Structural engineering of Ba0.5Sr0.5TiO3 epitaxial films

Abstract Ba 0.5 Sr 0.5 TiO 3 single-layered and multilayered films were epitaxially grown on a (001) LaAlO 3 substrate using single target and dual target pulsed laser deposition, respectively. Compared to the single-layered films, the multilayered films exhibited broader phase transition and improved thermo-stability. The microstructure of these epitaxial films was investigated using high-resolution transmission electron microscopy in details. Misfit and threading dislocations were observed in the single-layered film, while the threading dislocations were dramatically decreased and no misfit dislocations were found in the multilayered film. It is suspected that the difference in dislocation densities is responsible for the different behaviors of the permittivity with temperature.