Optimization of physical filtering for selective high temperature H2 sensors

This paper investigates the improvement in selectivity by means of applying a physical gas filter. Looking for a selective and highly sensitive hydrogen sensor, various filter systems, single, dual and buried filter systems, were deposited on top of a basic high-temperature semiconducting Ga2O3 thin film sensor. Sensor respondence on a big variety of gases present in domestic ambience and especially hydrogen and ethane, which is the hardest test on cross sensitivity, is shown. Using a single filter SiO2 layer a selective hydrogen sensor is realized, which is able to detect 50 ppm hydrogen at an operation temperature of 700°C in humid air without any interference caused by other gases. Dual SiO2/metal oxide filter systems and buried metal oxide layer filters show behaviors varying from selective ethane to selective hydrogen detection.