Formation of BiFeO₃ from a Binary Oxide Superlattice Grown by Atomic Layer Deposition

We report on the growth of polycrystalline BiFeO₃ thin films on SiO₂ /Si(001) and Pt(111) substrates by atomic layer deposition using the precursors ferrocene, triphenyl-bismuth, and ozone. By growing alternating layers of Fe₂ O₃ and Bi₂ O₃ , we employ a superlattice approach and demonstrate an efficient control of the cation stoichiometry. The superlattice decay and the resulting formation of polycrystalline BiFeO₃ films are studied by in situ X-ray diffraction, in situ X-ray photoelectron spectroscopy, and transmission electron microscopy. No intermediate ternary phases are formed and BiFeO₃ crystallization is initiated in the Bi₂ O₃ layers at 450 °C following the diffusion-driven intermixing of the cations. Our study of the BiFeO₃ formation provides an insight into the complex interplay between microstructural evolution, grain growth, and bismuth oxide evaporation, with implications for optimization of ferroelectric properties.