Oxygen-related defects in amorphous HfO₂ gate dielectrics

Formation energies and electronic properties of oxygen defects in amorphous HfO₂ gate dielectrics are investigated by employing the first-principles method based on the density functional theory. We have found that the formation energy of neutral oxygen vacancy in amorphous HfO₂ distributes from 4.7 to 6.1 eV, most of which is lower than the value for cubic HfO₂, 6.0 eV. The decrease of the formation energy is due to the small coordination number of oxygen atom in the amorphous structure. It is also found that the atomic oxygen incorporation is more favorable in amorphous HfO₂ than in crystal HfO₂.