The effects of La incorporation into HfO2 dielectrics were studied using first-principles total energy calculations. The author's computational result clearly showed that the formation energy of a neutral O vacancy (VO0) in the vicinity of substitutional La atoms at Hf sites was 0.7eV larger than that in pure HfO2, indicating that the concentration of VO0 was drastically reduced by La incorporation. This effect was understood to be caused by the decrease in the local dielectric constant around La atoms due to the strong ionic character of the La–O bond compared to the Hf–O bond.

Suppression of Oxygen Vacancy Formation in Hf-Based High-K Dielectrics by Lanthanum Incorporation. N.Umezawa, K.Shiraishi, S.Sugino, A.Tachibana, K.Ohmori, K.Kakushima, H.Iwai, T.Chikyow, T.Ohno, Y.Nara, K.Yamada: Applied Physics Letters, 2007, 91[13], 132904