Abstract
In this study, the properties of surface acoustic wave (SAW) filters, including phase velocity and electromechanical coupling coefficient (K 2 ) are investigated. The effective surface permittivity (ESP) method was employed to estimate the K 2 of bulk materials (single layer) and multi-layer (double-layer and trilayer) structures. In the cases of bulk materials, the calculation results agree with the experimental data, and the errors are less than 7% for quartz. In the cases of double-layer materials, the phase velocity and K 2 of various materials, such as ZnO/Diamond and LiNbO3/Diamond, were acquired, and the results demonstrate that LiNbO 3 /diamond is the optimal choice for high-frequency SAW devices. For the cases of trilayer, the structure of ZnO/PZT/diamond has relatively high K 2 and phase velocity. Therefore, this structure is the optimal trilayer structure for high-frequency SAW devices. The study demonstrates that ESP method can be successfully used for estimating SAW properties in piezoelectric multi-layer structures even though the structures contain nonpiezoelectric film (diamond). The proposed numerical computation has the potential to shorten the developing time of SAW device.