Atomistic Modeling of an MFM ferroelectric capacitor made of HfO 2 :Si

Abstract

Using ab initio simulation, we study a ferroelectric layer of a few nanometers made of hafnia (HfO 2 ) under the influence of Si doping with TiN electrodes. We evaluate the orthorhombic phase of Pca2 1 symmetry, its ferroelectric switching and the incidence of doping with silicon. We show that the ferroelectric switching can involve a 90° characteristic angle with corresponding activation energy which is lowered by a factor three due to Si doping at 3% at. A full MFM (Metal-Ferroelectric-Metal) model is derived in order to simulate finite-size effects. This model is compatible with a reversal of a polar HfO 2 :Si with a (111) preferential orientation. Validity and usefulness of such a model are discussed for ferroelectric devices optimization.