[10p-Z22-6~18] 1.6 Ultrasonics

[10p-Z22-12] Evaluation of Electromechanical Coupling Coefficients of Hydrothermally-Synthesized (K,Na)NbO₃ Films

〇Kazuma Yoshizawa¹, Masashi Suzuki¹, Shoji Kakio¹, Yoshiharu Ito², Akinori Tateyama², Hiroshi Funakubo², Tsuyoshi Wakabayashi³ (1.Univ. of Yamanashi, 2.Tokyo Institute of Technology, 3.Koike Co., Ltd.)

Keywords:surface acoustic wave, highovertone bulk acoustic resonator, hydrothermal synthesis method

For high performance surface acoustic wave filters and piezoelectric thin film resonators, piezoelectric materials with high electromechanical coupling coefficient (Kt) and low propagation loss are desired. In this report, we evaluated the bulk wave response of a thin-film resonator with a substrate (HBAR) using a (K,Na)NbO₃ (KNN) film prepared by hydrothermal synthesis method. We also fabricated the input and output interdigital transducers on a KNN film and evaluated the SAW propagation characteristics. As a result of the experiments, the optimum ratio of K/(K+Na) was found for obtaining the maximum Kt. When Na was not included, the measured Kt was small. In the future, we will study the fabrication conditions for obtaining a larger Kt.