Calculation of point defects in rutile TiO2 by the Screened Exchange Hybrid Functional

Abstract

The formation energies of the oxygen vacancy and titanium interstitial in rutile TiO2 were calculated by the screened exchange (sX) hybrid density functional method, which gives a band gap of 3.1 eV, close to the experimental value. The O vacancy gives rise to a gap state lying 0.7 eV below the conduction band edge, whose charge density is localised around the two of three Ti atoms next to the vacancy. The Ti interstitial generates four defect states in the gap, whose unpaired electrons lie on the interstitial and the adjacent Ti 3d orbitals. The formation energy for the neutral O vacancy is 1.9 eV for the O-poor chemical potential, and similar to that of the neutral Ti interstitial, and has a lower formation energy for Ti interstitial under O-rich conditions. This indicates that both the O vacancy and Ti interstitial are relevant for oxygen deficiency in rutile TiO2 but the O vacancy will dominate under O-rich conditions. This resolves the questions about defect localisation and defect predominance in the literature.

12 pages, 12 figures

References in corpus (3)

• Localization and delocalization errors in density functional theory and implications for band-gap prediction
• Polaronic hole localization and multiple hole binding of acceptors in oxide wide-gap semiconductors
• Hybrid functional calculations of the Al impurity in silica: Hole localization and electron paramagnetic resonance parameters

Cited by in corpus (4)

• First-principles Hubbard U and Hund's J corrected approximate density-functional theory predicts an accurate fundamental gap in rutile and anatase TiO2
• A study of Ti${}_n$O${}_{2n-1}$ Magnéli phases using Density Functional Theory
• The color center singlet state of oxygen vacancies in TiO${}_2$
• Ti interstitial flows giving rutile TiO${}_2$ reoxidation process enhanced in (001) surface