| ZnO thin films of thickness about 300 nm were deposited on glass substrate by means of reactive magnetron sputtering. Some of the films were then implanted at room temperature with 80 keV Au ions at a dose of 2×1015/cm2. All the samples were annealed at ambient of N2 gas in the temperature range up to 700oC for 1h. Techniques, such as x-ray diffraction (XRD), x-ray photoelectron spectroscopy(XPS), ultraviolet-visible spectrophotometer (UV-Vis), fluorescence spectrophotometer(PL) and atomic force microscope(AFM), have been used to study film structures, optical properties and their thermal evolutions. Our results show that with increase of annealing temperature, the structural properties of the as-deposited ZnO films could be improved, which leads to growth of grain size and increase in optical transmittance. The subsequent Au ion implantation could induce serious deterioration of the crystallinity and sharp decrease of optical transmittance. However, the subsequent annealing could significantly improve the surface morphologies, crystal quality and transparency. Photoluminescence (PL) measurements indicate that there exsits four PL peaks in the as-deposited ZnO films, which are situated at 2.38, 2.65, 2.75 and 3.0 eV, respectively. The PL peak at 3.0 eV could be attributed to interstitial zinc. The 2.75 eV peak may correspond to the electron transition from shallow oxygen vacancy level to valence band. The PL peaks at 2.65 and 2.38 eV may relate to the electron transition from singly ionized oxygen vacancies to valence band and oxygen vacancies, respectively. In addition, the possible reasons for modifications of PL properties in the Au ion-implanted and annealed ZnO films have been tentatively discussed.
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