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

Abstract

The effects of lanthanum incorporation into $\mathrm{Hf}{\mathrm{O}}_2$ 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 $\left(V_{\mathrm{O}}^0\right)$ in the vicinity of substitutional La atoms at Hf sites is $0.7\mathrm{eV}$ larger than that in pure $\mathrm{Hf}{\mathrm{O}}_2$ , indicating that the concentration of $V_{\mathrm{O}}^0$ ’s is drastically reduced by La incorporation. This effect is understood to be caused by the decrease in the local dielectric constant ${\kappa }_L$ around La atoms due to the strong ionic character of the La–O bond compared to the Hf–O bond.