有机高分子与无机半导体纳米材料的电子显微学研究

【作者】 商蕾；

【导师】 王乙潜；

【作者基本信息】 青岛大学 ， 材料学， 2014， 博士

【摘要】 一维纳米材料,如纳米管、纳米线和纳米带等,因其独特的物理化学性质,以及在纳米器件、光电子器件、微传感器等方面的潜在的应用前景,已经成为纳米科技研究的热点之一。本论文综合利用扫描电子显微镜、场发射高分辨透射电子显微镜、选区电子衍射、电子能量损失谱、X-射线能量谱及X-射线衍射仪等先进的表征手段对几种有机聚合物纳米管(线)以及两种无机半导体一维纳米材料进行了研究,主要工作如下：(1)采用聚合物溶液浸润模板法,分别制备了聚苯乙烯、聚酰胺6及聚酰胺66纳米管与纳米线,利用场发射高分辨透射电子显微镜,获得了聚苯乙烯及聚酰胺6纳米管的高分辨像；研究了聚苯乙烯和聚酰胺6纳米管的结晶情况,发现聚合物一维纳米材料的结晶度高于聚合物块材的结晶度；利用电子能量损失谱,结合场发射高分辨透射电镜,研究了聚苯乙烯纳米管的结构,计算了聚苯乙烯纳米管的C=C与C-C的比例,这一结果与理论计算结果一致；(2)对化学气相沉积法制备的单斜β-Ga2O3纳米材料进行了研究。研究发现：催化剂比例不同,制备的β-Ga2O3纳米线的形貌不同,分别为晶粒融合纳米线、单晶纳米线及纳米棒；在制备的β-Ga2O3纳米线中,还发现了核-壳结构的纳米线,利用电子能量损失谱证实核-壳结构的成分均为Ga2O3；单晶纳米线的择优生长取向为[202],利用气-固生长机理阐明了单晶β-Ga2O3纳米线的生长机制；(3)对固相源化学气相沉积法制备的InGaAs化合物半导体纳米线进行了研究。研究发现：InGaAs纳米线有两种不同的形貌,一种表面光滑,另一种表面呈锯齿形貌,两种形貌随机出现,同时存在。通过高分辨率透射电子显微镜分析发现,锯齿状的形貌是由于周期性出现的孪晶所导致,而InGaAs纳米线表面光滑部分的内部不存在孪晶等缺陷；另外,InGaAs纳米线头部催化剂颗粒有两种不同结构,一种是六方相的Au4In,另一种是立方相的AuIn2;催化剂颗粒微观结构的不同对InGaAs纳米线的微观结构没有影响,根据研究结果推断了InGaAs纳米线的生长机理。更多还原

【Abstract】 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.更多还原