Scanning tunneling microscopy and spectroscopy studies of graphite edges
Scanning tunneling microscopy and spectroscopy studies of graphite edges
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DOI：
10.1016/j.apsusc.2004.09.091
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发表时间：
2005-02-28
影响因子：
6.7
通讯作者：
Fukuyama, H
中科院分区：
文献类型：
--
作者：
Niimi, Y;Matsui, T;Fukuyama, H
我们从实验和理论上研究了剥离石墨表面单步边附近的电子局域态密度。在扫描隧道显微镜测量中，我们观察到(Root3xroot3)R30度和蜂窝超结构从锯齿形和扶手椅边缘延伸到3-4 nm。计算的依据是。密度泛函导出的非正交紧束缚模型表明，如果这两种边在真实的石墨阶梯边中相互混合，则这些超结构可以共存。在锯齿形边缘附近的扫描隧道谱测量表明，在低于费米能量20 meV的能量处，LDOS中有一个明显的峰，而在扶手椅边缘附近没有观察到这样的峰。我们的结论是，这个峰对应于理论上预测的石墨烯带的“边缘态”，因为通过第一性原理计算得到了类似的由边缘态引起的突出的LDOS峰。(C)2004爱思唯尔B.V.保留所有权利。
We studied experimentally and theoretically the electronic local density of states (LDOS) near single-step edges at the surface of exfoliated graphite. In scanning tunneling microscopy measurements, we observed the (root3 x root3)R30degrees and honeycomb superstructures extending over 3-4 nm both from the zigzag and armchair edges. Calculations based on. a density-functional-derived non-orthogonal tight-binding model show that these superstructures can coexist if the two types of edges admix each other in real graphite step edges. Scanning tunneling spectroscopy measurements near the zigzag edge reveal a clear peak in the LDOS at an energy below the Fermi energy by 20 meV No such a peak was observed near the armchair edge. We concluded that this peak corresponds to the "edge state" theoretically predicted for graphene ribbons, since a similar prominent LDOS peak due to the edge state is obtained by the first principles calculations. (C) 2004 Elsevier B.V. All rights reserved.