Unified Description of the Optical Phonon Modes in N-Layer MoTe2
DSpace at IIT Bombay
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Title |
Unified Description of the Optical Phonon Modes in N-Layer MoTe2
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Creator |
FROEHLICHER, G
LORCHAT, E FERNIQUE, F JOSHI, C MOLINA-SANCHEZ, A WIRTZ, L BERCIAUD, S |
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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 |
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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.
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Publisher |
AMER CHEMICAL SOC
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Date |
2016-01-15T06:15:26Z
2016-01-15T06:15:26Z 2015 |
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Type |
Article
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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 |
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Language |
en
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