The effects of lanthanum 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 oxygen vacancy (VO0) in the vicinity of substitutional La atoms at Hf sites is 0.7eV larger than that in pure HfO2, indicating that the concentration of VO0’s is drastically reduced by La incorporation. This effect is understood to be caused by the decrease in the local dielectric constant κL around La atoms due to the strong ionic character of the La–O bond compared to the Hf–O bond.

Density functional calculations are performed for lanthanum-oxide clusters in order to study the local dielectric properties of such clusters using the dielectric constant defined at local points. An increase in coordination number brings about an increase in electron population on the central lanthanum atom, leading to an increase in the local dielectric constant.

In this work, we investigate the electronic contribution to local dielectric property of La 2 O 3 and HfO 2 using cluster models. The relation between the coordinate number of metal atoms and their bonding energy shows a hint that hafnia takes the cubic structure by the incorporation of La 2 O 3 in HfO 2 . The local properties of polarizability and dielectric constant of La 2 O 3 and HfO 2 are closely similar to each other. It is considered to be one of the reasons why the incorporation of lanthanum atoms does not lower the permittivity of HfO 2 . We confirm this by the study of the local dielectric property of the HfLaO x cluster model. We compare the dielectric properties around an oxygen atom and that between the oxygen atom and a next metal atom. Our results show that the contribution to the dielectric response from the bond regions is not so large.

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