Electrostatic actuation and charge sensing in piezoelectric nanomechanical resonators with a two-dimensional electron gas

The features of electrostatic actuation are experimentally studied in nanomechanical resonators based on AlGaAs/GaAs heterostructures with a two-dimensional electron gas. First, it is found that, when the gate voltage is varied, the oscillation amplitude reaches its minimum and the resonant frequency reaches its maximum at different non-zero voltages. Using numerical modeling, it is shown that this feature can be explained by the influence of the bound charge induced due to the piezoelectric effect in the resonator performing flexural oscillations. Second, the amplitude as a function of the gate voltage does not reach zero at its minimum. A short illumination makes the minimal amplitude much closer to zero. These facts can be explained by the influence of the poorly conducting edges of a two-dimensional electron gas. The obtained results show that the measurement of the specific gate voltages corresponding to the minimal amplitude and maximal resonant frequency can be used for sensing the electrical charge induced by the illumination.