Effect of hydrogen on true leakage current characteristics of (Pb,La)(Zr,Ti)O₃ thin-film capacitors with Pt- or Ir-based top electrodes

The degradation behavior of polarization and leakage current characteristics of sol-gel-derived (Pb,La)(Zr,Ti)O₃ (PLZT) thin films, with Pt, Ir, and IrO₂ top electrodes, by annealing under a 4% H₂/96% N₂ atmosphere were investigated. The leakage current behaviors of Pt/PLZT/Pt and IrO₂/PLZT/Pt capacitors annealed at 300 °C for 20 min in 4% H₂ were well consistent with the space-charge-influenced injection model proposed. However, IrO₂/PLZT/Pt capacitors recovered at 700 °C for 10 min in Ar ambient after hydrogen anneal were not consistent with the proposed model because a conducting phase of IrPb was formed between the top electrode and PLZT during the recovery anneal at 700 °C in Ar ambient and modified the Schottky barrier height. The true leakage current behavior of IrO₂/PLZT/Pt capacitors recovered after hydrogen forming are similar to those of Ir/PLZT/Pt capacitors without the hydrogen-forming gas anneal. The P–E loops of Pt/PLZT/Pt and Ir/PLZT/Pt capacitors showed good recovery through recovery anneal after H₂ treatment. However, IrO₂/PLZT/Pt capacitors depended on the recovery anneal atmosphere (Ar or O₂).