The coupling of the electron system to lattice vibrations and their time-dependent control and detection provide unique insight into the nonequilibrium physics of semiconductors. Here, we investigate the ultrafast transient response of semiconducting monolayer 2H-MoTe2 encapsulated with hBN using broadband optical pump–probe microscopy. The sub-40 fs pump pulse triggers extremely intense and long-lived coherent oscillations in the spectral region of the A′ and B′ exciton resonances, up to ∼20% of the maximum transient signal, due to the displacive excitation of the out-of-plane A1g phonon. Ab initio calculations reveal a dramatic rearrangement of the optical absorption of monolayer MoTe2 induced by an out-of-plane stretching and compression of the crystal lattice, consistent with an A1g -type oscillation. Our results highlight the extreme sensitivity of the optical properties of monolayer TMDs to small structural modifications and their manipulation with light.
C. J. Sayers, A. Genco, C. Trovatello, S. Dal Conte, V. O. Khaustov, J. Cervantes-Villanueva, D. Sangalli, A. Molina-Sanchez, C. Coletti, C. Gadermaier, and G. Cerullo, Strong Coupling of Coherent Phonons to Excitons in Semiconducting Monolayer MoTe2, Nano Lett. 2023, 23, 20, 9235–9242 (2023)
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© 2023 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0.