Synthesis And Characterization Of II-VI Group Semiconductor Nanomaterials

Today, II-VI compound semiconductors is widely used as luminescent material, and the distinct properties of II-VI group nanostructures have opened new opportunities for the applications of II-VI group semiconductor materials in electronics, optoelectronics and so on. In this dissertation, II-VI group semiconductor nanomaterials were synthesised via thermal evaporating powder in a horizon tube furnace, and the phase, microstructure and optical properties were characterized systematically.(1) CdS nanostructure were synthesised via evaporate CdS powder in a horizon tube furnace under the Ar protection. By changing the parameters realizing the controled synthesis of the one-dimensional CdS nanostructure. Strong emission around 505 nm were obeserved of the one-dimensional CdS nanostructure from the photoluminescence spectrum which attribute to near-band-edge emission. Low temperature study of the nanobelts show that the near-band-edge emission of CdS nanostructure at room temperature was mainly consists of a superposition of the D⁰X, FX and their 1LO and higher order phonon replicas.(2) Spontaneous formation of 3D tetrapod-shaped CdS nanostructure networks has been achieved for the first time by vapor diffusion-deposition growth from CdS powders. The growth mechanism of the hexagonal and preferentially oriented CdS tetrapod-shaped nanostructures is a combination of the classic vapor–liquid–solid and vapor–solid processes, and the formation of a 3D network results from the spontaneous growths along the longitudinal and across the axial directions of the primarily formed CdS nanorods. Micro-photoluminescence measurements and near-field scanning optical microscopy investigations show that the synthesized CdS tetrapod networks have an excellent luminescence property. Near-field scanning optical microscopy investigations and FDTD simulations revealed that these nanorods are good optical waveguide cavitie and have potential application in optical devices.(3) Zn_xCd_1-xS one-dimensional nanostructures and Zn_xCd_1-xS@SiO₂ nanocomposites were achieved by thermal evaporation the mixture of CdS and ZnS powder via changing the pressure of the system. The ZnxCd1-xS one-dimensional nanostructures have a strong emission around 500 nm which attribute to the near-band-edge emission. For the ZnxCd1-xS@SiO₂ nanocomposites, two peaks were observed, the peak between 460～530nm belong to ZnxCd1-xS intrinsic emission while the peak between 600～650nm attribute to defection emission of the nanocomposites.