Modifications In Structure And Optical Properties Of Oxides By Metal Ion Implantation

Due to controlled energy and fluence, ion implantation is widely used insemiconductor doping, surface modification of materials and synthesis ofnanomaterials. Meanwhile, surface plasmon resonance of metal nanoparticles can beused to modify photoluminescence and Raman scattering. In this thesis, ionimplantation has been employed to synthesize metal nanoparticles, and investigatedtheir structral and optical properties. Further, luminescence and surface-enhancedRaman scattering of metal-implanted ZnO were investigated. The main results andconclusions of the thesis are as follow:Firstly, Si₃N₄/Si and SiO₂were injected with45keV Cu ion at a fluence of1×10¹⁷/cm²Cu ions. X-ray diffraction analysis showed that Cu（111） and Cu（200） wereformed. Further, high-resolution TEM images and electron diffraction analysisrevealed that the main crystalline of nanopariticles were Cu（111） and the average sizeof Cu nanoparticles was12.84nm. Surface plasmon resonances of Cu nanoparticles inSi₃N₄/Si and SiO₂substrate were located in565nm and569nm by using theUV-visible spectrophotometer. Annealing resulted in the growth of nanoparticles, andsurface plasmon resonance shifted from570nm to572nm. Luminescence of Cunanoparticles in Si₃N₄/Si and SiO₂substrate was located in600nm, and the quantumyield was about0.001. X-photoelectron spectroscopy revealed that Cu0was dominantstates.Sceondly, ZnO films were implanted with80keV Au ions at a fluence of2×10¹⁶/cm²and45keV Ag ions at the fluence of2×10¹⁶/cm²,6×10¹⁶/cm²and1×10¹⁷/cm², respectively. It was found that Au ion implantation induced formation of Aunanocrystals and new luminescence band （⁵30nm） was created. Meanwhile, Agnanocrystals also ware found in ZnO films, and Ag（111） was dominant structure.Subsequently, we used Raman spectroscopy to study surface enhanced Ramanscattering, and found that Ag NPs can effectively enhance Raman vibrations of ZnO.Effects of high fluence was significantly better than that of low fluence. However, theAg ion implantation has not modified the luminescence of ZnO. The relatedmechanism was discussed. Finally, we studied the geometry, electronic structure and optical properties of theCu-, Ag-, and Au-doped ZnO using standard density functional theory. It was foundthat the Cu-, Ag-, and Au-doped ZnO exhibited small lattice distortion. The electronicstructure showed that Cu-and Ag-doped ZnO prefered to form localized electron inthe valence band of ZnO, but Au doping can introduce impurity states. Subsequentoptical transitions showed that the doping of Ag and Au can effectively improve theelectronic structure and optical properties of ZnO.