Interlayer couplings, Moiré patterns, and 2D electronic superlattices in MoS 2 /WSe 2 hetero-bilayers
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
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AbstractBy using direct growth, we create a rotationally aligned MoS2/WSe2 hetero-bilayer as a designer van der Waals heterostructure. With rotational alignment, the lattice mismatch leads to a periodic variation of atomic registry between individual van der Waals layers, exhibiting a Moiré pattern with a well-defined periodicity. By combining scanning tunneling microscopy/spectroscopy, transmission electron microscopy, and first-principles calculations, we investigate interlayer coupling as a function of atomic registry. We quantitatively determine the influence of interlayer coupling on the electronic structure of the hetero-bilayer at different critical points. We show that the direct gap semiconductor concept is retained in the bilayer although the valence and conduction band edges are located at different layers. We further show that the local bandgap is periodically modulated in the X-Y direction with an amplitude of ~0.15 eV, leading to the formation of a two-dimensional electronic superlattice.
CitationZhang C, Chuu C-P, Ren X, Li M-Y, Li L-J, et al. (2017) Interlayer couplings, Moiré patterns, and 2D electronic superlattices in MoS 2 /WSe 2 hetero-bilayers . Science Advances 3: e1601459. Available: http://dx.doi.org/10.1126/sciadv.1601459.
SponsorsThis research was supported by grants from the Welch Foundation (F-1672) and the U.S. NSF (DMR-1306878 and EFMA-1542747). L.-J.L. thanks the support from the King Abdullah University of Science and Technology (Saudi Arabia); the Ministry of Science and Technology and Taiwan Consortium of Emergent Crystalline Materials, Academia Sinica (Taiwan); and the Asian Office of Aerospace Research and Development (FA23861510001) (USA). The STEM work was financially supported by the National Basic Research Program of China (grant nos. 2015CB921004 and 2014CB932500) and the National Science Foundation of China (grant nos. 51472215 and 51222202). The STEM experiments used the resources in the Center of Electron Microscopy of Zhejiang University. C.-P.C. and M.-Y.C. acknowledge support from the Thematic Project at Academia Sinica and the U.S. NSF (EFMA-1542747).
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