the adsorption of chemical species onto a semiconductor material acts as a gate voltage, tuning the channel conductivity across the bulk material. This phenomena has been widely used for chemical sensing [22,23]. When the sensor includes piezoelectric semiconductor materials and a Schottky junction at the metal–semiconductor interface, the voltage from the adsorbed species can alter the energy barrier height and regulate the carrier transport. At the same time, the barrier can also be tuned with the strain-induced piezoelectric potential