Low-Loss, High-Frequency and Large-Coupling SH SAW Resonators Based on SiN/LiNbO 3 /Si

By bonding the sub-wavelength-thick LN layer of rotated Y-cut to a high-velocity substrate, such as Si, the quasi-SH mode no longer couples with the bulk modes in substrate and the leaky component is effectively eliminated. As the propagation loss is no longer the biggest concern for choosing the substrate, Y-cut LN with a low rotation angle, enabling the ultra large coupling coefficient $(k^{2})$, can be used. In addition, by overlaying a high velocity layer, on top of LN/Si, the phase velocity $(v_{p})$ of the shear-horizontal (SH) wave can be visibly enhanced at a small cost of $k^{z}$. By carefully designing the LN and SiN thicknesses as well as the LN rotation angle, the high frequency and large $k^{2}$ can be achieved simultaneously, and the high-performance SiN/LN/Si SH devices show great potential for current and next generation RF front ends.