EFFECT OF OXIDATION TIME ON STRUCTURAL AND OPTICAL PROPERTIES OF ZNO FILMS PREPARED BY HYDROTHERMAL OXIDATION OF ELECTRODEPOSITED ZN COATING ON ITO SUBSTRATE

摘要

In this work, hydrothermal oxidation of electrodeposited zinc coatings is used to produce zinc oxide (ZnO) films. In the first step, zinc (Zn) coating is electrodeposited on indium tin oxide (ITO) coated glass substrate. The Zn films are then immersed in deionized water at 95 degrees C. The exposure time of Zn coating in deionized water is varied from 1 h to 24 h in sequence. At the 24 h exposure time, X-ray diffraction (XRD) patterns reveal that zinc film has been completely converted to ZnO. Scanning electron microscope (SEM) results show morphological changes from flakes (for pure Zn) or 2D plates to rod (ZnO) like morphology which further changes to cotton-flower like shapes with an increase in oxidation time. Diffuse reflectance spectral measurements show the band gap tuning with oxidation time (it decreases from 3.28 eV to 3.19 eV). Photoluminescence (PL) spectra have depicted phonon replicas with energy separation of similar to 124 meV for the ZnO films obtained after 6 and 12 h exposure time in deionized water at 95 degrees C temperature.