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Abstract: The morphology, the structure and the orientation of tungsten oxide nanorods grown on mica are investigated as a function of the deposition time. The previous results are recalled to point out the changes with the nanorod thickness. The investigations were conducted by Atomic Force Microscopy (AFM) and Reflection High Energy Electron Diffraction (RHEED). The results evidence two successive growth modes. In the first stage thin and long nanorods were formed. They grew layer by layer with a hexagonal tungsten bronze structure and two different (1−10) and (2–10) planes parallel to the mica surface. In the second stage, as the deposition time increased thin nanorods with the (1−10) orientation grew in thickness when the others preserve their morphology and structure. In the discussion the difference between the two growth modes is emphasized. In the first stage the nanorod growth proceeds mainly by the surface diffusion of K x WO3 species. In the second stage the growth is due to the by direct impinging of WO3 molecules on some thin nanorods having already the (1−10) orientation, leading to growth of thick nanorods with a monoclinic structure. [Copyright &y& Elsevier]

Abstract: Highly oriented AlN film was prepared on a c-plane sapphire substrate by laser chemical vapor deposition using a newly proposed aluminum acetylacetonate precursor and ammonia gas as source reactants. The c-axis oriented AlN films were obtained on the c-plane sapphire substrate at deposition temperatures from 900 to 1230K. AlN film prepared at 1047K showed an epitaxial relation as The full width at half maximum (FWHM) of the X-ray rocking curve for AlN (0002) plane increased with increasing deposition temperature. The c-axis lattice parameter decreased with increasing deposition temperature. [Copyright &y& Elsevier]