A P-matrix-based model for the frequency analysis of IDT/AlScN/Sapphire SAW-delay line

Abstract

In this paper, we propose a P-Matrix model for the frequency analysis of SAW-delay line based on AlScN/Sapphire layered structures with 12.5 %, 25 % and 37.5 % scandium (Sc) concentrations. The effect of scandium concentration on the acoustic surface wave velocity, the electrode reflectivity, the transduction coefficient, the propagation loss and the distributed finger capacitance was taken into account in the frequency analysis of the layered SAW delay line. The acoustico-mechanical characterization indicated that the AlScN exhibit higher piezoelectric properties compared with those of pure AlN films, leading to significant improvement of electromechanical coupling coefficient. It also found that the Young’s modulus and the hardness of AlN film decrease significantly when Sc is doped, and is responsible for the decreased acoustic velocity. Additionally, the frequency analysis of AlScN-SAW delay line showed that the lower insertion loss predicted from the high Sc concentration, demonstrating the potential applications of AlScN in RF-MEMS applications. The resonant frequency also shifted slightly to the lower frequencies with increasing scandium concentration.