Shear wave transducer using (112~0) textured ZnO film

Using a conventional RF magnetron sputtering system, we have successfully obtained ZnO films in which the crystallites' c-axis is unidirectionally aligned in the substrate plane without an epitaxial technique. These are almost pure (112~0) textured films. The alignment of the crystallite c-axis in the plane was then carefully investigated by X-ray pole figure analysis and AFM. We found that the crystallites of the film were oriented randomly at the anode center and unidirectionally near the edge of the anode. Using the ZnO film, we have fabricated an ultrasonic transducer which consists of a metal electrode/(112~0) textured ZnO film/Al electrode film structure. The transducer clearly excited a shear wave without any longitudinal waves. These results indicate the wide application of this film in shear-mode resonators and SH-type SAW devices on any substrates.