Formation of the secondary phases in the Pb-containing perovskite films by pulsed laser deposition

Abstract

The growth behavior of Pb2+-containing ferroelectric thin films has been systematically examined. The kinetics of the formation of perovskite phase were successfully enhanced by using a material containing no Zr4+-ions, viz., Pb0.95La0.05Ti0.9875O3 (PLT) films, and by utilizing platinum coating on silicon substrate. Meanwhile, the formation of TiO2 phase (rutile) on PLT/Pt(Si) films has been observed and was ascribed to both the outward diffusion of Ti4+-ions from the Ti-layer underneath the Pt-coating and the loss of Pb2+-ions on the surface of the films. The perovskite materials, which were free of either pyrochlore, Zr-rich phase, or TiO2 phase, can be obtained by in situ depositing the PLT films at 450 °C substrate temperature and 1 mbar oxygen pressure. Thus obtained thin films possessed high dielectric constant, ∊r = 1346 and tan δ = 0.071 at 10 kHz, and large charge storage density, Qc = 5.4 μC/cm2 at 50 kV/cm.