Love-type surface acoustic wave on<i>Y</i>–<i>X</i>LiTaO₃with amorphous Ta₂O₅thin film

Abstract

In this study, to obtain a substrate structure with a lower phase velocity, the propagation properties of a Love-type surface acoustic wave (Love SAW) on Y–X LiTaO3 (LT) with an amorphous tantalum pentoxide (a-Ta2O5) thin film were investigated using a simple delay line and a resonator with a wavelength λ of 8 µm. The insertion loss of a simple delay line was decreased markedly by loading with an a-Ta2O5 film owing to a transformation from a leaky SAW (LSAW) to a non-leaky Love SAW. A phase velocity of 3,340 m/s, a coupling factor of 5.8%, and a propagation loss of 0.03 dB/λ were obtained for a normalized thickness h/λ of 0.120. Moreover, the resonance properties of the Love SAW were almost equal or superior to those for an LSAW on Al/36° Y–X LT, except for the fractional bandwidth.