Investigations of dopants introduction in hafnia: Electronic properties, diffusion, and their role on the gate leakage current

To understand the role of dopants in the electronic properties of monoclinic hafnium dioxide, we have performed first-principles simulations using density functional theory. The structure, ionization energies, electron affinities, formation energies, and activation energies for fluorine and nitrogen atoms in different charge states are obtained. Compared to nitrogen incorporation, we observe that fluorine introduction improves more efficiently the dioxide performances, removing the band gap state induced by oxygen vacancy. Our results suggest that fluorine is the best passivant of oxygen vacancies and that its incorporation can be used to decrease the gate leakage current through hafnia-based devices. (c) 2008 American Institute of Physics.