First principles study of structural, electronic and optical properties of orthorhombic phase Ni-doped Bi2Se3 using density functional theory

Structural, electronic and optical properties of nickel (Ni) doped bismuth selenide (Bi2Se3) in orthorhombic phase was studied via first principles approach using density functional theory (DFT). A generalized gradient approximation (GGA) for Perdew-Burke-Ernzerhof for solids (GGA-PBEsol) was employed as functional of exchange-correlation. The structural parameters of pure Bi2Se3 are in good agreement with the previous experimental and theoretical data. Calculated electronic properties of pure Bi2Se3 such as band gap is in agreement with the experiments. The effect of Ni has reduced the band gap of Bi2Se3 from 0.99 eV to 0.32 eV. Optical properties such as dielectric function was also calculated together with other optical properties and a comprehensive comparison was made. It was found that Ni-doping has contributed a better dielectric function, increased refractive index, and decreased extinction coefficient that provides many useful supports for technological applications. However, Ni-doping has caused slight deterioration of the absorption coefficient and the rise of a loss function.