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Polycrystalline Thin Films (polycrystalline + thin_film)
Selected AbstractsInfluence of a polymeric solution buffer layer on the chemical bath deposition of polycrystalline PbS filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2005Y. González-Alfaro Abstract Polycrystalline thin films of PbS grown on glass substrates previously coated with PbS colloidal particles in a polyvinyl alcohol solution were obtained by chemical bath deposition (CBD). The X-ray diffraction procedures showed evidence of polycrystalline films of cubic PbS with a preferred normal orientation of the planes [100] with the growth direction. The film texture showed a strong influence of the initial conditions of the surface. Moreover, changes in colour, morphology and grain size of the films were observed by optic and atomic force microscopy (AFM). Rutherford backscattering spectrometry (RBS) showed a dependence of the thickness and roughness of the PbS films with the growth initial conditions. A kinetic growth model is proposed to explain the changes in the structure and morphology of the PbS. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of the substrate temperature on the structural, optical, and electrical properties of tin selenide thin films deposited by thermal evaporation methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2010N. Kumar Abstract Thin films of tin selenide (SnSe) were deposited on sodalime glass substrates, which were held at different temperatures in the range of 350-550 K, from the pulverized compound material using thermal evaporation method. The effect of substrate temperature (Ts) on the structural, morphological, optical, and electrical properties of the films were investigated using x-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission measurements, and Hall-effect characterization techniques. The temperature dependence of the resistance of the films was also studied in the temperature range of 80-330 K. The XRD spectra and the SEM image analyses suggest that the polycrystalline thin films having uniform distribution of grains along the (111) diffraction plane was obtained at all Ts. With the increase of Ts the intensity of the diffraction peaks increased and well-resolved peaks at 550 K, substrate temperature, were obtained. The analysis of the data of the optical transmission spectra suggests that the films had energy band gap in the range of 1.38-1.18 eV. Hall-effect measurements revealed the resistivity of films in the range 112-20 , cm for films deposited at different Ts. The activation energy for films deposited at different Ts was in the range of 0.14 eV-0.28 eV as derived from the analysis of the data of low-temperature resistivity measurements. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] In situ diffraction strain analysis of elastically deformed polycrystalline thin films, and micromechanical interpretationJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2009D. Faurie In situ tensile tests have been carried out under synchrotron radiation on supported gold (Au) thin films exhibiting a pronounced crystallographic texture. The 2, shift of X-ray diffraction lines has been recorded for different specimen orientations and several loading levels in the elastic domain. The data obtained demonstrate the large strain heterogeneities generated within the specimen because of the intergranular interactions associated with the large elastic anisotropy of Au grains. To interpret these results, the use of a multi-scale micromechanical approach is unavoidable. The theoretical background of such methods is described, and the points where exact results can be obtained and where approximations have to be introduced are highlighted. It is shown that the Vook,Witt model, for which a general formulation is provided, is the exact solution for polycrystals exhibiting a laminate microstructure, which is a significant departure from the standard thin-film microstructures. Among several standard models used in the field, the self-consistent model is the only one that reproduces the experimental data correctly. This is achieved by accounting for the actual crystallographic texture of the specimen, and assuming pancake-shaped two-point statistics for the morphological texture. A discussion of the limitations of this approach, originally developed for bulk materials, is given for the specific case of thin films. [source] Raman spectroscopy of Bi-Te thin filmsJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2008V. Russo Abstract The deposition of micro- and nanocrystalline bismuth telluride thin films with tailored structure and composition is of interest in view of improving the well-known material thermoelectric properties. Only a few works exist that discuss Raman scattering of Bi2Te3 crystals and films, while a Raman characterization of other phases, i.e. other lesser known compounds of the Bi-Te system, such as tsumoite (BiTe) and pilsenite (Bi4Te3), is still completely lacking. We here present a Raman investigation of Bi-Te polycrystalline thin films with controlled structure (stoichiometry and growth orientation), morphology and phase composition, produced by nanosecond pulsed laser deposition. Interpretation of Raman spectra from Bi-Te films was supported by scanning electron microscopy, energy dispersive spectroscopy (EDS) and X-Ray diffraction measurements, together with the predictions of the group theory. In this way, the first Raman characterization of Bi-rich phases (namely BiTe and Bi4Te3) has been obtained. For Bi-Te compositions characterized by a high Bi or Te content, Raman spectra reveal that segregation of elemental Bi or Te occurs. Copyright © 2008 John Wiley & Sons, Ltd. [source] ,-Gallium Oxide as Oxygen Gas Sensors at a High TemperatureJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007Marilena Bartic Resistive oxygen sensors based on gallium oxide were fabricated in order to analyze their sensing performances (as sensitivity, response, and recovery time) in an oxygen atmosphere at 1000°C. We prepared three types of sensors using a ,-Ga2O3 single crystal in a sandwich structure with Pt pad electrodes and ,-Ga2O3 polycrystalline thin films deposited by using both the sputtering technique and the chemical solution deposition method. For thin-film sensors, Pt interdigital electrodes were deposited on the surface of the films using the lift-off method. X-ray diffraction and atomic force microscopy investigations were performed to compare the structure and surface morphology of the samples. We achieved a response time of 10 s at 1000°C, while the sensitivity was 1.03 for the single crystal and 1.35,1.45 for thin films. The sensing properties depend on the preparation condition of Ga2O3 devices. [source] Silicon incorporation in CVD diamond layersPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2005J. Barjon Abstract The silicon incorporation in diamond is an important issue as silicon is widely used as a substrate for the growth of polycrystalline thin films. Incorporated silicon impurities are suspected to come from the hydrogen etching of the silicon substrate. To clearly establish this point we introduced a solid source of silicon during the growth of a homoepitaxial diamond layer on a HPHT diamond substrate. A quantitative SIMS analysis revealed concentrations of silicon up to 3 × 1019 cm,3 in the diamond layer. Then we propose a scenario for the contamination of polycrystalline diamond grown on silicon substrates: after nucleation, the progressive paving of the silicon surface by 3D grains causes a fast decrease of its incorporation. At coalescence, the silicon substrate is completely covered by a 2D diamond film and the silicon concentration in diamond reaches a residual level. The investigated MPCVD and HFCVD diamond layers grown on silicon substrates present comparable features. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||