石墨烯/硅烯纳米带中原子链的局域电子态及其调控研究

Graphene/silicene nanoribbnos have recently attracted considerable interest as two one-dimension channel new materials. Overall behaviors about all elections on the their surfaces such as conducting or semiconducting properties have extensive investigations, including the effects of impurities, defects, and electromagnetic fields. In this subject, we are interested in some the fundamental physical problems based on the fact that different carbon/silicon atoms have different positions on the surface of graphene/silicene nanoribbons. The anisotropic distributions of the electron states along the different chains on the surface of nanoribbons, such as the local diversity of electron structure and bond current between two interactional lattice sites at a chain etc, should be studied in a tight-binding Hamiltonian model. We firstly considerate two typical clean armchair-edged and zigzag-edged graphene/silicene nanoribbons, and then, it is expanded to more complicated cases in which the mixed boundary and multilayer, the electron-phonon interaction and electron-electron interaction, the effect of impurities and defects etc are reckoned. Additionally, We should also considerate how to manipulate the electron states at different lattice sites by using electromagnetic fields. By employing Green's function, we should theoretically investigate how to probe the above-mentioned rules about the chain-distribution of the local electron states on the surface of nanoribbons and distinguish types of naonribbons in the scanning tunneling microscopy (STM) experiments. Next, based on above the difference of distributions and their manipulations, we should research some new applications in the quantum transport systems. In our investigation, some new quantum behaviors and rules on nano-electronics level may be revealed; overall behaviors such as conducting or semiconducting properties of the graphene/silicene nanoribbons should be explained by the local features such as distribution of the electron sates at different lattice site; application channels of two typical materials may be increased and expanded in the future nanotechnology.

石墨烯/硅烯纳米带是最近颇受关注的准一维体系,人们已经对其表面上所有电子的整体性质及其受杂质、缺陷、外场等因素的影响进行了广泛研究。本项目研究因纳米带表面各格点位置的差异性而导致的一些基本物理问题。拟采用紧束缚近似格点模型，研究纳米带表面电子态在不同碳/硅原子链上的局域分布规律。先从理想的纳米带入手，逐步扩展到考虑计入边缘形貌(如混合边缘与吸附)、纳米带层数、电声相互作用、电子库仑相互作用、掺杂、缺陷等因素的影响，以及电、磁场对上述情况局域电子态的调控作用。在此基础上，拟采用格林函数方法，进一步研究如何依据电子态链分布规律对纳米带类型进行理论预测的方法，并在各种量子输运体系中寻求这种链分布局域电子态规律带来的新效应和新器件功能。相关研究能获得石墨烯/硅烯纳米带电子结构与输运性质更完整的知识，展现两种材料在纳米电子学与自旋电子学领域的一些新量子现象和新概念，拓宽在纳米技术中的应用。

石墨烯/硅烯纳米带是最近颇受关注的准一维体系,人们已经对其表面上所有电子的整体性质及其受杂质、缺陷、外场等因素的影响进行了广泛研究。本项目中，我们在北京大学马中水教授的指导下,采用紧束缚近似格点模型，研究了石墨烯/硅烯纳米带表面电子态在不同原子链上的局域分布规律,得到了一系列有趣的性质，现总结如下。. 我们借助双STM模型，研究了扶手椅石墨烯纳米带中电子原子链传输性质及其杂质调控，发现金属扶手椅边缘纳米带中存在着一系列彼此独立的并行电子传输通道，并且每个通道可以用一个嵌入杂质来实现其关闭、开启、导通。该成果显示金属扶手椅石墨烯纳米条带作为多通道材料可能在未来的纳米技术中有潜在的应用。. 研究了双层AA耦合的扶手椅石墨烯纳米带的电子态分布及其电场调控，发现该体系的能谱结构和电子态局域分布具有明显的尺寸效应，而且可以通过电场轻易调控这些性质。“3p”规律仅仅适用窄带， “3j”规律不适用宽的(3p+2)-条带，这完全不同于单层石墨烯。而且，“3p”和“3j”规律可以通过垂直电场来调控。. 研究了石墨烯片对单Kondo量子点双电极系统的电子输运的调控性质。发现当固定石墨烯片的Dirac point 在量子点双电极系统的费米能级上时，调节石墨烯片与量子点之间的耦合，量子点双电极系统中的Kondo resonance 会显著增强，这会大大增加Kondo resonance 的抗偏压能力。. 研究了扶手椅边缘硅烯纳米带的电子态原子链分布及其电场调控。发现扶手椅边缘硅烯纳米带中，也存在着类石墨烯电子态的“3j”规律。这个“3j” 规律可以通过垂直电场来调节。而且，当条带的边界被钝化，或者条带上存在少量结构缺陷，“3j”规律依然存在。 . 研究了锯齿边缘硅烯纳米带的电子态原子链分布及其局域磁性杂质的影响。发现体系的边缘态对分布在奇数链上的杂质非常敏感，但对分布在偶数链上的杂质不敏感。 而且，通过在边界上掺磁性杂质，一个从拓扑绝缘体到自旋自辩半导体的量子相变可以被实现。 . 以上研究，为2D器件的设计提供了有价值的理论支撑。