Fabrication and humidity sensing properties of nanostructured TiO2-SnO2 thin films

Nanostructured TiO2-SnO2 thin films have been prepared using a sol-gel process and the humidity sensing properties of the films were investigated. The films possess nano-sized grains and nanoporous structure. The TiO2-20 wt.% SnO2 film exhibits the highest sensitivity for the humidity, which shows over three orders change in the resistance during the relative humidity (RH) variation from 20 to 90%. The high humidity sensitivity is due to the protonic and electrolytic conduction between hydroxyl ions and water molecules adsorbed on the film surfaces with capillary nanopores. (C) 2002 Published by Elsevier Science B.V.