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The formation of moiré superlattices in twisted van der Waals (vdW) homostructures provides a versatile platform for designing the electronic band structure of two-dimensional (2D) materials. In graphene and transition metal dichalcogenides (TMDs) moiré systems, twist angle has been shown to be a key parameter for regulating the moiré superlattice. However, the effect of the modulation of the twist angle on moiré potential and interlayer coupling has not been the subject of experimental investigation. Here, we report the observation of the modulation of moiré potential and intralayer excitons in the WS2/WS2 homostructure. By accurately adjusting the torsion angle of the homobilayers, the depth of the moiré potential can be modulated. The confinement effect of the moiré potential on the intralayer excitons was further demonstrated by the changing of temperature and valley polarization. Furthermore, we show that a detection of atomic reconstructions by the low-frequency Raman mapping to map out inhomogeneities in moiré lattices on a large scale, which endows the uniformity of interlayer coupling. Our results provide insights for an in-depth understanding of the behaviors of moiré excitons in the twisted van der Waals homostructure, and promote the study of electrical engineering and topological photonics.
The authors acknowledge support from the National Natural Science Foundation of China (No. 61775241), Hunan Provincial Science Fund for Distinguished Young Scholars (No. 2020JJ2059), the Youth Innovation Team (No. 2019012) of CSU, Hunan province key research and development project (No. 2019GK2233), and the Science and Technology Innovation Basic Research Project of Shenzhen (No. JCYJ20190806144418859). The authors are also thankful for the support of the High-Performance Complex Manufacturing Key State Lab Project, Central South University (No. ZZYJKT2020-12). Z. W. L. thanks the support from the Australian Research Council (ARC Discovery Project, DP180102976).