Lithium niobate thin films deposited on silicon substrates and their SAW applications

Lithium niobate has a number of attractive piezoelectric and ferroelectric properties that have been exploited for many applications. The main purpose of our work was to grow lithium niobate thin films on silicon substrates and make surface acoustic wave (SAW) devices. Theoretical curves of SAW properties of bulk crystals and films lithium niobate on silicon with a coating of silicon oxide were also obtained. The theoretical results include elastic wave properties (velocities and power flow angle) in lithium niobate bulk crystals and SAW properties (velocities and coupling coefficients). Thin films of lithium niobate have been deposited on Si (100) substrates (with SiO2 coatings) by rf magnetron sputtering. Lithium niobate film samples with very good transparency and uniformity were obtained. The film samples were structurally analyzed using Bragg x-ray diffraction (XRD). Lithium niobate XRD peaks for specific sputtering conditions corresponding to thin film orientation of (012), (104) and (110) were identified. Highly textured films showing only one orientation of the lithium niobate could be grown for all those of these above orientation on identical amorphous substrates.