A Study on the Quartz Phononic Rayleigh Wave and Surface Transverse Wave Resonators
Date Issued
2015
Date
2015
Author(s)
Yeh, Sih-Ling
Abstract
This thesis presents results on the design and fabrication of Rayleigh wave and surface transverse wave (STW) resonators based on a ST-cut quartz in which the 2D air/quartz phononic crystals (PCs) were utilized as the reflective gratings. One of the modes is the Rayleigh wave mode along the x-axis, and the other one is the STW mode along the y-axis. A numerical and experimental study of the Rayleigh waves propagating in a 2D air/quartz PC along the x-axis is also presented. The finite element method was adopted to calculate the band structures of PC and inter-digital transducer (IDT), effective reflective distance from the PC boundary and further the admittance of the phononic surface wave resonant cavity. For the microelectromechanical system (MEMS) experiment, the reactive ion etching process with electron-beam lithography was utilized to fabricate the sub-micrometer phononic structures. For the transmission performance of the Rayleigh waves propagating in phononic structures, the results showed that the band gaps of the PC are accurately matched with the numerical prediction. In addition, both numerical and experimental results are demonstrated that there is a band gap, which is caused by the level repulsion. For the surface wave resonators performance, it is noted that using the 2D air/quartz phononic gratings can reflect the acoustic wave and enhance the quality factor of the surface wave resonator. The results of this study may serve as a basis for developing PC-based surface wave resonators.
Subjects
Phononic crystal
Rayleigh wave
Surface transverse wave
Level repulsion
Resonator
MEMS
Type
thesis