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 E¹_2g phonon modes followed the well-known Raman polarization selection rules. However, in thinner samples (≤ 2 ML), deviations from these rules are observed for the E¹_2g phonon intensity, whereas the A_1g phonon intensity remains the same regardless of layer number. As the number of layers decreased, the polarization anisotropy of the E¹_2g 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.