Germanene is one of the most promising two-dimensional materials beyond graphene. The electronic properties of germanene are outstanding. However, structural defects, which may appear during growth or processing, deteriorating the performance of germanene-based devices, are elusive. Here, we combine scanning tunneling microscopy/spectroscopy, Raman spectroscopy, and density functional theory calculations to investigate the defects in epitaxial ultraflat germanene on Cu(111). Three types of defects are found and their electronic properties are explored. Single germanium atom vacancy leads to three well-defined states in local density of states, whereas the mirror twin boundary induced four electronic states confirmed by theoretical calculations. Furthermore, strain induced wrinkles with enhanced electronic states occurred in ultraflat germanene. In addition, we synthesized bi- and trilayer germanene with significant different electronic properties, where a tiny band gap is opened due to the symmetry breaking.

中文翻译：

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Cu(111)上超扁平锗烯的缺陷


锗烯是除石墨烯之外最有前途的二维材料之一。锗烯的电子特性非常出色。然而，在生长或加工过程中可能出现的结构缺陷却难以捉摸，这些缺陷会降低基于锗烯的器件的性能。在这里，我们结合扫描隧道显微镜/光谱、拉曼光谱和密度泛函理论计算来研究Cu(111)上外延超平坦锗烯的缺陷。发现了三种类型的缺陷并探讨了它们的电子特性。单锗原子空位导致局域态密度中的三个明确定义的态，而镜像孪晶边界则产生了理论计算证实的四个电子态。此外，超扁平锗烯中出现了具有增强电子态的应变诱导皱纹。此外，我们合成了具有显着不同电子特性的双层和三层锗烯，其中由于对称性破缺而打开了微小的带隙。