Department of Physics, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore.
J Am Chem Soc. 2010 Aug 25;132(33):11481-6. doi: 10.1021/ja909531c.
Long, stable, and free-standing linear atomic carbon wires (carbon chains) have been carved out from graphene recently [Meyer et al. Nature (London) 2008, 454, 319; Jin et al. Phys. Rev. Lett. 2009, 102, 205501]. They can be considered as extremely narrow graphene nanoribbons or extremely thin carbon nanotubes. It might even be possible to make use of high-strength and identical (without chirality) carbon wires as a transport channel or on-chip interconnects for field-effect transistors. Here we investigate electron transport properties of linear atomic carbon wire-graphene junctions by combining nonequilibrium Green's function with density functional theory. For short wires, linear ballistic transport is observed in wires consisting of odd numbers of carbon atoms but not in those consisting of even numbers of carbon atoms. For wires longer than 2.1 nm as fabricated above, however, the ballistic conductance of carbon wire-graphene junctions is independent of the structural distortion, structural imperfections, and hydrogen impurity adsorbed on the linear carbon wires, except for oxygen impurity adsorption under a low bias. As such, the epoxy groups might be the origin of experimentally observed low conductance in the carbon chain. Moreover, double-atomic carbon chains exhibit a negative differential resistance effect.
最近，人们从石墨烯中成功分离出了长程、稳定且独立的线状原子碳链（碳链）[Meyer 等人，《自然》（伦敦），2008 年，454，319；Jin 等人，《物理评论快报》，2009 年，102，205501]。它们可以被视为非常窄的石墨烯纳米带或非常细的碳纳米管。甚至有可能利用高强度且相同（无手性）的碳线作为传输通道或场效应晶体管的芯片内互连。在此，我们通过将非平衡格林函数与密度泛函理论相结合，研究了线状原子碳线-石墨烯结的电子输运性质。对于短的碳线，由奇数个碳原子组成的碳线中观察到线性弹道输运，但由偶数个碳原子组成的碳线中则没有。然而，对于上述制造的长度超过 2.1nm 的碳线，碳线-石墨烯结的弹道电导不受结构扭曲、结构缺陷以及线性碳线上吸附的氢杂质的影响，除了在低偏压下氧杂质吸附的情况。因此，环氧基团可能是实验中观察到碳链低电导的原因。此外，双原子碳链表现出负微分电阻效应。
