SiO-Assisted Growth Of IIB-VI Semiconductor Nanomaterials

The synthesis, characterization,mechanism of growth and properties of several kinds of one-dimensional inorganic nanomaterials had been studied in this doctorial dissertation. The main results could be concluded as follows:Nanometer-sized coaxial cables with a single-crystal ZnS core and a thin amorphous SiO₂ shell were synthesized by simple thermal evaporation in vacuum. The ZnS/SiO₂ nanocables had diameters of ⁵0 nm, lengths of several tens of micrometers, and shell thickness of ⁴ nm. The core of the nanocable had a wurtzite structure with a growth direction along [001]. The nanocables showed strong photoluminescence with two peaks related to band gap and defect-related emission. The thin layer of SiO₂ wrapped on the ZnS nanowires may protect against oxidation and electron irradiation.Structural parameters had significant influences on the properties and application of nanostructures. In this work, a novel ZnS nanostructure made of three intersecting ribbons in the form of a dart-shaped tricrystal (DST) was prepared via a simple thermal evaporation of ZnS powders. The DST nanostructures was made of three intersecting ribbons sharing a common"spine"over the entire length of the structure, and the growth direction was the [-22-1]. Its strong and sharp UV emission band was at 332 nm. We believe that this kind of material could inspire extensive interest and would be widely applicable in the field of nonlinear nanotechnology.Nanoscaled co-axial materials with a periodically-twinned ZnSe crystal core and an amorphous silicon oxide shell were synthesized by a simple thermal evaporation process. The as-fabricated periodically-twinned ZnSe core had a sphalerate structure and a growth direction of [111]. The twinning period range in the core was about 10-40 nm and irrelevant with the cross section size of nanostructures. The formation mechanism could be realized to the concentration change and surface stress. The materials showed strong cathodoluminescence with a peak related to the band-gap emission. The single ZnSe/SiO₂ nanocable had pronounced photoconduction effect with a fast response time when using the laser irradiation. The results suggested that the periodically-twinned ZnSe nanocables had potentially application in nanoscaled photodetectors and optical switches.We reported the preparation of silica nanotubes by a simple 2-stage thermal evaporation of ZnSe and SiO powders. Firstly, nanocables with single crystalline ZnSe nanowires cores and amorphous SiO₂ shells were formed by a combined vapor-liquid-solid (VLS) and oxide-assisted growth (OAG) process. The ZnSe cores were then evaporated at high temperatures leaving behind SiO₂ nanotubes. The SiO₂ nanotubes were found to be amorphous, uniform, rigid and smooth. Room-temperature photoluminescence measurement showed that the synthesized SiO₂ nanotubes had a strong blue emission band at a wavelength of 420 nm. This method could be used to prepare other materials and morphology-controlled nanotubes.