Department of Physics, University of South Florida , Tampa, Florida 33620, United States.
Nano Lett. 2015 Feb 11;15(2):1135-40. doi: 10.1021/nl504167y. Epub 2015 Jan 30.
Artificial heterostructures assembled from van der Waals materials promise to combine materials without the traditional restrictions in heterostructure-growth such as lattice matching conditions and atom interdiffusion. Simple stacking of van der Waals materials with diverse properties would thus enable the fabrication of novel materials or device structures with atomically precise interfaces. Because covalent bonding in these layered materials is limited to molecular planes and the interaction between planes are very weak, only small changes in the electronic structure are expected by stacking these materials on top of each other. Here we prepare interfaces between CVD-grown graphene and MoS2 and report the direct measurement of the electronic structure of such a van der Waals heterostructure by angle-resolved photoemission spectroscopy. While the Dirac cone of graphene remains intact and no significant charge transfer doping is detected, we observe formation of band gaps in the π-band of graphene, away from the Fermi-level, due to hybridization with states from the MoS2 substrate.
由范德华材料组装的人工异质结构有望结合材料，而无需传统异质结构生长中的限制，如晶格匹配条件和原子互扩散。通过简单地堆叠具有不同性质的范德华材料，就可以制造出具有原子级精确界面的新型材料或器件结构。由于这些层状材料中的共价键仅限于分子平面，并且平面之间的相互作用非常弱，因此通过将这些材料堆叠在一起，预计电子结构只会发生很小的变化。在这里，我们制备了 CVD 生长的石墨烯和 MoS2 之间的界面，并通过角分辨光发射谱直接测量了这种范德华异质结构的电子结构。虽然石墨烯的狄拉克锥仍然完好无损，并且没有检测到明显的电荷转移掺杂，但我们观察到由于与 MoS2 衬底的状态杂化，在远离费米能级的位置，石墨烯的π带中形成了带隙。
