Breathing modes in few-layer MoTe2 activated by h-BN encapsulation

Breathing modes in few-layer MoTe2 activated by h-BN encapsulation

WoS Article

The encapsulation of few-layer transition metal dichalcogenides (TMDs) in hexagonal boron nitride (h-BN) is known to significantly improve their optical and electronic properties. However, it may be expected that the h-BN encapsulation may also affect the 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 MoTe2. 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 SiO2/Si substrate. The shear mode is not affected by changing the MoTe2 environment. The emerged structure of breathing modes is ascribed to the apparent interaction between the MoTe2 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 substantially affects the vibration properties of layered materials. Published under license by AIP Publishing.

The encapsulation of few-layer transition metal dichalcogenides (TMDs) in hexagonal boron nitride (h-BN) is known to significantly improve their optical and electronic properties. However, it may be expected that the h-BN encapsulation may also affect the 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 MoTe2. 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 SiO2/Si substrate. The shear mode is not affected by changing the MoTe2 environment. The emerged structure of breathing modes is ascribed to the apparent interaction between the MoTe2 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 substantially affects the vibration properties of layered materials. Published under license by AIP Publishing.

MOS2

MOS2

GRZESZCZYK, M.; MOLAS, M.; BARTOŠ, M.; NOGAJEWSKI, K.; POTEMSKI, M.; BABINSKI, A.

2021

11.05.2020

AMER INST PHYSICS

MELVILLE

1077-3118

Applied Physics Letters

116

19

United States of America

191601-1

191601-5

5

https://aip.scitation.org/doi/10.1063/1.5128048