${\rm NO}_{2}$ Detection With AlGaN/GaN 2DEG Channels for Air Quality Monitoring

Low-ppb room temperature NO₂ detection is demonstrated using recessed AlGaN/GaN heterostructures fabricated on silicon substrates. We employ the 2-D electron gas (2DEG) formed at the interface of the AlGaN/GaN heterostructure for the monitoring of low-ppb NO₂ concentrations. The dynamic range of these 2DEG structures can be tuned to that of interest for air quality monitoring (0-100 ppb) by recessing of the open gate areas. We find that in the presence of humidity, the interaction of NO₂ with the open gate area reversibly changes 2DEG conductivity. A slope-based detection scheme in combination with periodic heating-induced gas desorption enables continuous air quality (NO₂) monitoring.