FERROELECTRIC PROPERTIES OF Zr-DOPED Bi_3.25La_0.75Ti₃O₁₂ THIN FILM DEPOSITED BY RF MAGNETRON SPUTTERING

Abstract

Thin films of Bi 3.25 La 0.75 Ti 3 O 12 (BLT) and B-site substituted BLT by Zr, i.e. Bi 3.25 La 0.75 Ti 3−x Zr x O 12 (BLTZx, x = 0.20, 0.50, 0.75, 1.00 and 1.50) were fabricated on Pt/TiO 2 /SiO 2 /Si substrates by RF magnetron sputtering method. Effect of Zr 4+ amount on the microstructure and ferroelectric characteristics of the thin film BLTZx were investigated. X-ray diffraction shows that A-site La 3+ and B-site Zr 4+ co-substitution do not destroy the layered perovskite structure. Compared with the well-known BLT thin films, appropriate Zr 4+ added, such as the BLTZ0.20 thin film, has larger remnant polarization (2Pr) and better fatigue resistance. However, with further increasing Zr 4+ -doping concentration, the remnant polarization (2Pr) tends to decrease. When x > 0.75 the remnant polarization become lower than that of BLT thin film. The remnant polarization (2Pr) of the BLTZx thin films under the 12 V were 17. 8, 25.6, 22.4, 17.2, 11.6, 10.2 µC/cm 2 , respectively, for x = 0, 0.20, 0.50, 0.75, 1.00 and 1.50, whereas there are almost no obvious difference in the Vc values.