In this work, enhanced hydrogen sensing characteristics of a GaN-based Schottky diode-type sensor with a GaOx layer are studied and demonstrated. A thin GaOx layer inserted in Pd/GaN interface is oxidized by the immersion in an H2O2 solution at room temperature. Experimentally, a significantly high hydrogen sensing response of 1.8 × 105 and a large Schottky barrier height variation ratio of 33.1% are found upon exposure to a 1% H2/air gas at 300 K. In addition, a very low detection limit of 0.1 ppm H2/air at 300 K is obtained. These improved properties could be attributed to the effective dissociation of hydrogen molecules and rougher Pd surface caused by the presence of the GaOx layer. The response (recovery) time constant of 13.3 (23.6) s is obtained upon exposure to a 1% H2/air gas at 300 K. The related hydrogen adsorption analysis of the proposed device is also studied and demonstrated.
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