"Impurity Segregation via Extended Defects in Oxide Thin Films Probed by Aberration-Corrected STEM-EELS"

David J. Baek: Di Lu, Yasuyuki Hikita, Harold Y. Hwang and Lena F. Kourkoutis; Microscopy and Microanalysis, 07/25/16.

Additional Authors: Di Lu, Yasuyuki Hikita, Harold Y. Hwang and Lena F. Kourkoutis

Abstract:

To realize novel functional properties in perovskites, oxide thin films are often deposited on a dissimilar underlying substrate. However, as a consequence, misfit dislocations (MD) can form at the interface as a strain relaxation mechanism during growth. This in turn allows stress-assisted segregation of impurities to occur at the defects. As physical properties of oxides depend heavily on stoichiometric growth, it is critical to understand the precise role defects play during impurity segregation and migration. To address this issue, here, we employ aberration-corrected STEM-EELS to obtain atomic-scale information of the structural, chemical, and electronic changes that take place around defects. The oxide system probed in this work was prepared by depositing a [La0.7Sr0.3MnO3]5/[SrTiO3]5 superlattice (SL) film on top of the SrTiO3 (001) substrate with an intermediate layer of the elastic perovskite-like material Sr3Al2O6 (SAO) using pulsed laser deposition [1].