Pb(ZrxTi1-)O-3 (PZT) thin films have been prepared on Al2O3/Si and PbTiO3/Al2O3/Si substrates, respectively. On Al2O3/Si substrates, Ti-rich PZT thin films had lower perovskite transformation temperatures than those of Zr-rich PZT films. Therefore, PbTiO3 was used as the seeding layer on Al2O3/Si to form a PbTiO3/Al2O3/Si substrate. The threshold voltage shift of a PZT(53/ 47)/PbTiO3/Al2O3/Si capacitor reaches 9 V with +/-10 V writing voltages, which is much larger than the 2 V of the PZT(0/100)/PbTiO3/Al2O3/Si capacitor. Different memory mechanisms in the capacitance-voltage characteristics of capacitors were further examined and discussed in this paper. (C) 2003 The Electrochemical Society.