Interfacial dislocations in (111) oriented (Ba0.7Sr0.3)TiO3 films on SrTiO3 single crystal

Abstract

We have investigated the interfacial structure of epitaxial (Ba,Sr)TiO3 films grown on (111)-oriented SrTiO3 single-crystal substrates using transmission electron microscopy (TEM) techniques. Compared with the (100) epitaxial perovskite films, we observe dominant dislocation half-loop with Burgers vectors of a⟨110⟩ comprised of a misfit dislocation along ⟨112⟩, and threading dislocations along ⟨110⟩ or ⟨100⟩. The misfit dislocation with Burgers vector of a⟨110⟩ can dissociate into two ½a⟨110⟩ partial dislocations and one stacking fault. We found the dislocation reactions occur not only between misfit dislocations, but also between threading dislocations. Via three-dimensional electron tomography, we retrieved the configurations of the threading dislocation reactions. The reactions between threading dislocations lead to a more efficient strain relaxation than do the misfit dislocations alone in the near-interface region of the (111)-oriented (Ba0.7Sr0.3)TiO3 films.