The Effect of Substrate on Vibrational Properties of Single-Layer MoS2

We report on the Raman scattering from single-layer molybdenum disulfide (MoS2) deposited on various substrates: Si/SiO2, hexagonal boron nitride (h-BN), sapphire, as well as suspended. Room temperature Raman scattering spectra are investigated under both resonant (632.8 nm) and non-resonant (514.5 nm) excitations. A rather weak influence of the substrate on the Raman scattering signal is observed. The most pronounced, although still small, is the effect of h-BN, which manifests itself in the change of energy positions of the E' and A(1)' Raman modes of single-layer MoS2. We interpret this modification as originating from van der Waals interaction between the MoS2 and h-BN layers.