A dielectric film containing atomic layer deposited lanthanide doped TiO.sub.x and a method of fabricating such a dielectric film produce a reliable dielectric layer having an equivalent oxide thickness thinner than attainable using SiO.sub.2. The lanthanide doped TiO.sub.x dielectric layer is formed by depositing titanium and oxygen onto a substrate surface by atomic layer deposition, and depositing a lanthanide dopant by atomic layer deposition onto the substrate surface containing the deposited titanium and oxygen. The dopant can be selected from a group consisting of Nd, Tb, and Dy. Dielectric films containing atomic layer deposited lanthanide doped TiO.sub.x are thermodynamically stable such that the lanthanide doped TiO.sub.x will have minimal reactions with a silicon substrate or other structures during processing.