Enhanced Coupling Coefficient of Surface Acoustic Wave on AlN Film/High-Velocity Substrates with Periodic Trough Structure

This study aims to enhance the performance of surface acoustic wave (SAW) filters for next-generation communication systems by improving the coupling coefficient (K<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>) of SAW resonators using aluminum nitride (AlN) thin films on high-velocity substrates. In this study, the SAWs on a layered structure comprising a modified AlN film/floating electrode layer/high-velocity substrate are analyzed by using finite element method (FEM). The simulation results indicate that, compared with conventional AlN/Si structures, introducing a floating electrode and periodic troughs between the modified AlN film and the high-velocity Sapphire substrate enhances the K<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and V of the quasi-Sezawa mode. This positions the proposed structure as a viable candidate for advanced 5G applications, offering a feasible approach for fabricating high-performance SAW devices.