Electromechanical transconductance properties of a GaN MEMS resonator with fully integrated HEMT transducers

We investigate the response of a GaN microelectromechanical resonator where the strain detection is performed by a resonant high-electron mobility transistor (R-HEMT). The R-HEMT gate located above the 2-DEG (two-dimensional electron gas) appears to enable a strong control of the electromechanical response with a gate voltage dependence close to a transconductance pattern. A quantitative approach based on the mobility of the carriers induced in the device by the piezoelectric response of the GaN buffer is proposed. These results show for the first time the electromechanical transconductance dependence versus external biasing and confirm that active piezoelectric transduction is governed by the AlGaN/GaN 2-DEG transport properties.