Highly sensitive III–V nitride based piezoresistive microcantilever using embedded AlGaN/GaN HFET as ultrasonic detector

We report, for the first time, an ultra high gauge factor of more than 3500 observed using AlGaN/GaN Heterostructure Field Effect Transistor (HFET) embedded GaN piezoresistive microcantilever. In addition, the deflection transduction signal from the HFET was utilized to determine dynamic bending as well as AC frequency response of the cantilever. Finally, the piezoresistive microcantilver was used to detect very small acoustic pressure waves generated by a piezo chip oscillated at sub nm amplitude at the resonance frequency of the cantilever positioned 1 cm away, highlighting the utility of these cantilevers as highly sensitive ultrasonic transducers.