Strong Coupling of Coherent Phonons to Excitons in Semiconducting Monolayer MoTe<sub>2</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 37751559.
- Also identified by DOI 10.1021/acs.nanolett.3c01936 and PMC identifier 10603802.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
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 2<i>H</i>-MoTe<sub>2</sub> encapsulated with <i>h</i>BN 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 <i>A</i><sub>1g</sub> phonon. Ab initio calculations reveal a dramatic rearrangement of the optical absorption of monolayer MoTe<sub>2</sub> induced by an out-of-plane stretching and compression of the crystal lattice, consistent with an <i>A</i><sub>1g</sub> -type oscillation. Our results highlight the extreme sensitivity of the optical properties of monolayer TMDs to small structural modifications and their manipulation with light.