2-xC_x) films with mainly anatase structure were prepared by dual-cathode reactive sputtering of a metallic titanium target and a graphite target in a gas mixture of argon and oxygen. The power of graphite target was varied to alter the doping concentration. The incorporation of carbon into titanium oxide films not only changed the surface morphology but also extended the absorption spectra to the visible region and exhibited visible-light induced photocatalytic properties determined by the photoreduction of silver ions and the decoloration of methylene blue. The carbon-doped titanium oxide films also reveal superior superhydrophilicity. The incorporated carbon was examined by Raman spectra, X-ray photoelectron spectra, and transmission electron microscopy.
10:50 AM		C1-8 The Influence of Heat Treatment on the Photocatalytic Activity of TiO₂ Thin Films H.-J. Lin, C.-H. Wang (National United University, Taiwan) Titanium dioxide thin films on soda lime glass were prepared by radio frequency (R.F.) sputtering from TiO₂ target in a mixture of nitrogen and argon, and followed by heat treatment at different temperature and time. The crystal structures of films were characterized by glancing incident angle X-ray Diffraction (GID) and Raman scattering technique. The surface morphology and roughness were studied by a field-emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM). The photocatalytic activity was evaluated by the measurement of the decomposition of methylene blue under UV and visible light irradiation. The results showed that the anatase films can be successfully deposited on unheated substrate. The surface morphology is strongly influenced by the heat treated temperature. The morphology of as sputtered films looked like as islands. These islands agglomerated when the films were heated and covered all surface when heated temperature was at 550°C for 1 hour. A higher surface roughness was formed at higher temperature. The photocatalytic activity increased with the increase of N₂/Ar ratio and the decrease of heat treated temperature.
11:10 AM		C1-9 Determining Optical Constants for ThO₂ Thin Films Sputtered Under Different Bias Voltages from 1.0 to 6.5 eV by Spectroscopic Ellipsometry W.R. Evans, D.D. Allred (Brigham Young University) I report optical constants (n and k) between 1.24 and 6.5 eV of reactively sputtered ThO₂ thin films sputtered at bias voltages of 0, 50, 64, 65, 68 and 70 V. No significant dependences in refractive index (n) on bias voltage or film thickness were detected. We find n is dispersive over the full range, with values of 1.82 ± 0.06, 1.85 ± 0.06, 1.93 ± 0.06 2.24 ± 0.07, at 1.2, 2.5, 4.0 and 6.0 eV respectively. An absorption feature at about 6.5 eV in ThO₂ is most likely a narrow absorption band with a full width at half maximum of about 0.4 eV.
11:30 AM		C1-10 New Technologies in Fabrication of Flat ITO Thin Films Z. Qi, C. Fan (Lanzhou Physics Institute, PR China); W. Chai (Dalian Jiaotong University, PR China); X. Chen (Lanzhou Physics Institute, PR China); S. Xu, S. Xu (Shenzhen Hivac Vacuum Photo-Electronics Co., Ltd, PR China) The surface roughness of ITO films is an important effect in flat-panel display devices. Several different kinds of technologies were used in fabrication of indium-tin-oxide (ITO) thin films with a smooth surface on glass substrates. In this work, ceramic ITO targets were used for the deposition of ITO films at low substrate temperature of 100°C. As oxygen partial increases, the light transmission of ITO films increases, however, the conductivity increases first, and then decreases. Pulsed-DC power was used to quench the micro-arcs for eliminating the particulates on the film surface. H₂O was introduced into the chamber to reduce the grain size of ITO or even form amorphous ITO. The surface morphology of ITO films was investigated by using atomic force microscopy (AFM). It was found that the surface roughness of ITO films was significantly improved by using pulsed-DC sputtering with H₂O.