Faculty Publications

Title

Observation of interlayer phonon modes in van der Waals heterostructures

Document Type

Article

Journal/Book/Conference Title

Physical Review B - Condensed Matter and Materials Physics

Volume

91

Issue

16

Abstract

We have investigated the vibrational properties of van der Waals heterostructures of monolayer transition metal dichalcogenides (TMDs), specifically MoS2/WSe2 and MoSe2/MoS2 heterobilayers and twisted MoS2 bilayers, by means of ultralow-frequency Raman spectroscopy. We discovered Raman features (at 30-40cm-1) that arise from the layer-breathing mode (LBM) vibration between the two incommensurate TMD monolayers in these structures. The LBM Raman intensity correlates strongly with the suppression of photoluminescence that arises from interlayer charge transfer. The LBM is generated only in bilayer areas with direct layer-layer contact and an atomically clean interface. Its frequency also evolves systematically with the relative orientation between the two layers. Our research demonstrates that the LBM can serve as a sensitive probe to the interface environment and interlayer interactions in van der Waals materials.

Original Publication Date

4-8-2015

DOI of published version

10.1103/PhysRevB.91.165403

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