Thin-film lithium niobate on diamond-coated silicon substrates for surface acoustic wave applications

The goal of this project is to produce GHz-range electronic filters with low insertion loss for front-end radio-frequency surface acoustic wave (SAW) devices. Theory predicts that lithium niobate thin films on diamond/silicon substrates have high electromechanical coupling coefficients and SAW propagation velocities because of the interaction with the high-acoustic-velocity diamond layer. RF-magnetron sputtering technology is used to grow lithium niobate films on diamond coated silicon substrates, thus allowing the SAW filters to be integrated with electronic circuits, thereby achieving size reduction with increased bandwidth. The structural properties and morphology of the films are investigated by X-ray diffraction and atomic force microscopy. Interdigital transducers (IDT) are deposited onto the LiNbO₃/diamond/silicon films and the SAW properties are being studied.