Nano-structural variations of ZnO:N thin films as a function of deposition angle and annealing conditions: XRD, AFM, FESEM and EDS analyses

In this work the influence of the variation of the stoichiometry of the annealing gas as a mixture of oxygen and nitrogen on the morphology, shape and crystallography (chemical composition) of Zn thin films produced by the use of electron beam evaporation technique at different oblique angle depositions (OAD) is investigated. The different stoichiometry of annealing gas together with the void fraction resulting from the OAD provided conditions as a new route for formation of different shaped ZnO:N nanostructures (nano-columns, pyramids, nano-rods and particularly nano-bowls). Results, in particular show the formation of nano-bowl structure for high concentration of nitrogen in the annealing gas (80% of grains show formation of nano-bowls on the surface) while introduction of low flow of oxygen in the gas mixture prevents the formation of both zinc nitride and zinc oxide. However, further increase of oxygen in the gas mixture leads to formation of both of these structures in form of nano-bowls and hexagonal nano-columns of different shapes, respectively. This is the first report on the formation of ZnO:N nano-bowls. When, only oxygen is used for the annealing process only ZnO in nano-nail (conical hexagonal structure) shape is produced. Detailed morphological, chemical and structural investigations are carried out on all samples by field emission electron microscopy (FESEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM) and X-ray diffraction (XRD) methods. (C) 2018 Elsevier B.V. All rights reserved.