SURFACE ACOUSTIC WAVE ELEMENT

摘要

PURPOSE:To improve the reproducibility of piezoelectric characteristics and to reduce the transmission loss of a high frequency region, by using an elastic matter structure in which an aluminum nitride film is formed on an elastic substrate which has a positive delay time temperature coefficient to a surface acoustic wave. CONSTITUTION:An aluminum nitride film 2 is formed on a surface equivalent to the crystalline face (0001) of a sapphire substrate 1 having a positive delay time temperature coefficient to a surface acoustic wave. In this case, the piezoelectric axis of the film 2 is set vertical or horizontal to the substrate 1. Then a surface acoustic wave generating electrode 3 and a surface acoustic wave detecting electrode 4 are formed on the surface of the film 2. Thus a surface acoustic wave is excited in the direction equivalent to the direction of an axis 1-100 and on the surface (0001) of the substrate 1.