Influence of RE₂O₃ (Dy₂O₃, Yb₂O₃, and Lu₂O₃) buffer layers on the structural and ferroelectric characteristics of BiFeO₃ thin films

This study investigates the impact of RE₂O₃ (Dy₂O₃, Yb₂O₃, and Lu₂O₃) buffer layers on the structural and ferroelectric properties of BiFeO₃ thin films grown using a spin-coating method. BiFeO₃ thin films with various RE₂O₃ buffer layers were analyzed using x-ray diffraction, atomic force microscopy, secondary ion mass spectrometry, and x-ray photoelectron spectroscopy to determine their crystalline structures, surface topographies, depth profiles, and chemical compositions, respectively. The RE₂O₃-buffered BiFeO₃ film showed better electrical properties compared to the control BiFeO₃ film. The buffer layer composed of Yb₂O₃ showed the lowest leakage current of 6.82 × 10⁻⁶ A cm⁻², highest remnant polarization of 44.1 μC cm⁻², and smallest coercive field of 189 kV cm⁻¹ because of the incorporation of Yb³⁺ ions into the BiFeO₃ film, high degree of (110) preferred orientation, high Fe³⁺ content, low surface roughness, reduction of Fe³⁺ valence fluctuation to Fe²⁺ ions, and decrease in oxygen vacancies. Such BiFeO₃ thin films with various RE₂O₃ buffer layers using spin-coating method pave a pathway toward practical applications of spintronic, sensor and memory.