Suppression of oxygen vacancy formation in Hf-based high- k dielectrics by lanthanum incorporation

Abstract

The effects of lanthanum incorporation into Hf O2 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 0.7 eV larger than that in pure Hf O2, 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. © 2007 American Institute of Physics.