Double resonance Raman modes in mono- and few-layer MoTe$_2$
| Autor: | Guo, Huaihong, Yang, Teng, Yamamoto, Mahito, Zhou, Lin, Ishikawa, Ryo, Ueno, Keiji, Tsukagoshi, Kazuhito, Zhang, Zhidong, Dresselhaus, Mildred S., Saito, Riichiro |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Physical Review B 91, 205415 (2015) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.91.205415 |
| Popis: | We study the second-order Raman process of mono- and few-layer MoTe$_2$, by combining {\em ab initio} density functional perturbation calculations with experimental Raman spectroscopy using 532, 633 and 785 nm excitation lasers. The calculated electronic band structure and the density of states show that the electron-photon resonance process occurs at the high-symmetry M point in the Brillouin zone, where a strong optical absorption occurs by a logarithmic Van-Hove singularity. Double resonance Raman scattering with inter-valley electron-phonon coupling connects two of the three inequivalent M points in the Brillouin zone, giving rise to second-order Raman peaks due to the M point phonons. The predicted frequencies of the second-order Raman peaks agree with the observed peak positions that cannot be assigned in terms of a first-order process. Our study attempts to supply a basic understanding of the second-order Raman process occurring in transition metal di-chalcogenides (TMDs) and may provide additional information both on the lattice dynamics and optical processes especially for TMDs with small energy band gaps such as MoTe$_2$ or at high laser excitation energy. Comment: 10 pages, 5 figures |
| Databáze: | arXiv |
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