Electrode dependence of hydrogen-induced degradation in ferroelectric Pb(Zr,Ti)O3 and SrBi2Ta2O9 thin films

Forming gas annealing causes changes in the remanent polarization ${\mathrm{(P}}_r\mathrm{),}$ coercive field ${\mathrm{(E}}_c\mathrm{),}$ and leakage current ($I$ ) in both PZT $[{\mathrm{Pb(Zr,Ti)O}}_{\mathrm{3}}]$ and SBT $({\mathrm{SrBi}}_{\mathrm{2}}{\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{9}})$ samples with a variety of top electrode materials (Pt, Au, Ag, Cu, Ni, and ${\mathrm{In}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ ), and the degree of degradation depends strongly on the top electrode material. These results may be explained by a model that is based on the catalytic activities of the top electrode to dissociate hydrogen molecules into hydrogen atoms, with the latter subsequently migrating into PZT or SBT films to cause oxygen deficiency and its associated property degradation. This model can be expanded to explain the recovery phenomenon resulting from oxygen annealing, which also depends on the catalytic activity of the top electrode to produce atomic oxygen from molecular oxygen.