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Ferroelectric Bi3.25La0.75Ti3O12 (BLT) and Bi3.15Nd0.85Ti3O12 (BNT) thin films were fab- ricated on Pt/TiO2/SiO2/Si (100) substrates by a modified sol-gel technique. X-ray diffraction indicated that these films were of single phase with random polycrystal- line orientations. The surface morphologies of the films were observed by scanning electron microscope, showing uniform, dense films with grain size of 50―100 nm. Well-saturated hysteresis loops of the films were obtained in metal-ferroelectric- metal type capacitors with Cu top electrodes at an applied voltage of 400 kV/cm, giving the remanent polarization (2Pr) and coercive field (2Ec) values of the films of 25.1 μC/cm2 and 203 kV/cm for BLT, and 44.2 μC/cm2 and 296 kV/cm for BNT, re- spectively. Moreover, these capacitors did not show fatigue behaviors after up to 1.75×1010 switching cycles at the test frequency of 1 MHz, suggesting a fatigue-free character. The influences of the La3+ and Nd3+ doping on the properties of the films were comparatively discussed.
Ferroelectric Bi3.25La0.75Ti3O12 (BLT) and Bi3.15Nd0.85Ti3O12 (BNT) thin films were fab- ricated on Pt / TiO2 / SiO2 / Si (100) substrates by a modified sol- gel technique. These films were of single phase with random polycrystal-line orientations. The surface morphologies of the films were observed by scanning electron microscope, showing uniform, dense films with grain size of 50-100 nm. Well-saturated hysteresis loops of the films were in metal-ferroelectric- metal type capacitors with Cu top electrodes at an applied voltage of 400 kV / cm, giving the remanent polarization (2Pr) and coercive field (2Ec) values of the films of 25.1 μC / cm2 and 203 kV / cm for BLT, and 44.2 μC / cm2 and 296 kV / cm for BNT, re- spectively. These capacitors did not show fatigue behaviors after up to 1.75 × 1010 switching cycles at the test frequency of 1 MHz, suggesting a fatigue-free character The influences of the La3 + and Nd3 + doping on the properties of the films were comparatively discussed.