Low-frequency Raman signature of Ag-intercalated few-layer MoS 2

• Published in: 2d materials 2021-04, Vol.8 (2), p.25031
• Main Authors: Sheremetyeva, Natalya, Niedzielski, Drake, Tristant, Damien, Liang, Liangbo, Kerstetter, Lauren E, Mohney, Suzanne E, Meunier, Vincent
• Format: Article
• Language: English
• ISSN: 2053-1583; 2053-1583
• DOI: 10.1088/2053-1583/abdbcc

Density functional theory based calculations and experimental analysis on a limited number of real samples are performed to study how the presence of silver intercalated in the van der Waals gap of few-layer MoS 2 affects the low-frequency Raman active modes of this material. Silver is found to predominantly affect the breathing-like and shear-like vibrational modes of MoS 2 . These modes correspond to quasi-rigid movements of each individual layer with a restoring force (and, in turn, frequency) that is determined by modulations in the weak interlayer interactions. Noticeable red-shifts with increasing Ag concentration are found for all low-frequency modes. This finding indicates the potential for low-frequency vibrations as useful gauges for practical determination of silver concentration using low-frequency Raman spectroscopy. This work also describes a semi-classical linear chain model that allows to extrapolate results to a large number of layers. Further, first-principles calculations show how Raman spectroscopy can be used to characterize the quality of the two-dimensional interface between MoS 2 and a silver substrate.