First-principles methods, based upon density functional theory, were applied to substitutional and vacancy defects in monoclinic HfO2 and α-quartz. Neutral O vacancies and substitutional Si and Hf defects in HfO2 and SiO2, respectively, were investigated. The calculations showed that, for a large range of Hf chemical potentials, Si substitutional defects were most likely to form in HfO2; leading to the formation of a silicate layer at the HfO2/Si interface. It was also found that it was energetically more favorable to form O vacancies in SiO2 than in HfO2. This implied that O-deficient HfO2, grown on top of SiO2, would consume O from the SiO2.

Comparative Study of Defect Energetics in HfO2 and SiO2. W.L.Scopel, A.J.R.da Silva, W.Orellana, A.Fazzio: Applied Physics Letters, 2004, 84[9], 1492-4