Résumé
Heterostructures consisting of (001) LaAlO3 or (111) SrTiO3 substrates, SrRuO3 metallic oxide bottom electrodes and Pb[Yb1/2Nb1/2]O3-PbTiO3 ferroelectric films were deposited by pulsed laser deposition. The combination of oxidic perovskite-type materials results in highly - or -heteroepitaxial capacitors with well-defined and homogeneous columnar microstructures. Most of the films show room temperature dielectric constant greater than 1500 associated with low dielectric loss (tgδ < 4%) and exhibit saturated hysteresis loops with remanent polarizations up to P
r ∼ 50µC.cm−2. It was found that the ferroelectric characteristics and, in particular, the fatigue phenomena greatly depend on the orientation and crystalline quality of the as-grown films. The stabilization of the -orientation enhances the fatigue resistance and a good endurance up to 1011 cycles has been determined for highly -textured samples. In contrast, fatigue tests performed on strongly -oriented capacitors have revealed poor fatigue performances, with a progressive decrease in the switchable polarization by ac voltage cycling.