Threading dislocation generation in epitaxial (Ba,Sr)TiO_(3) films grown on (001) LaAlO_(3) by pulsed laser deposition

摘要

Epitaxial Ba_(0.6)Sr_(0.4)TiO_(3) films were grown onto (001) LaAlO_(3) 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.