Pt/AlGaN/GaN HEMT based ammonia gas sensors

We report on Pt/AlGaN/GaN HEMT based ammonia (NH
₃
) gas sensor for low concentration (50-10 ppm) sensing over the temperature range of 30-275 °C. The current decreased when the sensor was exposed to different concentrations of NH
₃
at 30 °C while it increased above 200 °C. The sensitivity values of 0.51 % and 0.83 % were achieved for 50 ppm NH
₃
at 30 °C and 275 °C, respectively. The sensing mechanisms corresponding to the temperature dependent response of NH
₃
have been explained.