Moiré Intralayer Excitons in a MoSe/MoS Heterostructure.

Spatially periodic structures with a long-range period, referred to as a moiré pattern, can be obtained in van der Waals bilayers in the presence of a small stacking angle or of lattice mismatch between the monolayers. Theoretical predictions suggest that the resulting spatially periodic variation of the band structure modifies the optical properties of both intra- and interlayer excitons of transition metal dichalcogenide heterostructures. Here, we report on the impact of the moiré pattern formed in a MoSe/MoS heterobilayer encapsulated in hexagonal boron nitride. The periodic in-plane potential results in a splitting of the MoSe exciton and trion in emission and (for the exciton) absorption spectra. The observed energy difference between the split peaks is fully consistent with theoretical predictions.