Impact of strain on the optical fingerprint of monolayer transition metal dichalcogenides

Abstract

Strain presents a straightforward tool to tune electronic properties of atomically thin nanomaterials that are highly sensitive to lattice deformations. While the influence of strain on the electronic band structure has been intensively studied, there are only few works on its impact on optical properties of monolayer transition metal dichalcogenides (TMDs). Combining microscopic theory based on Wannier and Bloch equations with nearestneighbor tight-binding approximation, we present an analytical view on how uni- and biaxial strain influences the optical fingerprint of TMDs including their excitonic binding energy, oscillator strength, optical selection rules, and the radiative broadening of excitonic resonances. We show that the impact of strain can be reduced to changes in the lattice structure (geometric effect) and in the orbital functions (overlap effect). In particular, we demonstrate that the valley-selective optical selection rule is softened in the case of uniaxial strain due to the introduced asymmetry in the lattice structure. Furthermore, we reveal a considerable increase of the radiative dephasing due to strain-induced changes in the optical matrix element and the excitonic wave functions.

References in corpus (5)

• Valley polarization in MoS2 monolayers by optical pumping
• Tightly bound excitons in monolayer WSe2
• Quasiparticle band structures and optical properties of strained monolayer MoS2 and WS2
• Phonon Softening and Direct to Indirect Bandgap Crossover in Strained Single Layer MoSe2
• Many-body and spin-orbit effects on direct-indirect band gap transition of strained monolayer MoS${}_2$ and WS${}_2$

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• Dielectric nano-antennas for strain engineering in atomically thin two-dimensional semiconductors
• Generalized scaling law for exciton binding energy in two-dimensional materials
• Impact of atomic reconstruction on optical spectra of twisted TMD homobilayers
• Engineering robust strain transmission in van der Waals heterostructure devices
• Tensile strain induced brightening of momentum forbidden dark exciton in WS${}_2$
• Criteria for deterministic single-photon emission in two-dimensional atomic crystals
• Microscopic theory of nonlinear phase space filling in polaritonic lattices
• Biaxial strain tuning of exciton energy and polarization in monolayer WS2
• Two dimensional semiconductors: optical and electronic properties