Graphene/hexagonal boron nitride/graphene nanopore for electrical detection of single molecules
Graphene/hexagonal boron nitride/graphene nanopore for electrical detection of single molecules
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DOI：
10.1038/am.2014.29
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发表时间：
2014-06-01
影响因子：
9.7
通讯作者：
Kawai, Tomoji
中科院分区：
文献类型：
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作者：
He, Yuhui;Tsutsui, Makusu;Kawai, Tomoji
石墨烯纳米孔器件自提出以来，在实现单分子检测目标方面取得了巨大进展。然而，在石墨烯上制备纳米精度电极的一个核心挑战仍未解决。在这里，我们从理论上展示了石墨烯/六方BN (h-BN)/石墨烯结构的可行性，其中顶层石墨烯层作为一个电接触，底层作为另一个电接触。基于量子化学/非平衡格林函数的研究，我们给出了清晰的物理图像，为什么上述非均质层的ABC堆叠会导致顶部和底部石墨烯电极的良好绝缘。另一方面，当目标分子在纳米孔内时，即使在纳米孔内有更多的h-BN层，通过h-BN介电介质的背景电导率也不会继续降低。该分子的存在通过量子干涉增强了h-BN介电介质的垂直透射。我们采用单能级分子模型，并定量地表明，所讨论的效应可以用作分子电导的强大信号放大器，从而将单分子的可测量性提高了3-4个数量级。
Graphene nanopore device, since its proposal, has witnessed tremendous progress toward the goal of single-molecule detection. However, one central challenge of preparing electrodes with nanometer precision on the graphene remains unsolved. Here we show theoretically the feasibility of graphene/hexagonal BN (h-BN)/graphene structure where top graphene layer acts as one electrical contact while the bottom layer as the other. Based on quantum chemistry/nonequilibrium Green's function investigation, we give clear physical pictures why ABC stacking of the above heterogeneous layers results in excellent insulating of the top and bottom graphene electrodes. On the other hand, when the target molecule is inside the nanopore the background conductance through the h-BN dielectric will not keep decreasing even though more layers of h-BN are inside the nanopore. The mechanism is illustrated as that the presence of the molecule will enhance the vertical transmission through the h-BN dielectric via quantum interference. We employ a single-level molecule model, and show quantitatively that the discussed effect can be utilized as a powerful signal amplifier for the molecule conductance, thus enhancing the measurability of single molecules by 3-4 orders.