Eur. Phys. J. B (2018) 91: 35
https://doi.org/10.1140/epjb/e2017-80399-5

Regular Article

First- and second-order Raman scattering from MoTe₂ single crystal^★,★★

¹ Physics Department, Sapienza University of Rome, P.le Aldo Moro, 00185 Roma, Italy
² CNR-SPIN and Physics Department, Sapienza University of Rome, P.le Aldo Moro, 00185 Roma, Italy
³ CNR-IOM and Physics Department, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Roma, Italy

^a e-mail: paolo.dore@roma1.infn.it

Received: 6 July 2017
Received in final form: 27 September 2017
Published online: 12 February 2018

Abstract

We report on Raman experiments performed on a MoTe₂ single crystal. The system belongs to the wide family of transition metal dichalcogenides which includes several of the most interesting two-dimensional materials for both basic and applied physics. Measurements were performed in the standard basal plane configuration, by placing the ab plane of the crystal perpendicular to the wave vector k_i of the incident beam to explore the in-plane vibrational modes, and in the edge plane configuration with k_i perpendicular to the crystal c axis, thus mainly exciting out-of-plane modes. For both configurations we performed a polarization-dependent study of the first-order Raman components and detailed computation of the corresponding selection rules. We were thus able to provide a complete assignment of the observed first-order Raman peaks, in agreement with previous literature results. A thorough analysis of the second-order Raman bands, as observed in both basal and edge plane configurations, provides new information and allows a precise assignment of these spectral structures. In particular, we have observed and assigned Raman active modes of the M point of the Brillouin zone previously predicted by ab initio calculations but never previously measured.