Heterostructures of BaTiO3 bilayer films grown on SrTiO3 (0Â 0Â 1) under different oxygen pressures

BaTiO3 bilayer films are deposited on SrTiO3 substrates under different oxygen pressures by pulsed laser deposition. The structural properties of the bilayers are investigated by means of X-ray diffraction, Rutherford backscattering spectrometry, conventional and high-resolution transmission electron microscopy. The BaTiO3 layer with the thickness of 115 nm deposited under higher oxygen pressure (3×10−1mbar) exhibits a cubic-like structure with lattice parameter a=0.399nm. The BaTiO3 layer with the thickness of 220 nm deposited under lower oxygen pressure (2×10−3 mbar) shows a c-axis-oriented domain structure with lattice parameters a=0.401nm and c=0.411nm. The interface of the BaTiO3 bilayer films is coherent and no interfacial dislocations can be seen over larger regions. The misfit dislocations with Burgers vector of type a〈1 0 0〉 are observed at the interface between bottom BaTiO3 layer and SrTiO3 substrates.