Conservative antiphase boundary in SrTiO3 films on LaAlO3 substrates with SrRuO3 buffer layers

We have studied the microstructure of SrTiO3 films on LaAlO3 substrates with the SrRuO3 buffer layer using high-resolution transmission electron microscopy. While high density of defects due to lattice mismatch were found at the SrRuO3/LaAlO3 interface, no misfit dislocation was observed at the SrTiO3/SrRuO3 interface. The {111} stacking fault in the SrRuO3 buffer layer propagates into the SrTiO3 film, giving rise to a type of antiphase boundary on the {110} plane with a crystallographic shear vector of a/2〈001〉. The boundary is a conservative one which does not lead to any charge defects. A model based on dislocation interactions is proposed to explain the generation mechanism of the antiphase boundary.