AlGaN/GaN HEMT-based high-sensitive NO 2 gas sensors

We report on a Pt/AlGaN/GaN HEMT-based gas sensor with interdigitated electrodes for NO 2 sensing over the temperature range of 30 °C–300 °C. The sensors show a change in current (Δ I ) of 0.5 mA with sensitivity of 1.2% for 10 ppm NO 2 at 30 °C and recovers at elevated temperature. The sensitivity increases with the increase in relative humidity (0 to 90%) at 30 °C. High sensitivity of 5.5% with a corresponding Δ I of 1.8 mA is achieved for 10 ppm NO 2 concentration at 300 °C, which is higher than the reported value under similar measurement conditions. The large surface area of the interdigitated electrodes and the catalytic property of the platinum functionalization layer enables high sensitivity for low NO 2 concentrations of <10 ppm.