Topology-Optimized 2D Silicon-Air Phononic Crystal Slabs for Enhancing Quality Factor of Laterally Vibrating Resonators

Zihao Xie, Yongqing Fu, Jin Xie*

*Corresponding author for this work

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Abstract

2D Phononic crystal (PnC) slabs have shown advantage in enhancing the quality factors (Q) of piezoelectric laterally vibrating resonators (LVRs) through topology optimization. However, the narrow geometries of most topology-optimized silicon air 2D PnC slabs are facing significant fabrication challenges owing to restricted etching precision, and anisotropic nature of silicon is frequently overlooked. To address these issues, this study employs finite element analysis (FEA) with appropriate discretization numbers and genetic algorithm (GA) to optimize the structures and geometries of 2D silicon-air PnC slabs. The optimized square lattice PnC slabs, featured with a rounded-cross structure oriented along the <110> directions of silicon, achieve an impressive relative bandgap (RBG) width of 82.2% for in-plane modes. When further tilted by 15 degrees from the <100> directions within the (001) plane, the optimal RBG width is expanded to 91.4%. We fabricated and characterized thin-film piezoelectricon-silicon LVRs, with or without optimized 2D PnC slabs. The presence of PnC slabs around anchors increases the series and parallel quality factors (i.e., Qs and Qp) from 2240 (and 2237) to 7118 (and 7501) respectively, with the PnC slabs oriented along the <110> directions of silicon.
Original languageEnglish
JournalNanotechnology and Precision Engineering
Publication statusAccepted/In press - 12 Jun 2024

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