ZnO薄膜/金刚石在不同激励条件下声表面波特性的计算与分析

本文首先以刚度矩阵法为基础, 给出了ZnO薄膜/金刚石在四种不同激励条件下的有效介电常数计算公式. 然后以此为工具, 分别计算了多晶ZnO(002) 薄膜/多晶金刚石和单晶ZnO(002) 薄膜/多晶金刚石的声表面波特性, 并根据计算结果及设计制作声表面波器件的要求, 对ZnO膜厚的选择进行了详细地分析. 最后讨论了ZnO/金刚石/Si复合晶片可以忽略Si衬底对声表面特性影响时对金刚石膜厚的要求. 关键词： 声表面波 压电多层结构 有效介电常数 刚度矩阵法

Calculation and analysis of surface acoustic wave properties of ZnO film on diamond under different excitation conditions

In the last twenty years, the ZnO/diamond layered structure for surface acoustic wave (SAW) devices have been widely studied and have attracted great attention, due to its advantages of high acoustic velocity, high electromechanical coupling coefficient and high power durability. Distinguished from the conventional single-crystal substrate (such as quartz, lithium niobate), ZnO/diamond layered structure shows dispersive SAW properties, which can be excited by four ways: interdigital transducer (IDT)/ZnO/diamond, IDT/ZnO/shorting metal/diamond, ZnO/IDT/diamond, and shorting metal/ ZnO/IDT/diamond. In this paper, the formulation based on the stiffness matrix method for calculating the effective permittivity of ZnO/diamond layered structure under four excitation conditions is given first. Then, by using this formulation, the SAW properties of the monocrystalline ZnO (002) film on polycrystalline diamond and the polycrystalline ZnO (002) film on polycrystalline diamond are calculated respectively. Based on the results of calculation, the ZnO film thicknesses qualified to design and fabricate SAW device are analyzed in detail. Finally, we discuss the function of diamond film thickness of ZnO/diamond/Si layered structure so as to avoid the influence of the silicon substrate on the SAW properties.
Keywords： surface acoustic wave piezoelectric multilayered structure effective permittivity stiffness matrix method