| 摘要 |
It is possible to obtain a surface acoustic wave which does not easily cause characteristic fluctuations by a temperature change, has a high reflection coefficient for one electrode finger of IDT, and can easily reduce the bandwidth. A surface acoustic wave device (1) includes an IDT electrode (3) formed on a piezoelectric substrate (2) formed by crystal having Euler angle (0 plus/minus 5 degrees, 0 to 140 degrees, 0 plus/minus 40 degrees). The IDT electrode (3) is covered with a piezoelectric film (4) formed by c-axis-oriented ZnO . A convex portion corresponding to the thickness of the IDT electrode (3) is formed on the surface of the piezoelectric film (4). As the surface acoustic wave, the Rayleigh wave is used. When the IDT electrode is formed by a metal material containing Al, Au, Ta, W, Pt, Cu, Ni, or Mo as a main content and the surface acoustic wave has a wavelength ?, the normalized film thickness normalized by the wavelength of the surface acoustic wave of the IDT electrode and the normalized film thickness normalized by the wavelength of the surface acoustic wave of the piezoelectric film are within the ranges defined for each of the main contents of the IDT electrode in Table 1 given below.TABLE 1: AA MAIN CONTENT METAL OF IDT ELECTRODE BB NORMALIZED FILM THICKNESS OF IDT ELECTRODE CC NORMALIZED FILM THICKNESS OF ZnO |
