Tuning the electronic structure of monolayer graphene/MoS2 van der Waals heterostructures via interlayer twist
Tuning the electronic structure of monolayer graphene/MoS2 van der Waals heterostructures via interlayer twist
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DOI：
10.1103/physrevb.92.201409
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发表时间：
2015-11-16
影响因子：
3.7
通讯作者：
Osgood, Richard M., Jr.
中科院分区：
文献类型：
--
作者：
Jin, Wencan;Yeh, Po-Chun;Osgood, Richard M., Jr.
我们直接测量了扭曲石墨烯/二硫化钼货车德瓦尔斯异质结构的电子结构，其中石墨烯和二硫化钼都是单层。我们使用阴极透镜显微镜和微探针角分辨光电子能谱测量图像的表面，确定扭转角，并映射这些人工异质结构的电子结构。对于单层MoS 2上的单层石墨烯，所得到的能带结构揭示了石墨烯和MoS 2电子状态之间不存在杂化。此外，异质结构中的石墨烯衍生的电子结构保持基本上完整，与两种材料之间的扭转角无关。然而，相比之下，发现与MoS 2层相关联的电子结构是扭曲角依赖性的;特别地，在MoS 2层的棒上的（γ）和棒上的（K）处的价带最大值的能量的相对差从大约0到0.2eV变化。我们的研究结果表明，单层MoS 2内的异质结构成为主要是一个间接的带隙系统的所有扭曲角，除了在30度附近。这一结果使得在由单层结构组成的货车德瓦尔斯异质结构中的潜在带隙工程成为可能。
We directly measure the electronic structure of twisted graphene/MoS2 van der Waals heterostructures, in which both graphene and MoS2 are monolayers. We use cathode lens microscopy and microprobe angle-resolved photoemission spectroscopy measurements to image the surface, determine twist angle, and map the electronic structure of these artificial heterostructures. For monolayer graphene on monolayer MoS2, the resulting band structure reveals the absence of hybridization between the graphene and MoS2 electronic states. Further, the graphene-derived electronic structure in the heterostructures remains essentially intact, irrespective of the twist angle between the two materials. In contrast, however, the electronic structure associated with the MoS2 layer is found to be twist-angle dependent; in particular, the relative difference in the energy of the valence band maximum at (Gamma) over bar and (K) over bar of the MoS2 layer varies from approximately 0 to 0.2 eV. Our results suggest that monolayer MoS2 within the heterostructure becomes predominantly an indirect band-gap system for all twist angles except in the proximity of 30 degrees. This result enables potential band-gap engineering in van der Waals heterostructures comprised of monolayer structures.