Flattening Phenomenon Observed during Epitaxial Growth of BaTiO3 by Alternating Deposition Method

We observed a flattening phenomenon during epitaxial growth of BaTiO3 films by alternate depositions of BaO and TiO2. When more than one monolayer (ML) of TiO2 was deposited excessively, surface smoothness degraded due to three-dimensional (3D) growth observed by reflection high-energy electron diffraction (RHEED) and atomic force microscope (AFM). However, subsequent BaO deposition onto the rough TiO2 surface significantly recovered the surface smoothness. It was found that a single-phase BaTiO3 film grew by repeating the alternate deposition cycle of roughening by excessive deposition of TiO2 and subsequent flattening by deposition of BaO.