Compositional dependence of electrical characteristics in SrBi2Ta2-xNbxO9 ferroelectric capacitor reduced by H-2 annealing

Degradation of electrical properties by annealing in hydrogen ambient is on e of the most significant problems associated with ferroelectric oxides use d in mainstream nonvolatile memory. A decrease in the degradation of the re manent polarization and the breakdown voltage of a ferroelectric SrBi2Ta2-x NbxO9 (SBTN) capacitor has been attempted by controlling the Ta/Nb ratio, a dding excess Bi oxide and adding excess Nb oxide. Substituting Nb for Ta im proves the remanent polarization, however, it also leads to a decrease in t he breakdown voltage. Excess Bi and Nb oxide both decrease the remanent pol arization. Regarding the breakdown voltage, the addition of excess Bi and N b oxide decrease the amount of the degradation caused by short-time H2- ann ealing, although it is not enough to prevent the degradation caused by long -time H-2 annealing. Furthermore, the reduction path in the ferroelectric c apacitor by low-temperature H-2 annealing is discussed.