Boosting Q of <100> Aligned ALN-on-Silicon Laterally Vibrating Resonators by Wide Acoustic Bandgap Phononic Crystal Anchors

We demonstrate the boosting of quality factor (Q) of a <100> aligned Aluminum Nitride (AlN) on Silicon (Si) laterally vibrating resonator (LVR) by using wide acoustic bandgap (ABG) phononic crystal (PnC) anchors. To date, Q-boosting strategies have been studied predominantly for the common <110> orientation. Given the anisotropy of Si, changing orientation could notably affect the effectiveness of Q-boosting strategies. We show experimentally that Qs of <100> aligned LVRs more than doubled to 10000 with the PnC anchors. To further corroborate the effectiveness of the PnCs, we also incorporated the PnCs into delay lines with wave propagation along the <100> axis, showing that the PnCs provide large acoustic attenuation of 45 dB.