Determination of elastic constants of thin films by dispersion of various SAW modes

For the determination of the mechanical properties of thin films the inverse problem of the surface acoustic wave (SAW) propagation has to be solved by using the phase velocity dispersion for input data. We have analysed the numerical solution of the inverse problem by calculating a two-dimensional error field of least-squares fits. The shape of the error field is a function of arbitrary elastic parameters with respect to their exact values. Various isotropic films deposited on Y-cut LiNbO/sub 3/ were considered. It was found that by the use of the dispersion of two independent SAW modes the elastic parameters of an isotropic thin film can be determined with high accuracy.