Breathing modes in few-layer MoTe${}_2$ activated by h-BN encapsulation

Abstract

The encapsulation of few-layer transition metal dichalcogenides (TMDs) in hexagonal boron nitride (h-BN) is known to improve significantly their optical and electronic properties. However, it may be expected that the h-BN encapsulation may affect also vibration properties of TMDs due to an atomically flat surface of h-BN layers. In order to study its effect on interlayer interactions in few-layer TMDs, we investigate low-energy Raman scattering spectra of bi- and trilayer MoTe${}_2$. Surprisingly, three breathing modes are observed in the Raman spectra of the structures deposited on or encapsulated in h-BN as compared to a single breathing mode for the flakes deposited on a SiO${}_2$/Si substrate. The shear mode is not affected by changing the MoTe${}_2$ environment. The emerged structure of breathing modes is ascribed to the apparent interaction between the MoTe${}_2$ layer and the bottom h-BN flake. The structure becomes visible due to a high-quality surface of the former flake. Consequently, the observed triple structure of breathing modes originates from the combination modes due to interlayer and layer-substrate interactions. Our results confirm that the h-BN encapsulation affects substantially vibration properties of layered materials.

arXiv comment10 pages, 9 figures

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Cited by in corpus (4)

• Exposing the trion's fine structure by controlling the carrier concentration in hBN-encapsulated MoS${}_2$
• The optical response of artificially twisted MoS${}_2$ bilayers
• Coherent Modulation of Two-Dimensional Moiré States with On-Chip THz Waves
• Heteroepitaxial growth of high optical quality, wafer-scale van der Waals heterostrucutres