On the mechanism of hydrogen sensing with SiO2 modificated high temperature Ga2O3 sensors

On the way to understand the detection mechanisms inside a high temperature metal oxide sensor with Ga2O3 as its sensitive material and a silicon dioxide top layer for increasing the sensitivity to hydrogen the sensor is exposed to dry and oxygen free gas mixtures. While the absence of oxygen decreases the selectivity of the sensor dramatically, dry air is without a major influence to the selectivity. The detection of hydrogen is possible in all cases. For additional investigations an electrode was mounted directly on top of the sensor influencing the space charges inside the sensor, which seems to be the major detection mechanism. This should lead to a further optimization of the hydrogen sensor, especially increasing the selectivity, and characterization of the environments the sensor can be utilized in.