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

We report on the growth of polycrystalline BiFeO thin films on SiO /Si(001) and Pt(111) substrates by atomic layer deposition using the precursors ferrocene, triphenyl-bismuth, and ozone. By growing alternating layers of Fe O and Bi O , we employ a superlattice approach and demonstrate an efficient control of the cation stoichiometry. The superlattice decay and the resulting formation of polycrystalline BiFeO 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 BiFeO crystallization is initiated in the Bi O layers at 450 °C following the diffusion-driven intermixing of the cations. Our study of the BiFeO formation provides an insight into the complex interplay between microstructural evolution, grain growth, and bismuth oxide evaporation, with implications for optimization of ferroelectric properties.