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小木虫论坛-学术科研互动平台 » 材料区 » 微米和纳米 » 前沿热点 » 纳米材料研究动态系列报道专栏
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wshk1980

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[交流] 纳米材料研究动态系列报道专栏

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美化学家发现金纳米棒自发地将自己组装成一种环状超结构
Science Daily — Rice University chemists have discovered that tiny building blocks known as gold nanorods spontaneously assemble themselves into ring-like superstructures.
链接：http://www.SciEI.com/news/science/Chemistry/Index.html
This finding, which will be published the chemistry journal Angewandte Chemie, could potentially lead to the development of novel nanodevices like highly sensitive optical sensors, superlenses, and even invisible objects for use in the military.

“Finding new ways to assemble nano-objects into superstructures is an important task because at the nanoscale, the properties of those objects depend on the arrangement of individual building blocks,” said principal investigator Eugene Zubarev, the Norman Hackerman-Welch Young Investigator and assistant professor of chemistry at Rice.

Although ring-like assemblies have been observed in spherical nanoparticles and other symmetrical molecules, until now such structures had not been documented with rod-shaped nanostructures.

Like many nanoscale objects, gold nanorods are several billionths of a meter, or 1,000 times smaller than a human hair. Zubarev used hybrid nanorods for this research because attached to their surface are thousands of polymer molecules, which are flexible chainlike structures. The central core of the nanorods is an inorganic crystal, but the polymers attached to the outside are organic species. The combination of the inorganic and organic features resulted in a hybrid structure that proved to be critical to the study.

英文全文：http://www.sciencedaily.com/releases/2007/03/070310145606.htm

[ Last edited by popsheng on 2007-4-28 at 18:12 ]
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1楼 2007-03-22 20:49:37
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zhaokelun1975

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Scientists Hand-Make Devices Smaller than 10 Nanometers
by Laura Mgrdichian

Two intersecting nanowires (left panel) were made into a four-terminal nanogap transistor (right panel) using the TEBAL method.A research team from the University of Pennsylvania has used an electron beam to hand-carve ultra-small metal structures and devices, all with dimensions below 10 nanometers, from very thin metal sheets. Their technique could impact the development of many nanotechnologies, including nanoelectronics.

Among the structures created by the two scientists, professor Marija Drndić and graduate student Michael Fischbein, the paper's lead author, are nanodisks, nanorings, nanowires, nanoholes, and multi-terminal nano-transistors.

“Many different approaches have been undertaken to fabricate the small structures needed to probe the phenomena that take place at the nanoscale, but the most widely used and versatile techniques are limited to tens of nanometers,” Drndić said to PhysOrg.com. “Reliably and consistently fabricating devices at the sub-10-nanometer scale from the top down is generally still challenging, but our technique offers a route to this regime.”
“It’s like using a magnifying glass and sun rays to sculpt an ice cube,” says Fischbein. “However, using an electron beam instead of sun rays allows for precision on the atomic scale.”

Among its advantages over other techniques, Drndić and Fischbein say, is the fact that theirs uses the imaging beam of a transmission electron microscope, which means the structures can be imaged with atomic resolution and inspected in real time as they are created. These characteristics result in structures with smooth surfaces (atomically speaking) and high reproducibility – creating nearly identical copies of the same structure.

Additionally, the technique (referred to as TEBAL, for transmission electron beam ablation lithography) allows the contacts between a nanostructure and its leads to be resistance-free, and thus more efficient. Structures made from bottom-up techniques, i.e., assembled from smaller components, typically first need to be placed on a chip and then connected to larger circuitry. TEBAL avoids these steps.

All of the structures created using TEBAL were done so by hand, with a human user guiding the electron beam and watching each structure take shape. “Computer control should offer an even higher degree of precision than we've demonstrated and produce highly intricate patterns over a wide area,” said Fischbein.

TEBAL has many potential applications in nanoscience because it has the ability to produce a wide variety of nanostructures. Running a current through TEBAL-created nanowires could allow them to be used as nanomagnets. Or, the wires could be used to test the effects of wire shape and size on their conductivity, using both regular and superconducting wires. The tiny transistors Drndić and Fischbein created have many uses in molecular electronics. Nanogap-nanohole devices can be used in the manufacture of single-molecule detectors and provide new opportunities for DNA nanopore sequencing.

This research is described in detail in the April 17, 2007, online edition of Nano Letters.

Citation: Michael D. Fischbein and Marija Drndić, “Sub-10 nm Device Fabrication in a Transmission Electron Microscope.” Nano Lett. ASAP Article, DOI: 10.1021/nl0703626

Copyright 2007 PhysOrg.com.
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7楼2007-04-28 17:43:39
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wshk1980

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Aberration-Corrected Imaging of Active Sites on Industrial Catalyst
Nanoparticle

Lionel Cervera Gontard, Lan-Yun Chang, Crispin J. D. Hetherington, Angus I. Kirkland,
Dogan Ozkaya, and Rafal E. Dunin-Borkowski

Angew. Chem. Int. Ed. 2007, 46, 1 – 4

http://www3.interscience.wiley.c ... /114199478/PDFSTART
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2楼2007-03-24 14:00:24
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wshk1980

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3楼2007-03-29 16:27:40
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zhaokelun1975

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IBM将摩尔定律推进到三维时代


赛迪网2007年4月27日讯    日前，IBM宣布在制造环境中实现了一种突破性的芯片堆叠技术，此举为制造三维芯片扫清了障碍，摩尔定律也将因此而突破原来预期的极限。这种被称为“穿透硅通道（through-silicon vias）”的技术可以大大缩小不同芯片组件之间的距离，从而设计出速度更快、体积更小和能耗更低的系统。

    IBM的这项突破实现了从二维芯片设计到三维芯片堆叠的转变，将传统上并排安装在硅圆片上的芯片和内存设备以堆叠的方式相互叠加在一起，最终实现了一种紧凑的组件层状结构，大大减小了芯片的体积，并提高了数据在芯片上各个功能区之间的传输速度。

    IBM半导体研发中心副总裁Lisa Su表示：“这一突破性的进展是IBM开展十多年探索研究的成果。我们可以将三维芯片从实验室走向制造生产环节，来支持各种各样的应用。”

    这种IBM新方法是依靠新的穿透硅通道技术而非长金属电线来连接目前的二维芯片，这实际上是在硅圆片上蚀刻出来的垂直连接通道，并在其中注满金属。这些通道可以使多个芯片堆叠在一起，同时支持芯片之间更大信息量的传输。

    这项工艺将信息在芯片上传输的距离缩短了1000倍，与二维芯片相比可以增加最多100倍的信息通道或路径。

    IBM已经在自己的生产线上运行使用这种穿透硅通道技术的芯片，并将在2007年下半年开始为客户提供使用这种方法制造的芯片样本，同时在2008年投入生产。这种穿透硅通道技术最早将被用于无线通信芯片领域，这些芯片将被安装在无线LAN和蜂窝应用所使用的功率放大器之中。另外，三维技术也将应用于更广泛的芯片应用领域，包括目前那些运行在IBM高性能服务器和超级计算机中的芯片，这些服务器和超级计算机支持着全球的商业活动、政府和科学研究工作。
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5楼2007-04-28 17:06:23
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