Polarization enhancement and coercive field reduction in W- and Mo-doped Bi3.35La0.75Ti3O12 thin films

Bi3.35La0.75(Ti1-xWx)(3)O-12 (BLTW) and Bi3.35La0.75(Ti1-xMox)(3)O-12 (BLTM) (x=0.3%, 0.5%, 1%, and 2%) films were fabricated on Pt/Ti/SiO2/Si<100> structures by a sol-gel method at 750 degreesC. The B-site substitution with high-valent cations, W6+ or Mo6+, in Bi3.35La0.75Ti3O12 (BLT) enhanced the remanent polarization and reduced the coercive field of the films. The remanent polarization (2P(r)) values of the BLTW05 (x=0.5%) and BLTM05 (x=0.5%) films were 26 and 27 muC/cm2, respectively, which were higher than that of BLT (20 muC/cm2). The coercive field (2E(c)) values of the BLTW05 and BLTM05 films were 125 and 126 kV/cm, respectively, which were much lower than that of BLT (190 kV/cm) and close to that of SrBi2Ta2O9 (similar to110 kV/cm). These films also showed fatigue-free response up to 2x10(9) switching cycles and lower leakage current densities than 4x10(-7) A/cm(2) up to 200 kV/cm. (C) 2003 American Institute of Physics.