Effects of Stone-Wales defects on optical properties of silicene: DFT study

Abstract

The electronic structure and optical properties of pristine and Stone-Wales (SW) defected silicene have been investigated using the full potential linearized augmented plane wave method by density functional theory. Our investigation on the electronic band structure and density of states (DOS) of silicene revealed that due to existence of SW defects, a band gap opening of about 0.084 eV occurs, which transforms it into a semiconductor. Charge density plots confirm formation of a stronger covalent bond due to the presence of SW defect. In order to figure out optical characteristics of pristine and SW-defected silicene, some important optical parameters of these structures including real and imaginary parts of the complex dielectric function, the energy loss function, the refraction index and the reflectivity for both parallel and perpendicular polarizations were computed. Our results indicate that for perpendicular polarization in the presence of SW-defect, the value of energy loss is reduced by about 25% and also, the position of main peak in ε2zz curve is shifted by about 0.11eV towards higher energies, with respect to pristine silicene. This is compatible with band gap opening due to SW defect. The obtained results suggest SW-defected silicene as a good candidate for using in optoelectronic applications.