Ferroelectric PLZT films grown on metal foils for power electronics applications

Ceramic films of high permittivity and breakdown strength are critical to advanced power electronic devices. We have grown ferroelectric films of lead lanthanum zirconate titanate (PLZT) on base metal foils by chemical solution deposition. We measured a dielectric constant of ≈700 and dielectric loss of ≈0.07 at -50°C and a dielectric constant of ≈2200 and dielectric loss of ≈0.06 at 150°C. At room temperature, we measured a leakage current density of ≈6.6 × 10^-9 A/cm², mean breakdown strength of 2.6 MV/cm, and energy density >;85 J/cm³. Highly accelerated lifetime testing (HALT) was performed to determine the reliability of these PLZT film-on-foil capacitors under high temperature and high field stress conditions. Samples were exposed to temperatures ranging from 100 to 150°C and electric fields ranging from 8.7 × 10⁵ V/cm to 1.3 × 10⁶ V/cm during HALT. The breakdown behavior of the samples was evaluated by Weibull analysis. The mean time to failure, >;3000 h, was projected at 100°C with a dc electric field of ≈2.6 × 10⁵ V/cm.