Structural properties and electrical characteristics of BiFeO₃ thin films with RE₂O₃ buffer layers

In this paper, we successfully utilized a simple sol-gel spin-coating method to deposit RE₂O₃-buffered (Ce₂O₃, Gd₂O₃, and Tb₂O₃) BiFeO₃ thin films onto SrRuO₃/n⁺-Si substrates. A thorough investigation of various characteristics, such as depth profile, structure, morphology, chemical components, leakage current density, and ferroelectric properties, was conducted. The results showed that the use of a Gd₂O₃ buffer layer significantly reduced the leakage current density to 4.28 × 10⁻⁶ A/cm², which is three orders of magnitude lower than that of the control BiFeO₃ thin film (7.65 × 10⁻³ A/cm²) at 300 kV/cm. Furthermore, the Gd₂O₃ buffer layer resulted in a higher remanent polarization (43 μC/cm²) and a lower coercive field (205 kV/cm). These outcomes can be attributed to the absence of oxygen vacancies, a high degree of (110) preferred orientation, low surface roughness, high Fe³⁺ content, and suppression of the valence fluctuation of Fe³⁺ to Fe²⁺ ions.