STEM beam channeling in BaSnO/LaAlO perovskite bilayers and visualization of 2D misfit dislocation network.

A study of the STEM probe channeling in a heterostructured crystalline bilayer specimens is presented here with a goal to guide STEM-based characterization of multilayer structures. STEM analysis of perovskite BaSnO/LaAlO bilayers is performed and the dominating effects of beam channeling on HAADF- and LAADF-STEM are illustrated. To study the electron beam channeling through BaSnO/LaAlO bilayers, probe intensity depth profiles are calculated, and the effects of probe defocus and atomic column alignment are discussed. Characteristics of the beam channeling are correlated to resulting ADF-STEM images, which is then tested by comparing focal series of plan-view HAADF-STEM images to those recorded experimentally. Additionally, discussions on how to visualize the misfit dislocation network at the BaSnO/LaAlO interface using HAADF- and LAADF-STEM images are provided.