Abstract
To address the growing need for high-frequency tunable surface acoustic wave (SAW) devices in power ultrasound applications, this study uses finite element method (FEM) for designing and simulation of an AlN/GaN composite heterogeneous piezoelectric thin film structure fabricated on a sapphire substrate. The configuration employs a double piezoelectric layer approach to significantly improve electromechanical conversion efficiency, achieving an electromechanical coupling coefficient of 0.42%. The thickness of AlN/GaN is optimized to enable a systematic investigation of the dispersion characteristics and acoustic field distribution of Rayleigh and Sezawa waves within multilayer heterostructures. This optimization aims to facilitate the precision of ultrasonic fields, enhancing the high-frequency ultrasonic power density and the local acoustic field intensity. Simultaneously, the incorporation of SiO(2) compensation layer into the AlN/GaN heterostructure results in the formation of periodic structure that exploits disparities in sound velocity and acoustic impedance. This facilitates enhanced acoustic energy, which significantly improves both the cavitation efficiency and the intensity of acoustic flow within the liquid-phase medium. The structured surface acoustic wave (SAW) devices exhibit high-frequency characteristics coupled with low insertion loss, rendering them highly suitable for deployment in high-power SAW microfluidic platforms aimed at achieving efficient liquid-phase microfluidic material transport and manipulation. These findings hold substantial value for the advancement of novel high-frequency power ultrasound devices, providing critical insights and implications for expanding the applications within the domains of microfluidics and biomedical acoustic manipulation.