First-principles study on point defects in rutile TiO_2-x

Eunae Cho, Seungwu Han, Hyo-Shin Ahn, Kwang-Ryeol Lee, Seong Keun Kim, Cheol Seong Hwang
 

We report on our first-principles results on point defects in TiO₂ in rutile phase. Both the oxygen vacancy and titanium interstitial are considered. The size effect of supercell has been examined and the localized state associated with the oxygen vacancy turns out to be sensitive to the supercell size. We find that the oxygen vacancy does not give rise to the defect level within the energy gap while the titanium interstitial creates a localized state 0.2eV below the conduction edge that can be related to the infrared absorption data. The charge accumulation around the oxygen vacancy is attributed to the small polarization of valence bands.