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Unified Description of the Optical Phonon Modes in N-Layer MoTe2

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Title Unified Description of the Optical Phonon Modes in N-Layer MoTe2
 
Creator FROEHLICHER, G
LORCHAT, E
FERNIQUE, F
JOSHI, C
MOLINA-SANCHEZ, A
WIRTZ, L
BERCIAUD, S
 
Subject TRANSITION-METAL DICHALCOGENIDES
RAMAN-SCATTERING
MONOLAYER MOS2
BAND-GAP
CRYSTALS
WSE2
BULK
PHOTOLUMINESCENCE
ALPHA-MOTE2
TRANSISTORS
two-dimensional materials
layered crystals
transition metal dichalcogenides
MoTe2
Raman spectroscopy
interlayer breathing and shear modes
force constants
Davydov splitting
surface effects
 
Description N-layer transition metal dichalcogenides provide a unique platform to investigate the evolution of the physical properties between the bulk (three-dimensional) and monolayer (quasi-two-dimensional) limits. Here, using high-resolution microRaman spectroscopy, we report a unified experimental description of the F-point optical phonons in N-layer 2H-molybdenum ditelluride (MoTe2). We observe series of N-dependent lowfrequency interlayer shear and breathing modes (below 40 cm(-1), denoted LSM and LBM) and well-defined Davydov splittings of the mid-frequency modes (in the range 100-200 cm(-1), denoted iX and oX), which solely involve displacements of the chalcogen atoms. In contrast, the high-frequency modes (in the range 200-300 cm(-1), denoted iMX and oMX), arising from displacements of both the metal and chalcogen atoms, exhibit considerably reduced splittings. The manifold of phonon modes associated with the in-plane and out-of-plane displacements are quantitatively described by a force constant model, including interactions up to the second nearest neighbor and surface effects as fitting parameters. The splittings for the iX and oX modes observed in N-layer crystals are directly correlated to the corresponding bulk Davydov splittings between the E-2u/E-1g and B-1u/A(1g) modes, respectively, and provide a measurement of the frequencies of the bulk silent E-2u and B-1u optical phonon modes. Our analysis could readily be generalized to other layered crystals.
 
Publisher AMER CHEMICAL SOC
 
Date 2016-01-15T06:15:26Z
2016-01-15T06:15:26Z
2015
 
Type Article
 
Identifier NANO LETTERS, 15(10)6481-6489
1530-6984
1530-6992
http://dx.doi.org/10.1021/acs.nanolett.5b02683
http://dspace.library.iitb.ac.in/jspui/handle/100/17907
 
Language en