Abstract
Electrical and optical properties of SnO2 and ZnO polycrystalline films were investigated to reveal the surface reactions relating to gas sensing of the semiconductor-type gas sensors. The SnO2 films were prepared by a liquid phase deposition method and the ZnO films were done by a sol-gel method. When the SnO2 films were treated in 0.5 % H2/N2, the absorption was enhanced at shorter-wavelength-region from 350 to 500 nm. Such absorption was related to the formation of oxygen vacancy but the carrier density of the film was not necessarily enhanced with the absorption.
