Fabrication of PbLa0.05TiO3∕Pb1.20(Zr0.52Ti0.48)O3∕PbLa0.05TiO3 ferroelectric structure on platinum electrodes by a sol-gel process

Ferroelectric PbLa0.05TiO3∕Pb1.20(Zr0.52Ti0.48)O3∕PbLa0.05TiO3 (PLT/PZT/PLT) thin films were fabricated on platinum-coated silicon wafers using a sol-gel process. The PbLa0.05TiO3 layers between the PZT and Pt electrode are used as seeding layers to improve the crystallization and can greatly enhance the ferroelectric properties of the PZT film. Compared with PZT and PbTiO3∕Pb1.20(Zr0.52Ti0.48)O3∕PbTiO3 (PT/PZT/PT) films, the PLT/PZT/PLT capacitors of thickness ∼250nm showed excellent ferroelectric properties in terms of larger remnant polarization (Pr) of ∼19μC∕cm2 (Ec∼60kV∕cm), higher saturation polarization (Ps) of about 45μC∕cm2 for an applied field of 600kV∕cm, fatigue-free characteristics of up to ⩾1010 switching cycles, and a low leakage current density of 10−8A∕cm2 at 200kV∕cm. A possible reason for the beneficial effect of PLT is the improved interfacial characteristics that may lead to the absorption of oxygen vacancies or other point defects from the PZT layer and result in better fatigue properties.