The effects of nitrogen ionization during preparation and oxygen pressure during annealing on the morphology, structure, and luminescent properties of Mg-doped ZnO thin films.

In order to understand the effects of nitrogen ionization during preparation and oxygen pressure during annealing (OPA) on the morphology, structure, and luminescent properties of Mg-doped ZnO thin films, Zn0.97Mg0.03O films were prepared in both ionized and non-ionized N2 using Pulsed Laser Deposition (PLD), followed by annealing at 600 °C under various oxygen pressures. X-ray Diffraction (XRD) results reveal that all Zn0.97Mg0.03O films exhibit a preferentially oriented hexagonal wurtzite structure along the (002) direction, with the films prepared in ionized nitrogen showing the presence of Zn3N2 phase. Field Emission Scanning Electron Microscopy (FESEM) observations indicate that the films prepared in non-ionized and ionized N2 exhibit near-spherical and conical shaped particles, respectively. Combined XRD and X-ray Photoelectron Spectroscopy (XPS) analyses indicate an increase in Zn interstitial (Zni) content in the films after annealing, with higher content observed at a higher OPA; films annealed under oxygen pressure of 100 Pa exhibit maximum tensile stress and highest N content. Photoluminescence (PL) spectra of both ionized and non-ionized films reveal a strong ultraviolet-violet peak (360–450 nm) and weaker blue-green peak (450–550 nm), with a broad and weak near-infrared (NIR) peak around 825 nm. The NIR peak primarily originates from the recombination of electrons bound to Zni and holes bound to oxygen vacancies (Vo) ; ionization of nitrogen enhances the green emission. [ABSTRACT FROM AUTHOR]