Comparison of structural, microstructural, and electrical analyses of barium strontium titanate thin films

The results of structural and electrical characterizations of a barium strontium titanate (Ba0.5Sr0.5TiO3) film, including low temperature x-ray diffraction, low temperature, field dependent Raman spectroscopy, transmission electron microscopy, and low temperature, field dependent microwave measurements, are compared and contrasted. The structural characterization showed the film to be a good single crystal, epitaxial with the (001) MgO substrate. In the ferroelectric state, the tetragonal axis lies in plane leading to a 90 degrees domain structure. A high density of misfit and threading dislocations was observed in the film. The transition to the paraelectric state on warming was shown to be diffuse and appeared to be strongly influenced by local variations in strain which were attributed to the defective microstructure. The dielectric response was also dominated by such effects.