Effect of RuO₂/Pt hybrid bottom electrode structure on the microstructure and ferroelectric properties of sol-gel derived PZT thin films

Ferroelectric PZT thin films on thin RuO₂ (10, 30, 50 nm)/Pt hybrid bottom electrodes were successfully prepared by using a modified chemical solution deposition method. It was observed that the use of a 10 nm RuO₂/Pt bottom electrode reduced leakage current, and gave more reliable capacitors with good microstructure compare to the use of thicker RuO₂/Pt bottom electrodes. Typical P-E hysteresis behavior was observed even at an applied voltage of 3 V, demonstrating greatly improved remanence and coercivity. Fatigue and breakdown characteristics, measured at 5 V, showed stable behavior, and only below 13-15% degradation was observed up to 10¹⁰ cycles. Thicker RuO₂ layers resulted in high leakage current density due to conducting lead ruthenate or PZT pyrochlore-ruthenate and a rosette-type microstructure.