XRD Study of Structure Transformations in Zn–In–O Nanocomposite Thin Films Prepared by Spray Pyrolysis Method

Structure and composition of spray pyrolized thin films in ZnO–In₂O₃ system with a relative atomic zinc content (Zn/In) in the range of 0.125–2 is investigated using X-ray diffraction analysis. These nanostructured films constitute of 1 to 5 In- and Zn-based oxide nanocrystalline phases including In₂O₃(ZnO)₃ with superlattice structure and ZnO with rather unexpected rocksalt structure. The octahedral coordination of Zn atoms and practically the same Zn–O distances as in the case of In₂O₃ facilitate a growth of ZnO rock salt on the surface of In₂O₃ nanocrystals. The modified Williamson-Hall method is applied to determine the crystallite size and micro-strain in the predominant In₂O₃ phase. The monotonous crystallite fineness of this phase with increase of Zn content and monotonous increase of In–Zn-based oxide crystallites is established. A mutual doping of In₂O₃ and ZnO nanocrystallites, leading to the formation of n–n⁺ contacts at their boundaries, has been revealed. Model representations about the influence of the nanocomposite structure of films on their electrical properties are proposed.