GaN hydrogen sensor with Pd-SiO2 mixture forming sensing nanoparticles

A high-performance GaN hydrogen sensor fabricated by a Pd-SiO₂ mixture to form a rough sensing surface with pores and nanoparticles is investigated. Hydrogen atoms trapped on the GaN surface and within the mixture form two-dimensional and three-dimensional dipoles, respectively, depending on biased voltages. Thus three sensing regions are found in current-voltage characteristics. The sensing response and barrier-height variation are over 10⁷ and 410 mV, which are the highest values ever reported. The response time is as short as 40 s, indicating the proposed hydrogen sensor is very promising for hydrogen detection.