Effect of oxygen vacancy on the structural and electronic characteristics of crystalline Zn2SnO4

Abstract

The effects of oxygen vacancies on the atomic and electronic structures in crystalline Zn₂SnO₄ were examined by ab initio calculations using a screened hybrid density functional. The formation energy and the electronic structure indicated that the neutral oxygen vacancy was stable in the n-type region with the formation of a deep level in the bandgap. The ionization energy of the oxygen vacancy was calculated to be around 2.0 eV, which can be excited by visible photon energy. The atomic movements and the Bader charge analyses around the neutral oxygen vacancy showed that Sn played a dominant role in changing the electronic properties by forming the Sn²⁺–V_O⁰ pair, which was accompanied by a reduction of the charge state of Sn due to its multiple oxidation states. In contrast, the electronic state of Zn hardly changed, despite its more predominant atomic shifts than Sn around the oxygen vacancy.