Formation of dislocations via misfit strain across interfaces in epitaxial BaTiO₃ and SrIrO₃ heterostructures

Abstract

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 6 nm. 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.

Rational Manipulation of Epitaxial Strains Enabled Valence Band Convergence and High Thermoelectric Performances in Mg3Sb2 Films

“…Herein, we summarize the typical cases of strain engineering in functional inorganic films, as shown in Figure 6e. Effective strain engineering could be realized by various approaches, such as utilizing the stretch stage, [59][60][61][62] the thermal mismatch engineering, [63][64][65][66][67] the interface engineering, [68][69][70][71][72][73] and the scaffold network. [74][75][76] Taking perovskite-structured compounds as examples, lattice strains up to ≈1.7%, ≈4.6%, ≈0.8%, and ≈2.6% could be introduced into the material by the above four approaches, respectively.…”

Misfit layered compounds: Unique, tunable heterostructured materials with untapped properties

“…Complex rearrangements of local bonding between layers in misfits generate structural distortions during the actual crystal growth, which reduces the amount of structural strain and stabilizes the misfit 89,[112][113][114] . Reprinted with permission from Elsevier 154 .…”