Quasi-Shear Mode Electromechanical Coupling Coefficient of c-Axis Tilted MgZnO Thin Films
Quasi-Shear Mode Electromechanical Coupling Coefficient of c-Axis Tilted MgZnO Thin Films
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DOI：
10.1109/ius54386.2022.9957826
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发表时间：
2022-10
期刊：
影响因子：
--
通讯作者：
Yohkoh Shimano;H. Kishi;S. Kudo;T. Yanagitani
中科院分区：
文献类型：
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作者：
Yohkoh Shimano;H. Kishi;S. Kudo;T. Yanagitani
Thickness-shear mode piezoelectric thin films with high electromechanical coupling coefficient $k^{\prime}{}_{35}^{2}$ are attractive for quasi-shear mode FBAR and shear horizontal (SH)-type SAW devices. In 2007, our group reported $k^{\prime}{}_{35}^{2}= 6.8\%$ for a polycrystalline ZnO film with a 23° tilt to the surface normal. Furthermore, in 2020, our group reported that Mg-substituted ZnO significantly improves thickness-extensional mode $k_{t}^{2}$. In this study, we report the fabrication of c-axis tilted MgZnO films. By using Mason's equivalent circuit model including both quasi-shear mode and thickness-extensional mode, quasi-shear mode electromechanical coupling coefficient $k^{\prime}{}_{35}^{2}$ and thickness-extensional mode electromechanical coupling coefficient $k^{\prime}{}_{t}^{2}$ were estimated to be 5.0% and 0.97%, respectively. The resonator excites not only fundamental mode but also 2nd overtone mode because of an existence of a piezoelectrically inactive layer. Therefore, Mason's model including piezoelectrically inactive layer showed good agreement with the experimental data.
