High Selectivity Hydrogen Gas Sensor Based on WO 3 /Pd-AlGaN/GaN HEMTs.

We investigated the hydrogen gas sensors based on AlGaN/GaN high electron mobility transistors (HEMTs) for high temperature sensing operation. The gate area of the sensor was functionalized using a 10 nm Pd catalyst layer for hydrogen gas sensing. A thin WO 3 layer was deposited on top of the Pd layer to enhance the sensor selectivity toward hydrogen gas. At 200 °C, the sensor exhibited high sensitivity of 658% toward 4%-H 2 , while exhibiting only a little interaction with NO 2 , CH 4 , CO 2 , NH 3 , and H 2 S. From 150 °C to 250 °C, the 10 ppm hydrogen response of the sensor was at least eight times larger than other target gases. These results showed that this sensor is suitable for H 2 detection in a complex gas environment at a high temperature.