Low Temperature Fabrication of BiFeO3 Films on Aluminum Foils under an N2-Rich Atmosphere

To be CMOS-compatible, a low preparation temperature (< 500 °C) of ferroelectric films is required. In this study, BiFeO3 films were successfully fabricated at a low annealing temperature (< 450 °C) on aluminum foils by a metal-organic decomposition process. The annealing atmosphere on performance of BiFeO3 films was assessed at 440 ± 5℃. By replacing an O2-rich atmosphere with an N2-rich one, a better crystalline morphology was achieved in BiFeO3 films, resulting in better electric properties targeted for high-density ferroelectric random-access memory applications. These properties included a large remnant polarization (Pr~78.1 μC/cm2 @ 1165.2 kV/cm) and a high rectangularity (~91.3% @ 1165.2 kV/cm) of the P-E loop, along with excellent charge-retaining ability up to 1.0 × 103 s and a fatigue resistance reaching 1.0 × 109 switching cycles. The enhanced performance of BiFeO3 film in an N2-rich atmosphere maybe originated from the slightly high content of oxygen vacancies during the annealing process. Furthermore, decent electrical properties (Pr~70 μC/cm2 @ 1118.1 kV/cm) of the BiFeO3 films were achieved at a very low annealing temperature of 365 ±5 °C on aluminum foil substrates. These results offer a new idea for lowering the annealing temperature for integrated ferroelectrics in high-density FeRAM applications.