Layer-dependent Raman polarization anisotropy in MoS₂ films grown by 200 mm-scale atomic layer deposition

Molybdenum disulfide (MoS₂) exhibits remarkable electronic and optical properties, making it a candidate of interest for various electronic and optoelectronic applications. We investigate the polarization-angle dependence of individual optical phonons as a function of layer number in MoS2 using polarized Raman spectroscopy. The MoS₂ layers are grown using 200 mm-scale atomic layer deposition (ALD) on 200 mm silicon wafers. For multilayer MoS2 samples (> 3 monolayers, ML), the polarization-angle-resolved intensity profiles of both the out-of-plane A1g and in-plane E12g phonon modes followed the well-known Raman polarization selection rules. However, in thinner samples (≤ 2 ML), deviations from these rules are observed for the E12g phonon intensity, whereas the A1g phonon intensity remains the same regardless of layer number. As the number of layers decreased, the polarization anisotropy of the E12g phonon mode increased, which is likely linked to stacking disorder and misalignment between the MoS2 layers. Raman and XPS analysis further support these findings. The stoichiometry of MoS2 improved with increasing number of layers, and the oxide/Mo ratio decreased correspondingly. This study highlights the potential for 200 mm-scale integration of these 2D materials in optoelectronic devices, offering valuable insights into their structural and optical properties.