High- ${Q}$ Butterfly-Shaped AlN Lamb Wave Resonators

Dissipation Analysis Methods and Q-Enhancement Strategies in Piezoelectric MEMS Laterally Vibrating Resonators: A Review

“…However, one problem of this strategy is that sufficient area is required for effective transformation of propagating waves to evanescent waves, which essentially reduces the maximum piezoelectric transduction area achievable [ 111 , 114 ]. There are some other design strategies, which are based on more abrupt geometric modifications, proposed to reduce anchor loss, such as using beveled, rounded or chamfered corners at the ends of the resonator bodies [ 115 , 116 , 117 ] and introducing etched slots or holes [ 118 , 119 ], but the broad applicability of these methods to different operating frequencies has not been investigated to date. Another strategy to enhance Q involves designing the electrical excitation configuration to suppress spurious modes which could carry the acoustic energy away from the resonator body [ 120 , 121 ].…”

“…This idea has led to an interesting work by Ghatge et al [ 113 , 114 ], which adopted wide tethers to support LVRs instead of using narrow tethers as shown in Figure 8 c. The benefits of employing wide tethers include enhancement of power handling capability, less vulnerability to mechanical shock and convenience in routing the I/O electrodes. Instead of designing gradually-changed width in the acoustic waveguides, Zou et al [ 115 , 116 ] and Lin et al [ 117 ] demonstrated Q enhancements in AlN LVRs using more abrupt variations in geometry at two ends of the resonator body such as design with beveled, rounded and chamfered corners as shown in Figure 8 d–f. Among these designs, the LVR design using rounded corner exhibited largest Q enhancement of 1.6 times.…”

“…This figure is reproduced from [ 113 ] (© 2019 IEEE); ( d ) SEM of a 863-MHz AlN LVR with beveled butterfly shape; ( e ) SEM of a 863-MHz AlN LVR with rounded butterfly shape. ( d , e ) are reproduced from [ 115 ] (© 2017 IEEE); ( f ) SEM of a 830-MHz AlN LVR with chamfered corners. This figure is reproduced from [ 117 ] (© 2015 IEEE); ( g ) simulated vibration mode shape of a 220-MHz AlN LVR with etched slot.…”

Surface acoustic wave-based ultraviolet photodetectors: a review

“…Although some improved methods have been proposed, such as use of a transparent upper electrode and control of the electrode layer thickness, these methods will greatly reduce the performance of the resonator. The Lamb wave resonator (LMR) may provide a good alternative because it combines the advantages of SAW devices and FBARs [104][105][106][107]. Fig.…”

Wide Acoustic Bandgap Solid Disk-Shaped Phononic Crystal Anchoring Boundaries for Enhancing Quality Factor in AlN-on-Si MEMS Resonators

“…This includes using biconvex plates to trap acoustic energy in the center of the acoustic cavity and thus minimizing the distribution of energy closed to the anchors [ 3 ]. For AlN-body resonators, butterfly-shaped AlN plates have been proposed [ 4 ]. Another approach has been to etch acoustic reflectors into the anchoring boundaries of the resonator to reflect the outgoing acoustic waves from the supports back into the resonator [ 5 ].…”