Experimental and modeling study of ZnO:Ni nanoparticles for near-infrared light emitting diodes

This work is devoted to the synthesis and study of the different properties of ZnO nanoparticles (NPs) doped with the Ni element. We have used a simple co-precipitation technique for the synthesis of our samples and various structural, morphological and optical techniques for their analysis. Energy-Dispersive X-ray spectroscopy (EDX) confirms the stoichiometry of the samples. The X-Ray Diffraction (XRD) patterns reveal the hexagonal wurtzite phase of polycrystalline ZnO with a P63mc space group. Debye Scherrer and Williamson-Hall methods show that the average size of crystallites is around 40 nm. Transmission electron microscopy (TEM) images confirm the XRD results. The optical spectrum of Zn_0.95Ni_0.5O shows the presence of near-band-edge (NBE) ultraviolet emission. The absorption defect bands appearing near the blue-green region and near infrared emission are attributed to the Ni²⁺ intra-3d luminescence. The electronic structure of the Ni²⁺ doped ZnO NPs confirms the T _d site symmetry of Ni²⁺ in the ZnO host crystal and leads to a perfect correlation between calculated and experimental energy levels.