Direct determination of momentum resolved electron transfer in the photo-excited MoS2/WS2 van der Waals heterobilayer by TR-ARPES

Abstract

Photo-induced charge separation in transition metal dichalcogenide heterobilayers is being explored for moiré excitons, spin-valley polarization, and quantum phases of excitons/electrons. While different momentum spaces may be critically involved in charge separation dynamics, little is known directly from experiments. Here we determine momentum-resolved electron dynamics in the WS2/MoS2 heterobilayer using time and angle resolved photoemission spectroscopy (TR-ARPES). Upon photoexcitation in the K valleys, we detect electrons in M/2, M, and Q valleys/points on time scales as short as ~70 fs, followed by dynamic equilibration in K and Q valleys in ~400 fs. The interlayer charge transfer is accompanied by momentum-specific band renormalization. These findings reveal the essential role of phonon scattering, the coexistence of direct and indirect interlayer excitons, and constraints on spin-valley polarization.

arXiv comment20 pages, including SI

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Cited by in corpus (10)

• One-Dimensional Moiré Excitons in Transition-Metal Dichalcogenide Heterobilayers
• Time-domain observation of interlayer exciton formation and thermalization in a MoSe${}_2$/WSe${}_2$ heterostructure
• Exciton-Driven Renormalization of Quasiparticle Band Structure in Monolayer MoS2
• Ultrafast phonon-driven charge transfer in van der Waals heterostructures
• Twist angle dependent interlayer transfer of valley polarization from excitons to free charge carriers in WSe${}_2$/MoSe${}_2$ heterobilayers
• Excitation-Dependent High-Lying Excitonic Exchange via Interlayer Energy Transfer from Lower-to-Higher Bandgap 2D Material
• Probing excitons with time-resolved momentum microscopy
• Twistronics and moiré superlattice physics in 2D transition metal dichalcogenides
• Effect of spin-dependent tunneling and intervalley scattering in magnetic-semiconductor van der Waals heterostructures on exciton and trion polarization
• Quantum siphoning of finely spaced interlayer excitons in reconstructed MoSe2/WSe2 heterostructures