Effects of barrier layers on the electrical properties of (Pb,La)(Zr,Ti)O3 films on nickel foils

The properties of (Pb0.92La0.08)(Zr0.52Ti0.48)O3 (PLZT) films deposited by chemical solution deposition onto base-metal nickel foils to develop volumetrically efficient, high charge density and high energy density capacitors were investigated. By utilizing barrier layers including Ru(RuO2) and LaNiO3 layers, high dielectric constants (K ∼ 1100 for PLZT/Ru(RuO2)/Ni and ∼900 for PLZT/LaNiO3/Ni) were obtained, which is comparable to dielectric constant (K ∼ 1250) of PLZT films deposited on platinized silicon substrates under same process condition. Excellent ultimate dielectric breakdown strength of more than 1 MV/cm and low leakage current density ranging from 1 × 10−9 to 4.5 × 10−9 A/cm2 under 10 Vdc stress were achieved for 0.9 μm PLZT films on foil substrates. Conductive barrier layers interposed between the ferroelectric films and the foil substrates were found to be very effective in improving dielectric properties without degrading ultimate dielectric breakdown strength and leakage current. Employing barrier layers, therefore, is one of the attractive solutions for achieving improved high-permittivity ferroelectric layers on base-metal foil substrates for inexpensive and high performance capacitor fabrication.