Influence of La substitution on the electrical properties of metal–ferroelectric (BiFeO3)-insulator (CeO2)-semiconductor nonvolatile memory structures

Metal–multiferroic (La-substituted BiFeO3)–insulator (CeO2)–semiconductor (MFIS) capacitors has been fabricated. The crystalline phase and amount of La3+ substitution at Bi-site were investigated by XRD and XPS in the postannealing temperature range from 500 to 700 °C, respectively. The microstructure and interfacial layer between CeO2 and Si substrate were characterized by HRTEM. The memory windows as functions of insulator film thickness and DC power for La were measured. The maximum memory window is about 1.9 V under ±6 V applied voltage. The ferroelectric polarization increases with increasing substitution amount. The morphologies of La-substituted BiFeO3 films were also studied by AFM.

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► We characterize the amount of La3+ substitution at Bi-site in BFO thin films.
► La-substituted BiFeO3 thin films improve the leakage current.
► MFIS structures with CeO2 as the insulator layer achieve large memory windows.