Formation and luminescence of ZnO nanoparticles embedded in MgO films

ZnO nanoparticles embedded in MgO thin films were prepared by a simple coevaporation method, and the subsequent thermal annealing in oxygen ambient at 300-1100 degrees C. X-ray diffraction and optical absorption spectra revealed that the size of ZnO nanoparticles embedded in MgO decreased with increasing annealing temperature, and MgZnO interlayers were formed between ZnO nanoparticles and MgO matrix. Analysis of Raman scattering spectra showed that the strain originated from lattice mismatch between ZnO and MgO was relaxed by annealing processes, and the MgZnO alloy layers between ZnO nanoparticles and MgO matrix were formed. In photoluminescence spectra, the exciton emissions of ZnO nanoparticles shift to shorter wavelengths with increasing annealing temperature. When the annealing temperatures exceeded 700 degrees C, a strong emission appeared at 3.58 eV, while the deep level emission band in the visible light region was dramatically quenched.