Of Zns Fluorescent Films And Their Characterization And Doping On Its Properties

ZnS is an important wide and direct band gap (Eg is about 3.7eV at room temperature) semiconductor materials. ZnS has been recognized as a promising material for use in many fields such as ultraviolet (UV) detectors, short-wavelength light-emitting diode (LED), laser diode (LD), and solar cells, etc. In order that ZnS films can be applied in various optoelectronics devices, it is necessary that we should improve (or change) physical and chemical properties of ZnS thin films, both doping and thermal annealing are very important means. In particular, it is very important that p-type ZnS thin films are obtained by doping method. At present, the ion implantation is an attractive doping technique for using in semiconductor materials.In this thesis, we study properties of ZnS thin films are enhanced (changed) by the ion implantation and thermal annealing. X-ray diffraction (XRD), photoluminescence (PL) spectra, optical transmittance spectra, four-probe method and so on had been utilized to characterize the structural, optical and electrical properties of the samples.The results have been listed as follow:1. Ti ions to a dose of 1×1017ions/cm2 were implanted at 80 KeV into ZnS films deposited on quartz substrates by vacuum evaporation method. After ion implantation, the as-implanted sample was annealed in argon ambient at different temperatures from (500-700)oC. Measurement results showed that the intensity of the diffraction peak decreased and the near band edge (NBE) emission peak and the deep level emission (DLE) peak disappeared after ion implantation. The diffraction peak intensity was recovered by annealing at 500oC. The absorption edge was observed to have a continuous blue-shift with increasing annealing temperature. Both NBE and DLE were enhanced with increasing annealing temperature.2. N ions to a dose of 1×1017ions/cm2 were implanted at 80 KeV into ZnS films deposited on quartz substrates by vacuum evaporation method. After ion implantation, the as-implanted sample was annealed in argon ambient at different temperatures from (500-700)oC. Measurement results showed that the diffraction peak disappeared after ion implantation. The diffraction peak intensity reappeared by annealing at 500oC. Both the NBE peak and the DLE band were enhanced with increasing annealing temperature when it exceeded 600 oC.3. N ions to a dose of 1×1017ions/cm2 were implanted at 80 KeV into ZnS films deposited on glass substrates by vacuum evaporation method. After ion implantation, the as-implanted sample was annealed in argon ambient at different temperatures from (400-500)oC. Measurement results showed that after ion implantation, the diffraction peak disappeared, the optical transmittances in the visible region increased, the optical band gap of the sample had blue-shift, both the intensity of the NBE peak and the DLE peak increased. The diffraction peak intensity reappeared by annealing at 500oC, the optical transmittances in the visible region increased by annealing at 400oC and decreased by annealing at 500oC, and both the NBE and the DLE increased by annealing at 400oC and decreased by annealing at 500oC.