纳米晶体管研究进展

纳米晶体管是尺寸小于100nm的晶体管。纳米晶体管大大提高了晶体管、集成电路、计算机以及其他电子器件的性能。Intel公司正在进行50nm以下Si晶体管的研制,他们研制的THzCMOS平面晶体管克服了小尺度给纳米晶体管制作所带来的诸如栅极漏电流、关闭状态下的漏电流、电阻增加以及开通电压升高等一系列困难。目前,Si纳米晶体管的小型化并没有停止的趋势,除此以外,碳纳米管晶体管、Mott转变纳米晶体管以及有机纳米晶体管都在受到大力关注和正在研制之中。     

基于肖特基接触的碳纳米管场效应晶体管

由于具有独特的一维纳米结构、稳定的化学特性和优异的电学性能,单壁碳纳米管被认为是制作高性能电子器件以及下一代纳米电路的理想材料,作为新型基础电子元件的一种,碳纳米管场效应晶体管一直是研究的热点。研究了一种基于非对称肖特基接触的碳纳米管场效应晶体管,金属钯与金属铝分别作为电极材料制作出的碳纳米管场效应晶体管分别表现出p型和n型的导通特性,当这两种金属分别作为源、漏电极制作在单根半导体性单壁碳纳米管的两端时,便构成了非对称肖特基接触结构碳纳米管场效应晶体管。器件表现出了优良的整流特性,整流比达到103,在栅压的调控下,正向电流的开关比接近103。     

基于碳纳米管的场效应晶体管研究获新进展

在国家自然科学基金委、科技部、中科院的大力支持下，化学所有机固体院重点实验室等在基于碳纳米管的场效应晶体管研究领域取得新进展。基于碳纳米管的电子器件是纳米电子学的热点研究课题之一，具有重要的科学意义和应用前景。场效应晶体管是利用改变电场来控制固体材料导电能力的有源器件，是微电子学中最重要的单元器件之一。     

基于Pd/SWNT/Al结构的场效应晶体管的研究

碳纳米管因具有良好的物理机械性能而得到广泛的研究,其最重要的应用之一是构建场效应晶体管(FET).文章提出并研究了一种非对称接触的单壁碳纳米管场效应晶体管(SWNT-FET),并对其电学特性进行了表征.在该器件中,SWNT被作为FET的沟道,两种不同功函数的金属被用来与SWNT形成肖特基接触;SWNT一端与低功函数金属Al形成源极,另一端与高功函数金属Pd形成漏极.该类器件可应用于下一代纳米集成电路中.     

碳纳米管在典型微纳电子器件中的应用进展

优异的电学、热学、机械特性和化学稳定性以及独特的一维纳米结构,使碳纳米管(CNT)成为应用在微纳电子器件中的理想功能材料。与传统电子器件相比,CNT微纳电子器件性能更为优异。本文综述了近年来制备和改进基于CNT的场发射器、晶体管和传感器的研究进展。经过特定方法的组装和处理,可使CNT场发射器获得低阀值电压、高发射电流和发射电流稳定等优异性能,使CNT晶体管具有高迁移率、大跨导和大电流开闭比,可提高各种CNT传感器的灵敏度。     

准一维碳纳米管的含时输运性质的研究(英文)

提出了一种数值模拟方法,用于研究准一维碳纳米管系统的含时输运特性。基于非平衡格林函数,通过提出的方法,对准一维碳纳米管系统的电学性质进行数值计算。计算结果显示:当同一连续方波作用于电极时,电极与碳纳米管之间的耦合能越大,电流的最初上升值越大,弛豫时间越短;当输入电压为低频正弦信号,响应电流曲线变得不规则。本仿真结果有利于对纳米材料电学性质的评估,为纳米电子器件的设计和优化提供理论指导。     

一种简便的制备碳纳米管装填Fe纳米丝的方法

自1991年Ijima发现碳纳米管以来，人们对碳纳米管及其复合物的关注方兴未艾。在碳纳米管中装填金属纳米丝，可能会改变它们的电学性质，增强金属纳米丝的机械强度和化学稳定性，这种复合结构可用作纳米电子器件中的导线、纳米电极及探针，特别是有希望在磁记录材料上得到应用，开展这方面的研究有重要的意义。到目前为止，已有一些将金属装入碳纳米管的物理和化学方法。     

全球首款全碳纳米管计算机

正2013年9月25日,美国斯坦福大学的研究人员在《自然》杂志发表论文[1],宣布其在下一代电子器件领域取得突破性进展,研制出了世界首款完全基于碳纳米管场效应晶体管的计算机原型。论文指出,这一成就具有两项关键贡献:首先,实现了碳纳米管电路的制造工艺。其次,验证了碳纳米管计算机的可行性。碳纳米管晶体管自被发明以来,一直存在两个阻碍其规模化应用的难题,其一,碳纳米管很难被排     

飞秒激光诱导多壁碳纳米管与金属电极连接的实验研究

碳纳米管因其独特的电学特性及一维纳米结构成为取代硅材料的重要电子材料,利用碳纳米管制备的微纳米电子器件具有尺寸小、响应快、功耗低等优点,但如何实现碳纳米管与金属电极之间可靠及有效的连接一直是构筑碳纳米管电子器件的难点与重点。针对该问题,首先,采用飞秒脉冲激光辐照技术诱导多壁碳纳米管与不同金属电极(金、镍)产生不同形式的连接;然后,通过测试互连前后多壁碳纳米管与金属电极之间的伏安特性曲线和界面接触电阻验证了该连接方法的可重复性及有效性,为后续大规模制备高性能碳纳米管场效应晶体管提供了一定的基础。     

碳纳米管随机网络场效应晶体管电学性能分析

利用电子束蒸发技术在Si衬底形成Au电极作为底栅电极,在底栅电极上生长SiO₂薄膜。超声分散CVD法合成的商用单壁碳纳米管(SWCNTs),使用匀胶机将单壁碳纳米管悬浮液均匀旋涂于SiO₂薄膜上。再利用荫罩式电子束蒸发技术,在单壁碳纳米管随机网络薄膜表面制备漏源电极。该工艺过程避免了碳纳米管过多的化学接触,有效地保护了碳纳米管的性状。在室温条件下对器件电学性能进行测试和分析。使用该方法制备的单壁碳纳米管随机网络薄膜场效应晶体管,具有器件性能稳定、重复性和一致性较好等优点,并可用于构建碳纳米管逻辑电路。该方法对于研究基于碳纳米管的大规模、低成本的集成电路,具有较高的借鉴价值。     

多壁碳纳米管薄膜在THz波段的传输与偏振特性

利用化学气相沉积法制备了三种类型多个超有序排列的多壁碳纳米管薄膜样品,通过太赫兹时域光谱技术,获取相位和振幅信息,详细研究了薄膜在太赫兹波段的传输特性。结果表明:超有序多壁碳纳米管薄膜在纳米管轴向方向与垂直于轴向方向表现出明显的光、电各向异性特性;测试的介电常数实部为负,虚部为正,证实了制备的薄膜具有金属性;薄膜具有的各向异性为研究其偏振特性提供了直接证据,随着薄膜厚度的增加,偏振度和消光比增加,其9 m厚的自由薄膜度可以获得99%的偏振度。研究结果对开展超有序多壁碳纳米管薄膜在太赫兹偏振器、调制器与光开关等领域的研究有重要指导意义。     

Highly Conductive Redox Protein–Carbon Nanotube Complex for Biosensing Applications

The integration of redox proteins with nanomaterials has attracted much interest in the past years, and metallic single‐walled carbon nanotubes (SWNTs) have been introduced as efficient electrical wires to connect biomolecules to metal electrodes in advanced nano‐biodevices. Besides preserving biofunctionality, the protein–nanotube connection should ensure appropriate molecular orientation, flexibility, and efficient, reproducible electrical conduction. In this respect, yeast cytochrome c redox proteins are connected to gold electrodes through lying‐down functionalized metallic SWNTs. Immobilization of cytochromes to nanotubes is obtained via covalent bonding between the exposed protein thiols and maleimide‐terminated functional chains attached to the carbon nanotubes. A single‐molecule study performed by combining scanning probe nanoscopies ascertains that the protein topological properties are preserved upon binding and provides unprecedented current images of single proteins bound to carbon nanotubes that allow a detailed I–V characterization. Collectively, the results point out that the use as linkers of suitably functionalized metallic SWNTs results in an electrical communication between redox proteins and gold electrodes more efficient and reproducible than for proteins directly connected with metal surfaces.     

Oscillations of the band gap of single-walled carbon nanotubes in the range of very small diameters

The electronic properties of carbon nanotubes with controllable chirality indices are studied in the range of very small diameters (0.3?C2.0 nm) of semiconductor single-walled carbon nanotubes. The density functional theory (DFT) in the local density approximation (LDA) (DFT-LDA) method and Gaussian and TubeGen software are used in the study. An unsteady oscillatory variation in the band gap is established. Such behavior is due to the small chirality indices that define the symmetry and curvature of nanotubes. It is found that, for semiconductor nanotubes with very small diameters and (0, 4) and (0, 5) chirality indices, the band structure is degenerate and this degeneracy is responsible for the metal properties and violation of the rule of the 3k classification of single-walled nanotubes according to their electrical properties.     

Replacing Copper Wires with Carbon Nanotube Wires in Electrical Transformers

Carbon nanotubes, with their unique physical properties, have the potential to outperform conventionally used electrical wiring metals. Any improvement in this area of technology would be of great importance to industry, the economy, and the environment, as the global need for electrical energy and its efficient transfer and conversion rapidly increases. Carbon nanotube fibers, which are assemblies made purely of carbon nanotubes, can uniquely be used in macroscopic electrical applications including electrical wires and devices where the operation is enabled by these conductors. This paper presents details of the working prototype of an electrical machine, a transformer, where conventional copper wires have been replaced with conducting wires made purely of carbon nanotube fibers.     

Carbon nanotubes and silver flakes filled epoxy resin for new hybrid conductive adhesives

Combining conductive micro and nanofillers is a new way to improve electrical conductivity. Micrometric silver flakes and nanometric carbon nanotubes (CNTs) exhibit high electrical conductivity. A new type of hybrid conductive adhesives filled with silver flakes and carbon nanotubes (DWCNTs or MWCNTs) were investigated. High electrical conductivity is measured as well as improved mechanical properties at room temperature. Small agglomerates and free MWCNTs dispersed in the silver/epoxy composites improve the electrical conductivity and a synergistic effect between MWCNTs and micro sized silver flakes is observed in hybrid composites. Glassy and rubbery storage moduli of the hybrid composites increase with increasing silver loading at fixed CNTs volume fraction. High value of the storage modulus, measured in DWCNTs/μAg hybrid composites at rubbery state, is caused by strong agglomeration of DWCNTs bundles. The electrical and mechanical properties are consistent with the morphologies of the hybrid composites characterized by SEM.     

On the temperature dependent electrical resistivity of CNT layers in view of Variable Range Hopping models

Thin films of randomly dispersed carbon nanotubes make highly promising material for transparent electrode applications. Knowing and understanding the nature of the films conductivity is crucial for improvement of their electrical properties. In the paper we present our investigation of electrical conductivity of single wall and multiwalled carbon nanotube (SWCNT and MWCNT) thin films deposited on a polymeric substrate by Langmuir-Schaefer technique. The conductivity of the films is consistent with the Variable Range Hopping (VRH) model. Moreover, remarkable differences in SWCNT and MWCNT films conductivity are observed. A significant impact of the thin film annealing and its temperature history on the conductivity properties is shown. The study of the carbon nanotubes layers transferred on polymeric substrate was undertaken in view of the films possible applications in flexible transparent electrodes. The VRH conductivity in carbon nanotube Langmuir-Schaefer layer is reported for the first time.     

Electrical Properties of Carbon Nanotube Based Fibers and Their Future Use in Electrical Wiring

The production of continuous fibers made purely of carbon nanotubes has paved the way for new macro‐scale applications which utilize the superior properties of individual carbon nanotubes. These wire‐like macroscopic assemblies of carbon nanotubes were recognized to have a potential to be used in electrical wiring. Carbon nanotube wiring may be extremely light and mechanically stronger and more efficient in transferring high frequency signals than any conventional conducting material, being cost‐effective simultaneously. However, transfer of the unique properties of individual CNTs to the macro‐scale proves to be quite challenging. This Feature Article gives an overview of the potential of using carbon nanotube fibers as next generation wiring, state of the art developments in this field, and goals to be achieved before carbon nanotubes may be transformed into competitive products.     

Supertubes [carbon nanotubes]

This paper discusses the different characteristics of carbon nanotubes which make them ideal for a number of potential applications ranging from ultrathin, breathable, waterproof fabrics to bright, rugged flat-panel displays for televisions and computer monitors. Carbon nanotubes can be far stronger than steel, lighter than aluminum and more conductive than copper. The electrical properties of carbon nanotubes are so attractive that researchers are already eyeing them as replacements for silicon circuits and are being considered as a most promising technology that may someday pick up where conventional CMOS devices lead off. As the dimensions of silicon CMOS transistors continue to shrink well into the next decade, problems resulting from increasing power dissipation, leakage currents, and variations in device parameters will continue to rise. If all goes well, carbon nanotube electronics will be poised to take over before the problems encountered by the continual downscaling of silicon CMOS dimensions become insurmountable.     

碳纳米管/石墨烯复合结构的第一性原理计算

为了研究碳纳米管/石墨烯复合结构的电学性质,采用密度泛函理论(DFT)下的第一性原理,对四种T型复合结构进行了几何结构优化,分析了该复合结构的结合能,能带结构,电子态密度,Mulliken电荷分布及功函数.结果表明复合结构均表现出半导体性质,其稳定性及电子结构取决于碳纳米管类型和复合结构的连接方式,而且复合材料的功函数...     

A Versatile,Molecular Engineering Approach to Simultaneously Enhanced,Multifunctional Carbon‐Nanotube– Polymer Composites

Single‐walled carbon nanotubes (SWNTs) are recognized as the ultimate carbon fibers for high‐performance, multifunctional composites. The remarkable multifunctional properties of pristine SWNTs have proven, however, difficult to harness simultaneously in polymer composites, a problem that arises largely because of the smooth surface of the carbon nanotubes (i.e., sidewalls), which is incompatible with most solvents and polymers, and leads to a poor dispersion of SWNTs in polymer matrices, and weak SWNT–polymer adhesion. Although covalently functionalized carbon nanotubes are excellent reinforcements for mechanically strong composites, they are usually less attractive fillers for multifunctional composites, because the covalent functionalization of nanotube sidewalls can considerably alter, or even destroy, the nanotubes' desirable intrinsic properties. We report for the first time that the molecular engineering of the interface between non‐covalently functionalized SWNTs and the surrounding polymer matrix is crucial for achieving the dramatic and simultaneous enhancement in mechanical and electrical properties of SWNT–polymer composites. We demonstrate that the molecularly designed interface of SWNT–matrix polymer leads to multifunctional SWNT–polymer composite films stronger than pure aluminum, but with only half the density of aluminum, while concurrently providing electroconductivity and room‐temperature solution processability.