Intervalley scattering in MoS${}_2$ imaged by two-photon photoemission with a high-harmonic probe

Abstract

We report on the direct mapping of electron transfer in the momentum space of bulk MoS${}_2$ by means of time- and angle-resolved two-photon photoemission with a high-harmonic probe. For this purpose, we have combined a high-repetition rate high-harmonic source with tunable femtosecond pump pulses and a 3D ($k_x,k_y,E$) electron spectrometer. We show that optical excitation slightly above the A exciton resonance results in an immediate occupation of the conduction band at $\overline{K}$ followed by an ultrafast transfer ($<50$~fs) to the conduction band minimum at $\overline{\Sigma }$. Both signals, at $\overline{K}$ and $\overline{\Sigma }$, do not vanish over the observed period of 400~fs. The technique described here enables direct access to the charge transfer dynamics in $k$-space and allows the study of decay times and decay channels in various systems with dependence on the excess energy or helicity of the excitation.

arXiv comment11 pages, 4 figures

References in corpus (16)

• Atomically thin MoS2: A new direct-gap semiconductor
• Van der Waals heterostructures
• Single-Layer MoS2 Phototransistors
• Mobility engineering and metal-insulator transition in monolayer MoS2
• Optical Spectrum of MoS${}_2$: Many-body Effects and Diversity of Exciton States
• Band structure of MoS_2, MoSe_2, and alpha-MoTe_2: Angle-resolved photoelectron spectroscopy and ab-initio calculations
• Hidden spin polarization in inversion-symmetric bulk crystals
• Direct view on the ultrafast carrier dynamics in graphene
• Direct observation of spin-polarised bulk bands in an inversion-symmetric semiconductor
• Momentum-dependent snapshots of a melting charge density wave
• Observation of Ultrafast Free Carrier Dynamics in Single Layer MoS${}_2$
• Electronic structure, spin-orbit coupling, and interlayer interaction in bulk MoS2 and WS2
• Charge carrier dynamics in bulk MoS2 crystal studied by transient absorption microscopy
• Tracking primary thermalization events in graphene with photoemission at extreme timescales
• High Intrinsic Mobility and Ultrafast Carrier Dynamics in Multilayer Metal Dichalcogenide MoS2
• Nonequilibrium Carrier Dynamics in Transition Metal Dichalcogenide Semiconductors

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