  The demand for high-performance electromechanical resonators is ever-growing
across diverse applications, ranging from sensing and time-keeping to advanced
communication devices. Among the electromechanical materials being explored,
thin-film lithium niobate stands out for its strong piezoelectric properties
and low acoustic loss. However, in nearly all existing lithium niobate
electromechanical devices, the configuration is such that the electrodes are in
direct contact with the mechanical resonator. This configuration introduces an
undesirable mass-loading effect, giving rise to spurious modes and additional
damping. Here, we present an electromechanical platform that mitigates this
challenge by leveraging a flip-chip bonding technique to separate the
electrodes from the mechanical resonator. By offloading the electrodes from the
resonator, our approach yields a substantial increase in the quality factor of
these resonators, paving the way for enhanced performance and reliability for
their device applications.
