Threading dislocation generation in epitaxial (Ba,Sr)TiO3 films grown on (001) LaAlO3 by pulsed laser deposition

Epitaxial Ba0.6Sr0.4TiO3 films were grown onto (001) LaAlO3 by pulsed-laser deposition, and the dislocation structures of the films were investigated using transmission electron microscopy. Misfit dislocations with a periodicity of about 7 nm and Burgers vectors b=a<100> were observed at the interface. A high density of threading dislocations was present the films and these also had b=a<100>. The data indicate that the threading dislocations are not generated as the result of half-loop climb from the deposit surface as proposed previously, but are instead formed when misfit dislocations are forced away from the interface during island coalescence. (C) 2004 American Institute of Physics.