Dislocations often occur in thin films with large misfit strain as a result of strain energy accumulation and can drastically change the film properties. Here the structure and dislocations in oxide heterostructures with large misfit strain are investigated on atomic scale. When grown on SrTiO₃ (001), the dislocations in both the monolithic BaTiO₃ thin film and its superlattices with SrIrO₃ appear above a critical thickness around 6nm. The edge component of the dislocations is seen in both cases with the Burgers vector of a ⟨100⟩. However, compared to monolithic BaTiO₃, the dislocation density is slightly lower in BaTiO₃/SrIrO₃ superlattices. In the superlattice, when considering the SrTiO₃ lattice constant as the reference, BaTiO₃ has a larger misfit strain comparing with SrIrO₃. It is found that in both cases, the formation of dislocation is only affected by the critical thickness of the film with larger lattice misfit (BaTiO₃), regardless of the existence of a strong octahedral tilt/rotation mismatch at BaTiO₃/SrIrO₃ interface. Our findings suggest that it is possible to control the position of dislocations, an important step toward defect engineering.

由于应变能积累，位错经常发生在具有大错配应变的薄膜中，并且可以极大地改变薄膜的特性。在这里，在原子尺度上研究了具有大错配应变的氧化物异质结构中的结构和位错。当在 SrTiO ₃ (001)上生长时，单片 BaTiO ₃薄膜及其具有 SrIrO _{3 的}超晶格中的位错出现在大约 6nm 的临界厚度之上。位错的边缘分量在两种情况下都可以通过⟨100⟩的 Burgers 向量看到。然而，与整体式 BaTiO ₃相比，BaTiO ₃ /SrIrO _{3 中}的位错密度略低 超晶格。在超晶格中，当以SrTiO ₃晶格常数为参考时，BaTiO ₃与SrIrO ₃相比具有更大的错配应变。发现在这两种情况下，位错的形成仅受具有较大晶格失配（BaTiO ₃）的薄膜临界厚度的影响，而不管BaTiO ₃ /SrIrO ₃界面是否存在强八面体倾斜/旋转失配. 我们的研究结果表明，控制位错的位置是可能的，这是缺陷工程的重要一步。