Tensile strain induced brightening of momentum forbidden dark exciton in WS${}_2$

Abstract

Transition-metal dichalcogenides (TMDs) host tightly bound quasi-particles called excitons. Based on spin and momentum selection rules, these excitons can be either optically bright or dark. In tungsten-based TMDs, momentum-forbidden dark exciton is the energy ground state and therefore it strongly affect the emission properties. In this work, we brighten the momentum forbidden dark exciton by placing WS${}_2$ on top of nanotextured substrates which put the WS${}_2$ layer under tensile strain, modifying electronic bandstructure. This enables phonon assisted scattering of exciton between momentum valleys, thereby brightening momentum forbidden dark excitons. Our results will pave the way to design ultrasensitive strain sensing devices based on TMDs.

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Cited by in corpus (3)

• Phonon-induced modification of polaritonic Rabi oscillations in the presence of the dark excitonic condensate
• Effects of Reduced Interlayer Interactions on the K-point Excitons of MoS${}_2$ Nanoscrolls
• Unconventional bright ground-state excitons in monolayer TiI${}_2$ from first-principles calculations