Lead based ferroelectric capacitors for low voltage non-volatile memory applications

We report on novel, low voltage properties of ferroelectric lanthanum doped lead zirconate titanate (PLZT) capacitors. These PLZT ferroelectric films sandwiched between lanthanum strontium cobaltite, (La0.5Sr0.5)CoO3(LSCO) electrodes were epitaxially grown on yttria stabilized zirconia (YSZ) buffered Si, using a bismuth titanate template. These epitaxial capacitors exhibit much lower switching voltages (∼0.5 V) compared to what has been reported on other PZT systems. Ferroelectric testing shows excellent fatigue, retention and imprint properties. Pulse width dependent measurements show that the low voltage performance is possible at widths less than 1 μsec. The dramatic change in the switching behavior is tentatively attributed to the reduction in the c-axis lattice parameter (due to La substitution) and the consequent absence of 90° domain walls.