Hexagonal Boron Nitride Functionalized AlGaN/GaN High Electron Mobility Transistor for Enhanced Carbon Dioxide Sensing

This study demonstrates design of a high-sensitivity carbon dioxide (CO₂) sensor utilizing an AlGaN/GaN High Electron Mobility Transistor (HEMT) functionalized with hexagonal boron nitride (hBN). The sensor leverages the unique electronic properties of III-nitride semiconductors, where a two-dimensional electron gas (2DEG) forms at the AlGaN/GaN interface, offering high electron mobility and enhanced sensing performance. The incorporation of hBN, known for its selective adsorption properties, significantly improves the sensor's CO₂ selectivity, resulting in a 56% response at 100 ppm CO₂, with a detection range spanning 1 ppm to 100 ppm and a rapid response time of 120 seconds. The material integration process involves epitaxial growth, metal deposition, photolithography, and hBN functionalization via mechanical exfoliation. This sensor is further integrated with an ESP32 IoT module for real-time environmental monitoring. The combination of advanced material engineering and IoT connectivity demonstrates the sensor's potential for precise CO₂ detection in environmental and industrial applications, overcoming limitations of conventional CO₂ sensors.