Band Alignment and Minigaps in Monolayer MoS2-Graphene van der Waals Heterostructures
Band Alignment and Minigaps in Monolayer MoS2-Graphene van der Waals Heterostructures
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DOI：
10.1021/acs.nanolett.6b00609
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发表时间：
2016-07-01
期刊：
影响因子：
10.8
通讯作者：
Ouerghi, Abdelkarim
中科院分区：
文献类型：
--
作者：
Pierucci, Debora;Henck, Hugo;Ouerghi, Abdelkarim
二维层状二硫化钼具有很高的光敏性，这是当体积尺寸减小到单个单层时，其间接向直接带隙转变的结果。本文对二硫化钼和石墨烯单层间形成的范德华异质结构的能带取向和相对论性质进行了详尽的研究。通过微拉曼光谱、高分辨率x射线光发射光谱（HRXPS）和扫描高分辨率透射电子显微镜（STEM/HRTEM）对mos2 -石墨烯界面进行了表征。此外，利用角分辨光谱学（ARPES）直接测定了MoS2/石墨烯范德华异质结构单层的能带结构，揭示了界面上低能电子动力学的基本特征，如掺杂、费米速度、杂化和带偏移。我们发现，在接近费米能级时，石墨烯表现出一个坚固的、几乎完美的、无间隙的、n掺杂的狄拉克锥，并且没有检测到从MoS2到石墨烯的明显电荷转移掺杂。然而，石墨烯能带结构的修饰发生在相当大的结合能下，因为可以观察到几个小带隙的打开。这些由二硫化钼和石墨烯层晶格叠加产生的小带隙施加了超周期电位。
Two-dimensional layered MoS2 shows great potential for nanoelectronic and optoelectronic devices due to its high photosensitivity, which is the result of its indirect to direct band gap transition when the bulk dimension is reduced to a single monolayer. Here, we present an exhaustive study of the band alignment and relativistic properties of a van der Waals heterostructure formed between single layers of MoS2 and graphene. A sharp, high-quality MoS2-graphene interface was obtained and characterized by micro Raman spectroscopy, high-resolution X-ray photoemission spectroscopy (HRXPS), and scanning high-resolution transmission electron microscopy (STEM/HRTEM). Moreover, direct band structure determination of the MoS2/graphene van der Waals heterostructure monolayer was carried out using angle-resolved photoemission spectroscopy (ARPES), shedding light on essential features such as doping, Fermi velocity, hybridization, and band-offset of the low energy electronic dynamics found at the interface. We show that, close to the Fermi level, graphene exhibits a robust, almost perfect, gapless, and n-doped Dirac cone and no significant charge transfer doping is detected from MoS2 to graphene. However, modification of the graphene band structure occurs at rather larger binding energies, as the opening of several miniband-gaps is observed. These miniband-gaps resulting from the overlay of MoS2 and the graphene layer lattice impose a superperiodic potential.