First-Principles Study of a MoS₂-PbS van der Waals Heterostructure Inspired by Naturally Occurring Merelaniite

Vertically stacked, layered van der Waals (vdW) heterostructures offer the possibility to design materials, within a range of chemistries and structures, to possess tailored properties. Inspired by the naturally occurring mineral merelaniite, this paper studies a vdW heterostructure composed of a MoS₂ monolayer and a PbS bilayer, using density functional theory. A commensurate 2D heterostructure film and the corresponding 3D periodic bulk structure are compared. The results find such a heterostructure to be stable and possess p-type semiconducting characteristics. Due to the heterostructure's weak interlayer bonding, its carrier mobility is essentially governed by the constituent layers; the hole mobility is governed by the PbS bilayer, whereas the electron mobility is governed by the MoS₂ monolayer. Furthermore, we estimate the hole mobility to be relatively high (~10⁶ cm²V^-1s^-1), which can be useful for ultra-fast devices at the nanoscale.