Microstructure of and Crystal Defects in Nanocrystalline Tin Dioxide Thin Films

Nanocrystalline SnO{sub 2} thin films, prepared by electron beam evaporation from high purity SnO{sub 2} and post deposition annealing in air at 700 C with different times, were investigated using HRTEM. The films are composed of nanocrystalline SnO{sub 2} crystallites and pores. Many of the crystallites consist of crystal defects, such as crystallographic shearing planes (CSPs), dislocations and twin boundaries (TBs). Atomistic structures of these defects were investigated. These defects interact with each other, resulting in different configurations of crystallites. The local composition at CSP and TB steps at dislocation cores varies with the type of dislocations and CSPs and is different from the stoichiometric composition of SnO{sub 2}. Thus, the electronic structure at these defects is different from that of the perfect SnO{sub 2}.