Davydov Splitting, Resonance Effect and Phonon Dynamics in Chemical Vapor Deposition Grown Layered MoS₂

We present comprehensive temperature dependent Raman measurements for chemical vapor deposition grown horizontally aligned layered MoS₂in a temperature range of 4-330 K under a resonance condition. Our analysis of temperature dependent phonon frequency shift and linewidth suggests a finite role of three and four phonon anharmonic effect. We observe Davydov splitting of the out-of-plane (A₁) and in-plane (E2g1) modes for both three layer (3L) and few layer (FL) systems. The number of Davydov splitting components are found more in FL compared to 3L MoS₂, which suggests that it increases with an increasing number of layers. Further, Davydov splitting is analyzed as a function of temperature. Temperature evaluation of the Raman spectra shows that the Davydov splitting, especially forA₁mode, is very strong and well resolved at low temperature. We observe thatA₁mode shows the splitting at low temperature, whileE2g1mode is split even at room temperature, which suggests a prominent role ofA₁mode in the interlayer interaction at low temperature. Further, an almost 60-fold increase in the intensity of the phonon modes at low temperature clearly shows the temperature dependent tuning of the resonance effect.