High Resistance Against Hydrogen-Induced Degradation in Ferroelectric Bi3.25La0.75Ti3O12 Thin Films

Abstract

Effects of forming gas annealing (FGA) were investigated on ferroelectric Bi3.25La0.75Ti3O12 (BLT) thin films fabricated by chemical solution deposition. In the case of low-temperature FGA below 350°C, the BLT films were found to have quite a high resistance against hydrogen-induced degradation compared to PbZr0.4Ti0.6O3 (PZT) films. After FGA at 300°C, the BLT capacitors showed only a small reduction of remanent polarization and no deformation of their hysteresis loops while the PZT capacitors showed a large polarization degradation and serious hysteresis loop deformations. Hydrogen depth profiles, analyzed by secondary ion mass spectroscopy after FGA, showed comparable amounts of hydrogen penetration for both BLT and PZT films. X-ray photoemission spectroscopy measurements suggested that, for BLT films, the chemical stability of BLT may be responsible in part for the observed hydrogen annealing resistance.