| 摘要 |
PURPOSE:To obtain a surface acoustic wave element which has a high electromechanical coupling constant and a high acoustic speed and is suitable to a high frequency range by using a high-density polycrystal alumina sintered body which has <=1mum surface roughness as a substrate material. CONSTITUTION:A high-density polycrystal alumina sinter substrate 1 is formed of the polycrystal alumina sintered body which is sintered to 3.90g/cm<3> high density and <=1mum surface roughness, preferably, enough to transmit visible light and has a few closed pores. Further, a reed screen type electrode 3 of an aluminum vapor-deposited film and a zinc oxide piezoelectric thin film 2 of oriented polycrystal obtained by sputtering on a specific condition are formed on the substrate 1. Thus, the surface acoustic wave element suitable to a high frequency range is obtained, and a metallic counter electrode facing the read screen type electrode is further provided on the top surface of the piezoelectric thin film to increase its frequency range more. |
