Electron Microscopy Studies Of Organic Polymer And Inorganic Semiconductor Nanomaterials

One-dimensional nanomaterials, including nanotubes, nanowires, nanobelts, etc., have attracted intense attention due to their unique physical and chemical properties and potential applications in a variety of areas, such as nano-devices, optoelectronic devices, micro-sensors and so on. In this dissertation, advanced scanning electron microscopy, field emission high-resolution transmission electron microscopy, selected area electron diffraction, electron energy loss spectroscopy, X-ray energy spectrum and X-ray diffraction were applied to systematically investigate several kinds of organic polymer nanotubes/nanowires and two types of one-dimensional inorganic semiconductor materials, and the main conclusions are described as following:(1) Polystyrene, polyamide6and polyamide66nanotubes and nanowires were successfully synthesized by the method of polymer solution template wetting. The morphology and microstructure of polystyrene and polyamide6nanotubes were analyzed by field emission high-resolution transmission electron microscopy. The crystallization of polystyrene and polyamide6nanotubes was studied, and the crystallinity degree of bulk polymer and polymer nanotube was also investigated respectively, which shows that crystallinity degree of polymer nanotube is higher than bulk polymer. Besides, the structure of polystyrene nanotubes was studied using electron energy loss spectroscopy attached to the high field emission resolution transmission electron microscopy. The ratio of C=C and C-C in PS nanotubes were determined by EELS spectrum, and the result is consistent with the theoretical calculation.(2) Monoclinic β-Ga2O3nanomaterials were successfully prepared by chemical vapor deposition method and were investigated by TEM. The results show that if the ratio of catalysts is different, morphology of β-Ga2O3nanowires is different. Three morphologies of β-Ga2O3nanowires were obtained, grains stacked nanowires, single crystal nanowires and nanorods, respectively. Besides, the core-shell structure namowire was formed, and the components of core and shell were all Ga2O3which was confirmed by electron energy loss spectroscopy. The preferential growth orientation of the single crystal nanowires is [202] and the growth mechanism of single crystal P-Ga2O3was clarified by gas-solid growth mechanism.(3) The morphology and microstructure of InGaAs compound semiconductor nanowires prepared by solid phase chemical vapor deposition were investigated. The SEM and TEM images show that InGaAs nanowires have two different morphologies:one is smooth surface and the other is jagged surface, and the two morphologies appear randomly and existed simultaneously. Jagged morphology results from the twins boundary occurring periodically by high-resolution transmission electron microscope, and there is no defect such as twining existed in the smooth surface. Furthermore, there are two kinds of structures of catalyst particles in top of InGaAs nanowires:one is hexagonal phase Au4In, and the other is cubic phase Auln2. While different microstructure of catalyst particles has no effect on the microstructure o f InGaAs nanowires. In addition, the growth mechanism of InGaAs nanowires is proposed based on the results the HRTEM analysis results.