| 摘要 |
PURPOSE:To increase electromechanical coupling, to quicken propagation speed of sound and to improve temperature characteristics, by providing a silicon oxide film and zinc oxide film on an alpha-alumina substrate. CONSTITUTION:A silicon oxide film 2 is vapor deposited on an alpha-alumina single substrate 1. Since the temperature characteristics are deteriorated when the film 2 is thicker, a film thickness (d) is regulated to 2<=kd<=9, where k=2pi/lambda and lambda is wavelength of surface acoustic wave. A short circuit electrode 3 is formed on a part of the silicon oxide film. A zinc oxide piezoelectric film 4 is vapor deposited on it. A comb type electrode 5 is disposed on the film 4 so that the electrode 5 can opposite to the short circuit electrode 3. The zinc oxide piezoelectric film 4 can be formed at low temperatures in high speed as multicrystal via the silicon oxide film 2. Excellent temperature characteristics can be realized by regulating the thickness of the zinc oxide piezoelectric film to 0.8<=kd<=3.7. |
