High-Frequency Surface Acoustic Wave Devices Based on Epitaxial Z-LiNbO3 Layers on Sapphire

International audienceFilter market demand pushes to the development of new piezoelectric materials to address modern telecommunication challenges. Composite wafers combining an epitaxial piezoelectric layer and a said high velocity and acoustic quality substrate is a promising way to answer that demand. However, the fabrication of high-quality LiNbO3 films with reproducible physical properties is complicated by the difficulty to control volatile Li2O incorporation into the film and to measure its composition. So far, large-scale production of films with physical properties suitable for the targeted applications is not available. In this paper, lithium niobate films with controlled nonstoichiometry were deposited by means of pulsed injection metalorganic vapor phase deposition. We have demonstrated a high acoustical performance for surface acoustic wave (SAW) devices operating in the frequency range from 3.7 GHz up to 5.3 GHz and based on grown epitaxial Z-axis oriented LiNbO3 films on sapphire. An electromechanical coupling of 8 % for the Rayleigh wave at 5.3 GHz was demonstrated experimentall