Oxygen vacancy in ZnO-wphase: pseudohybrid Hubbard density functional study.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Standard electronic structure calculations for zinc oxide (ZnO) often exhibit overhybridization between zinc 3d and oxygen 2p shells.
• The widely used LDA+U or GGA+U methods typically apply Hubbard correction only to transition metal orbitals, excluding oxygen orbitals.

Purpose of the Study:

• To investigate the electronic structure of an oxygen vacancy in ZnO using ab initio calculations.
• To explore the effects of applying Hubbard-type corrections to both zinc 3d (U_Zn-3d) and oxygen 2p (U_O-2p) orbitals.

Main Methods:

• Ab initio electronic structure calculations were performed on a ZnO supercell containing an oxygen vacancy.
• Two Hubbard-type corrections, U_Zn-3d and U_O-2p, were systematically applied and analyzed.

Main Results:

• The inclusion of U_O-2p significantly alters bulk ZnO properties, including lattice constants, charge carrier effective mass, and bandgap.
• A localized defect state associated with the oxygen vacancy was observed within the ZnO bandgap.
• This defect state shows maximal overlap with conduction band states calculated without Hubbard correction.

Conclusions:

• The U_O-2p correction is essential for accurate modeling of ZnO properties and defect states.
• Oxygen vacancies in ZnO create localized states primarily influenced by neighboring zinc atoms.
• The study highlights the importance of considering Hubbard corrections for oxygen orbitals in transition metal chalcogenides.