Gated piezoresistive GaN microcantilever as an acoustic transducer

In this article, we present for the first time, transduction of ultrasonic acoustic pressure using a gated piezoresistive AlGaN/GaN Heterojunction Field Effect Transistor (HFET) integrated on GaN microcantilever. With a periodic pressure generated in air, the microcantilever was found to oscillate, and the HFET was able to transduce the pressure variation of 150.4 μPa in ambient conditions with a tunable linear sensitivity of 33.2 mV/Pa, response time <; 40 ms, and power consumption of 45 μW. The device demonstrates 3 orders higher pressure sensitivity than simple piezoresistor, and also higher than the sensitivity of commercially available Knowles microphone; thereby offering a promising alternative for cantilever enhanced photoacoustic spectroscopy (PAS).