Diminution in the Optical Band Gap and Near Band Edge Emission of Nickel-Doped Zinc Oxide Thin Films Deposited by Sol-Gel Method

Abstract

Thin films of nickel-doped zinc oxide (Zn1−xNixO) show redshift in the optical band gap and in the near band edge (NBE) emission of the photoluminescence spectra. The Zn1−xNixO thin films obtained by sol-gel spin coating method show narrowing of the band gap from 3.23 to 3.00 eV as the concentration of nickel is increased from x = 0.00 to x = 0.06. All the Zn1−xNixO thin films have hexagonal wurtzite structure and show a decrease of 119 meV in the NBE emission as the dopant concentration is increased. X-ray diffraction (XRD) spectroscopy confirms the formation of ZnO in the films; Fourier transform infrared (FTIR) spectroscopy reaffirms this. Energy dispersive analysis (EDX) also ascertains the presence of Ni in the films and calculates the amount of dopant present in the films. Scanning electron microscopy (SEM) shows that all the Ni-doped ZnO thin films possess granular surface morphology.