Espectroscopia Raman em poucas camadas de MoTe2

Abstract

The Raman scattering of few-layered monoclinic 1T-MoTe2 is studied as a function of the excitation energy in the visible range (1.92 eV - 2.81 eV) using 16 laser lines. We observed the intensity variation of the Ag and Bg symmetry modes. The Raman excitation profiles of these modes symmetry show unusual behavior. Some Ag Raman modes are enhanced by two optical excitations located at around 1.9 eV and 2.7 eV, whereas others (and the 6Bg) are enhanced only by the 2.7 eV optical excitation. These results indicate distinct electron-phonon interaction and a possible symmetry-dependent coupling. Our observations establish a nondestructive Raman fingerprint for identifying few-layered 1T'-MoTe2 samples under different excitation lines and unveil the electron-phonon coupling in low-symmetry 2D materials.