PHASE-FORMATION AND FERROELECTRICITY OF SOL-GEL DERIVED (PB, LA)TIO3 THIN-FILMS

Ferroelectric lead lanthanum titanate (PLT) thin films with various la nthanum concentration were fabricated by sol-gel spin-on process onto Pt/Ti/SiO2/Si substrates. We investigated the crystal structure, micro structure, and dielectric and ferroelectric properties of PLT films ac cording to lanthanum doping concentration. The films annealed at 600 d egrees C for 30 min have the single perovskite phase having only tetra gonal or pseudocubic structure. The film microstructures were changed according to the doping concentration of La. The PLT films showed the typical polarization-electric field hysteresis loops and capacitance-v oltage characteristics representing the ferroelectric switching proper ty. The coercive field and remanent polarization decreased due to the phase transformation from ferroelectric to paraelectric phase with inc reasing La concentration. The effective dielectric constant and the le akage current density increased according to the increase of La conten t. (C) 1998 American Institute of Physics.