| Summary: | 碩士 === 東南技術學院 === 機電整合研究所 === 94 === ZnO films with different concentrations of Mg, Ca, Sr and Ba dopants have been grown on the ST-cut quartz substrate by RF magnetron sputtering technique. The influence of different dopants on crystalline structures and surface characteristics of films were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The sensitivity, electromechanical coupling coefficient, dielectric constant, and temperature coefficient of frequency of devices were measured.
The optimum sputtering parameters in our experiments, the R.F. power is 100W, working pressure is 1×10-2 torr and Ar/O2 ratio is 12/8. ZnO films with better crystalline structure and smoother surface when 1 mol% Mg were doped. The stronger electromechanical coupling coefficient and more temperature stability of Love wave filter were obtained as ZnO films with Sr dopants. Surface roughness increases with increasing of Ca dopants ZnO films and the Love sensor sensitivity increases obviously with increasing surface roughness. But the sensitivity would be reduced due to the over rough surface and imperfect crystalline structure when Ca over-doped. The ZnO film with Ba dopant is not suitability for Love wave devices applications.
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