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Poly(methyl methacrylate) (PMMA) encapsulated Pt-AlGaN/GaN Schottky diodes show highly sensitive (100 ppm, 0.01% by volume) room temperature detection of hydrogen and are insensitive to the presence of water in the sensing ambient. These diodes show no physical degradation or loss of sensitivity when repeatedly cycled (50 x, 1 min hold at each temperature) between 25-100degC. There is complete selectivity for hydrogen sensing over other gases, including CO, CO2, NO2, O2 and CH4. The PMMA encapsulation provides an effective and robust barrier to moisture, greatly increasing the range of environments in which the sensors can be used. more...

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. more...

We investigated the hydrogen sensing characteristics of Pt Schottky diodes on (2¯01)and (010) β-Ga2O3bulk crystals. The Pt Schottky diodes on β-Ga2O3wafer exhibited the fast, reversible, and cyclic response upon hydrogen exposure. The maximum value of the relative current change of the (2¯01)Ga2O3diode sensor was as high as 7.86 × 107(%) at 0.8 V, which is slightly higher than that of the (010) Ga2O3diode. The hydrogen responses of both β-Ga2O3diode sensors are believed to result from oxygen and gallium atomic configurations of Ga2O3surfaces for hydrogen adsorption. The Pt Schottky diodes of Ga2O3wafers 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 β-Ga2O3hold great potential for the applications of hydrogen gas sensors with high sensitivity and selectivity. more...