Indium phosphide nanowires as building blocks for nanoscale electronic and optoelectronic devices

Nanowires and nanotubes carry charge and excitons efficiently, and are therefore potentially ideal building blocks for nanoscale electronics and optoelectronics. Carbon nanotubes have already been exploited in devices such as field-effect and single-electron transistors, but the practical utility of nanotube components for building electronic circuits is limited, as it is not yet possible to selectively grow semiconducting or metallic nanotubes. Here we report the assembly of functional nanoscale devices from indium phosphide nanowires, the electrical properties of which are controlled by selective doping. Gate-voltage-dependent transport measurements demonstrate that the nanowires can be predictably synthesized as either n- or p-type. These doped nanowires function as nanoscale field-effect transistors, and can be assembled into crossed-wire p-n junctions that exhibit rectifying behaviour. Significantly, the p-n junctions emit light strongly and are perhaps the smallest light-emitting diodes that have yet been made. Finally, we show that electric-field-directed assembly can be used to create highly integrated device arrays from nanowire building blocks.     

Fabry - Perot interference in a nanotube electron waveguide

The behaviour of traditional electronic devices can be understood in terms of the classical diffusive motion of electrons. As the size of a device becomes comparable to the electron coherence length, however, quantum interference between electron waves becomes increasingly important, leading to dramatic changes in device properties. This classical-to-quantum transition in device behaviour suggests the possibility for nanometer-sized electronic elements that make use of quantum coherence. Molecular electronic devices are promising candidates for realizing such device elements because the electronic motion in molecules is inherently quantum mechanical and it can be modified by well defined chemistry. Here we describe an example of a coherent molecular electronic device whose behaviour is explicitly dependent on quantum interference between propagating electron waves-a Fabry-Perot electron resonator based on individual single-walled carbon nanotubes with near-perfect ohmic contacts to electrodes. In these devices, the nanotubes act as coherent electron waveguides, with the resonant cavity formed between the two nanotube-electrode interfaces. We use a theoretical model based on the multichannel Landauer-Büttiker formalism to analyse the device characteristics and find that coupling between the two propagating modes of the nanotubes caused by electron scattering at the nanotube-electrode interfaces is important.     

半导体芯片紫外荧光无损检测

Fe、Na、Ni等金属杂质对半导体器件芯片有严重的负面影响，往往导致器件失效，成品率下降，必须进行有效控制处理．采用紫外荧光(UVF)法可有效检测出硅晶片及半导体器件芯片(如GaP、GaAs等)的金属杂质沾污情况，还能检测金属杂质的相对沾污量，对半导体器件芯片的生产可实现实时非破坏性的检测分析．     

碳纳米管的催化合成、结构表征及应用研究

概述近10年来国内外在碳纳米管催化合成及其应用研究领域的发展动态,着重介绍本研究组在管径小而均匀碳纳米管的催化合成、结构性能表征、及其在作为新型催化剂载体材料及储氢等应用领域的研究进展。     

计算机高速通用串行总线接口开发

通用串行总线[USB]是一种新型的计算机外围接口标准.它具有即插即用、扩展方便、数据传输率高等特点.但由于USB总线协议复杂,使得USB设备的开发比较困难.本文首先介绍了USB的总体性能及特点,然后对USB总线的系统体系结构、通信模型、机械规范和电气规范以及USB设备结构作了简要介绍,总结了USB设备开发的一般过程,并对目前USB芯片进行了简要介绍.     

Controlled fabrication of fullerene derivative one-dimensional nanostructures via electrophoretic deposition of its clusters

Well-defined and controllable one-dimensional(ID) nanostructures of fullerene derivative have been prepared by an electrophoretic template synthesis method. The clusters of fullerene derivative formed in mixed solvents are introduced into the channels of porous alumina templates through a dc electric field. Four types of ID nanostructures(solid nanowires, solid-wall nanotubes, porous nanowires and porous-wall nanotubes) have been obtained by changing the deposition parameters. This,approach opens a new avenue to assemble fullerene derivatives, endohedral fullerenes, as well as other functional organic compounds, which can form clusters in ID nanostructure arrays for applications in chemical sensors, light energy conversion devices and nanoscale electronic and optoelectronic devices.     

非均匀介质下的可调光流控器件及其生化应用

 探讨了非均匀介质下不同光流控器件及其生化应用。在微流控芯片上，主要从2个方面开发和实现各类具有光波导、透镜、细胞计数、化学检测等功能的新器件。首先，在液液非均匀介质下，通过调节沟道内液体流速，控制液体间的对流扩散来实现液体在微腔内的渐变折射率分布和阶跃分布，从而得到其特殊的光学特性，例如光束分离、弯曲、自聚焦等。其次，在固体非均匀介质下，利用特殊的微流结构与液体相结合，实现更加灵敏可调的新型探测手段。这些新型技术手段分别在生物传感、能源生产、细胞探测及海水检测等诸多应用中可发挥关键性作用。     

Bandgap modulation of carbon nanotubes by encapsulated metallofullerenes

Motivated by the technical and economic difficulties in further miniaturizing silicon-based transistors with the present fabrication technologies, there is a strong effort to develop alternative electronic devices, based, for example, on single molecules. Recently, carbon nanotubes have been successfully used for nanometre-sized devices such as diodes, transistors, and random access memory cells. Such nanotube devices are usually very long compared to silicon-based transistors. Here we report a method for dividing a semiconductor nanotube into multiple quantum dots with lengths of about 10nm by inserting Gd@C82 endohedral fullerenes. The spatial modulation of the nanotube electronic bandgap is observed with a low-temperature scanning tunnelling microscope. We find that a bandgap of approximately 0.5eV is narrowed down to approximately 0.1eV at sites where endohedral metallofullerenes are inserted. This change in bandgap can be explained by local elastic strain and charge transfer at metallofullerene sites. This technique for fabricating an array of quantum dots could be used for nano-electronics and nano-optoelectronics.     

GaN基Micro-LED量子效率的研究进展

微米级发光二极管（Micro light-emitting diode, Micro-LED）器件具有高亮度、高耐热性、长寿命、低功耗以及极短的响应时间等优点,被视为下一代显示技术的基石,可满足手机、可穿戴手表、AR/VR、微型投影仪、超高亮度显示器等先进设备应用的个性化需求。Micro-LED显示芯片与目前用于高亮度照明的无机半导体芯片具有相似的特性。当管芯直径减小到微米级时,会出现尺寸效应与Droop效应,量子效率急剧下降,器件整体性能受限。介绍了发光二极管的量子效率及影响GaN基Micro-LED量子效率的因素,并提出提升内量子效率和光提取效率的措施,同时对Micro-LED的未来研究与应用进行了总结与展望。     

非磁性杂质对碳纳米管态密度的影响研究

针对非磁性杂质对碳纳米管的影响问题作了系统理论的分析,为设计和实现具有优良性能的基于碳纳米管的量子器件提供理论依据.应用格林函数方法计算态密度的结果表明,单个点缺陷在碳纳米管中引起准束缚态;给出准束缚态能级和峰宽的解析公式,分析它们与碳纳米管手型和直径之间的关系;逐点计算局域态密度发现,在实空间准束缚态是一个非常局域化的效应,离开缺陷即迅速衰减.同时,缺陷在碳纳米管中会引起Friedel振荡,其方向与碳纳米管手型有关.     

低维硼碳纳米材料第一原理研究

介绍了近年来关于低维硼碳纳米材料结构和电子性质的研究工作.通过第一原理计算,从理论上预言了稳定的低维硼纳米结构,并系统研究了以稳定硼平面为基础的硼纳米管和硼纳米带的电子性质.对于硼碳复合纳米材料,以BC3,BC5和BC7有序结构的平面为基础,发现对其剪裁、氢化修饰之后,硼碳纳米结构具有丰富的电磁学性质,可能在未来电子学器件中得到广泛的应用.     

非磁性杂质对碳纳米管态密度的影响研究

针对非磁性杂质对碳纳米管的影响问题作了系统理论的分析,为设计和实现具有优良性能的基于碳纳米管的量子器件提供理论依据.应用格林函数方法计算态密度的结果表明,单个点缺陷在碳纳米管中引起准束缚态;给出准束缚态能级和峰宽的解析公式,分析它们与碳纳米管手型和直径之间的关系;逐点计算局域态密度发现,在实空间准束缚态是一个非常局域化...     

机载设备电子芯片缓冲橡胶蜂窝夹层抗跌落冲击性能

 以飞机高速飞行环境下某机载设备电子芯片跌落为例,研究了电子芯片缓冲橡胶蜂窝夹层的抗冲击性能。对缓冲橡胶夹层采用不同的蜂窝构型,即分别纵向开孔、横向开孔和选择不同孔径,利用Abaqus 有限元分析软件进行仿真实验,研究蜂窝的开孔结构及孔径大小对缓冲橡胶夹层抗冲击性能的影响。结果表明,缓冲橡胶夹层的蜂窝结构相对于实体结构能显著提高其抗跌落冲击性能（提高22%~33%）,纵向开孔结构的抗冲击效果优于横向开孔结构（提高3%~6%）,而在设计范围内的孔径大小对抗冲击效果的影响不明显。     

Growth of nanowire superlattice structures for nanoscale photonics and electronics

The assembly of semiconductor nanowires and carbon nanotubes into nanoscale devices and circuits could enable diverse applications in nanoelectronics and photonics. Individual semiconducting nanowires have already been configured as field-effect transistors, photodetectors and bio/chemical sensors. More sophisticated light-emitting diodes (LEDs) and complementary and diode logic devices have been realized using both n- and p-type semiconducting nanowires or nanotubes. The n- and p-type materials have been incorporated in these latter devices either by crossing p- and n-type nanowires or by lithographically defining distinct p- and n-type regions in nanotubes, although both strategies limit device complexity. In the planar semiconductor industry, intricate n- and p-type and more generally compositionally modulated (that is, superlattice) structures are used to enable versatile electronic and photonic functions. Here we demonstrate the synthesis of semiconductor nanowire superlattices from group III-V and group IV materials. (The superlattices are created within the nanowires by repeated modulation of the vapour-phase semiconductor reactants during growth of the wires.) Compositionally modulated superlattices consisting of 2 to 21 layers of GaAs and GaP have been prepared. Furthermore, n-Si/p-Si and n-InP/p-InP modulation doped nanowires have been synthesized. Single-nanowire photoluminescence, electrical transport and electroluminescence measurements show the unique photonic and electronic properties of these nanowire superlattices, and suggest potential applications ranging from nano-barcodes to polarized nanoscale LEDs.     

电镀镍金板无法键合金线的失效分析

印制电路板(Printed Circuit Board,PCB)广泛用于各类电子产品,以实现元器件间的电气导通和信号传输.引线键合起着封装内部芯片和外部管脚以及芯片间的电气连接作用,且工艺简单成本较低,广为采用.现介绍了1批电镀镍金PCB板表面无法键合金线的失效概况,然后通过三维体式显微镜、扫描电镜(SEM)、能谱分析(EDS)等宏微观测试方法和表征手段,对失效样品进行了系统分析,发现金线键合不上是由镀金层太薄且硬脆引起,对预防相应失效提出了解决的建议.     

碳纳米管光伏器件的研究进展

碳纳米管（CNT）具有优异的电学特性和独特的一维纳米结构，是制作光伏器件的良好材料.文中介绍了单根/多根CNT光伏器件、CNT薄膜光伏器件、CNT 有机光伏器件、杯状叠层CNT光伏器件等典型CNT光伏器件，并阐述了这些CNT光伏器件的结构及特性，分析了CNT在器件中的作用.     

Two-substrate vertical deposition for stable colloidal crystal chips

By combining vertical deposition with micromolding in capillaries method, we have demonstrated the two-substrate vertical deposition, an alternative and versatile procedure for fabricating high-quality stable colloidal crystal chips. Apparent bright colors, special UV-vis spectra, scanning electron microscopy (SEM) and atomic force microscopy (AFM) images all prove that high-quality colloidal crystal structures are formed in between the two substrates.During the two-substrate vertical deposition for colloidal crystal chips, capillary force and evaporation of the medium are critical to the formation of the colloidal crystals; while the confinement in between two close substrates makes the resulting colloidal crystal chips more stable. Due to the excellent stability, these colloidal crystal chips can be used to construct some composite optical devices via a simpler and more flexible process. Meanwhile, they can also be further used as the templates for ordered multiporous materials.     

Y型分叉碳纳米管的研究

Y型结构碳纳米管几何结构独特,具有典型的应用价值,可作为网络状增强组分应用于高性能复合材料中,在三极管纳米电子器件等领域发挥作用,因此引起众多研究者的关注.用电弧法制备了Y型碳纳米管,研究了它的形成机理和制备工艺参数,并利用透射电子显微镜(TEM)、原子力显微镜(AFM)和电子能谱(EDS)考察了它们的形貌和结构特征.研究结果显示,Y型碳管在其拐点处存在催化剂粒子,由于催化剂的作用,在体系内产生了七元环拓扑缺陷,进而形成Y型分叉结构.Y型碳管结构的形态与制备参数有关,催化剂含量愈高,形成Y型和其它奇异结构碳管愈多.     

Reversible electromechanical characteristics of carbon nanotubes under local-probe manipulation

The effects of mechanical deformation on the electrical properties of carbon nanotubes are of interest given the practical potential of nanotubes in electromechanical devices, and they have been studied using both theoretical and experimental approaches. One recent experiment used the tip of an atomic force microscope (AFM) to manipulate multi-walled nanotubes, revealing that changes in the sample resistance were small unless the nanotubes fractured or the metal-tube contacts were perturbed. But it remains unclear how mechanical deformation affects the intrinsic electrical properties of nanotubes. Here we report an experimental and theoretical elucidation of the electromechanical characteristics of individual single-walled carbon nanotubes (SWNTs) under local-probe manipulation. We use AFM tips to deflect suspended SWNTs reversibly, without changing the contact resistance; in situ electrical measurements reveal that the conductance of an SWNT sample can be reduced by two orders of magnitude when deformed by an AFM tip. Our tight-binding simulations indicate that this effect is owing to the formation of local sp3 bonds caused by the mechanical pushing action of the tip.     

DNA芯片--世纪之交的技术革命

ＤＮＡ 芯片是以硅、玻璃等材料作固相载片,应用计算机、半导体、光化学合成等微加工技术,将数十万个寡核苷酸片段高密度集成于１ｃｍ ２ 左右的芯片上．它可以作为微反应进行ＰＣＲ、ＬＣＲ等反应,尤其是芯片上的探针列阵可用于检测人类遗传病的基因变异,加速人类基因组的研究及为临床医学开辟新路．ＤＮＡ 芯片有望成为研究生命信息的一种新的有力工具．