Effects of Ionic Doping on the Behaviors of Oxygen Vacancies in HfO2 and ZrO2: A First Principles Study
The effects of metallic ion (Al, Ti, or La) doping in HfO2 or ZrO2 on the behaviors of oxygen vacancies (VO) such as the formation energy, density of states, and migration energy were investigated by using first principles calculations. The calculations show that, 1) the doping causes an upward shift of deep VO levels; 2) dopant radius has a weak impact on the relaxed formation energy of VO (Ef) but a significant impact on the unrelaxed Ef ; 3) the relaxed formation energy Ef of VO is remarkably reduced by trivalent ion (Al or La) doping compared to by tetravalent ion (Ti) doping; 4) Al, Ti, or La doping impacts the migration barriers of VO along different directions.