Tailoring the electronic properties and optical responses in semiconductor-doped magnesium hydroxide monolayer for optoelectronic applications

Magnesium hydroxide (MH) belongs to the family of multifunctional alkali-earth metal hydroxide layered materials. It can be isolated from its layered bulk material to form a two-dimensional (2D) nanostructure, resulting in a single monolayer sheet. This work employs density functional theory (DFT) to investigate the properties of engineered wide bandgap 2D MH monolayers. The substitutional doping of group-IVA semiconducting materials from the periodic table can modify these monolayers. The impact of semiconductor doping on chemical reactivity is examined. The doping does not significantly affect the electronic bandgap. Moreover, it results in new localized electronic states appearing in the bandgap region of the electronic structure. These localized energy levels significantly improve the dielectric and optical response in the near-infrared, visible, and low-energy ultraviolet regions, a feature absent in the pure 2D MH monolayer. The 2D sheet is modeled with adequate vacuum spacing in the vertical direction to ensure the convergence of electronic properties. However, the dielectric function varies with cell volume. Therefore, we also shed light on the role of cell volume (or vacuum spacing) in calculating the intrinsic dielectric and optical responses of the doped and undoped 2D MH monolayer, comparing them with their corresponding nonintrinsic (dielectric and optical quantities with vacuum spacing) values. The light absorption in the doped materials indicates that they are suitable for low-energy light absorption, making them suitable for use in polarization filters. Thus, this study reveals the potential applications of engineered 2D MH for possible anisotropic electronics and optoelectronic applications.