Optical properties of nanocolumnar ZnO crystals

Oriented nanocolumnar ZnO single crystals were prepared by the electrodeposition technique on conducting glass substrates by using different growth parameters. A factorial design at two levels of three growth parameters such as current density, exposition time and temperature of the bath has been used to study their influence on the height of ZnO columns. The average height of the Zn nanocolumns was obtained by means of atomic force microscopy. X-ray diffraction and scanning electron microscope were used to characterize the morphology of the nanocolumnar ZnO crystals. The optical properties were investigated by means of transmittance and photoluminescence. It was found that further annealing of the electrodeposited samples was necessary in order to achieve good optical properties which are very sensitive to the duration and temperature of the annealing. (C) 2004 Elsevier Ltd. All rights reserved.