Self-assembling growth of (Ba,Sr)TiO3 epitaxial thin films

Abstract

Ferroelectric thin films of SrTiO3, BaTiO3, and (Ba,Sr)TiO3 were fabricated epitaxially on SrTiO3(100) and Si(111) single crystal substrates in an ultrahigh vacuum (10−5 Pa) by laser molecular beam epitaxy. The lowest crystallization temperatures of homoepitaxial thin films of SrTiO3 and heteroepitaxial thin films of BaTiO3 and (Ba,Sr)TiO3 on SrTiO3(100) substrates obtained were as low as 280, 330, and 340 °C, respectively. With the growth rate lower than 0.17 Å/s, it was discovered that the thickness of each layer of BTO film was an integral of the BTO unit cell height. When the growth rate was decreased from 0.17 to 0.05 Å/s, the thickness of each layer varied from nine unit cells to one unit cell. It is very important to construct a nanometer structure of inorganic ABO3 perovskite oxides by this kind of self-assembly.