Au-MgF2复合纳米颗粒薄膜的制备和微结构

用射频磁控共溅射法制备了Au体积分数分别为6%、15%、25%、40%、50%和60%的Au-MgF2复合纳米颗粒薄膜.用X射线衍射、透射电镜、X射线光电子能谱对薄膜的微结构和组分进行了测试分析,分析结果表明:制备的Au-MgF2复合纳米颗粒薄膜由fcc-Au晶态纳米微粒镶嵌于主要为非晶态的MgF2陶瓷基体中构成,当Au体积百分含量由15%增至60%时,其平均晶粒尺寸由5.1nm增大到21.2 nm,晶格常数由0.399 84nm增大到0.407 43nm;随Au体积百分含量由6%增至50%,其颗粒平均粒径则由9.8nm增至21.4 nm.名义组分为vol.60%Au-MgF2样品中Au的体积百分含量约为62.6%,与设计值基本一致.     

纳米晶复合永磁材料在微结构与制备工艺上的设计

介绍了Skomski和Coey等人提出的各向异性纳米晶复合永磁体的理想模型，对比分析了当前制备工艺得到的纳米晶复合永磁材料与该模型的差异，并因此在微结构和制备工艺设计上提出了一些思路，以期充分发挥该材料诱人的高性能。     

纳米线阵列及纳米图形制备技术的研究进展

当今纳米技术研究的前沿和热点之一是将纳米线按一定方式排列与组装构成纳米线阵列及纳米图形,它们是下一代纳米结构器件设计的材料基础,在激光技术、信息存储及计算技术、生物技术等各领域均有广阔的应用前景.介绍了在纳米线阵列材料制备以及纳米图形制作方面的技术研究进展,详述了模板法、自组装法以及纳米刻蚀法等技术的发展.     

溅射气压对Ge/Si纳米点表面形貌的影响

利用磁控溅射技术在Si(100)衬底上直接外延生长一系列不同压强下的Ge纳米点样品,并利用AFM、Raman和XRF对Ge纳米点样品形貌和结构进行了研究。结果表明Ge薄膜表面粗糙度在某一临界压强下发生突变,高能粒子热化的临界值与这种转变密切相联;分析讨论了Ge岛在不同溅射气压下的生长过程,在一定范围随着压强的增大会显示典型生长阶段的特征。     

金属氧化物纳米线和纳米棒的制备及应用

本文综述了金属氧化物纳米线、纳米棒研究的新进展。重点评述了气相热化学合成法、热分解前驱物法、溶胶-凝胶电泳沉积法制备纳米线的过程及各自的生长机制，并对金属氧化物纳米线／棒的潜在应用作了介绍。     

聚乳酸/银纳米线纳米复合材料的制备与结晶行为

采用多元醇法合成银纳米线(AgNWs),并使用油酸(OA)对其进行表面改性;然后采用溶液浇铸法制备了聚乳酸(PLA)/AgNWs纳米复合材料。采用X射线衍射和傅里叶变换红外光谱表征了AgNWs的晶体结构、微观形貌和组成。扫描电子显微镜结果显示,AgNWs的长径比约为428,修饰OA后的AgNWs在PLA基体中分散均匀。采用差示扫描量热仪和偏光显微镜研究了PLA/AgNWs的玻璃化转变和结晶行为,结果表明,加入AgNWs使PLA基体的玻璃化转变温度下降了5～6℃;等温和非等温结晶行为研究显示,少量的AgNWs能够促进PLA结晶,而过量的AgNWs对PLA的结晶有一定的阻碍作用;当AgNWs质量分数为5%时,PLA基体的成核密度、结晶度、结晶速率达到最大。     

ZnO纳米线/棒阵列结构制备原理及方法概述

概述了ZnO纳米线/棒阵列结构的用途、制备原理和方法,重点介绍气相合成法和液相合成法中的几种典型制备ZnO阵列结构方法。展望了ZnO纳米线/棒阵列结构的发展方向及应用前景。     

一维,二维和三维Si基纳米线的制备

在Ar气氛中，SiC粉末分别在Fe、Co、Fe：Co(1：1)的催化下，经一步反应制备了一维、二维和三维si基纳米线。SEM、HRTEM、EDX分析表明一维线状和二维网状Si基纳米线由C、Si、O组成，存在两类纳米线，一类是SiO，包裹的Si纳米线；另一类是SiO，包裹的SiC纳米线。三维Si基纳米线组成象花一样的结构，仅由SiOx组成。SiOx和Si是无定形结构，SiC是β-SiC单晶。     

硬脂酸法制备纳米TiO_2及微结构控制

采用硬脂酸法制备了不同掺杂量的ＴｉＯ２纳米晶．通过ＦＴＩＲ、ＸＲＤ和ＴＥＭ等实验手段对所得纳米ＴｉＯ２进行分析和表征,并对反应历程进行了初步探讨．实验结果表明,利用硬脂酸法,金红石型ＴｉＯ２能在５００℃获得,掺杂Ｎａ＋和Ｋ＋后则得到锐钛矿型ＴｉＯ２,且随着掺杂量的增加,ＴｉＯ２的粒径减小．     

不同结构镍纳米线阵列的制备及其磁性

采用直流电沉积在多孔有序氧化铝模板中制备了不同结构的有序镍纳米线阵列。采用扫描电子显微镜和透射电子显微镜对所制备的镍纳米线的形貌和结构进行了表征。研究了镍纳米线不同结构对镍纳米线阵列磁性性能的影响规律。当电沉积电压为2.5V时制备的镍纳米线为多晶结构;电沉积电压4V时,镍纳米线为沿[220]择优取向的单晶结构;电沉积电压大于5V时,择优取向由[220]转为[111]方向。磁滞回线结果表明,单晶镍纳米线阵列与多晶纳米线阵列相比具有更高的矩形度,沿[111]择优取向的单晶纳米线相比沿[220]取向的单晶镍纳米线具有更大的矩形度,表现出显著的磁各向异性。     

Ge/Si nanowire mesoscopic Josephson junctions

The controlled growth of nanowires (NWs) with dimensions comparable to the Fermi wavelengths of the charge carriers allows fundamental investigations of quantum confinement phenomena. Here, we present studies of proximity-induced superconductivity in undoped Ge/Si core/shell NW heterostructures contacted by superconducting leads. By using a top gate electrode to modulate the carrier density in the NW, the critical supercurrent can be tuned from zero to greater than 100 nA. Furthermore, discrete sub-bands form in the NW due to confinement in the radial direction, which results in stepwise increases in the critical current as a function of gate voltage. Transport measurements on these superconductor-NW-superconductor devices reveal high-order (n = 25) resonant multiple Andreev reflections, indicating that the NW channel is smooth and the charge transport is highly coherent. The ability to create and control coherent superconducting ordered states in semiconductor-superconductor hybrid nanostructures allows for new opportunities in the study of fundamental low-dimensional superconductivity.     

Fabrication and characterization of a flow-through nanoporous gold nanowire/AAO composite membrane

The fabrication of a composite membrane of nanoporous gold nanowires and anodic aluminum oxide (AAO) is demonstrated by the electrodeposition of Au-Ag alloy nanowires into an AAO membrane, followed by selective etching of silver from the alloy nanowires. This composite membrane is advantageous for flow-through type catalytic reactions. The morphology evolution of the nanoporous gold nanowires as a function of the diameter of the Au-Ag nanowire 'precursors' is also investigated.     

Performance analysis of a Ge/Si core/shell nanowire field-effect transistor

We ana/lyze the performance of a recently reported Ge/Si core/shell nanowire transistor using a semiclassical, ballistic transport model and an sp3d5s* tight-binding treatment of the electronic structure. Comparison of the measured performance of the device with the effects of series resistance removed to the simulated result assuming ballistic transport shows that the experimental device operates between 60 and 85% of the ballistic limit. For this approximately 15 nm diameter Ge nanowire, we also find that 14-18 modes are occupied at room temperature under ON-current conditions with ION/IOFF = 100. To observe true one-dimensional transport in a 110 Ge nanowire transistor, the nanowire diameter would have to be less than about 5 nm. The methodology described here should prove useful for analyzing and comparing on a common basis nanowire transistors of various materials and structures.     

硅纳米线阵列光阳极的制备及其光电转换性能研究

结合光刻和金属援助硅化学刻蚀法成功地制备出了用于光伏型光电化学池的图形化硅纳米线阵列光阳极,并表征和研究了其光电转换性能.扫描电子显微镜和漫反射光谱测试表明光阳极表面为多孔状,在300nm - 1000nm的光谱范围之内光反射率低于5％.基于该光阳极的光电化学池具有明显的光响应,光电转换效率为0.33％.通过光电转换过...     

Single-crystalline Ni2Ge/Ge/Ni2Ge nanowire heterostructure transistors

In this study, we report on the formation of a single-crystalline Ni(2)Ge/Ge/Ni(2)Ge nanowire heterostructure and its field effect characteristics by controlled reaction between a supercritical fluid-liquid-solid (SFLS) synthesized Ge nanowire and Ni metal contacts. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies reveal a wide temperature range to convert the Ge nanowire to single-crystalline Ni(2)Ge by a thermal diffusion process. The maximum current density of the fully germanide Ni(2)Ge nanowires exceeds 3.5 × 10(7) A cm(-2), and the resistivity is about 88 μΩ cm. The in situ reaction examined by TEM shows atomically sharp interfaces for the Ni(2)Ge/Ge/Ni(2)Ge heterostructure. The interface epitaxial relationships are determined to be [Formula: see text] and [Formula: see text]. Back-gate field effect transistors (FETs) were also fabricated using this low resistivity Ni(2)Ge as source/drain contacts. Electrical measurements show a good p-type FET behavior with an on/off ratio over 10(3) and a one order of magnitude improvement in hole mobility from that of SFLS-synthesized Ge nanowire.     

图案化金属铜纳米线阵列的制备与表征

采用紫外线光刻技术与电化学沉积相结合的方法,成功制备了不同图案的铜纳米线阵列:一种是圆形图案;另一种是QDU图案.首先利用紫外线光刻技术在多孔阳极氧化铝模板(AAO)生成预设图案,以此作为"二次模板";再利用电化学方法将铜纳米线沉积到"二次模板"的开孔中.扫描电镜(SEM)测试结果表明,大面积、高规整的铜纳米线图案阵列各自独立地立在基底上, 同时,用电子能谱(EDS)分析了铜纳米线的化学成分.透射电镜(TEM)也探测到了铜纳米线的微结构.     

Diffusion in Si(x)Ge(1-x)/Si nanowire heterostructures

Si0.48Ge0.52/Si tip/nanowire heterostructures were grown by pulsed laser vaporization (PLV) at a growth temperature of 1100 degrees C. Ge diffusion in [111]-growth Si nanowires was studied for different post-synthesis annealing temperatures from 200 degrees C to 800 degrees C. Ge composition profiles were quantified by energy-dispersive X-ray spectroscopy in a transmission electron microscope. The compositional profiles were modeled by a limited-source diffusion model to extract temperature-dependent diffusion coefficients. The Ge diffusion coefficients followed an Arrhenius relationship with an activation energy of 0.622 +/- 0.050 eV. This rather low activation energy barrier is similar to the previously reported activation energy barrier of 0.67 eV for Ge surface diffusion on Si, suggesting that surface diffusion may dominate in nanowires at this length scale.     

Fabrication of superhydrophobic surfaces by a Pt nanowire array on Ti/Si substrates

Superhydrophobic surfaces were prepared on Ti/Si substrates via the fabrication of a platinum (Pt) nanowire array. The Pt nanowire array was obtained by dc electrodeposition of Pt into the pores of an anodic aluminium oxide (AAO) template on the substrate followed by the removal of the template. Transmission electron microscopy (TEM) examination demonstrated that all the nanowires have uniform diameter of about 30?nm. Field emission scanning electron microscopy (FE-SEM) showed that the structures at both the micrometre scale and nanometre scale bestowed the prerequisite roughness on the surfaces. The chemical surface modification made the Pt nanowire array superhydrophobic. The surface modified Pt nanowire array exhibited superhydrophobicity even in corrosive solutions over a wide pH range, such as acidic or basic solutions. The results demonstrated that the Pt nanowire array will have good potential applications in the preparation of superhydrophobic surfaces.     

Fabrication and device characterization of omega-shaped-gate ZnO nanowire field-effect transistors

Omega-shaped-gate (OSG) nanowire-based field effect transistors (FETs) have attracted a great deal of attention recently, because theoretical simulations predicted that they should have a higher device performance than nanowire-based FETs with other gate geometries. OSG FETs with channels composed of ZnO nanowires were successfully fabricated in this study using photolithographic processes. In the OSG FETs fabricated on oxidized Si substrates, the channels composed of ZnO nanowires with diameters of about 110 nm are coated with Al(2)O(3) using atomic layer deposition, which surrounds the channels and acts as a gate dielectric. About 80% of the surfaces of the nanowires coated with Al(2)O(3) are covered with the gate metal to form OSG FETs. A representative OSG FET fabricated in this study exhibits a mobility of 30.2 cm(2)/ (V s), a peak transconductance of 0.4 muS (V(g) = -2.2 V), and an I(on)/I(off) ratio of 10(7). To the best of our knowledge, the value of the I(on)/I(off) ratio obtained from this OSG FET is higher than that of any of the previously reported nanowire-based FETs. Its mobility, peak transconductance, and I(on)/I(off) ratio are remarkably enhanced by 3.5, 32, and 10(6) times, respectively, compared with a back-gate FET with the same ZnO nanowire channel as utilized in the OSG FET.