Temperature-dependent Raman linewidths in transition-metal dichalcogenides

Using a semi-ab-initio theoretical method we examine the temperature-dependent linewidth of the Raman modes in bulk and monolayer transition-metal dichalcogenides (TMDs) MoS2, WS2, and MoTe2. It is found that different Raman modes show different linewidths and different temperature dependencies with respect to each other for a given sample and across different TMDs. We explain these characteristics as arising from a combination of phonon density of states, Raman mode frequency, and the relative contributions of temperature-independent mass-defect scattering and temperature-dependent intrinsic anharmonic interactions. Reported measurements for samples prepared under experimental conditions have been explained by adding frequency-dependent inhomogeneity-related background contribution to our theoretical results for the pure and homogeneous samples.