Coherent Phonons in van der Waals MoSe<sub>2</sub>/WSe<sub>2</sub> Heterobilayers.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 37603607.
- Also identified by DOI 10.1021/acs.nanolett.3c02316 and PMC identifier 10510584.
- 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 increasing role of two-dimensional (2D) devices requires the development of new techniques for ultrafast control of physical properties in 2D van der Waals (vdW) nanolayers. A special feature of heterobilayers assembled from vdW monolayers is femtosecond separation of photoexcited electrons and holes between the neighboring layers, resulting in the formation of Coulomb force. Using laser pulses, we generate a 0.8 THz coherent breathing mode in MoSe<sub>2</sub>/WSe<sub>2</sub> heterobilayers, which modulates the thickness of the heterobilayer and should modulate the photogenerated electric field in the vdW gap. While the phonon frequency and decay time are independent of the stacking angle between the MoSe<sub>2</sub> and WSe<sub>2</sub> monolayers, the amplitude decreases at intermediate angles, which is explained by a decrease in the photogenerated electric field between the layers. The modulation of the vdW gap by coherent phonons enables a new technology for the generation of THz radiation in 2D nanodevices with vdW heterobilayers.