Thermodynamic Stability and Vacancy Defect Formation Energies in SrHfO3

Density functional theory based ab initio calculations are used to investigate the thermodynamic stability, defect formation energies, and electronic properties of isolated neutral and charged vacancies in SrHfO3 under various chemical environments. We find that cation defects lead the system into a hole-doped state, while oxygen vacancies yield defect levels near the conduction band minimum. The partial and full Schottky defect reaction energies and mixed electron hole conduction behavior of SrHfO3 is also evaluated. Furthermore, various cases for neutral oxygen vacancy clustering are examined for tuning the electrical properties of oxygen deficient SrHfO3. We show that ordered oxygen vacancies in HfO layers are energetically favorable and induce metallicity in this system which emerges due to charge transfer between the vacancy site and the hafnium dangling bond.