Investigation of the Performance of HEMT-Based NO, NO2 and NH3 Exhaust Gas Sensors for Automotive Antipollution Systems

We report improved sensitivity to NO, NO [GRAPHICS] and NH [GRAPHICS] gas with specially-designed AlGaN/GaN high electron mobility transistors (HEMT) that are suitable for operation in the harsh environment of diesel exhaust systems. The gate of the HEMT device is functionalized using a Pt catalyst for gas detection. We found that the performance of the sensors is enhanced at a temperature of 600 degrees C, and the measured sensitivity to 900 ppm-NO, 900 ppm-NO [GRAPHICS] and 15 ppm-NH [GRAPHICS] is 24%, 38.5% and 33%, respectively, at 600 degrees C. We also report dynamic response times as fast as 1 s for these three gases. Together, these results indicate that HEMT sensors could be used in a harsh environment with the ability to control an anti-pollution system in real time.