Properties of oxygen vacancy in W-doped monoclinic HfO2 based on the first principle calculations

In this paper, density functional theory (DFT) calculations of formation energy and relaxed structure were performed in W-doped HfO₂ system, and electrical levels of oxygen vacancy and vacancy chain were also compared in monoclinic HfO₂. The simulation shows that the formation energy of threefold and fourfold oxygen vacancy in the vicinity of W atom is lower compared to dopant-free monoclinic HfO₂. However, the formation energy of oxygen vacancy far from dopant keeps the same. The dopant W atom makes the oxygen vacancy states shifted downward, and at the same time, the shallow level of 5d states may cause the electrons more easily to be thermally activated to be free conduction carriers.