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

There is a burgeoning need for miniaturized sensors to detect H2 leaks throughout the entire value chain while envisioning a hydrogen economy. Developing a user-centric approach for manufacturing H2 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 H2 sensing device capable of detecting extremely low concentrations (~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 H2 at RT respectively, with an exceptionally low detection limit of 0.5 ppm. The selectivity of the fabricated sensor was also investigated. Sensitivity toward NO<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{2},}$ </tex-math></inline-formula> CO<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{2},}$ </tex-math></inline-formula>H2 S, NH<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{3}} $ </tex-math></inline-formula>, and SO2 was approximately 1.5%, 4%, 2%, 3%, and 6.5%, respectively, compared to ~33% for H2. Furthermore, the sensor displayed marvelous replicability, working in a highly humid environment while operating in a temperature range of 20–<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$75~^{\circ }$ </tex-math></inline-formula>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 H2 sensor with enhanced characteristics can be envisioned for further technology demonstration.