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.

1.
B.
Radisavljevic
,
A.
Radenovic
,
J.
Brivio
,
V.
Giacometti
, and
A.
Kis
, “
Single-layer MoS2 transistors
,”
Nat. Nanotechnol.
6
,
147
(
2011
).
2.
M. S.
Choi
,
G.-H.
Lee
,
Y.-J.
Yu
,
D.-Y.
Lee
,
S. H.
Lee
,
P.
Kim
,
J.
Hone
, and
W. J.
Yoo
, “
Controlled charge trapping by molybdenum disulphide and graphene in ultrathin heterostructured memory devices
,”
Nat. Commun.
4
,
1624
(
2013
).
3.
H.
Wang
,
L.
Yu
,
Y.-H.
Lee
,
Y.
Shi
,
A.
Hsu
,
M. L.
Chin
,
L.-J.
Li
,
M.
Dubey
,
J.
Kong
, and
T.
Palacios
, “
Integrated circuits based on bilayer MoS2 transistors
,”
Nano Lett.
12
,
4674
4680
(
2012
).
4.
S.
Zhou
and
J.
Zhao
, “
Electronic structures of germanene on MoS2: Effect of substrate and molecular adsorption
,”
J. Phys. Chem. C
120
,
21691
21698
(
2016
).
5.
O. A.
Ajayi
,
J. V.
Ardelean
,
G. D.
Shepard
,
J.
Wang
,
A.
Antony
,
T.
Taniguchi
,
K.
Watanabe
,
T. F.
Heinz
,
S.
Strauf
,
X.
Zhu
 et al, “
Approaching the intrinsic photoluminescence linewidth in transition metal dichalcogenide monolayers
,”
2D Mater.
4
,
031011
(
2017
).
6.
S.
Tongay
,
J.
Zhou
,
C.
Ataca
,
J.
Liu
,
J. S.
Kang
,
T. S.
Matthews
,
L.
You
,
J.
Li
,
J. C.
Grossman
, and
J.
Wu
, “
Broad-range modulation of light emission in two-dimensional semiconductors by molecular physisorption gating
,”
Nano Lett.
13
,
2831
2836
(
2013
).
7.
L.
Su
,
Y.
Yu
,
L.
Cao
, and
Y.
Zhang
, “
Effects of substrate type and material-substrate bonding on high-temperature behavior of monolayer WS2
,”
Nano Res.
8
,
2686
2697
(
2015
).
8.
G.-H.
Lee
,
X.
Cui
,
Y. D.
Kim
,
G.
Arefe
,
X.
Zhang
,
C.-H.
Lee
,
F.
Ye
,
K.
Watanabe
,
T.
Taniguchi
,
P.
Kim
 et al, “
Highly stable, dual-gated MoS2 transistors encapsulated by hexagonal boron nitride with gate-controllable contact, resistance, and threshold voltage
,”
ACS Nano
9
,
7019
7026
(
2015
).
9.
Y.
Cao
,
A.
Mishchenko
,
G.
Yu
,
E.
Khestanova
,
A.
Rooney
,
E.
Prestat
,
A.
Kretinin
,
P.
Blake
,
M. B.
Shalom
,
C.
Woods
 et al, “
Quality heterostructures from two-dimensional crystals unstable in air by their assembly in inert atmosphere
,”
Nano Lett.
15
,
4914
4921
(
2015
).
10.
S.
Ahn
,
G.
Kim
,
P. K.
Nayak
,
S. I.
Yoon
,
H.
Lim
,
H.-J.
Shin
, and
H. S.
Shin
, “
Prevention of transition metal dichalcogenide photodegradation by encapsulation with h-BN layers
,”
ACS Nano
10
,
8973
8979
(
2016
).
11.
F.
Cadiz
,
E.
Courtade
,
C.
Robert
,
G.
Wang
,
Y.
Shen
,
H.
Cai
,
T.
Taniguchi
,
K.
Watanabe
,
H.
Carrere
,
D.
Lagarde
 et al, “
Excitonic linewidth approaching the homogeneous limit in MoS2-based van der Waals heterostructures
,”
Phys. Rev. X
7
,
021026
(
2017
).
12.
M. R.
Molas
,
A. O.
Slobodeniuk
,
K.
Nogajewski
,
M.
Bartos
,
L.
Bala
,
A.
Babiński
,
K.
Watanabe
,
T.
Taniguchi
,
C.
Faugeras
, and
M.
Potemski
, “
Energy spectrum of two-dimensional excitons in a nonuniform dielectric medium
,”
Phys. Rev. Lett.
123
,
136801
(
2019
).
13.
X.
Cui
,
G.-H.
Lee
,
Y. D.
Kim
,
G.
Arefe
,
P. Y.
Huang
,
C.-H.
Lee
,
D. A.
Chenet
,
X.
Zhang
,
L.
Wang
,
F.
Ye
 et al, “
Multi-terminal electrical transport measurements of molybdenum disulphide using van der Waals heterostructure device platform
,” arXiv:1412.5977 (
2014
).
14.
A. S.
Mayorov
,
R. V.
Gorbachev
,
S. V.
Morozov
,
L.
Britnell
,
R.
Jalil
,
L. A.
Ponomarenko
,
P.
Blake
,
K. S.
Novoselov
,
K.
Watanabe
,
T.
Taniguchi
 et al, “
Micrometer-scale ballistic transport in encapsulated graphene at room temperature
,”
Nano Lett.
11
,
2396
2399
(
2011
).
15.
J.-U.
Lee
,
K.
Kim
, and
H.
Cheong
, “
Resonant Raman and photoluminescence spectra of suspended molybdenum disulfide
,”
2D Mater.
2
,
044003
(
2017
).
16.
G.
Froehlicher
,
E.
Lorchat
,
F.
Fernique
,
C.
Joshi
,
A.
Molina-Sánchez
,
L.
Wirtz
, and
S.
Berciaud
, “
Unified description of the optical phonon modes in N-layer MoTe2
,”
Nano Lett.
15
,
6481
6489
(
2015
).
17.
M.
Grzeszczyk
,
K.
Gołasa
,
M.
Zinkiewicz
,
K.
Nogajewski
,
M.
Molas
,
M.
Potemski
,
A.
Wysmołek
, and
A.
Babiński
, “
Raman scattering of few-layers MoTe2
,”
2D Mater.
3
,
025010
(
2016
).
18.
M.
Boukhicha
,
M.
Calandra
,
M.-A.
Measson
,
O.
Lancry
, and
A.
Shukla
, “
Anharmonic phonons in few-layer MoS2: Raman spectroscopy of ultralow energy compression and shear modes
,”
Phys. Rev. B
87
,
195316
(
2013
).
19.
Y.
Zhao
,
X.
Luo
,
H.
Li
,
J.
Zhang
,
P. T.
Araujo
,
C. K.
Gan
,
J.
Wu
,
H.
Zhang
,
S. Y.
Quek
,
M. S.
Dresselhaus
 et al, “
Interlayer breathing and shear modes in few-trilayer MoS2 and WSe2
,”
Nano Lett.
13
,
1007
1015
(
2013
).
20.
X.
Zhang
,
W.
Han
,
J.
Wu
,
S.
Milana
,
Y.
Lu
,
Q.
Li
,
A. C.
Ferrari
, and
P.
Tan
, “
Raman spectroscopy of shear and layer breathing modes in multilayer MoS2
,”
Phys. Rev. B
87
,
115413
(
2013
).
21.
S.
Kim
,
K.
Kim
,
J.-U.
Lee
, and
H.
Cheong
, “
Excitonic resonance effects and Davydov splitting in circularly polarized Raman spectra of few-layer WSe2
,”
2D Mater.
4
,
045002
(
2017
).
22.
M.-L.
Lin
and
P.-H.
Tan
, “
Ultralow-frequency Raman spectroscopy of two-dimensional materials
,”
Raman Spectroscopy of Two-Dimensional Materials
(
Springer
,
2019
), pp.
203
230
.
23.
R.
Loudon
, “
The Raman effect in crystals
,”
Adv. Phys.
13
,
423
482
(
1964
).
24.
S.-Y.
Chen
,
C.
Zheng
,
M. S.
Fuhrer
, and
J.
Yan
, “
Helicity-resolved Raman scattering of MoS2, MoSe2, WS2, and WSe2 atomic layers
,”
Nano Lett.
15
,
2526
2532
(
2015
).
25.
M.
O'Brien
,
N.
Scheuschner
,
J.
Maultzsch
,
G. S.
Duesberg
, and
N.
McEvoy
, “
Raman spectroscopy of suspended MoS2
,”
Phys. Status Solidi B
254
,
1700218
(
2017
).
26.
Y.
Zhao
,
X.
Luo
,
J.
Zhang
,
J.
Wu
,
X.
Bai
,
M.
Wang
,
J.
Jia
,
H.
Peng
,
Z.
Liu
,
S. Y.
Quek
 et al, “
Interlayer vibrational modes in few-quintuple-layer Bi2Te3 and Bi2Se3 two-dimensional crystals: Raman spectroscopy and first-principles studies
,”
Phys. Rev. B
90
,
245428
(
2014
).
27.
J.
Urban
,
M.
Baranowski
,
A.
Surrente
,
D.
Wlodarczyk
,
A.
Suchocki
,
G.
Long
,
Y.
Wang
,
L.
Klopotowski
,
N.
Wang
,
D.
Maude
 et al, “
Observation of A1g Raman mode splitting in few layer black phosphorus encapsulated with hexagonal boron nitride
,”
Nanoscale
9
,
19298
19303
(
2017
).
28.
J.
Jadczak
,
L.
Bryja
,
J.
Kutrowska-Girzycka
,
P.
Kapuściński
,
M.
Bieniek
,
Y.-S.
Huang
, and
P.
Hawrylak
, “
Room temperature multi-phonon upconversion photoluminescence in monolayer semiconductor WS2
,”
Nat. Commun.
10
,
107
(
2019
).
29.
J.-W.
Kang
,
J.-W.
Jung
,
T.
Lee
,
J. G.
Kim
, and
C.-H.
Cho
, “
Enhancing exciton diffusion in monolayer WS2 with h-BN bottom layer
,”
Phys. Rev. B
100
,
205304
(
2019
).
30.
S.-K.
Son
,
M.
Šiškins
,
C.
Mullan
,
J.
Yin
,
V. G.
Kravets
,
A.
Kozikov
,
S.
Ozdemir
,
M.
Alhazmi
,
M.
Holwill
,
K.
Watanabe
 et al, “
Graphene hot-electron light bulb: Incandescence from hBN-encapsulated graphene in air
,”
2D Mater.
5
,
011006
(
2017
).
31.
M.-L.
Lin
,
Y.
Zhou
,
J.-B.
Wu
,
X.
Cong
,
X.-L.
Liu
,
J.
Zhang
,
H.
Li
,
W.
Yao
, and
P.-H.
Tan
, “
Cross-dimensional electron–phonon coupling in van der Waals heterostructures
,”
Nat. Commun.
10
,
2419
(
2019
).

Supplementary Material

You do not currently have access to this content.