Mechanism of Hydrogen Sensing by AlGaN/GaN Pt-Gate Field Effect Transistors: Magnetoresistance Studies

Physical mechanism responsible for hydrogen sensing by AlGaN/GaN transistors was investigated. Original resistance studies versus magnetic fields (up to 8 T) were used to determine precisely hydrogen-induced change of carrier mobility and density. Results clearly show that the carrier mobility change is responsible for <;5% and that the hydrogen sensitivity is mainly related (more than 95%) to the carrier density change. These results support the physical model that relates hydrogen sensing with a change of surface charges resulting in modification of the GaN depletion layer.