Operation of NO₂ Gas Sensors based on Pd-AlGaN/GaN HEMT up to 500 °C

We investigated the performance of NO₂ gas sensors based on AlGaN/GaN high electron mobility transistors (HEMTs) at high temperatures up to 500 °C. A 30-nm Pd catalyst layer as the gate of the transistor sensor was deposited by e-beam evaporator for NO₂ sensing. At 500 °C, the sensor showed high sensitivity (8.1%), fast response (6 s) and recovery times (7 s) under 1 ppm NO₂, thereby proving to be a great candidate for semiconductor sensors under extreme conditions.