Impact of annealing on the relaxation processes in Pt/SrTiO₃/Pt thin film capacitors

In this paper, the effect of the post-annealing on the dielectric properties of SrTiO₃ thin films (200 nm) grown by ion beam sputtering has been investigated. The measured dielectric constant dramatically increased after the post-annealing which is a consequence of the formation of the perovskite phase. A low frequency relaxation mechanism is clearly identified in the amorphous state of this material. Once crystallized, a second relaxation mechanism of lower amplitude is detected at high frequencies and for high measuring temperature. It is assumed that this second relaxation process is related to the space charges bound at the grain boundaries, whereas the first one was assigned to the thermally activated motions of the ionized oxygen vacancies and interfacial polarization under alternating field.