Effect of annealing on the structures and properties of Al and F co-doped ZnO nanostructures

Al–F co-doped ZnO (AFZO) nanocrystals were successfully synthesized onto glass substrates by the sol–gel method and the structure and morphology of the films as a function of annealing temperature were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicated that all the films were polycrystalline with a hexagonal wurtzite structure and exhibited a c-axis preferred orientation. The XPS study confirmed that co-doping ions are successfully incorporated into the ZnO nanostructure. AFZO thin films annealed at 500 °C exhibited the lowest resistivity due to the higher carrier concentration and mobility. The knowledge acquired in this work is important for the AFZO thin films with applications in optoelectronic devices.