Hydrogen gas sensor with self temperature compensation based on β-Ga2O3 thin film

Field-effect hydrogen gas sensor devices with self-temperature compensation based on β-Ga2O3 thin films were fabricated. A β-Ga2O3 thin film was deposited on a sapphire substrate by gallium evaporation in oxygen plasma. The resistance between two ohmic electrodes on a β-Ga2O3 thin film with a Pt gate was decreased in H2 atmosphere. The sensor could detect 100 ppm H2 in 20% O2/N2 at 400 °C. The resistance of the device without the Pt gate electrode did not change significantly with variation in the atmospheric composition. A sensor device with self temperature compensation was constructed by the in-series connection of devices with and without gate electrodes. The output of the sensor device remained stable, even for temperature fluctuations over 100 °C in the region of approximately 400–550 °C.