Ti-doped ThO2: a first-principles study of dielectric properties

We determine electronic structure and dielectric response of 25 and 50% Ti-substituted thoria (ThO2), using first-principles density functional theory calculations based on pseudopotentials and a plane wave basis. We find that Th0.75Ti0.25O2 is more promising as a high-k material than Th0.5Ti0.5O2. We show that the IR-active phonon modes in pure thoria can be tuned upon Ti doping and the softened modes cause an enhanced dielectric response of 25% Ti-doped thoria. As the material remains insulating, it holds promise for applications such as a gate oxide material.