Influence of misfit dislocation on dopant segregation at complex oxide heterointerfaces

Complex oxide heterointerfaces and thin-films have emerged as promising candidates for diverse applications, wherein interfaces formed by joining two different oxides play a central role in novel properties not present in individual components. Lattice mismatch between the two oxides leads to the formation of misfit dislocations, which influence vital properties. In oxides, doping is often used as a strategy to improve properties. However, dopant segregation to misfit dislocations, an outcome not well understood, could be detrimental for e.g. ionic transport. We have used atomistic simulations to study the influence of misfit dislocations on dopant segregation at SrTiO₃/MgO heterointerfaces, considering two interfacial chemistries where the misfit dislocation structure differs. For both interfaces, we will examine doping of SrTiO₃ with various trivalent dopants. We find that all dopants have a thermodynamic preference to go to the interface, but the tendency to segregate is much stronger at TiO₂-terminated interfaces. Our results indicate that different dislocation structures at the interface could impact dopant segregation, thereby influencing ionic transport. Overall, our results offer a fundamental atomic-scale perspective of dopant behavior at complex oxide heterointerfaces.