SAW Characteristics of AlN/SiO₂/3C-SiC Layered Structure With Embedded Electrodes

A layered structure of aluminum nitride (AlN)/silicon dioxide (SiO₂)/cubic silicon carbide with embedded electrodes, which enables the growth of high-quality AlN thin films, is proposed and studied. The phase velocity, coupling factor, and temperature coefficient of frequency (TCF) of surface acoustic waves in the proposed structure have been investigated using the finite-element method. The simulation results show that a high velocity of 5485 m/s and a large effective coupling factor ( K²) of 1.45% can be simultaneously obtained for the first mode. The dramatic enhanced K² of 10.5% is also obtainable on the proposed structure employing Sc0.4Al0.6N thin film. Besides, the excellent zero TCF is also achieved without deteriorating the coupling factor by adding an amorphous SiO₂ overlay.