Lu Ning, Guo Hongyan, Wang Lu, Wu Xiaojun, Zeng Xiao Cheng
Center for Nano Science and Technology, Department of Physics, Anhui Normal University, Wuhu, Anhui 241000, China.
Nanoscale. 2014 May 7;6(9):4566-71. doi: 10.1039/c4nr00783b.
We perform a comprehensive first-principles study of the electronic properties of van der Waals (vdW) trilayers via intercalating a two-dimensional (2D) monolayer (ML = BN, MoSe2, WS2, or WSe2) between a MoS2 bilayer to form various MoS2/ML/MoS2 sandwich trilayers. We find that the BN monolayer is the most effective sheet to decouple the interlayer vdW coupling of the MoS2 bilayer, and the resulting sandwich trilayer can recover the electronic structures of the MoS2 monolayer, particularly the direct-gap character. Further study of the MoS2/BN superlattices confirms the effectiveness of the BN monolayer for the decoupling of the MoS2-MoS2 interaction. In addition, the intercalation of a transition-metal dichalcogenide (TMDC) MoSe2 or WSe2 sheet makes the sandwich trilayer undergo an indirect-gap to direct-gap transition due to the newly formed heterogeneous S/Se interfaces. In contrast, the MoS2/WS2/MoS2 sandwich trilayer still retains the indirect-gap character of the MoS2 bilayer due to the lack of the heterogeneous S/Se interfaces. Moreover, the 3D superlattice of the MoS2/TMDC heterostructures also exhibits similar electronic band characters to the MoS2/TMDC/MoS2 trilayer heterostructures, albeit a slight decrease of the bandgap compared to the trilayers. Compared to the bulk MoS2, the 3D MoS2/TMDC superlattice can give rise to new and distinctive properties. Our study offers not only new insights into electronic properties of the vdW multilayer heterostructures but also guidance in designing new heterostructures to modify electronic structures of 2D TMDC crystals.
我们通过在二硫化钼双层之间插入二维（2D）单层（ML = 氮化硼、二硒化钼、二硫化钨或二硒化钨）来形成各种二硫化钼/ML/二硫化钼夹心三层结构，对范德华（vdW）三层结构的电子性质进行了全面的第一性原理研究。我们发现，氮化硼单层是解耦二硫化钼双层层间vdW耦合的最有效薄片，由此产生的夹心三层结构可以恢复二硫化钼单层的电子结构，特别是直接带隙特性。对二硫化钼/氮化硼超晶格的进一步研究证实了氮化硼单层对解耦二硫化钼 - 二硫化钼相互作用的有效性。此外，插入过渡金属二硫属化物（TMDC）二硒化钼或二硒化钨薄片会使夹心三层结构由于新形成的异质S/Se界面而经历间接带隙到直接带隙的转变。相比之下，二硫化钼/二硫化钨/二硫化钼夹心三层结构由于缺乏异质S/Se界面，仍然保留了二硫化钼双层的间接带隙特性。此外，二硫化钼/TMDC异质结构的三维超晶格也表现出与二硫化钼/TMDC/二硫化钼三层异质结构相似的电子能带特性，尽管与三层结构相比带隙略有减小。与块状二硫化钼相比，三维二硫化钼/TMDC超晶格可以产生新的独特性质。我们的研究不仅为vdW多层异质结构的电子性质提供了新的见解，也为设计新的异质结构以修饰二维TMDC晶体的电子结构提供了指导。
