HRTEM Study of the Extended Defect Structure in Epitaxial Ba_(0.3)Sr_(0.7)TiO_3 Thin Films Grown on (001) LaAlO_3

摘要

The defect structure of a 350-nm-thick epitaxial Ba_(0.3)Sr_(0.7)TiO_3 thin film grown on (001) LaAlO_3 has been investigated using conventional and high-resolution transmission electron microscopy. The predominant defects in the film are threading dislocations (TDs) with Burgers vectors b = <100> and <110>. A high density of extended stacking faults (SFs) with displacement vectors R = (1/2)<110> were also observed in the near-interface region of the film. The faults are associated with dissociated dislocations and partial halfloops. Some findings about dislocation dissociation and the atomic structure of the (1/2)<110> faults are observed for the first time in perovskites to our knowledge. The mechanisms for the generation, dissociation and evolution of the TDs as well as for the formation mechanism of the SFs are discussed.