ZnO Micro-Cauliflowers on Aluminium Substrates

Cauliflower-like zinc oxide (ZnO) microstructures were synthesized as thin films using the spray pyrolysis (SP) technique on aluminum substrates at a substrate temperature of 350 ± 5°C. The films were characterized by X-ray diffraction (XRD), and scanning electron microscopy assisted by X-ray energy-dispersive spectroscopy as accessary (SEM-EDS). XRD diffractograms revealed that the films are polycrystalline with sharp diffraction peaks associated with the hexagonal (wurtzite) structure. The preferred direction of crystal growth is perpendicular to the (002) plane, meaning that it is along the c-axis perpendicular to the substrate. SEM observations revealed that the morphology of the films resembles micro-cauliflowers formed through self-assembly of ZnO hexagonal rods of different dimensions. EDS spectra revealed that the films contain chlorine, and aluminum, in addition to zinc and oxygen. ImageJ software was used for dimensional analysis, as well as surface occupancy plots and profile plots of the products. This non-catalyst production of ZnO micro-cauliflowers on the aluminum substrates may have potential applications in the manufacture of thin-film photovoltaic solar cells, dye-sensitized solar cells (DScs), and gas sensors.