| abstract |
A surface acoustic wave element includes a hard layer containing a composition component essentially consisting of at least one of diamond and a diamond-like carbon film, a piezoelectric layer formed on the hard layer, a silicon dioxide (SiO 2 ) layer formed on the piezoelectric layer, and electrodes combined with the piezoelectric layer to perform electro-mechanical conversion. The surface acoustic wave element has a larger electro-mechanical coupling coefficient and a higher surface acoustic wave propagation velocity than does a conventional surface acoustic wave element having no silicon dioxide layer, thereby obtaining a surface acoustic wave element that can operate in a high-frequency range. In particular, the electro-mechanical coupling coefficient is increased. The SiO 2 layer is an electric insulator and rarely reacts with moisture or acids. The SiO 2 layer protects the piezoelectric layer and the electrodes from effects of the external environment, thereby providing a surface acoustic wave element having good high-frequency characteristics and a high resistance to adverse environments. |