吳政忠臺灣大學：應用力學研究所鄭宗誠Cheng, Tsung-ChengTsung-ChengCheng2007-11-292018-06-292007-11-292018-06-292006http://ntur.lib.ntu.edu.tw//handle/246246/62403During 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.Acknowledgements I Abstract II Lists of Notations III Table of Contents VII List of Figures IX List of Tables XI Chapter 1 Introduction 1 1-1 Motivation 1 1-2 Literature Review 2 1-3 Contents of the Chapters 3 Chapter 2 Simulation of 2-D Phononic Crystal 6 2-1 Plane Wave Expansion 6 2-1.1 Equation of Motion 7 2-1.2 Mass Density and Elastic constants 7 2-1.3 Displacement Vector 9 2-1.4 Surface and Bulk Waves in 2-D Phononic Crystals 10 2-2 Simulation of 2-D Air/Silicon Phononic Crystal 13 2-2.1 Square lattice 13 2-2.2 Design Parameters in PWE 14 2-2.3 The Dispersion Relation of 2-D Air/Si Phononic Crystal 14 Chapter 3 Analysis of Layered SFIT SAW Filter 21 3-1 Characteristics of SAW on Layered Structure 21 3-1.1 Effective Permittivity 21 3-1.2 Electromagnetic Coupling Coefficient 24 3-2 Analysis of COM Parameters on Layered Structure 25 3-2.1 Phase Velocity Shift 26 3-2.2 Reflection Coefficient 28 3-2.3 Transduction Coefficient 29 3-2.4 Thin Film Finger Capacitance and Resistance 30 3-2.5 Propagation Loss 31 3-3 Simulation of a Layered SFIT SAW Filter 31 3-3.1 Simulation Method of SFIT 31 3-3.2 SFIT/ZnO/Silicon Layered SAW Filter 34 3-4 Experimental Design and Frame of This Study 34 3-4.1 Propagation Loss Measurement 35 3-4.2 Total Band Gap Measurement 35 3-4.3 Experimental Frames 36 Chapter 4 Fabrications and Experimental Results 45 4-1 Growth of ZnO Thin Film on Silicon Substrate 45 4-1.1 Deposition of ZnO Thin Film 45 4-1.2 Analysis of Thin Film Properties 46 4-2 Fabrication of Layered SFIT and 2-D Phononic Crystal 48 4-2.1 Fabrication Process of IDT/ZnO/Silicon Layered SFIT 48 4-2.2 Fabrication Process of 2-D Air/Silicon Phononic Crystal 49 4-3 Experimental Results of the Layered SFIT 51 4-3.1 Time Gating Approach 51 4-3.2 Phase Velocity Modification 52 4-3.3 Propagation Loss Modification 53 4-4 2-D Air/Si Phononic Crystal Total Band Gap Measurement 55 4-4.1 The effect of beam steering 55 4-4.2 The Total Band Gap Measurement 56 Chapter 5 Conclusions and Future Works 74 5-1 Conclusions of this thesis 74 5-2 Future works 75 Appendix 76 References 782500517 bytesapplication/pdfen-US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SAWSFITlayered SFITphononic crystalstotal band gapthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/62403/1/ntu-95-R93543018-1.pdf