Zhang Hui, Zhang Shu-yi, Zheng Kai
Laboratory of Modern Acoustics, Institute of Acoustics, Nanjing University, Nanjing 210093, PR China.
Ultrasonics. 2006 Dec 22;44 Suppl 1:e737-40. doi: 10.1016/j.ultras.2006.05.085. Epub 2006 Jun 5.
Generally, in theoretical calculations of high-overtone bulk acoustic resonators (HBAR), metal electrode effects were always ignored. However, the acoustical impedance, thickness and loss of the electrodes affect practically the performances of HBAR operating at high-frequency. For very high-frequency cases, the thickness of the metal electrode is always on the same order of that of the piezo-film and the electrode effects on modes cannot be negligible. In this paper, based on the resonance frequency spectra and Butterworth Van Dyke equivalent circuit of HBAR, the effects of the material, loss, and thickness of the electrodes on the figure of merit, effective electromechanical coupling factor, quality factor, etc. are analyzed. It is demonstrated that the performance of HBAR can also be optimized by using the electrodes with proper impedance, loss and thickness.
一般来说，在高泛音体声波谐振器（HBAR）的理论计算中，金属电极的影响总是被忽略。然而，电极的声阻抗、厚度和损耗实际上会影响高频工作的HBAR的性能。对于非常高频的情况，金属电极的厚度总是与压电薄膜的厚度处于同一量级，电极对模式的影响不可忽略。本文基于HBAR的共振频谱和巴特沃思-范戴克等效电路，分析了电极的材料、损耗和厚度对品质因数、有效机电耦合系数、品质因子等的影响。结果表明，使用具有适当阻抗、损耗和厚度的电极也可以优化HBAR的性能。
