Khazaei Mohammad, Lee Sang Uck, Pichierri Fabio, Kawazoe Yoshiyuki
Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
ACS Nano. 2008 May;2(5):939-43. doi: 10.1021/nn7004377.
Using first-principles calculations we propose a new approach for the design of functional units obtained by interconnecting carbon nanotubes (CNTs) with different numbers of zinc layers. The theoretical investigations on electron transport properties of the resulting 1D heterojunctions containing CNTs with same or different chiralities (i.e., metallic or semiconducting) and one, two, or three zinc layers illustrate that the junctions with two semiconducting CNTs show semiconducting I-V characteristics while the junctions with two different CNT electrodes (metallic and semiconducting) show rectifying diode properties. The remarkable features emerging from this study is that the zinc layers behave as a momentum filter (near the Fermi energy the Bloch states having the same orbital character as the molecular states conduct well) when they are inserted within metallic CNT electrodes thereby providing 1D heterojunctions that can act as a wire-like, negative differential resistance (NDR), or varistor-type nanoscale device. Our results prove the idea that it is possible to design specific heterojunctions, which can select a conducting channel between two electrodes. Also, it is worth mentioning that in this study for the first time we have designed a nanoscale device with the characteristics of a varistor.
通过第一性原理计算，我们提出了一种设计功能单元的新方法，该功能单元通过将具有不同锌层数的碳纳米管（CNT）相互连接而获得。对所得包含相同或不同手性（即金属或半导体）的碳纳米管以及一层、两层或三层锌层的一维异质结的电子输运性质的理论研究表明，具有两个半导体碳纳米管的异质结表现出半导体的电流-电压（I-V）特性，而具有两个不同碳纳米管电极（金属和半导体）的异质结则表现出整流二极管特性。这项研究中出现的显著特征是，当锌层插入金属碳纳米管电极内时，它们充当动量滤波器（在费米能量附近，具有与分子态相同轨道特征的布洛赫态传导良好），从而提供可作为线状、负微分电阻（NDR）或变阻器型纳米级器件的一维异质结。我们的结果证明了这样一种观点，即有可能设计出特定的异质结，其可以在两个电极之间选择一个导电通道。此外，值得一提的是，在本研究中我们首次设计了一种具有变阻器特性的纳米级器件。
