Evolution of dislocation arrays in epitaxial $BaTiO3$ thin films grown on (100) $SrTiO3$

Dislocation arrays and dislocation half-loops in $BaTiO3$ thin films were characterized using transmission electron microscopy (TEM). $BaTiO3$ films with thicknesses ranging from 2 to 20 nm were grown on (100) $SrTiO3$ by reactive molecular beam epitaxy (MBE). The critical thickness for dislocations to occur in this system was found to lie between 2 and 4 nm. The misfit dislocations are mainly 〈100〉 type. The average spacing between the dislocations in the array becomes smaller when the film is thicker, which indicates gradual relaxation of mismatch strain with increasing film thickness.