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

Abstract

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 E2g1 phonon modes followed the Raman polarization selection rules. In contrast, the polarization-angle dependence of the E2g1 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 E2g1 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 E2g1 phonon in the multilayer region is attributed to stacking disorder between MoS2 layers.