Abstract
The electrical characteristics of metal-ferroelectric-insulator-silicon (MFIS) structures are studied. The ferroelectric layer is lead-zirconate-titanate (PZT). High dielectric constant films of La2O3, HfO2 and Dy2O3 are used as the insulator layer . This structure is studied for the potential application of non-volatile memory devices. The PZT and the high-κ dielectric films are deposited by RF magnetron sputtering. The orientation of C-V hysteresis loop is found to depend on both the polarization of the ferroelectric layer and the trapped charges injected into the insulator layer. For the Al/Pb(Zr0.6,Ti0.4)O3 (PZT)/ La2O3/Si structure, the memory window is agreement with the theoretical result of ΔV= 2dfEc (1.7 V) at an applied voltage of 5 V .The leakage current density is about 10-7 A/cm2 at room temperature and is about 4×10-5 A/cm2 at 425 K under the bias of 10 V . For the Al/PZT/Dy2O3/Si system, the C-V orientation is counterclockwise when the applied voltage is below 8 V and clockwise above 8 V. The memory window measured from the C-V curves first increases and then decreases with the applied sweep voltage. These phenomena are explained by the combination of the polarization of the ferroelectric film and the injected charge effects in the Al/PZT/Dy2O3/Si MFIS system .The leakage current density is about 9×10-7 A/cm2 at room temperature and rises to 5×10-2 A/cm2 at 450K under the bias of 10 V.