Strain-induced effects on the dielectric constant for thin, crystalline rare earth oxides on silicon

Abstract

Thin epitaxial rare earth oxide layers on Si exhibit K values that are much larger than the known bulk values. We investigate the thickness dependence of that enhancement effect for epitaxial Gd2O3 on Si(111). Controlling the oxide composition in ternary (Gd1-xNdx)2O3 thin films enables us to tune the lattice mismatch to silicon and thus the K values of the dielectric layer from 13 (close to the bulk value) up to 20. We show that simple tetragonal distortion of the cubic lattice is not sufficient to explain the enhancement in K. Therefore, we propose more severe strain induced structural phase deformations.