The Synthesis And Nonlinear Optical Properties Of CdS_xSe_1-x Semiconductor Nanomaterials

Due to the unique optical and electrical properties as well as the potential applications in microelectronic devices,the semiconductor nanostructures have attracted great attention of the scientific researchers. Specially, the typical II-VI semiconductor materials, such as Cadmium Sulfide(CdS) and Cadmium Selenium(CdSe) have important application prospect due to their optoelectronic performance, such as LEDs, nanolasers and optoelectronic detectors in the visible spectrum range. The solid solution CdSxSe1-x semiconductor nanostructure has many similar properties with its original binary compound CdS and CdSe. The flexibility of the CdSxSe1-x semiconductor nanostructure's band gap will also greatly enhance the ternary compound application value for optoelectronic devices. The main content of this thesis are as follows:Highly pure and crystalline CdSxSe1-x nanostructures have been successfully synthesized via Chemical Vapor Deposition(CVD) method, changing the components of x,in order to adjust the band gap of materials, and the relationship with the lattice constant. Using X-ray Diffraction(XRD) to characterize the phase structures and elemental compositions of the samples, and using Field Emission Scanning Electron Microscopy(FESEM) to observe the surface morphology of CdSxSe1-x nanomaterials and confirm the VLS growth mechanism. Using the High Resolution Transmission Electron Microscopy(HRTEM) and Selected Area Electron Diffraction(SAED) to analyze the crystal structure and the growth direction of the materials.Compared with the ordinary optical microscope, the home-built cage optical confocal microscope measurement configuration, which is flexible, stable and is of high resolution, has been designed and set up by ourselves. In the experiments, we can easily use the system to measure and image a single nanoscale sample precisely. The system using the center wavelength of 800 nm femtosecond laser as the excitation light source, researched the fluorescence peak position of CdSxSe1-x under different component x of the nanomaterials, or the change of the band gap. Meanwhile, the excitation of seed femtosecond laser was used to study the nonlinear optical effects of CdSxSe1-x nanomaterial, such as the effect of the two-photon fluorescence, Second Harmonic Generation(SHG) and optical waveguide effect.