A comparison of some ferroelectric and piezoelectric films for SAW devices on silicon

Abstract

A comparative study of a few ferroelectric and piezoelectric films for surface acoustic wave devices on a Si substrate is reported. Theoretical dispersion curves of phase velocity and coupling coefficient as a function of normalized thickness have been calculated for a film-Si structure with an interdigital transducer at the top of film. The material parameters for bulk crystals/ceramics have been used for calculation of the phase velocity and coupling coefficient. To make use of the large coupling coefficients of ferroelectric films on Si, comparatively thick films are required. The material parameters in the thin films are different from the bulk materials. The problem in estimating these constants for films is considered by comparing the theoretical and experimentally reported SAW data of ZnO films.<>