Effects of IrO2/Pt hybrid electrodes on the crystallization and ferroelectric performances of sol-gel-derived Pb(Zr,Ti)O3 thin film capacitors

The effects of IrO2/pt layered hybrid bottom and/or top electrode structures on the leakage current density versus voltage (J-V) polarization versus voltage (P-V), ferroelectric imprint, and fatigue properties of chemical-solution-derived Pb(ZrxTi1-x)O-3 (PZT, Zr/Ti = 35/65) thin films were investigated. The best P-V and J-V performances were obtained from a capacitor with nonhybrid electrodes (Pt/PZT/Pt capacitor). However, the poor fatigue performance of the capacitor required the adoption of hybrid electrode structures. A thin IrO2 layer, as thin as 6 nm, which was inserted between top Pt electrode and PZT layer was sufficient for improving the fatigue performance without any degradation of the other ferroelectric properties. However, the same layer adopted on the bottom Pt electrode was not effective in improving the fatigue performance with degradation in P-V and J-V properties. This was ascribed to IrO2 layer dissolution into the PZT layer during the crystallization annealing of the PZT thin film. A thicker IrO2 layer resulted in more serious degradation.