The Titanate Hungry Modification Of Ferroelectric Thin Films

In the new generation of non-volatile Ferroelectric Memory, Pb(ZrxTi1-x)O3 (PZT) and SrBi2Ta2O9 (SBT) were the most used ferroelectric materials. However, the former has poor anti-fatigue property and may cause Environmental Contamination, while the latter has higher process temperature (750～850℃) and lower remnant polarization (4～16μC/cm2) which blocked the commercial application process of Ferroelectric Memory. Thus, people are eager to find some new ferroelectric materials.Rare-earth doped Bi4Ti₃O₁₂ (BTO for short) ferroelectric thin films have become most potential materials replacing the conventional PZT thin films for application in non-volatile Ferroelectric Memory, due to its higher remnant polarization (2Pr), excellent fatigue endurance, relatively low crystallization temperature. And the studies on the film fabrication and the improvements of the ferroelectric performance are central issues. Especially in the study of Bi loss during the heat treatment, how much Bi excess should be added.The BLT thin films with excess Bi contents were prepared onto a Pt (111)/Ti/SiO2/Si(110) substrate by the Sol-Gel technique. The microstructure and ferroelectric properties were investigated by XRD, AFM, P-E and etc methods. The results show that the ferroelectric properties of the BLT thin film which is Bi excess 10mol% are better. To be exact, the grains of thin films with 10mol excess are smooth and uniform. And it has a great P-E loop with 2Pr and Ec value is 34.90μC/cm2 and 38.55kV/cm separately. The effect of the annealing temperature on the microstructure and ferroelectric properties of BLT thin films are studied. The results show that the best annealing temperature for BLT is 700oC. To be exact, the grains of the film are ellipsoidal and uniform. And it has a great P-E loop. It shows fatigue after about 108 switching cycles. Nd-doped BTO (Bi4-xNdxTi₃O₁₂, x=0.25, 0.50, 0.75) ferroelectric thin films were deposited on Pt(111)/Ti/SiO2/Si(110) substrate by the Sol-Gel technique. The microstructure and ferroelectric properties of Bi4-xNdxTi₃O₁₂, x=0.25, 0.50, 0.75 ferroelectric thin films were also investigated by XRD, AFM, P-E and etc methods. The results showed that the ferroelectric properties of the Bi_3.50Nd_0.50Ti₃O₁₂ thin films are better. We also investigated the effect of the annealing temperature. These results show that the best annealing temperature for Bi_3.50Nd_0.50Ti₃O₁₂ is also 700℃. To be exact, the grains of the thin film are uniform. It has a good P-E loop with 2Pr and Ec is 12.56μC/cm2 and 71.25kV/cm separately. It shows fatigue after about 108 switching cycles.