Effects of excess Pb and substrate on crystallization processes of amorphous Pb(Zr, Ti)O-3 thin films prepared by RF magnetron sputtering

Effects of excess Pb and substrate on the crystallization processes of amorphous lead-zirconate-titanate (a-PZT) thin films by post-annealing in oxygen ambient were investigated to lower the crystallization temperature of the films with a single perovskite phase. A-PZT films were prepared on Ir and Pt substrates with a 2-nm-thick Ti buffer layer on their surfaces, and on a SrRuO3 substrate by cosputtering Pb(Zr0.5Ti0.5)O-3 and PbO targets. Analyses by in situ heating X-ray diffraction revealed that the crystallization processes strongly depend on the amount of excess Pb contained in the as-prepared a-PZT and substrates. By controlling the rf power supplied to the PbO target during the deposition, we obtained single perovskite phase PZT films at 480 degrees C, 520 degrees C and 580 degrees C on SrRuO3, Ir and Pt substrates, respectively. The crystallized PZT films exhibited excellent ferroelectric properties. For the 150-nm-thick PZT film, crystallized by rapid thermal annealing at 600 degrees C for 20 s, we obtained a coercive field of 40 kV/cm (0.6 V), a remanent polarization density of 15 mu C/cm(2) and polarization switching endurance over 1 x 10(9) cycles with Ir top and bottom electrodes.