Optical Properties Of One Dimensional ZnO-based Nano-materials

One dimensional ZnO-based nano-materials having direct band gaps in ultraviolet(UV) and special optical modes can be exploited for UV-optoelectronic devices and quantum information.Recently,there has been much interest in nanowires and nanocables which show enhanced transmission at specific wavelengths.In this thesis,we focus our attention on the luminescent and transmission properties of Zn₂SiO₄ nanowires and Zn-Zn₂SiO₄ nanocables to reveal their physical origins.The optical properties of Zn₂SiO₄ nanowires are studied by experiment measurements and theoretical calculations.The luminescent origin is discussed by analysing the Zn₂SiO₄ surface states using a first principles calculation.The varieties of the cathodoluminescence(CL) spectra on different areas are clarified with the resonance of whispering-gallery mode(WGM) in the nanowires.The optical transmission properties of Zn-Zn₂SiO₄ nanocables are measured by CL technique.The optical modes,corresponding to the emissions bands on spectrum in mid-UV,visible,and infrared regions,are analyzed experimentally and theoretically in detail.It is revealed that propagation of surface plasmon(SP) is responsible for the enhancement at the root and the annihilation at the top of nanocable for the mid-UV emission.The coupling between the exciton and cavity resonant mode in the SP-assisted nanocavity are studied experimentally.Compared with WGM and waveguide mode, SPR mode is known to have the smallest effective mode volume and the highest finesse.The split in mid-UV emission implies a strong coupling take place in the optical nanocavity.Further temperature dependent CL measurement exhibits a special anticrossing due to the unsymmetrical wavelength-selectivity of SPR.