Electrical control of intralayer moiré excitons and trions in a twisted bilayer of MoS₂

Moiré superlattices (mSLs) in twisted bilayers (tBLs) induce multiple sub-bands for the quasiparticles. We experimentally demonstrate the modulation of mSL-induced intralayer excitons and trions in a MoS₂-tBL with dual gating using near-0⁰ twisted samples in H-type stacking. We attribute the formation of intralayer trions to the carriers injected at the indirect band minima. While the spatial modulation of excitonic bandgap remains constant with gating, the variation in moiré potential for individual carriers tunes their corresponding localization and thereby modulates the formation of trions. We present the conceptual model and the corresponding experimental evidence for the localized and delocalized phases of both moiré excitons and trions using different levels of gating and optical excitation. We observe that the moiré excitons also exhibit strong valley coherence that changes in a striking W-shape with gating under near-resonant excitation. We further demonstrate the electrical tunability of moiré exciton-resonant Raman scattering due to the modulation of the oscillator strength of the moiré excitons. Such an electrical control of various optical properties of MoS₂-tBL offers numerous possibilities of designing photonic and valleytronic devices with mSLs.