Department of Solid State Electronics, The Angstrom Lab, Uppsala University, Uppsala, Sweden.
IEEE Trans Ultrason Ferroelectr Freq Control. 2009 Dec;56(12):2701-10. doi: 10.1109/TUFFC.2009.1361.
Improved performance thin-film plate acoustic wave resonators (FPAR) using the lowest order symmetric Lamb wave (S0) propagating in highly textured AlN membranes have been previously demonstrated for the first time. In this work, an experimental study of the resonators' performance vs. a variety of design parameters is performed. Devices operating in the vicinity of the stopband center exhibiting a Q-value of up to 3000 at a frequency of around 875 MHz are demonstrated. Further, low-loss high-Q micromachined 2-port longitudinally coupled thin-film resonators using the S0 mode are demonstrated for the first time. For the analysis of the proposed structures, the coupling-of-modes (COM) approach is successfully employed. Initially, the COM model is used for the extraction of physical parameters from one-port FPAR measurements. Subsequently, using the COM model, a satisfactory agreement with the proposed experimental frequency characteristics of S0 2-port FPARs has been achieved, and possibilities for further improvements in the performance discussed. Finally, the frequency spectrum of the one-port devices has been studied and the excited plate modes at different frequencies identified and presented with their Q-factors and temperature coefficients of frequency (TCF).
先前已经证明，在高度织构化的 AlN 膜中传播的最低阶对称兰姆波（S0）可用于提高薄膜体声波谐振器（FPAR）的性能。在这项工作中，对谐振器的性能与各种设计参数进行了实验研究。展示了在大约 875 MHz 的频率下，工作在截止带中心附近的器件的 Q 值高达 3000 的性能。此外，还首次展示了使用 S0 模式的低损耗、高 Q 值的微机电 2 端口纵向耦合薄膜谐振器。为了分析所提出的结构，成功地采用了模式耦合（COM）方法。最初，COM 模型用于从单端口 FPAR 测量中提取物理参数。随后，使用 COM 模型，与所提出的 S0 2 端口 FPAR 的实验频率特性实现了令人满意的吻合，并讨论了进一步提高性能的可能性。最后，研究了单端口器件的频谱，确定了不同频率下激励板的模式，并给出了它们的 Q 值和频率温度系数（TCF）。
