The Effect of Annealing in High Vacuum on the Oxidation and Photoluminescence of Zinc/Silicon Nanoparticles in Thin Films

Abstract

Zinc/silicon nanoparticles in thin films were prepared by the pulsed laser deposition method in a vacuum chamber using a rotary target which exposed the zinc and silicon materials to the laser alternately. The as-prepared sample was a mixture of silicon and zinc nanoparticles which were slightly oxidized. When the samples were annealed in vacuum, XPS results indicated that the oxidation degree of Zn and Si in the film increased with temperature. The as-prepared sample shows only the silicon PL peak, while the ZnO PL peak appeared only in the annealed samples. This PL peak in the wavelength region of 400-550 nm was attributed to ZnO nanoparticles and their interaction with silicon oxide. The slight blue shift of the ZnO PL peak with increasing annealing temperature and duration confirmed the gradual oxidation of Zn to ZnO. Moreover, our results confirmed that the interface effect between the Si and Zn nanoparticles strongly affects the PL of the interfacial ZnO nanoparticles.