Propagation and interaction of {111} planar defects in the SrRuO3 buffer layer in SrTiO3/SrRuO3 two-layer films on LaAlO3 substrates

We studied the microstructure of {111} planar defects, including stacking faults and nanotwins, in the SrRuO3 buffer layer in SrTiO3 /SrRuO3 two-layer films on LaAlO3 substrates by means of high- resolution transmission electron microscopy. Most of the defects stop propagation in the buffer layer by mutual intersection with one another as well as by themselves without intersection. Single Frank or Shockley partial dislocations are found at the terminating end of an isolated stacking fault. We show several types of dislocation barrier formed by the intersection of two {111} stacking faults as well as when an extended dislocation changes its gliding- climbing plane. The formation mechanism of the dislocation barriers is discussed on the basis of reactions between the partial dislocations bounding the stacking faults. We also show a {111} nanotwin and its transition to an extrinsic stacking fault by a Frank partial dislocation. The contribution of the planar defects to the strain relaxation in the SrRuO3 buffer layer is discussed.