Synthesis, Structural, Morphological, Electronic, Optical and Luminescence Properties of Pure and Manganese-Doped Zinc Oxide Nanostructured Thin Films: Effect of Doping

In this study, Manganese-doped Zinc oxide (ZnO) nanostructured thin films with different Mn doping concentrations (0, 1, 3, 5 and 7 mol.%) were synthesized on glass substrates by the sol-gel spin coating technique. The concentration of metal ions was fixed at 0.6 mol.L-1. Structural, surface morphological, optical and luminescence properties of the films were investigated by XRD, AFM, UV-Vis spectrometry and PL spectroscopy techniques. The XRD results showed that the films had hexagonal wurtzite structure and exhibited preferred orientation along the c-axis. Crystallite size, lattice parameters, strain and residual stress were influenced by Mn doping, where average crystallite size decreased from 45 to 10 nm with doping concentration. Atomic force microscope (AFM) images revealed the good uniformity for all the films, and reduction of grain size and surface roughness is observed with the increase of doping concentration. The average transmittance in the visible region was higher than 80% for all the films. Unlike the Urbach energy, the optical band gap of Zinc oxide films decreased with Manganese doping. The origin of ultraviolet, violet, blue and green emissions observed from photoluminescence spectra, and the effect of Mn doping on the luminescence properties and defects concentration were discussed in details. It is worth noting that the fabricated Zinc oxide (ZnO) thin films, which presented good properties, can be used for potential applications in optoelectronic devices.