First-principles calculations were performed in order to study the role of F in O vacancies in HfO2 and HfSiO4. It was found that F behaved completely differently in the 2 dielectrics. The F could completely passivate the gap states of HfO2, but had no effect upon the passivation of O vacancies in HfSiO4. This was considered to furnish a possible explanation for a controversy which surrounded the leakage current in electronic devices.

Comparative Study of Passivation Mechanism of Oxygen Vacancy with Fluorine in HfO2 and HfSiO4. Q.Q.Sun, W.Chen, S.J.Ding, M.Xu, H.L.Lu, H.C.Lindh-Rengifo, D.W.Zhang, L.K.Wang: Applied Physics Letters, 2007, 90[14], 142904 (3pp)