The Preparation And Photoluminescence Property Of Mn-doped CdS Micronano-materials

One dimension nanostructures have attracted many researchers attention because of their novel physical and chemical properties which differ from their corresponding bulk materials. Here, we synthesize several kinds of one dimension micro/nanostructures, such as hexagonal nanosheets, doped triangular （hexagonal, rectangular） nanowires, nanobelts, by one step chemical vapor deposition. The as-prepared products are characterized by NSOM, Raman, Uv-Vis, SEM, TEM, XRD and we also analyze the growth mechanism and optical properties. The main research results are shown as following:（1） Several Mn-doped CdS nanostructures, including hexagonal nanosheets, nanobelts, nanowires have been achieved by a one-step chemical vapor deposition of Au-catalyzed thermal evaporation process. The temperature of the substrates is the critical experimental parameter for the formation of varied morphologies of Mn-doped CdS nanostructures and so as the substrates material. We found that the temperature of the substrates and the concentration of the resource vapor are the critical experimental parameters for the formation of different morphologies of the Mn-doped CdS nanostructures. We found that heavy doping of Mn leads to the periodic nanostructure in nanowires and nanobelts. We also found that the periodic nanostructures is good F-P optical cavity, which leads to the multilevel peaks in the photoluminescence graphs, by the investigation of the optical waveguide behavior via NSOM system. Some of the nanostructures show strong defect state emission. At the same time, we studied the hexagonal nanosheets and found that the photoluminescence is because of the formation of whispering gallery mode （WGM） in the nanosheets. With the waveguide cavity, we can achieve the tunable emission in the visible light or emission of lasing.（2） We synthesized the Mn-lightly-doped CdS triangular nanowires, hexagonal nanowires and rectangular nanowires only by changing the MnCl2 molar ratio in the reaction mixture. As the concentration of the Mn increase in the reaction mixture, the morphology of Mn-doped CdS nanowires changs from hexagonal to triangular and rectangular. We find the most suitable mechanism to demonstrate the process of the growth. The oriented attachment mechanism demonstrates that the surface attaching tention force between the facets of hexagonal nanowires and the Mn²⁺ plays an important role in formation of the triangular and rectangular nanowires. The photoluminescence of the nanowires is composed of intrinsic emission of CdS and the emission of Mn²⁺. We also detected the surface photovoltage of the nanowires and found the surface photovoltage enhanced when applied to the electric field.