Center for the Physics of Materials and Department of Physics, McGill University , Montreal, Quebec H3A 2T8, Canada.
National Institute for Nanotechnology, National Research Council of Canada , Edmonton, Alberta T6G 2M9, Canada.
Nano Lett. 2017 Jan 11;17(1):322-327. doi: 10.1021/acs.nanolett.6b04125. Epub 2016 Dec 7.
A single line of dangling bonds (DBs) on Si(100)-2 × 1:H surface forms a perfect metallic atomic-wire. In this work, we investigate quantum transport properties of such dangling bond wires (DBWs) by a state-of-the-art first-principles technique. It is found that the conductance of the DBW can be gated by electrostatic potential and orbital overlap due to only a single DB center (DBC) within a distance of ∼16 Å from the DBW. The gating effect is more pronounced for two DBCs and especially, when these two DB "gates" are within ∼3.9 Å from each other. These effective length scales are in excellent agreement with those measured in scanning tunnelling microscope experiments. By analyzing transmission spectrum and density of states of DBC-DBW systems, with or without subsurface doping, for different length of the DBW, distance between DBCs and the DBW, and distance between DB gates, we conclude that charge transport in a DBW can be regulated to have both an on-state and an off-state using only one or two DBs.
在 Si(100)-2×1:H 表面上，一条孤立悬挂键（DB）可形成完美的金属原子线。在这项工作中，我们通过最先进的第一性原理技术研究了这种悬挂键线（DBW）的量子输运性质。研究发现，由于 DBW 附近距离约为 16Å 的位置仅有一个 DB 中心（DBC），因此 DBW 的电导可以通过静电势和轨道重叠来调控。对于两个 DBC 而言，门控效应更加明显，特别是当这两个 DB“门”彼此之间的距离约为 3.9Å 时。这些有效长度尺度与扫描隧道显微镜实验测量的结果非常吻合。通过分析具有或不具有次表面掺杂的 DBC-DBW 系统的传输谱和态密度，对于不同长度的 DBW、DBC 与 DBW 之间的距离以及 DB 门之间的距离，我们得出结论，仅使用一个或两个 DB 即可调控 DBW 中的电荷输运，使其具有导通和关断两种状态。
