Raman Modes of MoS2 Used as Fingerprint of van der Waals Interactions in 2-D Crystal-Based Heterostructures

• Published in: ACS nano Vol. 8; no. 10; pp. 9914 - 9924
• Main Authors: Zhou, Kai-Ge, Withers, Freddie, Cao, Yang, Hu, Sheng, Yu, Geliang, Casiraghi, Cinzia
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 28.10.2014
• Subjects: strain; 2D crystals; van der Waals interaction; heterostructures; Raman spectroscopy; MoS2
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn5042703

In this work, we use Raman spectroscopy as a nondestructive and rapid technique for probing the van der Waals (vdW) forces acting between two atomically thin crystals, where one is a transition metal dichalcogenide (TMDC). In this work, MoS2 is used as a Raman probe: we show that its two Raman-active phonon modes can provide information on the interaction between the two crystals. In particular, the in-plane vibration (E2g 1) provides information on the in-plane strain, while the out-of-plane mode (A1g) gives evidence for the quality of the interfacial contact. We show that a vdW contact with MoS2 is characterized by a blue shift of +2 cm–1 of the A1g peak. In the case of a MoS2/graphene heterostructure, the vdW contact is also characterized by a shift of +14 cm–1 of the 2D peak of graphene. Our approach offers a very simple, nondestructive, and fast method to characterize the quality of the interface of heterostructures containing atomically thick TMDC crystals.