Coupled Valence Carrier and Core-Exciton Dynamics in WS${}_2$ Probed by Few-Femtosecond Extreme Ultraviolet Transient Absorption Spectroscopy

Abstract

Few-femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy, performed with optical 500-1000 nm supercontinuum and broadband XUV pulses (30-50 eV), simultaneously probes dynamics of photoexcited carriers in WS${}_2$ at the W O${}_3$ edge (37-45 eV) and carrier-induced modifications of core-exciton absorption at the W N${}_{6,7}$ edge (32-37 eV). Access to continuous core-to-conduction band absorption features and discrete core-exciton transitions in the same XUV spectral region in a semiconductor provides a novel means to investigate the effect of carrier excitation on core-exciton dynamics. The core-level transient absorption spectra, measured with either pulse arriving first to explore both core-level and valence carrier dynamics, reveal that core-exciton transitions are strongly influenced by the photoexcited carriers. A $1.2\pm 0.3$ ps hole-phonon relaxation time and a $3.1\pm 0.4$ ps carrier recombination time are extracted from the XUV transient absorption spectra from the core-to-conduction band transitions at the W O${}_3$ edge. Global fitting of the transient absorption signal at the W N${}_{6,7}$ edge yields $\sim 10$ fs coherence lifetimes of core-exciton states and reveals that the photoexcited carriers, which alter the electronic screening and band filling, are the dominant contributor to the spectral modifications of core-excitons and direct field-induced changes play a minor role. This work provides a first look at the modulations of core-exciton states by photoexcited carriers and advances our understanding of carrier dynamics in metal dichalcogenides.

arXiv comment18 pages, 13 figures

References in corpus (19)

• Exciton Binding Energy and Nonhydrogenic Rydberg Series in Monolayer WS2
• Extraordinary room-temperature photoluminescence in WS2 monolayers
• Observation of Moiré Excitons in WSe2/WS2 Heterostructure Superlattices
• Probing Excitonic Dark States in Single-layer Tungsten Disulfide
• Valley-selective optical Stark effect in monolayer WS2
• Lorentz meets Fano spectral line shapes: A universal phase and its laser control
• Imaging moiré flat bands in 3D reconstructed WSe2/WS2 superlattices
• Direct and Simultaneous Observation of Ultrafast Electron and Hole Dynamics in Germanium
• A Room Temperature Polariton Light-Emitting Diode Based on Monolayer WS2
• Momentum-Resolved View of Electron-Phonon Coupling in Multilayer WSe${}_2$
• Zeeman Splitting and Inverted Polarization of Biexciton Emission in Monolayer WS2
• Unravelling the intertwined atomic and bulk nature of localised excitons by attosecond spectroscopy
• Attosecond time-domain measurement of core-excitonic decay in magnesium oxide
• Hot Phonon and Carrier Relaxation in Si(100) Determined by Transient Extreme Ultraviolet Spectroscopy
• Time-resolved four-wave-mixing spectroscopy for inner-valence transitions
• Carrier-Specific Femtosecond XUV Transient Absorption of PbI2 Reveals Ultrafast Nonradiative Recombination
• Differentiating Photoexcited Carrier and Phonon Dynamics in the Δ, L, and Γ Valleys of Si(100) with Transient Extreme Ultraviolet Spectroscopy
• Source noise suppression in attosecond transient absorption spectroscopy by edge-pixel referencing
• $\Gamma$-valley assisted intervalley scattering on monolayer and bilayer WS2 revealed by time-resolved Kerr rotation spectroscopy

Cited by in corpus (2)

• Ultrafast electron localization and screening in a transition metal dichalcogenide
• Carrier and Phonon Dynamics in Multilayer WSe2 captured by Extreme Ultraviolet Transient Absorption Spectroscopy