Micromechanical devices based on piezoelectric resonators

A piezoelectrically transduced resonator device comprising:

• a wafer including a substrate, a buried oxide layer formed on the substrate, and a device layer formed on the buried oxide layer, the wafer further including an air gap in which portions of the buried oxide layer and device layer have been removed;
• and
• a resonator suspended within the air gap of the wafer above the substrate, the resonator comprising a portion of the device layer, a piezoelectric layer, and top and bottom electrodes contacting top and bottom sides of the piezoelectric layer, wherein the portion of the device layer is not directly connected to the wafer;
• wherein the resonator is configured to move relative to the substrate under electrostatic force to tune the frequency of the resonator device when a direct current voltage is applied between the substrate and the portion of the device layer of the resonator.