Initial growth stages of epitaxial BaTiO_3 films on vicinal SrTiO_3:Nb (001) substrates

摘要

The growth mechanism of epitaxial BaTiO_3 films on vicinal Nb-doped SrTiO_3 (SrTiO_3:Nb) (001) substrate surfaces was studied in terms of surface morphology, crystalline orientation, microstructure, and film/substrate interface. Well-oriented BaTiO_3 thin films were grown on SrTiO_3 substrates with well-defined terraces by pulsed laser deposition. The regularly terraced TiO_2-terminated surfaces of vicinal SrTiO_3:Nb (001) substrates were prepared by a definite chemical and thermal treatment. Under our conditions, BaTiO_3 seems to grow with a layer-then-island (Stranski-Krastanov) growth mechanism. In order to investigate the orientation and crystallinity of the BaTiO_3 films, x-ray diffraction and high-resolution transmission electron microscopy were performed. Ferroelectricity of the BaTiO_3 films was proved by electrical measurements performed on Pt/BaTiO_3/SrTiO_3:Nb heterostructures.