Optical properties of nanocluster-assembled ZnO thin films by nanocluster-beam deposition

Nanocluster-assembled ZnO thin films have been synthesized by nanocluster-beam deposition, and the films exhibit a band-gap energy at 323.7nm (3.84eV) and ultraviolet (UV) light emission at 373nm (3.32eV) with an average particle size of 6nm. A comparison of the optical properties of the annealed films with that of as-grown one is presented. It is found that, after the film is annealed, the shoulder in the absorbance spectra turns steeper and the intensity of UV light emission band becomes stronger. Moreover, blueshifts of band-gap energy and a UV emission band are both observed as decreasing the annealing temperature and ascribed to the quantum-confinement effect.

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