Electrical properties of lead lanthanum titanate thin-film capacitors prepared by sol-gel method

High-quality (Pb1-xLax)Ti1-x/4O3 (x=0.05) [PLT] thin films were fabricated successfully by sol-gel processing onto Pt/Ti/SiO2/Si and p-Si substrates. The optimum route and the conditions for preparing homogeneous and crack-free thin films mere systematically investigated. Ferroelectric perovskite phase was observed in the PLT thin films annealed at 600 degrees C for 30 min. We studied the electrical properties of the PLT film capacitors with the metal-ferroelectric-metal (MFM) and the metal-ferroelectric-semiconductor (MFS) structure for use in ferroelectric memories. The dielectric constant and dissipation factor measured for MFM capacitor were 225 and 0.018 at 100 kHz, respectively. The remanent polarization (P-r) and coercive field (E(c)) of the PLT film were 8.5 mu C/cm(2) and 110 kV/cm. respectively. Also the film with 600 nm thickness showed current density as low as 10(-6) A/cm(2) at the electric field of 200 kV/cm, which corresponds to the electric resistivity of similar to 10(12) (Omega . cm) and represents excellent insulating properties. The MFS capacitor showed ferroelectric switching properties in C-V characteristics and the memory window of the hysteresis loop was about 1 V in the operation of +/-10 V.