Low temperature dielectric relaxation and charged defects in ferroelectric thin films

We report a dielectric relaxation in BaTiO3-based ferroelectric thin films of different composition and with several growth modes: sputtering (with and without magnetron) and sol-gel. The relaxation was observed at cryogenic temperatures (T < 100 K) for frequencies from 100 Hz up to 10 MHz. This relaxation activation energy is always lower than 200 meV and is very similar to the relaxation that we reported in the parent bulk perovskites. Based on our Electron Paramagnetic Resonance (EPR) investigation, we ascribe this dielectric relaxation to the hopping of electrons among Ti3+-V(O) charged defects. Being dependent on the growth process and on the amount of oxygen vacancies, this relaxation can be a useful probe of defects in actual integrated capacitors with no need for specific shaping