Abnormal current-voltage characteristics of WO3-doped SnO2 oxide semiconductors and their applications to gas sensors

We have investigated abnormal current-voltage characteristics of an oxide semiconductor and have developed a novel method of detecting reducing gases utilizing the self-heating mechanism of the sensing layer without an additional heater. Planar-type sensors based on WO3-doped SnO2 were fabricated using a screen-printing technique. The applied voltage across the sensing layer caused heating of the sensing layer and the current abruptly varied upon exposure to a gas, mainly as a result of surface reactions. A fascinating aspect of the gas sensing scheme is that no additional heater is necessary for detection. The new sensing method has been applied to C2H5OH gas in this preliminary work.