Hydrogen sensing characteristics of Pt Schottky diode on nonpolar m-plane 11¯00 GaN single crystals

We investigated the hydrogen sensing capabilities of Pt Schottky diodes using nonpolar 101¯0m-plane GaN (m-GaN) bulk crystals. The Pt Schottky diodes on m-GaN wafer exhibited the fast and reversible response upon exposure to various hydrogen concentrations. The maximum sensitivity of m-GaN diode sensor was measured as high as 2 × 104% at the forward bias of 0.1 V upon 4% hydrogen exposure. The Pt Schottky diodes on m-GaN sensors showed the selective sensing to hydrogen and negligible response to other gas species including CO, CH4, CO2, NO2, and NH3 at 25 °C. Our finding shows that Pt/m-GaN diode hold great potential for highly-sensitive hydrogen gas sensors due to the presence of nitrogen atoms having a much higher affinity to hydrogen than gallium atoms on nonpolar m-plane surface.