碳纳米管的制备、修饰及其应用

简要介绍了碳纳米管的制备及其纯化技术，以及近年来碳纳米管修饰、管内填充方面的研究，并概述了碳纳米管在复合材料、发光材料、纳米器件方面的应用及其在固体基片上的定向组装。     

用于悬浮纳米结构制作的氢氟酸气相刻蚀研究

针对纳米悬浮结构的制作,对不同温度和不同气相条件下的氢氟酸(HF)气相刻蚀进行了研究.利用自制的研究装置,使用HF/水混合气体和HF/乙醇混合气体分别进行了HF对PECVD SiO_2的气相刻蚀实验,同时测量了不同衬底温度下刻蚀速率的变化.研究结果表明,在常温常压下,HF/乙醇混合气体气相刻蚀速率约为7.6 nm/s,而HF/水混合气体气相刻蚀速率约为11.5 nm/s.在衬底温度分别为35,40和50℃时,HF/水混合气体的气相刻蚀速率分别为10.25,7.95和5.18 nm/s.利用HF气相腐蚀进行SiO_2牺牲层释放,得到了悬浮的纳米梁结构,梁与衬底的间距为400 nm.     

铁电纳米材料和纳米结构研究的进展

铁电纳米材料和纳米结构(如纳米线、纳米管、纳米环)具有新型尺寸效应特性,在铁电基电子器件的微型化方面受到广泛关注.近年来在铁电纳米材料和纳米结构的制备和(电性能和微结构)表征及理论模拟方面取得了相当进展,本文对这方面的最新进展进行评述.首先对高质量的铁电纳米材料和纳米结构的制备方法进行了简短评述,然后介绍铁电纳米材料和纳米结构的纳尺度物性表征.随后介绍了最近发展的四种理论模型(尤其对铁电纳米管、纳米线、纳米点),以及从第一原理出发理论模拟铁电纳米结构的新现象,如铁电纳米结构的自发极化螺旋有序和自发极化涡旋结构.最后总结了铁电纳米材料和纳米结构的微结构研究进展,并讨论了有关铁电纳米结构中自发极化螺旋畴的一些基础物理问题以及实验上寻找自发极化螺旋畴的研究进展.     

碳纳米管中纳米空间的物质结构

填充碳纳米菅不但能改变碳纳米管本身的电学和力学性质,而且能改变被填充物质的性质.本文就有关多层、双层、单层碳纳米管的管内填充,主要以TEM为表征技术,对碳纳米管内纳米限域空间中物质的结构、性质等的研究作了简要的总结.     

纳米金修饰碳纳米管阵列结构的表面增强拉曼散射

研究了纳米金粒子修饰碳纳米管阵列结构的表面增强拉曼散射性能.通过FDTD理论模拟仿真了不同粒径纳米金颗粒的场强分布;并采用化学还原的方法制备出直径分别为20、40和60 nm三种不同粒径的金颗粒,然后将纳米金粒子修饰到有序定向的碳纳米管阵列表面,并将该结构作为表面增强拉曼基底.FDTD软件仿真结果表明,60 nm粒径的纳米金颗粒周围场强分布最强,是入射场场强的15倍.同时将罗丹明6G溶液用于测试几组不同尺寸的金颗粒对拉曼散射光强的影响,发现60 nm金颗粒对R6G拉曼信号增强最大.FDTD理论模拟仿真和罗丹明6G溶液实验测试结果表明:金颗粒尺寸在20～60 nm内,颗粒尺寸越大,拉曼散射光的光强越大.     

贵金属纳米颗粒催化刻蚀硅表面微纳结构现状北大核心

简述了目前一些贵金属纳米颗粒催化刻蚀Si表面微纳结构的研究工作,并叙述了催化刻蚀反应的主要过程。在系统介绍催化刻蚀化学反应机理的基础上,对催化刻蚀的阴极、阳极反应进行了细致的探讨。根据不同的阳极和阴极反应方程式,讨论了不同的中间产物以及不同中间产物在反应中的作用机理。然后介绍了贵金属纳米颗粒的物理法和化学法两种制备方法。结合目前国内外研究进展,讨论了贵金属纳米颗粒种类、尺寸以及溶液成分比例对硅表面微纳结构的影响。最后对贵金属纳米颗粒催化刻蚀硅表面微纳陷光结构的未来前景进行了展望。     

混合纳米结构：两全其美的选择

普遍认为,碳纳米管(CNT)和纳米线将在未来的半导体技术中大显身手。除了显然的可应用于纳米尺度以外,CNT还具有非常高的机械强度和良好的导电能力,这使得它们能够用于比现今的先进铜互连快许多倍的高速互连技术。而且金纳米线的光学和电学性能也很受关注。然而CNT的生长位置和晶向都是随机的,这使它们很难应用到电子产品中。ITRS也强调了CNT用于量产器件所面临的挑战。[1]     

基于碳纳米管的微纳机电器件应用研究

综述了近年来碳纳米管在微纳传感器、纳米发电机、纳米执行器、纳米电子器件、纳米收音机与薄膜扬声器等方面取得的瞩目成果及典型应用,介绍了基于碳纳米管的微纳机电器件的制造工艺、器件性能及其研究进展,指出了碳纳米管基微纳机电器件在多元化发展、工艺多样化、材料复合化、产业化工程等方面的发展趋势。     

反应温度对合成纳米羟基磷灰石粉体的粒度和相结构的影响

采用化学沉淀法在Ca（OH）2／H3PO4／H2O体系下合成了纳米羟基磷灰石（HA）粉体,研究了影响纳米羟基磷灰石生成的重要参数——反应温度对粒度和相结构的影响,用FT-IR、XRD、TEM等对HA的粒度、相结构和形貌进行了表征。结果表明,反应温度不仅影响纳米卧粉体的粒度、结晶度,而且影响纳米结晶的生长习性。在25％。90℃范围内合成了纳米HA粉体,随反应温度的提高,纳米羟基磷灰石颗粒的结晶尺寸呈先增加后减小的趋势,形状由针状变为短棒状。     

原位电子束诱导沉积制备碳纳米结构

以多壁碳纳米管为基本材料,利用电子束诱导沉积的方法进行了纳米结构加工、修饰研究.电子束诱导沉积实现了二个碳纳米管端部之间的牢固焊接,实现了纳米材料间的几乎无损伤连接.原位测量表明多壁碳纳米管间的连接为欧姆接触.进一步对碳纳米管施加外电场可以使端部碳原子间的π键打开,外部碳原子经电子束诱导沉积在碳纳米管的端部,并定向生长成非晶态碳纳米线.由于碳纳米管和纳米线结合处的.键作为绝缘界面,形成了电子输运的势垒,所得到的碳纳米管-纳米线复合结构具有整流特性.利用电子显微镜进行纳米材料的结构加工、修饰,具有选择位置精确、可实时监测、对纳米材料几乎无损伤、重复性和可靠性高,以及加工尺度可人为控制的特点.     

Photocrosslinkable liquid-crystalline polythiophenes with oriented nanostructure and stabilization for photovoltaics

A novel stable and photocrosslinkable electron-donor material, liquid-crystalline polythiophene containing cyano-biphenyl mesogenic pendant, namely, poly{3-[6-(4′-cyano-biphenyloxy)hexyl]thiopheneylenethiophene-alt-3-(6-bromohexyl)thiophene} (PTcbpTT), was designed and synthesized. The structural anisotropy originating from cyano-biphenyl mesogens can induce the PTcbpTT to assemble into a well ordered morphology and consequently lead to the red-shift absorption, enhanced photoluminescence. The thermal treatment drives further development of the morphology of the copolymer and its blend films mixed with [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM), towards a state of microphase separation in the nanometer scale. Furthermore, the bulk heterojunction devices based on the PTcbpTT:PCBM (1:1 wt.%) active layer have been constructed. Without extensive optimization, the LC annealing device yields an enhancement of power conversion efficiency from 0.5% to 1.2%, showing a significantly increased J_sc and FF with respect to its untreated counterpart, thanks to the ordered microphase separation channels for charge transportation. The high V_oc value of 0.731 V is due to the low HOMO level of PTcbpTT. Unlike devices prepared from PTcbpTT:PCBM blend without UV treatment, photocrosslinked PTcbpTT:PCBM devices are stable even when annealed for two days at the elevated temperature of 150 °C, implying that the photocrosslinked structure dramatically suppresses largescale phase segregation.     

Polyaniline micro‐ and nanostructure

A hierarchic polyaniline micro‐ and nanostructure is presented as a result of electron microscope studies. Molecular organisation is also discussed on the basis of experimental data and computer modelling. Copyright © 1999 John Wiley & Sons, Ltd.     

花状纳米结构ZnS:Cu的制备与光学性质研究

采用水热法合成了具有花状纳米结构的ZnS:Cu粉末.利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)和荧光光谱仪研究了在不同正硅酸四乙酯(TEOS)含量的条件下制备的样品的物相、形貌与光致发光(PL)性质.测试结果表明:制备的ZnS:Cu样品都具有立方相闪锌矿结构;由于TEOS分子...     

Nonlinear response of a double-well nanostructure with electron-electron interaction

Semiconductors - The self-consistent solution for the Schrödinger and Poisson equations in the Hartree-Fock approximation is applied to the study of the effect of electron-electron interaction...     

蓝宝石表面纳米结构随杂质靶距离的演化

使用微波回旋共振离子源刻蚀蓝宝石（C向）表面，引入金属不锈钢杂质，研究了不同靶距处蓝宝石表面自组织纳米结构的演化规律及光学性能。采用原子力显微镜来观察样品表面的形貌变化，Taylor Surf CCI 2000白光干涉表面测量仪测量蓝宝石样片表面的粗糙度；选择X射线光电子能谱对样品表面的化学成分进行了表征。实验结果表明:当离子束能量为1000 eV，束流密度为487 μA/cm2，入射角度为65°，刻蚀时间为60 min，蓝宝石样片与杂质靶距离从1 cm增加到4 cm时，样片表面出现岛状结构并逐渐演变为连续的条纹结构。同时，自组织纳米结构随靶距增加，有序性增加，纵向高度逐渐减小，空间频率基本不变。刻蚀后样品表面的金属杂质残留很少，微结构的形成对蓝宝石具有增透作用。在离子束溅射过程中，岛状结构的出现促进了样品表面条纹纳米结构的生长，破坏了纳米结构的有序性。     

一种新型光学装饰材料

主要论述了可作为新型装饰材料的微珠结构的光学定向散射膜片的原理及其实现方法，给出此种装饰材料的制做试验结果。     

Enhanced field emission and hysteresis characteristics of aligned carbon nanotubes with Ti decoration

The field emission behavior of aligned carbon nanotubes (CNTs) is remarkably improved by decorating their surfaces with Ti nanoparticles through a sputtering process. The CNT/Ti(4 nm) sample shows a low turn-on field of 0.63 V/μm at 10 μA/cm², low threshold field of 1.06 V/μm at 1 mA/cm², and maximum field emission current density of 23 mA/cm² at 1.80 V/μm. The enhanced field emission properties of the CNT/Ti samples are attributed to the added defect sites and Ti nanoparticles, which increase the field enhancement factor and density of emission sites. Stability measurements indicate that the Ti coating, which acts as a protective layer, also strengthens the field emission stability of the CNT arrays. Moreover, the extent of hysteresis in the current–voltage sweep highly depends on the voltage-sweep speed.     

Pentacene phototransistor with gate voltage independent responsivity and sensitivity by small silver nanoparticles decoration

In this study, a Pentacene phototransistor (PT) decorated with silver nanoparticles (Ag-NPs) in bottom gate structure was demonstrated. With the ultra-small Ag-NPs, this device exploits surface plasmon resonance at 445 nm and established a stable surface conduction channel under light illumination. Therefore, the PT exhibit gate voltage independent responsivity and photosensitivity in broad range of gate voltage. The light-induced magnetized in ultra-small Ag-NPs that generate polarized surface electrons were used to explain the gate-voltage independent photocurrent. The maximum photosensitivity and responsivity are 2.1 × 10³ and 17.7 mA/W, respectively, under white-light illumination. They are enhanced around 25 times at gate voltage of 20 V than conventional phototransistor. This device may be used in flexible optical interactive display, white-light indoor communication, or optical sensors.     

Nonlinear ionization of a two-dimensional nanostructure

Analytical expressions are obtained for the ionization rate and partial probabilities of ionization of a two-dimensional quantum dot in the field of a linearly polarized electromagnetic wave. The total probability of the ionization of a two-dimensional quantum dot by a dc electric field is calculated. The probability of the ionization of a system upon the superposition of dc and low-frequency electric fields of the same direction is determined. The results are compared with data obtained previously for one- and three-dimensional nanostructures with the short-range confining potential.