Growth and characterisation of electrodepo sited ZnO thin films

The electrochemical method has been used to deposit zinc oxide (ZnO) thin films from aqueous zinc nitrate solution at 80 degrees C onto fluorine doped tin oxide (FTO) coated glass substrates. ZnO thin films were grown between -0.900 and -1.025 V vs Ag/AgCl as established by voltammogram. Characterisation of ZnO films was carried out for both as-deposited and annealed films in order to study the effect of annealing. Structural analysis of the ZnO films was performed using X-ray diffraction, which showed polycrystalline films of hexagonal phase with (002) preferential orientation. Atomic force microscopy was used to study the surface morphology. Optical studies identified the bandgap to be similar to 3.20 eV and refractive index to 2.35. The photoelectrochemical cell signal indicated that the films had n-type electrical conductivity and current-voltage measurements showed the glass/FTO/ZnO/Au devices exhibit rectifying properties. The thickness of the ZnO films was found to be 0.40 mu m as measured using the Talysurf instrument, after deposition for 3 min. Environmental scanning electron microscopy was used to view the cross-section of glass/FTO/ZnO layers. (c) 2007 Elsevier B.V. All rights reserved.