Effect of initial stress on the propagation behavior of SAW in a layered piezoelectric structure of ZnO/Al2O3

Theoretical analysis of surface acoustic wave (SAW) propagation in a pre-stressed layered piezoelectric structure basing on the modified ordinary differential equation (ODE) is described. Numerical calculations involve a thin piezoelectric layer of ZnO bonded perfectly to an elastic substrate of Al2O3. ZnO thin films are deposited on Al2O3 substrates using plasma assisted molecular beam epitaxial (MBE). The crystallographic orientation of ZnO thin films and the surface morphology are analyzed by X-ray diffraction (XRD) and atomic force microscopy (AFM) respectively. The density and the thickness of the ZnO films are determined by X-ray reflectivity. The initial stress and strain of ZnO films are measured by X-ray diffraction method. The effect of initial stress on the propagation behavior of Rayleigh and Love waves and on the coupled electromechanical factor is discussed.