Molecular manipulation using a tunnelling microscope

In a very short time the scanning tunnelling microscope has become an important tool in surface science, and physics in general. Its primary use has been to obtain atomic-resolution images of surfaces, but recently, efforts have been made to use it to manipulate materials as well as image them. One may now reasonably ask if it is possible to move and alter matter predictably on an atomic scale. Here we report the accomplishment of the smallest yet, purposeful, spatially localized changes in matter, effected on a graphite surface. We believe that the changes result from the pinning of individual organic molecules to the graphite. The reverse manipulation, the removal of pinned molecules, has also been demonstrated. Finally, we have evidence that we can remove a portion of a pinned molecule, effectively performing transformations on single molecules using the tunnelling microscope.     

Molecular cocrystal odyssey to unconventional electronics and photonics

Cocrystal has been discovered and studied for more than 170 years since 1844,while the applications to optoelectronics only begin in the last decade.Several gen...     

Nanometre-scale electronics with III-V compound semiconductors

For 50 years the exponential rise in the power of electronics has been fuelled by an increase in the density of silicon complementary metal-oxide-semiconductor (CMOS) transistors and improvements to their logic performance. But silicon transistor scaling is now reaching its limits, threatening to end the microelectronics revolution. Attention is turning to a family of materials that is well placed to address this problem: group III-V compound semiconductors. The outstanding electron transport properties of these materials might be central to the development of the first nanometre-scale logic transistors.     

带电胶体系统固液相变的分子动力学研究

在修正Yukawa相互作用的基础上，采用常温分子动力学方法数值研究了带电胶体系统的大离子屏蔽效应和多分散性效应对其固液边界的影响．研究结果发现，在屏蔽长度较大时，固液相变曲线出现了明显偏差．初步定性认为这种相边界偏差现象来自于系统多体效应的增强．另外，数值研究了固液相变时键接取向序参数的变化．     

Towards molecular electronics with large-area molecular junctions

Electronic transport through single molecules has been studied extensively by academic and industrial research groups. Discrete tunnel junctions, or molecular diodes, have been reported using scanning probes, break junctions, metallic crossbars and nanopores. For technological applications, molecular tunnel junctions must be reliable, stable and reproducible. The conductance per molecule, however, typically varies by many orders of magnitude. Self-assembled monolayers (SAMs) may offer a promising route to the fabrication of reliable devices, and charge transport through SAMs of alkanethiols within nanopores is well understood, with non-resonant tunnelling dominating the transport mechanism. Unfortunately, electrical shorts in SAMs are often formed upon vapour deposition of the top electrode, which limits the diameter of the nanopore diodes to about 45 nm. Here we demonstrate a method to manufacture molecular junctions with diameters up to 100 microm with high yields (> 95 per cent). The junctions show excellent stability and reproducibility, and the conductance per unit area is similar to that obtained for benchmark nanopore diodes. Our technique involves processing the molecular junctions in the holes of a lithographically patterned photoresist, and then inserting a conducting polymer interlayer between the SAM and the metal top electrode. This simple approach is potentially low-cost and could pave the way for practical molecular electronics.     

利用网络资源拓展电力电子技术课程实验教学水平

电力电子技术课程具有很强的理论性、实践性和应用性,考虑到传统电力电子实验教学中种种不足,提出一种应用网络实验平台开展实践教学的新模式,并通过实例给出具体的实现方法。作为传统实践教学的有益扩充,该方法能节省实验资源投入,实验灵活高效,具有实验的先进性和创新性,能在提高学生动手实践能力的同时有效提高学生的创新能力和工程意识。     

碳材料:新兴电子器件的未来

集成电路芯片是现代信息技术的基石。然而,硅基电子器件正在逼近其物理及设计极限,新一代非硅电子学的发展备受瞩目。碳材料家族众多同素异形体的独特性质以及碳基器件具有的更快响应速度,更低功耗及更高性能等诸多优点随着不断升级的制备技术和持续革新的器件设计正在创造着一场电子技术革命。本文基于碳材料家族中具有代表性的一维碳纳米管、二维石墨烯和三维金刚石,系统总结了其结构、特性及制备方法。同时从不同应用领域出发,列举了碳纳米管、石墨烯及金刚石的众多先进电子学应用。此外,新型全碳复合材料基于多维同素异构体复合的互补特性更加呈现出了碳材料在新一代非硅电子学应用的不可替代性。随着高质量材料制备技术、高性能器件优化设计及规模化生产的逐步完善,碳电子的未来已经到来。     

Nanotube electronics: large-scale assembly of carbon nanotubes

Nanoscale electronic devices made from carbon nanotubes, such as transistors and sensors, are much smaller and more versatile than those that rely on conventional microelectronic chips, but their development for mass production has been thwarted by difficulties in aligning and integrating the millions of nanotubes required. Inspired by biomolecular self-assembly processes, we have created chemically functionalized patterns on a surface, to which pre-grown nanotubes in solution can align themselves in huge numbers. This method allows wafer-scale fabrication of millions of carbon-nanotube circuits with single-nanotube precision, and may enable nanotube-based devices, such as computer chips and high-density sensor arrays, to be produced industrially.