Microstructures and ferroelectric properties of PbTiO3/PbZrO3 superlattices deposited by pulse laser deposition

In general, the strain effect and the electrostatic effect are important factors influencing the electrical properties of ferroelectric superlattices. However, the interfacial diffusion may also greatly influence the electrical properties of ferroelectric superlattices. Here, we deposited PbTiO₃/PbZrO₃ (PTO/PZO) superlattices on Nb-doped SrTiO₃ (NSTO) single-crystal substrates by pulse laser deposition with the same deposition processes but different cooling processes to explore the effects of interface diffusion on the structural and electrical properties of the superlattices. The experimental results showed that with increasing the holding time in the cooling process after deposition, the ferroelectric and dielectric properties were enhanced, meanwhile, the leakage current density was reduced. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) results showed that the PTO/PZO interfaces became blurred with increasing cooling time. Therefore, the increase in ferroelectric and dielectric properties and the decrease in leakage current density may be due to the interdiffusion of Ti and Zr ions at the PTO/PZO interfaces resulting in the formation of Pb(Zr_xTi_1-x)O₃ (PZT) and the decrease of interface defects at the PTO/PZO interfaces. Our results demonstrate that besides the strain and electrostatic effects, the interdiffusion of the elements at the interfaces is also an important factor that influences the electrical properties of ferroelectric superlattices.