Effects of Pb/Pt Top Electrode on Hydrogen-Induced Degradation in Pb(Zr,Ti)O3.

Hydrogen-induced ferroelectric degradation of Pb(Zr,Ti)O3 (PZT) films was studied by measuring the hysteresis curves after hydrogen annealing at various temperatures and times. It was found that hydrogen annealing at temperatures below 100°C resulted in an increase of remanent polarization due to the accumulation of hydrogen ions at the Pt/PZT interface. After hydrogen annealing at 400°C, the ferroelectric characteristics of the Pt/PZT/Pt capacitor deteriorated very rapidly. However, when a thin (50 A) layer of Pb was deposited on top of the Pt electrode, it was found that the hydrogen-induced ferroelectric degradation was significantly retarded at 400°C. It is presumed that the kinetic path for producing highly reducing hydrogen ions by dissociative adsorption of hydrogen on Pt electrode surfaces was effectively blocked by the poisoning effect of Pb.