A 100 nm Thick, 32 kHz X-Cut Lithium Niobate Piezoelectric Nanoscale Ultrasound Transducer for Airborne Ultrasound Communication

In this letter we present the first demonstration of an ultra-thin (100 nm) lithium niobate (LN) flexural resonator for airborne ultrasound transduction. Due to the aggressively scaled thickness of the monocrystalline X-cut LN layer, the trasnsducers exhibit a low resonance frequency of 32 kHz while occupying an area of only 120 mu m x 120 mu m. An innovative electrode design converts the applied electric field to out-of-plane deflections excited by the e(21) piezoelectric coefficient. The displacement per unit of voltage at different in-plane rotation angles scales consistently with the theoretical e(21) coefficients of X-cut LN. Overall, the transducer is capable of sensitivity per unit area that is significantly larger than the state-of-the-art. [2020-0340]