Propagation characteristics of shear-horizontal-type surface acoustic wave on langasite with Au of Ta2O5 thin film

The propagation characteristics, mainly the propagation loss and the bulk wave radiation loss of a pure shear-horizontal-type surface acoustic wave on (0°, 0, 90°)-cut langasite with a high-density thin film such as a gold (Au) film or a tantalum pentoxide (Ta₂O₅) dielectric film, are investigated experimentally. The cut angles θ of 0°, 10° and 20° were chosen because the coupling factor of 1.0% and a zero temperature coefficient of delay (TCD) can both be expected around these cut angles. The experimental results showed that the propagation characteristics, that is the energy-trapping effects of loading with the with the Ta₂O₅ film, depend on the cut angle. For the Au film, the propagation loss and the bulk wave radiation loss showed relatively small values at θ=10.