Hydrogen-Sensing Properties of a Pd/AlGaN/GaN-Based Field-Effect Transistor Under a Nitrogen Ambience

The hydrogen-sensing characteristics of a Pd/AlGaN/GaN heterostructure held-effect transistor (HFET) under a nitrogen ambience are studied in this paper. Good and stable hydrogen-sensing behaviors are obtained over the operating temperature from 30°C to 250°C. In addition, HFET shows the significant hydrogen-detecting ability under an extremely low hydrogen concentration of 10-ppb H
₂
/N
₂
. Good transient responses are also observed even at room temperature. In addition, a small and nearly constant value of recovery time (≈20 s) is acquired when the hydrogen concentration is higher than 1-ppm H
₂
/N
₂
at room temperature. Therefore, the studied device shows a promise for high-performance, high-temperature electronics, microsensors, and microelectromechanical system applications.