Effect of Gd doping on structure and photoluminescence properties of ZnO nanocrystals

Gd doped ZnO nanoparticles with varying dopant concentration are synthesized by simple wet chemical method. X-ray diffraction measurements confirm that the prepared samples are of hexagonal wurtzite structure with grain size around 50-60 nm. Gd doping induces lattice expansion in ZnO as the average crystallite size increases with the evolution of Gd2O3 phase after Gd doping. Electron microscopic studies show the presence of two types of particle distribution belonging to ZnO and Gd2O3 phases with an average size of 55 nm where the later surrounds the surface of ZnO. UV-VIS spectra show red-shift of absorption band of ZnO with Gd doping. A suppression of band edge UV emission and intensification of visible emission is observed in the photoluminescence spectra of doped ZnO. This has been explained on the basis of incorporation of impurity levels by the dopant along with intrinsic defect such as oxygen vacancies in the band gap of ZnO.