Micro-structure and ferroelectric properties of BiFeO3 thin films formed on Pt-coated r-plane sapphire substrates

作者：Singh S K^*; Ishiwara H

来源：Journal of Electroceramics, 2006, 16(4): 553-556.

DOI：10.1007/s10832-006-9917-x

• magnetoelectrics
• BiFeO3 thin films
• chemical solution deposition
• micro-structure
• ferroelectrics properties

Magnetoelectric BiFeO3 (BFO) materials exhibit ferroelectric and ferromagnetic properties simultaneously, therefore they have a potential to be applied in magnetic as well as ferroelectric devices. BFO thin films were formed by depositing sol-gel solutions on Pt-coated r-plane sapphire dielectric substrates. We did not observe any secondary phase such as Bi2Fe4O9 on the r-plane sapphire substrates, which is generally observed on Si substrates. We observed small ferroelectric grains of about 0.1 mu m on Pt/sapphire structures. The leakage current density in BFO films was found to be decreased dramatically after optimizing process conditions of stoichiometric BFO chemical solution. The leakage current densities were in the range of 10(-7) A/cm(2) at room temperature and 10(-9) A/cm(2) at 80 K under 0.4 MV/cm applied electric field. The main reason for low leakage current is considered to be reduction of oxygen vacancies due to the presence of exclusive Fe3+ valance state in the films. An applied electric field higher than 0.5 MV/cm was required to pole the BFO films, which made it difficult to obtain the saturated polarization at room temperature. We could measure the saturated remanent polarization in the BFO films at 80 K and the obtained remanent polarization was 100 mu C/cm(2).

• 出版日期2006-7