The surface acoustic wave propagation characteristics of 41/spl deg/ lithium niobate with thin-film SiO/sub 2/

Abstract

The surface acoustic wave (SAW) propagation properties of 41/spl deg/ Y-X lithium niobate (LiNbO/sub 3/) with SiO/sub 2/ film layers have been investigated using interdigital transducer structures. Different thicknesses of SiO/sub 2/ from 500 nm to 1500 nm were deposited on the 41/spl deg/ LiNbO/sub 3/ by RF diode sputtering from a glass target. An arrayed transducer pattern of aluminum interdigital transducer electrodes on the upper SiO/sub 2/ film surface facilitated the excitation of a wide frequency band of harmonic waves and permitted delineation of SAW velocity and propagation loss characteristics for several values of film-thickness to acoustic-wavelength (t//spl lambda/) ratio. With resonator patterns at the substrate/film interface, the capacitance ratio (C/sub m//C/sub 0/), related to coupling factor, and the temperature coefficient of frequency (TCF) were determined.