Correlation between the microstructure and gas sensing characteristics of nanocrystalline ZnO thin films

In order to accurately evaluate the effects of crystallite size and lattice defects on the physical properties of nanocrystalline metal oxide semiconductors, in this work, one of the advanced methods of X-ray diffraction analysis i.e. whole powder pattern modeling (WPPM) was developed for hexagonal systems. The initial information about the shape and distribution behavior of grains, extracted from SEM images, was applied to WPPM and the lattice constants, crystallite size, size distribution behavior, dislocation density, outer cut-off radius of dislocation and fraction of Burgers vector types were determined as a function of annealing temperature. The variations of activation energy and sensitivity of films (for the exposure of 1000 ppm of acetone vapor) were also investigated versus substrate and annealing temperature. Finally the correlation between the results of WPPM and gas sensing properties of ZnO films was evaluated.