Patent ID: 8004148

Claim:
A surface acoustic wave element, comprising: a diamond layer; an alumina nitride layer provided on the diamond layer; a silicon oxide layer provided on the alumina nitride layer; and a pair of electrodes provided between the alumina nitride layer and the silicon oxide layer, the electrodes applying a voltage to the alumina nitride layer, wherein if a thickness of the alumina nitride layer is represented by H 1 , a thickness of the silicon oxide layer is represented by H 2 , a wavelength of a surface acoustic wave is represented by λ, x is defined as x=2πH 1 /λ, and y is defined as y=2πH 2 /λ, (x, y) meets all of formulas 1 to 4, the formula 1 being y≦0.750×x+0.325, the formula 2 being y≦−0.300×x+1.690, the formula 3 being y≧−0.500×x+0.950, the formula 4 being y≧0.700×x−0.610.