ABSTRACTAluminum Nitride (AlN) is a promising piezoelectric material for Acoustic Wave (AW) sensor application due to its high acoustic velocity, linear thermal coefficient and high electromechanical coupling coefficient. Epitaxial AlN thin films were successfully grown on the Sapphire C plane substrate by Plasma Source Molecular Beam Epitaxy (PSMBE). Standard two-port resonator structures were fabricated on the AlN/Sapphire by standard photolithography. Excimer laser micromachining techniques were utilized to fabricate microgroove gratings on the surface of thin film. Beside Surface Acoustic Wave (SAW), Surface Transverse Wave (STW) propagation was also found on the devices with those microgroove and classical metal strip gratings. Laser micromachinined microgroove gratings were found to enhance the propagation of STW. Further, sensors based on STW showed little attenuation in the liquid environment, while sensors based on SAW suffered excess loss when exposed to liquid.
