Reversibility of the perovskite-to-fluorite phase transformation in lead-based thin and ultrathin films

As film thicknesses decrease below 50 nm, control of cation stoichiometry in Pb-based dielectrics becomes increasingly difficult, a problem that is exacerbated by interaction with technologically important Pt bottom electrodes. Post-crystallization annealing in a Pb-rich atmosphere is shown to be a general technique to reversibly convert low-permittivity Pb-deficient fluorite into ferroelectric high-permittivity stoichiometric perovskite with outstanding dielectric properties (see figure).