Effects of annealing on properties of ZnO thin films prepared by electrochemical deposition in chloride medium

    Authors

    O. Lupan; T. Pauporte; L. Chow; B. Viana; F. Pelle; L. K. Ono; B. R. Cuenya;H. Heinrich

    Comments

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    Abbreviated Journal Title

    Appl. Surf. Sci.

    Keywords

    ZnO; Thin films; Electrodeposition; Photoluminescence; Annealing; ZINC-OXIDE FILMS; RAY PHOTOELECTRON-SPECTROSCOPY; PEROXIDE OXYGEN; PRECURSOR; CATHODIC VACUUM-ARC; RAMAN-SCATTERING; OPTICAL-PROPERTIES; RADIATION HARDNESS; ROOM-TEMPERATURE; SPRAY-PYROLYSIS; GALLIUM NITRIDE; Chemistry, Physical; Materials Science, Coatings & Films; Physics, ; Applied; Physics, Condensed Matter

    Abstract

    The development of cost-effective and low-temperature synthesis techniques for the growth of high-quality zinc oxide thin films is paramount for fabrication of ZnO-based optoelectronic devices, especially ultraviolet (UV)-light-emitting diodes, lasers and detectors. We demonstrate that the properties, especially UV emission, observed at room temperature, of electrodeposited ZnO thin films from chloride medium (at 70 degrees C) on fluor-doped tin oxide (FTO) substrates is strongly influenced by the post-growth thermal annealing treatments. X-ray diffraction (XRD) measurements show that the films have preferably grown along (0 0 2) direction. Thermal annealing in the temperature range of 150-400 degrees C in air has been carried out for these ZnO thin films. The as-grown films contain chlorine which is partially removed after annealing at 400 degrees C. Morphological changes upon annealing are discussed in the light of compositional changes observed in the ZnO crystals that constitute the film. The optical quality of ZnO thin films was improved after post-deposition thermal treatment at 150 degrees C and 400 degrees C in our experiments due to the reducing of defects levels and of chlorine content. The transmission and absorption spectra become steeper and the optical bandgap red shifted to the single-crystal value. These findings demonstrate that electrodeposition have potential for the growth of high-quality ZnO thin films with reduced defects for device applications. (C) 2009 Elsevier B. V. All rights reserved.

    Journal Title

    Applied Surface Science

    Volume

    256

    Issue/Number

    6

    Publication Date

    1-1-2010

    Document Type

    Article

    Language

    English

    First Page

    1895

    Last Page

    1907

    WOS Identifier

    WOS:000273151900050

    ISSN

    0169-4332

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