Native Point Defects in yttria as a High-Dielectric-Constant Gate Oxide Material: A First-Principles Study

Yttria (Y₂O₃) has become a promising gate oxide material to replace silicon dioxide in metal-oxide-semiconductor (MOS) devices. The characterization of native point defect in Y₂O₃ is essential to understand the behavior of the material. We used the first-principles pseudopotential method to study the electronic structure, defect structure and formation energy of native point defects in Y₂O₃. Vacancies, interstitials and antisites in their relevant charge states are considered. The dominant defect types are identified under different chemical potentials and different Fermi levels. Oxygen vacancies are the dominant defect types under high yttrium chemical potential condition. Lower yttrium chemical potential leads to oxygen interstitials and ultimately yttrium vacancies when Y₂O₃ is used as a high dielectric constant gate oxide material in MOS devices.