Structural evolution of dislocation half-loops in epitaxial $BaTiO3$ thin films during high-temperature annealing

$BaTiO3$ thin films were grown on $(001)SrTiO3$ by reactive molecular beam epitaxy. Transmission electron microscopy studies showed that there is a high density of dislocation half-loops inside 8- and $12-nm$-thick films. By thermal annealing at $1000°C$⁠, the isolated small dislocation half-loops grow and combine to form a self-assembled regular dislocation network at the film/substrate interface. Threading dislocations in the films are removed and the lattice mismatch strain in the film is nearly completely relaxed by annealing at high temperature.