Hydrogen Sensing Characteristics of α-phase Ga2O3 Based Schottky Diode

Abstract An α-phase Ga2O3 (α-Ga2O3 ) thin film layer was grown on a sapphire substrate by halide vapor phase epitaxy (HVPE), and an α-Ga2 O3 based Schottky diode hydrogen sensor was fabricated. Hydrogen sensing characteristics on the α-Ga2O3 surface were investigated at temperature range from 25 to 500°C. The device showed a hydrogen responsivity of 187% for 500 ppm hydrogen exposure, and exhibited a distinctive current increase response to 50 -500 ppm hydrogen concentrations at 100°C. The hydrogen sensor presented a distinctive hydrogen response up to 500°C, and a decent hydrogen cross-selectivity over other gases including N₂, CO, CO2 , CH4 , NO2 , NH3 , and O2 . Furthermore, the effect of crystal structure of the α-Ga2O3 surface on the hydrogen sensing behavior was examined.