Hierarchical Controlled Synthesis, Morphology And Property Modulation Of Znic-based II-VI Semiconductor Nanomaterials

Morphology and property modulation of nanomaterials are leading tendencies of the current nanomaterials research. The present thesis focuses on the controlled synthesis, morphology and property modulation of ZnO and ZnS semicondutor nanomaterials and the main research results and originalities of the thesis are as follows.1, ZnO microcrytal/nanocavities/nanowalls/nanorods complex nanostructures are controlled synthesized by a developed CVD and hierarchical growth technique. Through controlling the morphologies, the relative intensity of UV emission to green emission in photoluminescence spectra and the peak position of E_2H mode ranging from 431 to 439 cm^-1 in Raman spectra can be facilely tuned.2, Bundle-like parallel-aligned ZnO nanorod aggregations are synthesized through controlling the suspending time of ZnO nanorods in the reaction vapor environment by developing the traditional CVD route. A new self-assembly, parallel- aligned and oriented growth mode is proposed on the growth mechanism of the aggregations. The ZnO aggregations show excellent exciton emissions in room temperature.3, Various novel morphologies of ZnS nanostructures are controlled synthesized through adjusting dynamic parameters, such as nucleation style, growth interface, vapor supersaturation, diffusion rate and diffusion distance of molecules, by designing the experimental project. These architectures show many novel physical properties, which don't emerge in the simple structures. For example, very strong yellow emissions and two anomalous Raman modes at 233 and 488 cm^-1 are observed in the tower-like structures.4, The abnormal photoluminescence (PL) unstable behaviors of ZnO nanomaterials, such as with the decrease of the excitation intensity, UV peak position blueshifts while green position redshifts, and width of the two bands become narrow and intensity of the two bands become first strong and then weak, are investigated by designing the fluorescence experiment. We point out this abnormal PL phenomena are induced by the laser heating effect, and aren't correlated with the new PL properties of ZnO nanomaterials. Furthermore, we provide an effective way to solve the problem of this PL instability.