Home About us Contact
|
Home About us Contact | ||
|
|
||
Columnar Grains (columnar + grain)
Selected AbstractsPreparation of Oriented Aluminum Nitride Thin Films on Polyimide Films and Piezoelectric Response with High Thermal Stability and FlexibilityADVANCED FUNCTIONAL MATERIALS, Issue 3 2007M. Akiyama Abstract c -Axis oriented aluminum nitride (AlN) thin films are successfully prepared on amorphous polyimide films by radiofrequency magnetron reactive sputtering at room temperature. Structural analysis shows that the AlN films have a wurtzite structure and consist of c -axis oriented columnar grains about 100,nm wide. The full width at half maximum of the X-ray diffraction rocking curves and piezoelectric coefficient d33 of the AlN films are 8.3° and 0.56,pC,N,1, respectively. The AlN films exhibit a piezoelectric response over a wide temperature range, from ,196 to 300,°C, and can measure pressure within a wide range, from pulse waves of hundreds of pascals to 40,MPa. Moreover, the sensitivity of the AlN films increases with the number of times it was folded, suggesting that we can control the sensitivity of the AlN films by changing the geometric form. These results were achieved by a combination of preparing the oriented AlN thin films on polyimide films, and sandwiching the AlN and polymer films between top and bottom electrodes, such as Pt/AlN/polyimide/Pt. They are thin (less than 10,,m), self powered, adaptable to complex contours, and available in a variety of configurations. Although AlN is a piezoelectric ceramic, the AlN films are flexible and excellent in mechanical shock resistance. [source] Processing of Bulk Alumina Ceramics Using Laser Engineered Net ShapingINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 3 2008Vamsi Krishna Balla Application of rapid prototyping (RP) in ceramics manufacturing is motivated by advances in engineering ceramics where attaining complex shapes using traditional processing is difficult. Laser Engineered Net Shaping (LENSÔ), a commercial RP process, is used to fabricate dense, net-shaped structures of ,-Al2O3. Shapes such as cylinder, cube, and gear have been fabricated successfully with 10,25 mm section sizes. As-processed structures show anisotropy in mechanical properties with a high compressive strength normal to the build direction and columnar grains along the build direction. Heat treatment did not alter strength and anisotropy, but increased the grain size from 6 to 200 ,m and hardness from 1550 to 1700 Hv. [source] Effects of Individual Layer Thickness on the Microstructure and Optoelectronic Properties of Sol,Gel-Derived Zinc Oxide Thin FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2008Noureddine Bel Hadj Tahar Zinc oxide (ZnO) thin films were prepared under different conditions on glass substrates using a sol,gel process. The microstructure of ZnO films was investigated by means of diffraction analysis, and plan-view and cross-sectional scanning electron microscopy. It was found that the preparation conditions strongly affected the structure and the optoelectronic properties of the films. A structural evolution in morphology from spherical to columnar growth was observed. The crystallinity of the films was improved and columnar film growth became more dominant as the zinc concentration and the substrate withdrawal speed decreased. The individual layer thickness for layer-by-layer homoepitaxy growth that resulted in columnar grains was <20 nm. The grain columns are grown through the entire film with a nearly unchanged lateral dimension through the full film thickness. The columnar ZnO grains are c -axis oriented perpendicular to the interface and possess a polycrystalline structure. Optical transmittance up to 90% in the visible range and electrical resistivity as low as 6.8 × 10,3·,·cm were obtained under optimal deposition conditions. [source] Preparation of SnS films by low temperature sulfurizationPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2009Takehiro Minemura Abstract Polycrystalline tin sulfide (SnS) films were grown by sulfurization of Sn precursor at low temperatures of 120,220 °C. The p- type conductivity SnS film grown at 170 °C comprises densely packed 3,5-,m-diameter columnar grains, which is appropriate for use in photoabsorption layers of solar cells. The SnS film had an optical bandgap of about 1.3 eV. Using an appropriate SnS film, n -CdS/p -SnS heterojunction was fabricated on Mo-coated soda-lime glass substrates. These results are the first step toward realizing an optical device as a solar cell using a SnS film grown using sulfurization. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A stacked chalcopyrite thin-film tandem solar cell with 1.2,V open-circuit voltagePROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 4 2003S. Nishiwaki Abstract CuGaSe2 (CGS) thin films were prepared on tin-doped indium oxide (ITO) coated soda-lime glass substrates by thermal co-evaporation to fabricate transparent solar cells. The films consisted of columnar grains with a diameter of approximately 1,,m. Some deterioration of the transparency of the ITO was observed after deposition of the CGS film. The CGS solar cells were electrically connected in series with Cu(In,Ga)Se2 (CIGS) solar cells and mechanically stacked on the CIGS cells to construct tandem cells. The tandem solar cell with the CGS cell as the top cell showed an efficiency of 7.4% and an open-circuit voltage of 1.18,V (AM,1.5, total area). Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||