Propagations of Rayleigh and Love waves in ZnO films/glass substrates analyzed by three-dimensional finite element method

• Published in: Chinese physics B 2017-08, Vol.26 (8), p.468-473
• Main Author: 王艳 谢英才 张淑仪 兰晓东
• Format: Article
• Language: English
• Subjects: Love波; Rayleigh波; ZnO薄膜; 三维有限元方法; 传播特性; 有限元法分析; 玻璃基板; 频率温度系数
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/26/8/087703

Propagation characteristics of surface acoustic waves（SAWs） in ZnO films/glass substrates are theoretically investigated by the three-dimensional（3D） finite element method. At first, for（11ˉ20） ZnO films/glass substrates, the simulation results confirm that the Rayleigh waves along the [0001] direction and Love waves along the [1ˉ100] direction are successfully excited in the multilayered structures. Next, the crystal orientations of the ZnO films are rotated, and the influences of ZnO films with different crystal orientations on SAW characterizations, including the phase velocity, electromechanical coupling coefficient, and temperature coefficient of frequency, are investigated. The results show that at appropriate h/λ, Rayleigh wave has a maximum k~2 of 2.4% in（90°, 56.5°, 0°） ZnO film/glass substrate structure; Love wave has a maximum k~2 of 3.81% in（56°, 90°, 0°） ZnO film/glass substrate structure. Meantime, for Rayleigh wave and Love wave devices, zero temperature coefficient of frequency（TCF） can be achieved at appropriate ratio of film thickness to SAW wavelength. These results show that SAW devices with higher k~2 or lower TCF can be fabricated by flexibly selecting the crystal orientations of ZnO films on glass substrates.