Preparation and humidity sensing behaviors of nanocrystalline SnO2/TiO2 bilayered films

The single- and bi-layered nanocrystalline SnO2/TiO2 films are prepared using a sol-gel process and the humidity sensing behaviors of the films are investigated. The films possess the grain size of nanometer order and nanoporous structure. The bilayered films exhibit a better linearity with narrower hysteresis loop in the resistance variation for relative humidity than single layered films. The bilayered SnO2/TiO2 film shows high sensitivity with nearly three orders change in the resistance during the relative humidity variation from 30 to 90%. The humidity sensing behaviors in the single- and bi-layered films are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.