Microstructure and strain in thin ferroelectric BaTiO3 films epitaxially grown on MgO substrates

High-resolution x-ray diffraction and high-resolution scanning electron microscopy have been applied to characterize BaTiO3 films of different thicknesses, metal-organic chemical vapour deposition grown on MgO substrates. We found a strong correlation between the strain state of the films and the amount of specific material discontinuities, the latter serving as an effective channel of strain relaxation. The results obtained are explained by considering the structural misfit arising at the interface between in-plane oriented 90 deg domains.