Pd/AlGaN/GaN HEMT-Based Room Temperature Hydrogen Gas Sensor

There is a burgeoning need for miniaturized sensors to detect H-2 leaks throughout the entire value chain while envisioning a hydrogen economy. Developing a user-centric approach for manufacturing H-2 sensors exhibiting high performance, long-term stability, and ease in data communication still poses a significant challenge. With this objective in mind, we develop a Pd/AlGaN/GaN high electron mobility transistor (HEMT)-based Internet of Thing (IoT)-enabled H-2 sensing device capable of detecting extremely low concentrations (similar to 0.5 ppm) at room temperature (RT). The fabrication process of the device involves a photolithography technique for its fabrication and functionalization of the active area between the drain and source by Pd nanoparticles using the dc sputtering method. Afterward, Pd nanoparticles were functionalized onto the HEMT surface and sputtering times were also optimized. The sensor demonstrated shallow time parameters, with a recovery time of 52 s and a response time of 29 s for 10 ppm H-2 at RT respectively, with an exceptionally low detection limit of 0.5 ppm. The selectivity of the fabricated sensor was also investigated. Sensitivity toward NO2, CO2, H2S, NH3, and SO2 was approximately 1.5%, 4%, 2%, 3%, and 6.5%, respectively, compared to similar to 33% for H-2. Furthermore, the sensor displayed marvelous replicability, working in a highly humid environment while operating in a temperature range of 20-75 degrees C. The sensor was incorporated into a prototype featuring a wireless capable Nano ESP32 IoT platform for real-time conditions. The reported proof of concept on the RT H-2 sensor with enhanced characteristics can be envisioned for further technology demonstration.