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arXiv · 2512.09783

Mechanical Detuning of Exciton-Phonon Resonance in WS2

Álvaro Rodríguez·Carmen Munuera·Andres Castellanos-Gomez
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Abstract

Controlling resonant Raman scattering in two-dimensional semiconductors typically requires tuning the excitation energy to match excitonic transitions. Here we show that mechanical deformation can achieve the same effect without changing the laser energy, enabling a controlled transition between resonant and non-resonant Raman scattering at fixed excitation. By applying biaxial strain up to 1.3% to WS2, the B exciton is red-shifted by 180 meV. This large excitonic shift leads to a pronounced collapse of the double-resonant 2LA(M) mode under 532 nm excitation, quantitatively described by a resonance model formulated in terms of the B exciton energy. Meanwhile, first-order phonons remain narrow and reversible, confirming elastic deformation and efficient strain transfer. These results establish mechanical strain as an effective knob to control exciton-phonon mediated light-matter interactions. They enable deterministic and reversible tuning of resonance-enhanced Raman scattering and excitonic optical responses in layered semiconductors.

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Álvaro Rodríguez, Carmen Munuera, Andres Castellanos-Gomez. 2025-12-10. Mechanical Detuning of Exciton-Phonon Resonance in WS2. https://doi.org/10.1021/acsphotonics.5c03089

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