  In this work, we have successfully engineered and examined suspended
laterally vibrating resonators (LVRs) on a lithium niobate thin film on lithium
niobate carrier wafer (LN-on-LN) platform, powered by aluminum interdigital
transducers (IDTs). Unlike the lithium niobate-on-silicon system, the LN-on-LN
platform delivers a stress-neutral lithium niobate thin film exhibiting the
quality of bulk single crystal. The creation of these aluminum-IDTs-driven
LN-on-LN resonators was achieved utilizing cutting-edge vapor-HF release
techniques. Our testing revealed both symmetric (S0) and sheer horizontal (SH0)
lateral vibrations in the LVR resonators. The resonators displayed a quality
factor (Q) ranging between 500 and 2600, and coupling coefficient $k_{eff}^2$
up to 13.9%. The figure of merit (FOM) $k_{eff}^2 \times Q$ can reach as high
as 294. The yield of these devices proved to be impressively reliable.
Remarkably, our LN-on-LN devices demonstrated a consistently stable temperature
coefficient of frequency (TCF) and good power handling. Given the low thermal
conductivity of lithium niobate, our LN-on-LN technology presents promising
potential for future applications such as highly sensitive uncooled sensors
using monolithic chip integrated resonator arrays.
