Structural and Electrical Properties of Bi_(3.25)La_(0.75)Ti_3O_(12) and Bi_(3.25)Pr_(0.75)Ti_3O_(12) Thin Films for Memory Applications

摘要

In this work, Bi_(3.25)La_(0.75)Ti_3O_12 (BLT) and Bi_(3.25) Pr_(0.75)Ti_3O_12 (BPT) thin films were prepared by chemical solution deposition and characterized by X-ray diffraction, scanning electron microscope and electrical measurements. Layered perovskite BLT and BPT films ran be achieved by 180 s annealing at a temperature as low as 650 deg C. Both BPT and BLT films are composed of closely packed spherical grains. BPT shows larger tenant polarization (Pr) and smaller coercive field. The Pr values of 700 deg C annealed BLT and BPT films are 18.3 muC/cm~2 and 20.5 muC/cm~2, respectively, while BLT films show better-saturated hysteresis loops. The leakage current density of BPT films is significantly (about one order) lower than that of BLT. The dielectric properties of BLT and BPT films were measured and compared. Both films exhibit large dielectric constant and small loss tangent. Under bipolar switching cycles, BLT films showed little polarization reduction but a 30 percent polarization loss was observed for BPT films after 2 X 10~9 cycles.