Electrically Tunable Localized versus Delocalized Intralayer Moire Excitons and Trions in a Twisted MoS2 Bilayer

Moire superlattice (mSL)-induced sub-bands in twisted van der Waals homo- and heterostructures govern their optical and electrical properties, rendering additional degrees of freedom such as twist angle. Here, we demonstrate the moire superlattice effects on the intralayer excitons and trions in a twisted bilayer of MoS2 of H-type stacking at marginal twist angles. We identify the emissions from localized and delocalized sub-bands of intralayer moire excitons and show their electrical modulation by the corresponding trion formation. The electrical control of the oscillator strength of the moire excitons also results in the strong tunability of resonant Raman scattering. We find that the gate-induced doping significantly modulates the electronic moire potential; however, leaves the excitonic moire confinement unaltered. This effect, coupled with variable moire trap filling by tuning the optical excitation density, allows us to delineate the different phases of localized and delocalized moire trions. We demonstrate that the moire excitons exhibit strong valley coherence that changes in a striking nonmonotonic W-shape with gating due to motional narrowing. These observations from the simultaneous electrostatic control of quasiparticle-dependent moire potential will lead to exciting effects of tunable many-body phenomena in moire superlattices.

Automated summary

This study demonstrates the effects of Moire superlattice on excitons and trions in a twisted bilayer of MoS2. The results show that the optical and electrical properties of the system can be controlled by the moire superlattice, providing additional degrees of freedom such as twist angle.