A surface acoustic wave (SAW) device that is made with diamond, that has
high efficiency, and that can be operated at high frequencies,
particularly from 9.5 to 10.5 GHz. The SAW device comprises a diamond
layer formed singly or formed on a substrate, a ZnO piezoelectric layer,
interdigital transducers (IDTs), and a short-circuiting electrode as
required. The SAW device has a structure in which the thickness of the ZnO
layer, the wavelength of a harmonic of the SAW, and the line width of the
IDTs fall in a specified range. With this structure, a large
electromechanical coupling coefficient is obtained in a high-frequency
range of 10 GHz band by utilizing the third or fifth harmonic of the SAW.