The Effects of Mica Substrate on Exfoliated Molybdenum Disulfide

Molybdenum disulfide is a two-dimensional semiconductor which has recently caught a lot of attention due to its 2D behavior and unique electronic and optical properties, emerging as an analogue to graphene with the advantage of a non-zero band gap. MoS2 consists of atomically thin sheets stacked on top of each other and held together by van der Waals forces, which easily allows for interlayer cleaving. However, as-grown MoS2 usually is strongly doped. We wanted to understand the effects the substrate on which the MoS2 is exfoliated has on the crystal's properties. We carefully mechanically exfoliated MoS2 on Mica and Hafnium Oxide substrates, and took Raman and photoluminescence measurements of the exfoliated flakes ranging from 1 layer to 5 layer thicknesses. Obtained results contribute to our understanding of substrate-to-crystal interactions, in addition to the crystal lattice and optical properties of two-dimensional atomic crystals.