Thirty one layer TiO2/SiO2 optical filters with graded refractive index profiles were fabricated by helicon plasma sputtering at room temperature. Multilayer films were deposited on glass (BK7) and Si (100) substrates simultaneously and sequentially. The measured transmittance spectrum exhibited a reflectance of 99.8% at a central wavelength of 730 nm and high transmittance over the wavelength region outside of the reflected band as a result of the suppression of the sidelobes. The experimental transmittance spectrum corresponded almost completely with that calculated based on the optical multilayer film theory and using the measured refractive indices of TiO2, SiO2 and TiO2–SiO2 composite films. Transmission electron microscopic observations confirmed the expected microstructure of the filter.
Au/SiO 2 nano-composite multilayers were prepared by helicon plasma sputtering. The Au particles dispersed in the SiO 2 matrix grew with increasing deposition time in the initial time less than 10 s, then changed from network-like to film-like microstructure with increasing deposition time. The optimum deposition time for preparing the Au particles was 8 s, and the size of Au particles was about 6 to 8 nm. The absorption peak due to the surface plasmon resonance of Au particles was observed at the wavelength of 560 nm in the optical absorption spectra for the as-deposited Au/SiO 2 thin films containing 3.3 to 10.3 vol%Au. The intensity of the absorption peak increased with increasing Au content, and the optimum Au content was about 10.3 vol%.
AlN epitaxial films have been fabricated on Ir- and Pt-coated α-Al2O3 substrates via electron cyclotron resonance plasma-assisted chemical vapor deposition (ECRPACVD) using an AlBr3-N2-H2-Ar gas system at substrate temperatures ranging from 500 to 700 °C. The epitaxial relationships between AlN films and substrates were determined by x-ray diffraction, x-ray pole figure, and reflection high-energy electron diffraction. The results are useful in practical applications, such as AlN/metal/α-Al2O3 structure in surface acoustic wave (SAW) devices.
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