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

Abstract This study investigates the impact of RE 2 O 3 (Dy 2 O 3 , Yb 2 O 3 , and Lu 2 O 3 ) buffer layers on the structural and ferroelectric properties of BiFeO 3 thin films grown using a spin-coating method. BiFeO 3 thin films with various RE 2 O 3 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 RE 2 O 3 -buffered BiFeO 3 film showed better electrical properties compared to the control BiFeO 3 film. The buffer layer composed of Yb 2 O 3 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 Yb 3+ ions into the BiFeO 3 film, high degree of (110) preferred orientation, high Fe 3+ content, low surface roughness, reduction of Fe 3+ valence fluctuation to Fe 2+ ions, and decrease in oxygen vacancies. Such BiFeO 3 thin films with various RE 2 O 3 buffer layers using spin-coating method pave a pathway toward practical applications of spintronic, sensor and memory.