Polarization-dependent anisotropic Raman response of CVD-grown vertically stacked MoS₂ layers

We report on the polarized Raman scattering results of vertically stacked few-layer MoS₂ grown by chemical vapor deposition. Results of monolayer MoS₂ showed that the polarization-angle-resolved intensity profiles of both out-of-plane A_1g and in-plane E¹ _2g phonon modes followed the Raman polarization selection rules. In contrast, the polarization-angle dependence of the E¹ _2g phonon intensity in the multilayer region showed a deviation from the polarization selection rules, whereas that of the A_1g phonon intensity remained unchanged regardless of the layer number. Furthermore, the polarization anisotropy of the E¹ _2g phonon intensity increased with an increase in layer number. The vertically stacked MoS₂ multilayers had oblique, deformed edge boundaries that were not parallel to the basal monolayer edge, suggesting the presence of slight interlayer twisting and/or sliding between neighboring layers. Therefore, we suggest that the polarization-dependent anisotropic behavior of the E¹ _2g phonon in the multilayer region is attributed to stacking disorder between MoS₂ layers.