Electronic and Optical Properties of Sn Doped Hexagonal BN Monolayer: A First-principles Study

In this paper, first-principles based density functional theory (DFT) calculation is applied for studying the electronic and optical properties of Tin (Sn) doped hexagonal boron nitride (hBN) monolayer. Two configurations were used for doping Sn atom in hBN monolayer. In the first structure, Boron atom (B) was replaced with Sn atom (sample 1) and in the second structure, Nitrogen (N) atom was replaced by Sn atom (sample 2). Formation energy calculation has been done on both samples and they are energetically favorable. It is observed that Sn atom substitution in hBN layer develops impurity states due to the valance bands pushing up at the Fermi energy (EF) level which results in a semi-metallic hBN monolayer. Some inter-band transitions caused by the impurity states initiate some anomalous trends in the optical properties of hBN monolayer. All the optical properties precisely, absorption coefficient, reflectivity, refractive index, dielectric function and loss function for Sn atom doped hBN structures were investigated using DFT. Pure hBN monolayer has insignificant absorption from 400 to 700 nm visible spectrum. When Sn atom is substituted, a significant value of absorption coefficient is attained in the visible wavelength range plus in the whole solar spectra in both samples. Relatively low static reflectivity is achieved in the visible spectrum because of Sn atom replacement in hBN monolayer. Other optical properties explicitly dielectric functions, refractive index and loss function show comparatively high-values in the visible spectrum.