CuO纳米线阵列的制备与特性

CuO nanowire arrays were prepared by oxidation of copper nanowires embedded in anodic aluminum oxide （AAO） membranes. The AAO was fabricated in an oxalic acid at a constant voltage. Copper nanowires were formed in the nanopores of the AAO membranes in an electrochemical deposition process. The oxidized copper nanowires at different temperatures were studied. X-ray diffraction patterns confirmed the formation of a CuO phase after calcining at 500 ？C in air for 30 h. A transmission electron microscopy was used to characterize the nanowire morphologies. Raman spectra were performed to study the CuO nanowire arrays. After measuring, we found that the current–voltage curve of the CuO nanowires is nonlinear.     

硅纳米线的制备与热氧化处理

采用金属催化化学腐蚀法制备硅纳米线(SiNW),并进行热氧化处理。制备的硅纳米线的线径减小。研究了热氧化处理对硅纳米线线径的影响。利用光电显微镜和扫描电子显微镜(SEM)观察实验结果,刻蚀后形成了长度为100 μm、线径为100 nm的排列整齐的硅纳米线。在温度为400 ℃、时间为20 min的热氧化处理后,硅纳米线的线径由100 nm减小至50 nm。这表明,通过热氧化处理后的硅纳米线具有更小的线径。     

CuO纳米线对挥发性有机化合物的气敏性能

通过简单经济的水溶液法并配合后续煅烧制备出了一维Cu O纳米线。利用SEM、XRD、XPS等手段对所得纳米线的形貌、组成和晶体结构进行了表征,同时还测试了其在200℃下对常见挥发性有机物(VOC)的气敏响应状况。结果显示,Cu O纳米线气敏传感器对(10~1 000)×10–6(体积分数,以下同)的乙醇、甲醇、丙酮体现出优良的气敏响应特性,在(10~100)×10–6范围内,灵敏度随气体浓度增加呈线性增长,超过100×10–6后增长趋于平缓;响应时间均在10 s以内;浓度累加实验和多次重复实验显示出材料良好的稳定性和重复性;对所测11种VOC中的乙醇、甲醇、丙酮有一定的选择性;响应恢复基线无明显漂移;在300℃下,Cu O纳米线气敏传感器对(10~1 000)×10–6乙醇的灵敏度始终高于商用Sn O2气敏传感器。     

纯闪锌矿结构GaAs纳米线的等高生长研究

本文报道了金辅助生长纯闪锌矿结构GaAs纳米线,它采用金属有机化学气相沉淀技术运用气-液-固生长机制在GaAs(111)B衬底上生长而形成。实验结果显示GaAs纳米线具有圆柱状的均匀形貌,并且生长速率与直径无关。透射电子显微镜研究显示,GaAs纳米线是无缺陷的纯闪锌矿结构的晶体。实验结果表明Au-Ga合金在纳米线生长过程中是作为热解催化剂而不是扩散原子的收集器,较大的催化剂直径以及催化剂液滴中高的过饱和度是得到等高生长的纯闪锌矿结构GaAs纳米线的原因。     

CuO纳米线中的取向畴

通过简单的热氧化法,可以得到不同取向畴的CuO纳米线结构.利用群论的知识,从理论上推导出CuO纳米线中存在11种畴壁结构,其中5种已经被实验证实.同时,在800℃下得到直径较大的CuO纳米线,利用透射电子显微学相关技术分析发现,这种纳米线中存在一种新的畴壁结构,而且也属于理论上得到的11种畴壁之一.本文利用群论分析,解释了CuO纳米线中取向畴结构的生成机制,对调控CuO纳米材料的生长具有指导作用.     

氧化钨纳米线定域制备及其场发射特性研究

冷阴极在X射线源中有重要应用。本文结合微加工技术和磁控溅射镀膜技术,采用直接热氧化法实现了在玻璃衬底上大面积定域制备氧化钨(WO3)纳米线阵列。制备所得的WO3纳米线具有较大的长径比。场发射特性测试表明,该WO3纳米线冷阴极具有良好的场发射特性,开启电场为4.9V/μm,发射均匀性好,有望应用在平板X射线源中。     

石墨烯上生长GaN纳米线

采用金属Ga升华法在石墨烯/蓝宝石衬底上生长了高质量GaN纳米线,研究了不同的生长条件,如NH3流量、反应时间、催化剂和缓冲层等对GaN纳米线形貌的影响,采用扫描电子显微镜(SEM)对GaN纳米线进行表征.研究发现,在适当的NH3流量且无催化剂时,衬底上可以生长出粗细均匀的GaN纳米线.反应时间为5 min时,纳米线密集分布在衬底上,表面光滑.在石墨烯/蓝宝石上预先低温生长GaN缓冲层,然后升温至1 100℃进行GaN纳米线生长,获得了具有择优取向的GaN纳米线结构.研究表明,石墨烯和缓冲层对获得GaN纳米线结构有序阵列具有重要的作用.     

ZnO纳米线的快速生长机理及其场发射性能研究

为了快速制备具有优良场发射性能的ZnO纳米线,对ZnO纳米线的生长机理及场发射性能进行研究。首先采用优化的两步法制备出高长径比的ZnO纳米线,其次采用SEM对ZnO的微观形貌进行表征,然后,在分析形貌特点的基础上,说明了强碱体系下ZnO纳米线薄膜的快速生长机理。最后,对典型样品的场发射性能进行了测试。测试果表明,优化后的两步法,只需3h即可获得直径为40~50nm,长度为2.2~2.7μm,长径比高达54的纳米线。薄膜的开启电场为3.6V/μm,阈值场强为9.1V/um,场增强因子β高达3 391。研究表明,高pH值溶液可以加快ZnO纳米线沿C轴方向的择优生长,获得高长径比的ZnO纳米线,进而获得优良的场发射性能。     

CuO纳米线阻变存储器的组装及电阻开关特性

用热氧化法在空气中加热铜片制备了CuO纳米线(CuO NWs),通过FESEM对纳米线表面进行了观察,并用液体转移法组装成功了一种简单的阻变存储器件。通过I-V测试系统观察到了Cu/CuO NWs/Cu器件表现出了明显的双极型和单极型。最后通过对比高阻态(HRS)和低阻态(LRS)的表面形貌,解释了Cu/CuO NWs/Cu器件的阻变机制。     

醇还原法制备银纳米线及其生长机制的探究

本文以硝酸银(AgNO3)为银源,乙二醇(EG)为还原剂和溶剂,聚乙烯吡咯烷酮(PVP)为生长导向剂,氯化铜(CuCl2)为晶型诱导剂,采用多元醇还原法制取银纳米线.通过SEM、TEM、XRD、XPS和UV?vis等测试方法,分析了银纳米线的生长机制,并探讨了PVP辅助银纳米线定向生长的具体原理.研究结果表明,银纳米结构是在五边孪晶晶种上定向生长为一维的纳米线,PVP中的氧原子会与纳米银表面的银原子产生强烈的相互作用来控制着银纳米线的单向生长过程,并且当PVP与AgNO3的摩尔浓度比为6时可制取形貌规整、长度超过60 um的银纳米线.     

Indium and tin oxide nanowires by vapor-liquid-solid growth technique

Regular three-dimensional (3-D) arrays of crystalline SnO₂-In₂O₃ nanowires were produced on m-sapphire using a gold catalyst-assisted vapor-liquid-solid growth process. The growth characteristics at multiple growth conditions were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), x-ray photoemission spectroscopy (XPS), and Rutherford backscattering spectroscopy (RBS) to evaluate the functional dependence of nanowire structure and composition on growth parameters such as temperature and source composition. The results indicate that nanowires of mixed composition are not possible from the catalytic clusters; rather, a mixture of indium and tin oxide wires are formed in the range of conditions investigated here.     

Metalorganic chemical vapor deposition of GaN nanowires: From catalyst-assisted to catalyst-free growth,and from self-assembled to selective-area growth

With the increasing attention dedicated to GaN nanowires for the realization of advanced optoelectronic devices, important efforts have been devoted to the nanowire growth optimization. This review covers the developments achieved so far in the growth of GaN nanowires by Metal Organic Chemical Vapor Deposition. Different approaches are discussed, including growth with and without catalyst, self-assembled growth as well as selective-area growth; their respective advantages and limits are detailed.     

非晶SiO2纳米线的合成及其显微结构和光学性质的研究

本研究以硅片为衬底,热蒸发一氧化硅粉末在较低温度下合成了大量直径均匀的非晶SiO2纳米线.这些纳米线直径分布在15 nm～40 nm之间,长度几十微米.选区电子衍射(SAED)、能谱(EDS)、电子能量损失谱(EELS)分析结果表明这些纳米线为非晶SiO2纳米线.光致发光(PL)谱测试结果显示纳米线在波长550 nm处存在一个较强的PL峰.本文进一步指出了蒸发源SiO粉末的颗粒度和蒸发温度对纳米线生长有强烈的影响.     

纯铁离子注氮后的激光热处理

研究了工业纯铁离子注N后的连续CO_2激光热处理效应。用AES、TEM、SEM和X射线衍射等测试技术,研究了注N试样在激光热处理前后N原子的深度分布和组织结构,提出了注N纯铁在激光作用下N原子的热扩散模型。     

Effect of dissolved oxygen on thermal oxidation in Ta2O5/Ta sandwiches

Chemical analysis, structural investigations, and electrical capacitance measurements have been performed on Ta₂O₅/Ta foils annealed at 753K in air for different initial concentration of oxygen in Ta. It was shown that the initial concentration of oxygen in Ta plays a crucial role in formation of thermal nonstoichiometric oxide layer between tantalum and anodic Ta₂O₅, namely only Ta with low initial oxygen content covered with thin Ta₂O₅ layer is resistant to thermal oxidation. The obtained results may explain the degradation of real capacitors made of fine Ta powders.     

Fully transparent flexible transistors built on metal oxide nanowires

Transparent electronics has attracted great research efforts in recent years due to its potential to make significant impact in many area, such as next generation displays, ultraviolet (UV) detectors, solar cells, charge-coupled devices (CCDs), and so on. Central to the realization of transparent electronics is the development of high performance fully transparent thin-film transistors (TFTs). One-dimensional (1-D) nanostructures have been the focus of current researches due to their unique physical properties and potential applications in nanoscale elec-tronics and optoelectronics. Among 1-D nanostructures, transparent metal oxide nanowires are one of the best candidates to make fully transparent TFTs. We provide in this paper the most recent development on the fabrication of fully transparent TFT using metal oxide nanowires as the device elements. First, the review article gives a general introduction about the development of transparent elec-tronics using different kinds of materials as the devices elements, including organic semiconductors, metal oxide thin films, and metal oxide nanowires. Second, the growth of metal oxide nanowires using vapor phase methods governed by two different growth mechanisms: vapor-solid mechanism and vapor-liquid-solid mechanism, respectively, are described. Third, the fabrication of transparent and flexible TFTs using different metal oxides nanowires is comprehensively described. In conclusion, the challenges and prospects for the future are discussed.     

Anomalous oxidation rate in 6H-SiC depending on the partial pressure of O2 and H2O

On the thermal oxidation of silicon carbide, the partial pressure of H₂O affects the oxidation rate very differently from silicon. We have found that the oxide thickness shows the bell-shape as the function of the relative partial pressure of H₂O, called the p parameter. The main reason for this is that the diffusion limiting process diminishes according to the reduction of p while the linear rate constant does not depend on p strongly until p=0.15. The reduction of the oxide thickness below p=0.15 is explained by the abrupt reduction of the linear rate constant. In addition, the interface quality for oxides grown in the different p has been investigated. For the reduction of the surface states, the large p (over p=0.8) is favorable.     

Cu 纳米线的制备及其力学性能的研究

采用购买的直径为40～50 nm的AAO模板,利用直流电沉积方法在AAO模板上制备了Cu纳米线.TEM观察发现,Cu 纳米线的直径为(45±5)nm,与AAO模板的内孔 直径一致.利用碳膜卷曲的方法,在JEOL 2010F型场发射透射电子显微镜中对单根 Cu 纳米线进行了原位弯曲变形实验.实验发现,存在于纳米线内部的孪...