Electronic and optical properties of W-doped SnO2 from first-principles calculations

The electronic and optical properties of W-doped SnO2 are investigated by first-principles calculations in this work. The results show that the Fermi level shifts into the conduction band and the compound exhibits n-type metallic characters with high conductivity when W atoms substitute Sn atoms. As for defect cases, oxygen vacancies increase the density of states near the Fermi level resulting in a possible increase in the conductivity of W-doped SnO2, while the Sn vacancies make the Fermi level shift into the valence band and narrow the band gap. And the formation energy analysis indicates the possibility of W dopant and related defects forming in SnO2 crystal. The W-doped SnO2 shows high optical anisotropy, and the blue-shift of optical spectra can be observed. Additionally, the increased absorption in the visible region can be expected with the presence of oxygen vacancies in the crystal.