Affiliation of Author(s):航空学院
Journal:Int J Mech Sci
Abstract:In this paper, the mode coupling vibration of finite ZnO thin film resonator (FBAR) with its c-axis along the thickness direction operating at the thickness-extensional mode is studied. The dispersion curve of unbounded fully-electroded ZnO thin film indicates that the thickness-extensional mode couples to two unwanted spurious modes. Since the displacement solutions consisting of the sum of three mode branches in the dispersion curve have satisfied the differential equations and boundary conditions on the top and bottom surfaces exactly, the substitution of them into Hamilton principle as weak boundary condition (WBC) can give an integral boundary condition across plate thickness at the side edge of ZnO thin film resonator. Two other WBCs are also employed to study the same coupling problem to prove the validity of Hamilton principle. The frequency spectra obtained through all three WBCs indicate that the extent of mode couplings is sensitive to plate length/thickness ratios. The desirable values of plate aspect ratios where thickness-extensional mode weakly couples to two spurious modes are all located at the flat part of the obtained frequency spectra. Besides, the frequency spectra obtained through Hamilton principle include those obtained through other two WBCs because the mathematical expressions of Hamilton principle contain all terms in other two WBCs. The frequency spectra predicted by Hamilton principle have wider flat part than those from other WBCs providing more structural choices for device designers. These obtained results provide a significant guidance to the design and optimization of FBARs. © 2018 Elsevier Ltd
ISSN No.:0020-7403
Translation or Not:no
Date of Publication:2018-11-01
Co-author:Zhao, Zinan,Zhu, Jiaqi,Qian Zhenghua
Correspondence Author:wb