  Silicon nitride (SiN) mechanical resonators with high quality mechanical
properties are attractive for fundamental research and applications. However,
it is still a challenge for them to achieve efficient electrical integration
on-chip due to weak coupling with surrounding electrical circuits. Here, we
present a SiN drum resonator covered with an aluminum thin film, enabling large
capacitive coupling to a suspended top-gate. Implementing the full electrical
measurement scheme, we demonstrate a high quality factor ~1E4 comparable to
bare drums at room temperature and present our ability to detect ~10 mechanical
modes at low temperature. The drum resonator is also coupled to a microwave
cavity, which enables to do optomechanical sideband pumping with fairly good
coupling strength G and to perform the mechanical parametric amplification
through the gate. This SiN drum resonator design provides efficient electrical
integration and exhibits promising features for exploring mode coupling and
signal processing.
