电纺掩模制备铜纳米线网络透明电极

通过真空蒸镀技术、静电纺丝技术和湿法腐蚀法成功制备出铜纳米线网络透明电极.首先优化纺丝条件,制备出均匀的聚丙烯腈(PAN)纳米纤维,然后将PAN纳米纤维作为掩模腐蚀铜膜得到铜纳米线网络透明电极.通过对纺丝时间、纺丝接收取向、蒸气处理时间和湿法腐蚀时间等制备条件进行优化,得到表面光滑连续、形貌良好的铜纳米线网络透明电极....     

飞秒激光前向转移诱导产生金属纳米结构薄膜

使用掺镱光子晶体光纤飞秒激光放大系统作为加工光源,利用激光诱导前向转移(LIFT)技术对铜膜进行加工,产生纳米结构。通过控制飞秒激光光源参数,得到不同纳米结构的金属薄膜。在功率较低时,能够得到纳米团簇;随着功率升高,团簇尺寸变大;到达一定功率时,出现纳米线结构。通过实验分析了飞秒激光与材料相互作用时发生的物理过程。利用该机理,对20,40,200nm三种厚度的铜膜在相同实验条件下的实验结果进行比较,获得了产生纳米团簇和纳米线结构薄膜的最佳条件。     

铜/多孔铝纳米有序阵列的近红外偏振特性研究

利用二次阳极氧化法在稀硫酸溶液中制备了不同孔径的多孔铝模板,并用交流电化学沉积的方法在多孔铝中合成了铜纳米线.测量了铜/多孔铝复合膜的透射光谱及偏振光谱.实验结果表明,这种含铜纳米线多孔铝膜微偏振器件在近红外光区有较好的透射率和消光比,且随着铜纳米线直径的增加,样品的透射率下降而其消光比却明显提高.通过分析得出,优化模板参数可制备出高效率的铜/多孔铝微偏振器.这种微偏振器件制备方法简单、效率高、造价低,在光电集成领域有着广泛的应用前景.     

BaTiO3铁电纳米膜制备及物性和微结构表征

采用脉冲激光淀积法在硅基氧化铝纳米有序孔膜版介质上（膜版孔径平均尺寸20nm,内生长Pt纳米线作为底电极一部分）制备了BaTiO3铁电纳米膜,并对其物性（铁电和介电性能）和微结构进行了表征。结果表明厚度170nm BaTiO3铁电膜的介电常数,随着测量频率的增加（103Hz至106Hz）,从400缓慢下降到350;介电损耗在低频区域（103～105Hz）从0.029缓慢增加到0.036,而在高频率区域（〉105Hz）后,则迅速增加到0.07。这是由于BaTiO3铁电薄膜的介电驰豫极化引起的。电滞回线测量结果表明,该薄膜的剩余极化强度为17μC/cm2,矫顽场强为175kV/cm。剖面扫描透射电子显微镜（STEM）图像表明,BaTiO3纳米铁电薄膜与底电极Pt纳米线直接相连接,它们之间的界面呈现一定程度的弯曲。选区电子衍射图和高分辨电子显微像均表明BaTiO3铁电薄膜具有钙钛矿型结构。在BaTiO3纳米铁电薄膜退火晶化处理后,部分Pt纳米线的再生长导致顶端出现分枝展宽现象。为了兼顾氧化铝纳米有序孔膜版内的金属纳米线有序分布和BaTiO3纳米薄膜结晶度,合适的退火温度是制备工艺过程的关键因素。     

图案化铜纳米线阵列的制备

采用紫外光刻法制得图案化的阳极氧化铝模板。在模板上蒸镀金膜后,采用电化学沉积法制备了铜纳米线,用扫描电子显微镜观察,研究了最佳电化学沉积时间。结果表明,铜纳米线阵列的图案与掩膜的图案完全一致,呈直径约5μm的圆形。铜纳米线的长度随沉积时间的增加而增长,沉积时间20min,即可制得长度约5μm的铜纳米线阵列结构。在此基础上可研制微器件。     

纳米多孔铝的制备技术及应用

介绍了阳极氧化方法制备纳米多孔铝的技术。阳极氧化多孔铝由于孔径可以控制在纳米尺度,因而在半导体纳米线料的制备方面具有广泛的用途。     

模板合成法制备ZnO纳米线的研究

在草酸和硫酸电解液中分别制备了孔径为40 nm和20 nm左右的多孔氧化铝模板,用直流电化学沉积的方法,在模板孔洞内电解沉积Zn,对其进行高温下的氧化,可得到高度有序的ZnO纳米线.扫描电子显微镜观察显示,多晶的Zn纳米线均匀地填充到多孔氧化铝六角排布的孔洞里,直径与模板孔径相当.X射线衍射谱测量证实,制备的Zn纳米线和ZnO纳米线均为多晶结构,并且对比了模板孔径对纳米线结构的影响.测量了多孔氧化铝厚膜和Zn/Al2O3组装体的吸收光谱,发现其在红外波段的吸收系数有逐渐降低的趋势.     

Cu/PAA纳米复合结构的制备与偏振特性研究

通过改变二次氧化过程中的氧化电压,制备了不同孔径的多孔Al(PAA)模板;采用交流电沉积的方法,制备了含Cu阳极PAA膜.X射线衍射(XRD)分析表明,阳极PAA膜上确有Cu生成;扫描电镜(SEM)显示,Cu纳米线粗细均匀,具有很好的线栅结构.Cu/PAA复合膜的透射光谱及偏振光谱表明:这种含Cu纳米线PAA膜在近红外光区有较好的透射率和消光比,且随着膜板孔径(Cu纳米线直径)的增加,样品的透射率下降而其消光比却明显提高.因此,可以通过优化模板参数,制备出实用的Cu/PAA偏振器.     

纳米压痕技术控制电迁移现象中铝原子积聚位置研究

在利用电迁移现象制备铝纳米线的过程中,铝纳米线的生长位置取决于铝原子的积聚位置。为实现铝原子积聚位置控制,基于纳米压痕技术改变试样中铝膜的横截面结构,制备了铝膜试样。通过输入并调节直流电大小使铝膜内产生电迁移现象。试验结果表明,纳米压痕技术可有效提高局部区域的电流密度,显著增强铝原子的电迁移强度,并在压痕区域出现铝原子积聚现象。     

基于纳米操作的纳米线钎焊结构组装及互连

近年来,纳米线在纳米电子学、纳米光子学、纳米医学和纳米机电系统等领域的应用逐渐广泛,纳米线的连接已经成为未来器件小型化和集成化的关键问题。为了实现良好的纳米线互连,提出了一种基于扫描电子显微镜(SEM)的纳米线-纳米钎料原位互连结构组装、钎焊互连的方法。利用开发的SEM纳米操作平台,实现了直径为100 nm左右的ZnO纳米线与直径为180～300 nm的Ag纳米钎料的同基底互连结构组装。利用SEM聚焦电子束辐照熔融纳米钎料实现了纳米线钎焊互连,利用双探针纳米操作系统对焊接后的纳米线进行电流-电压(I-V)测试,钎焊后的纳米互连结构成功实现电流导通。     

阳极氧化法制备氧化铝纳米线

将Al片在较高的电压下进行阳极氧化,制备了氧化铝纳米线。其形成机制主要是多孔氧化铝膜生长的同时,其微结构单元阵列在薄膜应力作用下沿薄壁处破裂,从而生成了氧化铝纳米线。扫描电镜和透射电镜观测表明,所得产物结构外形基本一致,呈凹柱面正三棱柱形,表观直径约30～300nm,长度为几微米至数十微米。采用BET法对产物的比表面积进行测量,实验值为5.8×104m2/kg,接近于理论计算值6.2×104m2/kg。实验表明,这种氧化铝一维纳米结构材料对超小Ag和CdS纳米颗粒具有较强的吸附能力,对很难用传统的过滤和离心沉淀法去除的超小纳米颗粒(直径小于10nm)也能做到有效吸附,有望成为超级吸附与过滤材料。     

Ni/AAO纳米复合薄膜的制备及其光学性能

采用交流电化学沉积方法,以经过阶梯降压处理的多孔氧化铝(AAO)为模板,制备出Ni/AAO纳米复合薄膜。研究了薄膜的结构及光学性能。结果表明:Ni/AAO纳米复合薄膜中Ni呈线状均匀分布在AAO纳米孔隙中,直径与AAO孔径一致,约80nm,并沿[111]方向择优生长,具有面心立方结构。光谱分析表明,该复合薄膜的光学带隙为3.18eV,较AAO模板(3.38eV)自身红移;光致发光峰位于465nm,与AAO模板相同,发光强度较模板自身减弱。     

Synthesis and Photoluminescence of GaN Nanowires with Nb Catalyst

Large-scale GaN nanowires are successfully synthesized by ammoniating Ga2O3 films on Nb layer deposited on Si（111） substrates at 850 ℃. X-ray diffraction （XRD）, scanning electron microscopy （SEM）, field-emssion transmission electron microscope（FETEM）, Fourier transformed infrared spectrum（FTIR） are used to characterize the structural and morphological properties of the as-synthesized GaN nanowires. The results reveal that the nanowires are pure hexagonal GaN wurtzite structure with a length of about several microns and a diameter between 50 nm and 100 nm. Finally, discussed briefly is the formation mechanism of gallium nitride nanowires.     

Flexible and Robust 2D Arrays of Silver Nanowires Encapsulated within Freestanding Layer‐by‐Layer Films

Freestanding layer‐by‐layer (LbL) films encapsulating controlled volume fractions (? = 2.5–22.5 %) of silver nanowires are fabricated. The silver nanowires are sandwiched between poly(allylamine hydrochloride)/poly(styrene sulfonate) (PAH/PSS) films resulting in nanocomposite structures with a general formula of (PAH/PSS)₁₀PAH Ag(PAH/PSS)₁₀PAH. The Young's modulus, toughness, ultimate stress, and ultimate strain are evaluated for supported and freestanding structures. Since the diameter of the nanowires (73 nm) is larger than the thickness of the LbL films (total of about 50 nm), a peculiar morphology is observed with the silver nanowires protruding from the planar LbL films. Nanowire‐containing LbL films possess the ability to sustain significant elastic deformations with the ultimate strain reaching 1.8 %. The Young's modulus increases with increasing nanowire content, reaching about 6 GPa for the highest volume fraction, due to the filler reinforcement effect commonly observed in composite materials. The ultimate strengths of these composites range from 60–80 MPa and their toughness reaches 1000 kJ m^–3 at intermediate nanowire content, which is comparable to LbL films reinforced with carbon nanotubes. These robust freestanding 2D arrays of silver nanowires with peculiar optical, mechanical, and conducting properties combined with excellent micromechanical stability could serve as active elements in microscopic acoustic, pressure, and photothermal sensors.     

Depletion-Mode Photoconductivity Study of Deep Levels in GaN Nanowires

The steady-state photoconductivity (PC) response of deep level defects to sub-bandgap illumination was studied in GaN nanowires (NWs) grown by metalorganic chemical vapor deposition. Photoemission from defects residing in the NW surface depletion region alters the depletion width, and the PC response arises mainly from the resulting enhancement of the cross-sectional area of the electrically conductive NW core. The advantages of emphasizing depletion region processes for deep level spectroscopy of NWs are discussed. A simple electrostatic model was adopted to explain the strong relative increase of sub-bandgap PC response with decreasing NW width. NW deep level spectra were similar to those widely reported for planar GaN films, suggesting that the corresponding defects are located throughout the NW volume and are not specific to the surface.     

Controlling the diameter of silicon nanowires grown using a tin catalyst

Silicon nanowires were grown on ITO-coated glass substrates via a pulsed plasma enhanced chemical vapor deposition method, using tin as a catalyst. The thin films of catalyst, with different thicknesses in the range 10–100 nm, were deposited on the substrates by a thermal evaporation method. The effect of the thickness of the thin film catalyst on the morphology of the silicon nanowires was investigated. The scanning/transmission electron microscopy images showed that the wire diameter increased as the thickness of the thin film catalyst increased. The nanowires grown using a thin film thickness of 10 nm were inhomogeneous in diameter, whereas the other thicknesses led to an increase in the homogeneity of the diameters of the nanowires. The dominant wire diameter of the grown silicon nanowires ranged from 70 to 80 nm with 10 nm catalyst thin film thickness, and increased to a range of 190–200 nm with 100 nm catalyst thin film thickness.     

Synthesis,Chemical Modification,and Surface Assembly of Carbon Nanowires

Carbon nanotubules and nanowires were synthesized by pyrolysis of polymer precursors in the pores of alumina membranes. The nanowires were released by dissolving the membranes, and were then made hydrophobic or hydrophilic by chemical surface derivatization. These nanowires could be placed into lithographically defined wells on surfaces by means of electrostatic interactions with monolayers at the bottoms of the wells.     

Title: Using Alignment and 2D Network Simulations to Study Charge Transport Through Doped ZnO Nanowire Thin Film Electrodes

Factors affecting charge transport through ZnO nanowire mat films were studied by aligning ZnO nanowires on substrates and coupling experimental measurements with 2D nanowire network simulations. Gallium doped ZnO nanowires were aligned on thermally oxidized silicon wafer by shearing a nanowire dispersion in ethanol. Sheet resistances of nanowire thin films that had current flowing parallel to nanowire alignment direction were compared to thin films that had current flowing perpendicular to nanowire alignment direction. Perpendicular devices showed ～5 fold greater sheet resistance than parallel devices supporting the hypothesis that aligning nanowires would increase conductivity of ZnO nanowire electrodes. 2‐D nanowire network simulations of thin films showed that the device sheet resistance was dominated by inter‐wire contact resistance. For a given resistivity of ZnO nanowires, the thin film electrodes would have the lowest possible sheet resistance if the inter‐wire contact resistance was one order of magnitude lower than the single nanowire resistance. Simulations suggest that the conductivity of such thin film devices could be further enhanced by using longer nanowires.     

Fabrication of Si-nanowires controlled by spontaneously formed nanoholes on annealed Au thin films

Si nanowires (Si-NWs) were fabricated by a simple process that consists of deposition of Au thin films, annealing of the Au films to form porous structure and Si wet-etching using the kinetically appearing porous Au films as a template. The deformation behavior of the Au thin films was investigated by scanning electron microscopy and atomic force microscopy. The nanohole diameter and density of the Au films can be controlled by selecting Au film thickness, annealing temperature and annealing time. The formation mechanism of these porous Au films can be explained by a model that consists of nanohole formation at the grain boundaries of the Au films and ridge formation by Au atom diffusion to the hole periphery. The ridge structure suppresses further deformation of the Au films and keeps the nanohole structure kinetically stable. When a thermal energy larger than the activation energy to destroy the ridge structure is supplied, it transforms to the island structure.