Based upon first-principles density-functional calculations, it was shown that F

interstitials in SiO2 behaved as negative fixed charges or as charge traps; depending

upon their positions relative to the Si/SiO2 interface. On the other hand, they

deactivated O vacancies, which were the predominant charge traps in SiO2, by

forming F-pair complexes at O sites, while a defect complex consisting of an O vacancy and a F atom remained an electrically active negative-U center. The

present model successfully explained controversial aspects of earlier experimental

analyses and suggested that correct annealing below a moderate F doping level

would lead to improved electrical properties of SiO2 by effectively deactivating the

O vacancies and F interstitials into F-pair complexes.

Mutual Deactivation of Electrically Active F Interstitials and O Vacancies into

Fluorine-Oxygen-Vacancy Complexes in SiO2. E.C.Lee, H.Ju: Physical Review B,

2009, 79[19], 193203