Coherent Phonons in van der Waals MoSe2/WSe2 Heterobilayers

Li, Changxiu; Scherbakov, Alexey V.; Soubelet, Pedro; Samusev, Anton K.; Ruppert, Claudia; Balakrishnan, Nilanthy; Gusev, Vitalyi E.; Stier, Andreas V.; Finley, Jonathan J.; Bayer, Manfred; Akimov, Andrey V.

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 MoSe2/WSe2 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 MoSe2 and WSe2 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.

Citation

Li, C., Scherbakov, A. V., Soubelet, P., Samusev, A. K., Ruppert, C., Balakrishnan, N., …Akimov, A. V. (2023). Coherent Phonons in van der Waals MoSe2/WSe2 Heterobilayers. Nano Letters, https://doi.org/10.1021/acs.nanolett.3c02316

• Journal Article Type: Article
• Acceptance Date: Aug 16, 2023
• Online Publication Date: Aug 21, 2023
• Publication Date: Sep 13, 2023
• Deposit Date: Aug 23, 2023
• Journal: Nano Letters
• Print ISSN: 1530-6984
• Electronic ISSN: 1530-6992
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1021/acs.nanolett.3c02316
• Keywords: Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering