Pure Shear Bulk Acoustic Wave of the Oriented AJN

Characteristics of bulk acoustic wave (BAW) propagating in (100)-, (002)-, (110)-, (200)-, (210)- and (300)-oriented AlN were investigated in this study. It was found the (002)-oriented AlN provided a pure longitudinal mode, while the (100)-, (110)-, (200)-, (210)- and (300)-oriented AlN supported a pure fast shear mode with the phase velocity 5867 m/s and the piezoelectric coupling constant (K2) 2.45 %. The (100)-, (110)-, (200)-, (210)- and (300)-oriented AlN can be employed for the design of thin film acoustic wave resonator (FBAR) liquid sensor.