A differential extended gate-AlGaN/GaN HEMT sensor for real-time detection of ionic pollutants

In this study, we propose a differential extended gate (DEG)-AlGaN/GaN high electron mobility transistor (HEMT) sensor to detect ionic pollutants in solution. The DEG-AlGaN/GaN HEMT sensor consists of two extended gate sensing units, which combine the differential method with the extended gate structure. Ionic pollutant Fe3+ is used to test the feasibility of the device. Compared to the conventional AlGaN/GaN HEMT sensor, DEG-AlGaN/GaN HEMT sensors can effectively reduce the effect of noise factors and successfully improve the detection limit to 10 fM. At the same time, the DEG sensor shows that Fe3+ can be detected in a wide range of concentrations, varying from 10 fM to 100 μM, and it shows better linearity (R2 = 0.9955) than the conventional AlGaN/GaN HEMT sensor. These results demonstrate that the unique DEG design can overcome the drawbacks of the conventional AlGaN/GaN HEMT sensor, and significantly improve the overall performance of the AlGaN/GaN HEMT sensor. As a result, this novel sensor has the potential to be a real-time and high-performance test tool for environmental monitoring.