Ferroelectric properties of highly c-axis oriented Bi4−xLaxTi3O12 film-based capacitors

Highly c-axis oriented lanthanum-modified bismuth titanate (Bi4−xLaxTi3O12) films having a variety of lanthanum (La) contents were grown on Pt/TiO2/SiO2/Si(100) substrates using metal-organic sol deposition and subsequent annealing at 650 °C for 1 h. After systematically examining the ferroelectric properties of Bi4−xLaxTi3O12 films as a function of the La-content, it was concluded that the film with x=0.85 had the largest remanent polarization in the direction parallel to the c-axis. The Pt/Bi3.15La0.85Ti3O12/Pt capacitor showed a well-saturated polarization–electric field (P–E) switching curve with the switching remanent polarization (2Pr) value of 33 μC/cm2 and the coercive field (Ec) of 68 kV/cm at an applied voltage of 10 V. More importantly, the capacitor exhibited fatigue-free behavior up to 6.5×1010 read/write switching cycles at a frequency of 1 MHz. The capacitor also demonstrated an excellent charge-retaining ability and a strong resistance against the imprinting failure.