Anharmonic phonon scattering study of 2H–MoTe2 crystal by Raman spectroscopy

Investigation of the anharmonic phonon effects in 2H–MoTe2 crystal is crucial, not only for understanding its phonon-mediated heat transport but also for developing MoTe2-based functional devices with high performance. Here, through in-depth temperature-dependent Raman spectroscopy studies over a wide temperature from 80 to 680 K, the nonlinear frequency shift and linewidth broadening have been observed for both out-of-plane A1g and in-plane E12g modes, which are associated with the phonon decay mechanisms. For the A1g mode, the integration of thermal expansion, three- and four-phonon scattering can describe the experimental data well. While for the E12g mode, the analysis including three-phonon and four-phonon processes is enough. Moreover, it is confirmed that the E12g mode has stronger anharmonicity than that of A1g. The calculations on phonon dispersions and phonon density of states guarantee the viability of possible symmetric and asymmetric phonon scattering channels. Therefore, our temperature-dependent Raman studies and the first-principles calculations jointly shed deep insight into the phonon-phonon interactions in 2H–MoTe2.