The determination of band alignments and defect levels was demonstrated for the technologically relevant Si–SiO2–HfO2 gate stack. The proposed scheme, which combines first-principles molecular dynamics for model generation and hybrid density functionals for electronic-structure calculations, yields band offsets in close agreement with experiment. Charge transition and pinning levels associated with O vacancies were aligned with respect to the silicon band edges. The vacancies were shown to preferentially reside in the amorphous transition layer, consistent with experimental observations of Fermi-level pinning.

Band Alignments and Defect Levels in Si–HfO2 Gate Stacks - Oxygen Vacancy and Fermi-Level Pinning. P.Broqvist, A.Alkauskas, A.Pasquarello: Applied Physics Letters, 2008, 92[13], 132911