Propagation characteristics of longitudinal-type leaky surface acoustic wave on layered structure consisting of Sc x Al 1− x N film/LiNbO 3 substrate

A longitudinal-type leaky surface acoustic wave (LLSAW) has a high phase velocity. Therefore, LLSAW devices are suitable for applications to high-frequency filters. However, the attenuation of LLSAWs is higher than that of other SAW modes. This higher attenuation of LLSAWs, which causes a low Q factor, can be reduced by growing a higher-velocity film on a piezoelectric substrate. On the other hand, K 2 in the layered structure decreases because of the small piezoelectricity in high-velocity films. In this study, LLSAW propagation characteristics on a layered structure consisting of high-piezoelectric ScAlN film/X-cut 36°Y-propagation LiNbO 3 were investigated. When a or ScAlN film was loaded, the reduction of the attenuation was observed, but K 2 for this layered structure is lower than that of LiNbO 3 . On the other hand, K 2 for Sc 0.4 Al 0.6 N film/LN is higher than that of LiNbO 3 .