Electrical characteristics of the MOD-derived SrBi2xTa2O9 and SrBi2.4(Ta,Nb)2O9 thin films

Ferroelectric and leakage current characteristics of the MOD-derived SrBi_2xTa₂O₉ (0.8 x 1.6) and SrBi_2.4(Ta_1-yNb_y)₂ O₉ (0 y 1) thin films were investigated. The SBT and SBTN films were fully crystallized to Bi-layered perovskite structure by annealing at 800°C for 1 hour in oxygen atmosphere. The ferroelectric characteristics of the SBT films were optimized at the Bi/Ta mole ratio x of 1.2. The leakage current density of the Bi-excess SBT films decreased remarkably by the post-metallization annealing at 800°C for 10 minutes in oxygen ambient. The ferroelectric characteristics of the SBTN films were optimized with the SBN content y of 0.25. The SrBi_2.4(Ta_0.75Nb_0.25)₂ O₉ film exhibited 2P_r and E_c of 19.04 C/cm² and 24.94 kV/cm at ±5 V, which were superior to 2P_r of 11.3 C/cm² and E_c of 39.6 kV/cm obtained for the SrBi_2.4Ta₂O₉ film after the post-metallization annealing. The MOD-derived SrBi_2.4(Ta_0.75Nb_0.25)₂O₉ film did not exhibit the polarization fatigue after 10¹¹ switching cycles at ±5 V.