Electrostatic coupling-driven dielectric enhancement of PZT/BTO multilayer thin films

In this study, PbZr0.52Ti0.48O3/BaTiO3 (PZT/BTO) multilayers with varying layer fractions were deposited on Pt/Ti/SiO2/Si substrates by sol–gel process. The films were characterized by X-ray diffraction and scanning electron microscopy (SEM). The result shows that there exists a dielectric enhancement when the BTO layer fraction x is around 0.5, and at this fraction, the dielectric constant of PZT/BTO is 590 at 100 kHz, which is far more than that of monolithic PZT or BTO films (478 and 284, respectively). The thermodynamic analysis shows that the measured dielectric constant is close to the simulation values when x closes to 0.5; otherwise it fit the values caculated by series connection. The result indicates that the internal field resulting from the polarization mismatch between two ferroelectric layers contributes to the enhancement of PZT/BTO heterogeneous thin films.