GROWTH-STRUCTURE OF YTTRIA-STABILIZED-ZIRCONIA FILMS DURING OFF-NORMAL ION-BEAM-ASSISTED DEPOSITION

Biaxially aligned YSZ thin films with strong [100] fiber texture were formed on a polycrystalline Ni-based alloy by off-normal ion-beam-assi sted deposition. Growth structures were characterized by x-ray diffrac tion (XRD), transmission electron microscopy (TEM), atomic force micro scopy (AFM), etc., and the alignment mechanism was discussed using a s elective growth model. Peculiar structural evolution of the crystallin e orientation was observed and its development was well described by a n exponential equation. It was explained as a collaboration of an anis otropic growth condition and epitaxial crystallization. The [100] fibe r texture was formed by columnar structures of diameter of 30-100 nm, which were composed of 5-10 nm diameter crystallites, Very smooth surf aces were observed by AFM imaging with a roughness of 2-3 nm and a pec uliar ripple structure. The origin of the azimuthal alignment was disc ussed with emphasis on the surface structure of YSZ films produced usi ng ion-beam-assisted deposition (IBAD) and the etching rate measuremen ts of (100) surfaces of YSZ single crystals.