| 摘要 |
The present invention provides a surface wave acoustic element which has a large surface acoustic wave propagation velocity and can be used in high-frequency regions by using a hard layer other than diamond which has inferior surface flatness. This surface acoustic wave element has a sapphire single crystal substrate, a hard layer formed on the sapphire single crystal substrate and having a composition containing (Al1-xM1x)2O3 (0<=x<=0.5) in which at least one element M1 (M1=B, Ga, In, Ti, V, Cr, Mn, Fe, Co) is added to sapphire, and a piezoelectric layer formed on the hard layer.
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