Synthesis of low-content Mn-doped ZnO thin films: Characterizations and density functional theory studies

Abstract

This study aims to prepare manganese-doped zinc oxide (MZO) thin films with low Mn content (x = 0, 2, 4 %) using the sol–gel spin coating method and to characterize their structural, optical, and magnetic properties. Experimental techniques were complemented by Density Functional Theory calculations with Hubbard correction (DFT-LDA + U). All films exhibit a polycrystalline wurtzite hexagonal phase of ZnO. As the Mn doping increases, all diffraction peaks are getting weaker, which leads to deterioration in the crystallinity of the samples. Furthermore, Mn doping affects the grain size (57.44–38.20 nm), the surface morphology (rms: 45.24–30.47 nm), the transmittance (93–54 %) and the optical band gap energy (E_g: 3.27–3.18 eV). Photoluminescence spectra reveals ultraviolet peaks (386–395 nm) along with weak green (525 nm) and strong (438 nm) and weak (475 nm) blue peaks. DFT-LDA + U calculations exhibits an antiferromagnetic phase with slightly reduced E_g (3.379 eV for x = 0 % and 3.267 for 3.7 %), attributed to the influence of Mn3d states near the Fermi level. This study presents a comprehensive analysis of low-content Mn-doped ZnO thin films by combining experimental and theoretical approaches. The findings provide valuable insights into the electronic, structural, optical, and magnetic properties of MZO, emphasizing the critical role of Mn 3d states in altering the magnetic behavior and adjusting E_g.