Visualization of dark excitons in semiconductor monolayers for high-sensitivity strain sensing

Abstract

Transition metal dichalcogenides (TMDs) are layered materials that have a semiconducting phase with many advantageous optoelectronic properties, including tightly bound excitons and spin-valley locking. In Tungsten-based TMDs, spin and momentum forbidden transitions give rise to dark excitons that typically are optically inaccessible but represent the lowest excitonic states of the system. Dark excitons can deeply affect transport, dynamics and coherence of bright excitons, hampering device performance. Therefore, it is crucial to create conditions in which these excitonic states can be visualized and controlled. Here, we show that compressive strain in WS2 enables phonon scattering of photoexcited electrons between momentum valleys, enhancing the formation of dark intervalley excitons. We show that the emission and spectral properties of momentum-forbidden excitons are accessible and strongly depend on the local strain environment that modifies the band alignment. This mechanism is further exploited for strain sensing in two-dimensional semiconductors revealing a gauge factor exceeding 10^4.

References in corpus (23)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Control of valley polarization in monolayer MoS2 by optical helicity
• Excitons in atomically thin transition metal dichalcogenides
• Elastic properties of freely suspended MoS2 nanosheets
• Large-scale quantum-emitter arrays in atomically thin semiconductors
• Deterministic strain-induced arrays of quantum emitters in a two-dimensional semiconductor
• Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides
• Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2
• Intrinsic Transport Properties of Electrons and Holes in Monolayer Transition Metal Dichalcogenides
• Acoustic phonon limited mobility in two-dimensional semiconductors: Deformation potential and piezoelectric scattering in monolayer MoS2 from first principles
• Directly visualizing the momentum forbidden dark excitons and their dynamics in atomically thin semiconductors
• Dark excitons in transition metal dichalcogenides
• Valley Phonons and Exciton Complexes in a Monolayer Semiconductor
• Phonon-assisted Photoluminescence from Dark Excitons in Monolayers of Transition Metal Dichalcogenides
• Emerging Photoluminescence from the Dark-Exciton Phonon Replica in Monolayer WSe2
• Strain-tunable orbital, spin-orbit, and optical properties of monolayer transition-metal dichalcogenides
• Strain engineering in single-, bi- and tri-layer MoS2, MoSe2, WS2 and WSe2
• Impact of strain on the excitonic linewidth in transition metal dichalcogenides
• Probing dark exciton navigation through a local strain landscape in a WSe${}_2$ monolayer
• Nonclassical Exciton Diffusion in Monolayer WSe2
• Excitonic complexes in $n$-doped WS${}_2$ monolayer
• Dark-exciton based strain sensing in transition metal dichalcogenides
• Direct probing of phonon mode specific electron-phonon scatterings in two-dimensional semiconductor transition metal dichalcogenides: Symmetry and Berry phase

Cited by in corpus (6)

• Interaction-driven transport of dark excitons in 2D semiconductors with phonon-mediated optical readout
• Tensile strain induced brightening of momentum forbidden dark exciton in WS${}_2$
• Two dimensional semiconductors: optical and electronic properties
• Influence of Dynamical Floquet Spectrum on the Plasmon Excitations and Exchange Energy of tilted monolayer 1T${}^{\prime }$MoS${}_2$
• Strain-induced exciton mobility in layered WS2 from first principles
• Emergence of new optical resonances in single-layer transition metal dichalcogenides with atomic-size phase patterns