Hydrogen Detection Performance of a Pt-AlGaN/GaN HEMT Sensor at High Temperatures in Air Ambient

A Pt-gated AlGaN/GaN high electron mobility transistor (HEMT) was fabricated and used for sensing hydrogen (H 2 ) gas in air ambient at extreme temperatures. Compared to previous studies, this work extends the investigation of GaN HEMT device H 2 detection capabilities to temperatures as high as 450 °C in air background. The performance of the device was comprehensively demonstrated and analyzed over a wide temperature range from 200 to 450 °C. To begin with, an optimum operating drain-source ( V ds ) and gate-source voltages ( V gs ) were found as 4.5 and 0 V, respectively. At this bias, the sensor demonstrated the highest sensitivity (28.19%) in conjunction with fast response (48.62 s), and recovery time (109.48 s) at 450 °C. The impact of temperature on sensitivity, response, and recovery time was also discussed, revealing that sensitivity ranged from 24.9 to 28.2% between 250 and 450 °C, which is significantly higher than the sensitivity at 200 °C (18.8%). Additionally, response times under 50 s were obtained from 350 to 450 °C, with the lowest being 39.54 s at 400 °C. Furthermore, the signal-to-noise ratio consistently exceeded 30 dB across the temperature range of 250 to 450 °C. Finally, the first-derivative method, utilized for assessing the triggering capability of the sensor, revealed peak performance at 300 °C.