Hydrogen Sensing Characteristics of Pt Schottky Diodes on () and (010) Ga2O3 Single Crystals

We investigated the hydrogen sensing characteristics of Pt Schottky diodes on and (010) b-Ga2O3 bulk crystals. The Pt Schottky diodes on b-Ga2O3 wafer exhibited the fast, reversible, and cyclic response upon hydrogen exposure. The maximum value of the relative current change of the Ga2O3 diode sensor was as high as 7.86 x 107 (%) at 0.8 V, which is slightly higher than that of the (010) Ga2O3 diode. The hydrogen responses of both b-Ga2O3 diode sensors are believed to result from oxygen and gallium atomic configurations of Ga2O3 surfaces for hydrogen adsorption. The Pt Schottky diodes of Ga2O3 wafers did not show any clear response to other gases, such as N2, CO, CO2, O2, CH4, NO2, and NH3. Our finding suggests that the Pt Schottky diodes on b-Ga2O3 hold great potential for the applications of hydrogen gas sensors with high sensitivity and selectivity.