Effect of Zr/Ti ratios on characterization of Pb(Zr_xTi_1-x)O₃ thin films on Al₂O₃ buffered Si for one-transistor memory applications

Pb(Zr_xTi_1-x)O₃ (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.