Structural and electrical characteristics of chemical-solution-derived (Bi, La)4Ti3O12 thin films with various Bi2O3 template layers

Ferroelectric (Bi, La)(4) Ti3O12 (BLT) thin films with different Bi2O3 template layers were prepared on Pt/Ti/SiO2 /Si substrates by a chemical-solution deposition method. The BLT films with a thin Bi2O3 bottom layer and those with a thin Bi2O3 intermediate layer had a (117) preferentially oriented growth after annealing at 750 degreesC, while those with a thin Bi2O3 upper layer and those without a Bi2O3 template layer exhibited a high c-axis orientation. The surface morphologies changed with different preferential orientations. The electrical measurements showed that the use of Bi2O3 template layers improved significantly the P-E hysteresis loops of BLT thin films. The remanent polarization (2P(r)) and coercive field (E-c) values of BLT films without a Bi2O3 template layer, with a Bi2O3 upper layer, with a Bi2O3 bottom layer, and with a Bi2O3 intermediate layer annealed at 750 degreesC were 10.8, 29.12, 26.17, and 19.67 muC/cm(2); 79.0, 74.5, 75.5, and 76.3 kV/cm, respectively, at an applied electric field of 350 kV/cm. The dielectric constants and dissipation factors were 184, 303, 243, and 217; 0.036, 0.044, 0.039, and 0.039, respectively, at the frequency of 100 kHz, for these BLT films without a Bi2O3 template layer, with a Bi2O3 upper layer, with a Bi2O3 bottom layer, and with a Bi2O3 intermediate layer. All the capacitors with Bi2O3 template layers showed good polarization fatigue characteristics at least up to 3 x 10(10) bipolar pulse cycles and excellent retention properties up to 3 x 10(4) s. (C) 2003 American Institute of Physics.