Electronic structure and optical properties of Nb-doped Sr₂TiO₄ by density function theory calculation

This paper investigates the effect of Nb doping on the electronic structure and optical properties of Sr₂TiO₄ by the first-principles calculation of plane wave ultra-soft pseudo-potential based on density functional theory (DFT). The calculated results reveal that due to the electron doping, the Fermi level shifts into conduction bands(CBs) for Sr₂Nb_xTi_1-xO₄ with x=0.125 and the system shows n-type degenerate semiconductor features. Sr₂TiO₄ exhibits optical anisotropy in its main crystal axes, and the c-axis shows the most suitable crystal growth direction for obtaining a wide transparent region. The optical transmittance is higher than 90% in the visible range for Sr₂Nb_0.125Ti_0.875O₄.