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

Abstract

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.

Bandgap inhomogeneity of MoS2 monolayer on epitaxial graphene bilayer in van der Waals p-n junction

“…Meanwhile, the widths of the peaks, calculated by means of a Lorentzian fitting, are barely unchanged. Based on the Raman shift values of the E 1 2g mode, we can estimate the strain induced by varying the angle between the transferred MoS 2 and graphene used as a supporting substrate using the following formula [42,43]:…”

MoS2 graphene fiber based gas sensing devices

“…Raman spectroscopy is a powerful tool for the noninvasive characterization of graphene and other 2D crystals [36][37][38][39] . The Raman spectra of the as-synthesized composites is shown in Figure 3.…”

Nanomaterials in transistors: From high-performance to thin-film applications

“…2 are becoming an attractive possibility for transistors, including the use of all 2D nanomaterials for fabricating transistors (e.g., graphene contacts, TMD channel, and hexagonal boron nitride gate dielectric) (39)(40)(41), as well as the stacking of diverse TMDs in a fashion similar to epitaxial III-V materials (42)(43)(44)(45)(46)(47)(48)(49). Work continues on understanding what governs transport at these nanomaterial heterostructure junctions.…”