Interlayer exciton structure and moiré-localization revealed by time- and angle-resolved photoemission spectroscopy

Heterobilayers made by stacking two monolayers of transition-metal dichalcogenide semiconductors feature a moiré pattern that spatially modulates the electronic band-structure, and with it the energies of interlayer excitons (ILXs) – electron-hole pairs bound across the interlayer gap. It is thus expected to confine ILXs in the moiré potential wells. In this talk, I will present a quantitative analysis of this effect in the MoS₂/WSe₂ heterobilayer based on time- and angle-resolved photoemission spectroscopy measurements that reveal separately momentum-images of the electron and hole components of the ILX. Aided by theoretical analysis of the photoemission signatures, we extract the real-space structure of the ILX wavefunction, including both its size and its surprisingly strong center-of-mass localization by the moiré potential. This information is fundamental to understanding interactions between moiré-localized ILXs and their potential as single-photon emitters.