Electrical Properties of Lead Lanthanum Titanate Thin-Film Capacitors Prepared by Sol-Gel Method

Abstract

High-quality (Pb1-x Lax )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 were systematically investigated. Ferroelectric perovskite phase was observed in the PLT thin films annealed at 600° 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 µC/cm2 and 110 kV/cm, respectively. Also the film with 600 nm thickness showed current density as low as 10-6 A/cm2 at the electric field of 200 kV/cm, which corresponds to the electric resistivity of ∼1012 (Ω·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.