The initial stage of BaTiO3 epitaxial films on etched and annealed SrTiO3 substrates

Effects of the surface states on the initial stage of the epitaxial growth of BaTiO3 films have been studied. Surface of (100) SrTiO3 substrate is modified by pre-treatment (annealing or KCl etching). By the AFM observation, it is shown that the surface of the annealed substrate composes of steps and terraces. The 60 nm thick BaTiO3 films are deposited by a RF-magnetron sputtering method on the as-received, the etched, and the annealed substrates. The XRD and RHEED patterns reveal that these films grow epitaxially, and that the crystallinities of these films are different in each of them. The effects of the surface states of three kinds of substrates on the initial stage of the BaTiO3 films (below 3 nm thick) are investigated using RHEED and AFM. There are differences in their growth processes.