Measurement and applications of total band gap with Si-based phononic crystals
Date Issued
2006
Date
2006
Author(s)
Cheng, Tsung-Cheng
DOI
en-US
Abstract
During the past two decades, there has been a great deal of interest in studying a novel class of structures that are the phononic crystals. In this kind structure, the special character, that is the band gap phenomenon, prohibiting acoustic waves of specific frequencies from traveling through the crystals. Recently, the band gap along x direction has been measured in the micro-scale 2-D air/silicon phononic crystal. However, another character, the so-called total band gap, forbids acoustic wave along any directions. The location of total band gap will be measured by wide-band surface acoustic wave (SAW) filter in this study. In order to predict the total band gap width of surface waves of micro-scale phononic crystals, the plane wave expansion (PWE) has been used to simulate the dispersion relation of 2-D air/silicon phononic crystals.
In general, the slanted finger interdigital transducer (SFIT) is utilized as the wide-band filter. Since silicon is not a piezoelectric material, we need another layer of piezoelectric material to excite surface acoustic wave and the layered structure SFIT/ZnO/Silicon is chosen in this study. For the layered structure, the dispersive relation is calculated by the effective permittivity approach, and the frequency response can be simulated by the coupling-of-modes (COM) model. Because the actual parameters of a layered SFIT are different slightly from the designed parameters, the simulated frequency response must be modified. The results demonstrating the modified simulations are in good agreement with experimental frequency response.
Finally, the lower limit of first total band gap and frequency range of 2-D air/silicon phononic crystals in micro-scale are successfully measured by the layered SFIT.
Subjects
表面聲波
斜交指叉換能器
層狀表面聲波元件
聲子晶體
全頻溝
SAW
SFIT
layered SFIT
phononic crystals
total band gap
Type
thesis
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