Design of Phononic Crystal Tethers for Frequency-selective Quality Factor Enhancement in AlN Piezoelectric-on-silicon Resonators

Abstract

In this work, we experimentally demonstrate frequency-selective improvement of unloaded quality factor (Qu) using one-dimensional (1D) phononic crystal (PnC) ring tethers in Aluminium Nitride (AlN) thin-film piezoelectric-on-silicon (TPoS) micromechanical resonators. We show that the 1D-PnC tethers help boost Qu by 3 times specifically at the desired resonant modes that lie in the PnC stopband but not for resonant modes lying outside the PnC stopband. These results show that the 1D-PnCs serve as frequency-selective acoustic reflectors.