Single and multilayer ferroelectric PbZr_xTi_1-xO₃ (PZT) on BaTiO₃

Ferroelectric PbZr_xTi_1-xO₃ (PZT) thin films have been deposited on Pt-coated Si substrates by using r.f. magnetron sputtering. The optimized processing condition to obtain proper stoichiometric PZT, the desired ferroelectric perovskite phase, and better dielectric properties was demonstrated using a PZT target with Pb/(Zr + Ti) ratio of 1.2 and depositing at 350°C, followed by thermal treatment at 620°C for 30 min. The structural and electrical properties of the PZT layer were further improved by fabricating a novel multilayer structure which combined the PZT with the nanolayer BaTiO₃. The leakage current density was reduced from 2 X 10^-7 A cm^-2 for the single layer structure to 2 X 10_-9 A cm^-2 for the multilayer structure at a field of 4 X 10⁵ V cm^-1', while maintaining the high relative effective dielectric constant of 442. The relative dielectric constant of the PZT film in the multilayer structure was calculated to be about 880.