Preparation, micromorphology and stability of tin dioxide thin films

Some issues will be presented concerning the stability of polycrystalline oxide films to be used as semiconductor gas sensors. They are mostly related to the yet incomplete knowledge and control of inner and outer surface properties. One aspect will be considered in detail, namely the connection of film morphology, grain growth and reshaping with the electrical response stability of the material. Specifically, the correlation is studied between the preparation parameters and the characteristics of SnO2 thin films. Tin dioxide films were deposited by spray-pyrolysis of a metallorganic tin compound at 300-400 degrees C. X-ray line broadening analysis and Transmission Electron Microscopy allowed the evaluation of the grain shape and of their growth under operating conditions. The effect of the deposition conditions on the film morphology and properties was also analyzed, in view of the use of these films as gas sensitive materials.