Effect of nonstoichiometry on microstructure of epitaxially grown BaTiO3 thin films

The microstructural features over a wide range of cation nonstoichiometry in barium titanate thin films grown on (100) SrTiO3 substrates by pulsed laser deposition were investigated by X-ray diffraction and transmission electron microscopy. Well-crystallized perovskite barium titanate was heteroepitaxially grown even with 20% excess titanium,but the film contained column-like amorphous secondary phases and some planar defects; In the case of 50% excess titanium, the film consisted of columnar nanocrystallites epitaxially grown on the substrate and a surrounding titanium-rich amorphous-matrix. The incorporation of 50% excess barium, on the other hand, significantly degraded film crystallinity due to the formation of nanometer-scale amorphous phases.