DIRECT DETERMINATION OF MOMENTUM-RESOLVED ELECTRON TRANSFER IN PHOTOEXCITED MoS2/WS2 VAN DER WAALS HETEROBILAYER

Liu, Fang

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https://hdl.handle.net/2142/107348 Copy

Description

Title

DIRECT DETERMINATION OF MOMENTUM-RESOLVED ELECTRON TRANSFER IN PHOTOEXCITED MoS2/WS2 VAN DER WAALS HETEROBILAYER

Author(s)

Liu, Fang

Contributor(s)

Zhu, Xiaoyang ; Li, Qiuyang

Issue Date

25-Jun-20

Keyword(s)

Plenary

Abstract

Photo-induced charge separation in transition metal dichalcogenide heterobilayers is being explored for moir\'{e} 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 \chem{WS_2/MoS_2} 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 $\sim$70 fs, followed by dynamic equilibration in K and Q valleys in $\sim$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.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

English

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http://hdl.handle.net/2142/107348

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