High temperature hydrogen gas sensing property of GaN prepared from α-GaOOH

Extremely stable gas sensors at elevated temperature (T > 400 °C) with rapid detection of hydrogen gas are urgently demanded especially for hydrogen production industry which typically involves a high-temperature system. Gallium nitride (GaN) possesses excellent physicochemical properties and is expected to be one candidate for high temperature gas sensor. In this work, the GaN preparation from α-GaOOH precursors by a direct nitridation method under NH3 flow is presented. The nitridation was done at various temperatures to obtain GaN with different oxygen contents, which played a vital role in gas sensing response of thick film GaN in various concentration of H2 gas at 500 °C. The sensitivity of the obtained GaN with 2.07 wt.% of oxygen content was 10 times higher than that sample with the lowest oxygen content (1.9 wt.%) and the sensitivity drastically decreased when the oxygen content was 2.53 wt.%. The sensors also demonstrated high stability as indicated by their repeatable feature after being exposed at a various concentration of H2 (150-750 ppm). Furthermore, the GaN showed higher sensitivity than that of β-Ga2O3 sensor.