A dielectric film containing lanthamide doped TiO.sub.x and a method of fabricating such a dielectric film produce a reliable gate dielectric having an equivalent oxide thickness thinner than attainable using SiO.sub.2. A dielectric film is formed by ion assisted electron beam evaporation of TiO.sub.2 and electron beam evaporation of a lanthamide selected from a group consisting of Nd, Tb, and Dy. The growth rate is controlled to provide a dielectric film having a lanthamide content ranging from about ten to about thirty percent of the dielectric film. These dielectric films containing lanthamide doped TiO.sub.x are amorphous and thermodynamically stable such that the lanthamide doped TiO.sub.x will have minimal reactions with a silicon substrate or other structures during processing.