SYNTHESIS AND OPTICAL PROPERTIES OF Ni-DOPED ZnO GROWN BY ELECTROCHEMICAL DEPOSITION

Abstract

This paper is targeted at studying the patterns of deposition by electrochemical method of Ni-doped ZnO films, including registering and analyzing their photoluminescence and Raman scattering spectra. We have studied the electrochemical deposition of nickel-doped zinc oxide films on single-crystal silicon substrates from aqueous solutions of zinc and nickel nitrates. The deposition was conducted from aqua solutions of Zn and Ni nitrates in a standard double-electrode electrochemical cell in galvanostatic mode with the current density from 5 to 20 mA/cm² and deposition time from 5 to 30 min. The Raman scattering on nickel-doped zinc oxide films was examined via laser Raman spectrometer SOL Instruments Confotec NR500. The analysis of Raman spectra showed that an increase of cathodic current density deposition leads to an enhanced concentration of a doping agent in the films. Photoluminescence spectra of the samples were registered on a laser spectral measuring system based on monochromator-spectrograph SOLAR TII MS 7504i where a monochromatic line with the 345-nm wavelength, which was extracted from the spectrum of Xe-lamp by means of double monochromator Solar TII DM160, was used as the excitation source. The research demonstrates that the emmission intensity increases with the thickness of the deposited film, and the position of maximums of the radiation line remains unchanged in a visible wavelength range and on photoluminescence spectra with fixed current density. The change in the density of the cathode current leads to a shift in the position of the photoluminescence spectra maximum, which indicates restructuring of defects and dopant atoms in the doped semiconductor, which in turn changes the position of the corresponding levels in the band gap of the material.