Optimization of seed layer of PbTiO3/PbZr0.3Ti0.7O3/PbTiO3 sandwich structure ferroelectric thin film

Abstract

The PT/PZT/PT and PZT thin films were prepared by sol-gel method. Different Pb content (x) (x=0, 005, 010, 015, 020) were added in excess to the PT precursor to optimize PT seed layer. The XRD and AFM results show that the crystalline phase and microstructure of the films were greatly affected by the excess Pb content (x) in PT layers. The pure perovskite structure PT/PZT/PT films with dense, void-free and uniform fine grain size were obtained for the proper choice of excess Pb content (x=010—015). EDX results showed that, in the interlayer and surface regions, the Pb deficiently and Pb abandance are obvious for the samples of x=0 and x=02, respectively. The ferroelectric, fatigue and leakage current properties of the films are not obviously relate to the change of excess Pb content (x), but correlate obviously with the crystalline behavior of PT layers. A well-saturated hysteresis loop with high remnant polarization, excellent fatigue properties and low leakage curremt were obtained for the films of excess Pb content x= 010 and 015. The excess Pb content (x) in PT layers affects the crystallization of PT layer, which will act as a nucleation site or seeding layer for PZT films and affect the perovskite phase formation of the PZT films. The optimized seed layer with excess Pb content x=010—015 improves not only the microstructure, but also the electric properties.