STEM beam channeling in BaSnO3/LaAlO3 perovskite bilayers and visualization of 2D misfit dislocation network

TL;DR

This paper investigates STEM beam channeling effects in BaSnO3/LaAlO3 bilayers, providing insights into image formation and visualization of dislocation networks for complex perovskite heterostructures.

Contribution

It offers a detailed analysis of beam channeling effects in STEM imaging of perovskite bilayers and proposes methods to visualize misfit dislocation networks.

Findings

Beam channeling significantly influences HAADF- and LAADF-STEM images.

Probe defocus and atomic alignment affect electron propagation and image contrast.

Comparison of simulated and experimental focal series validates the analysis.

Abstract

A study of the STEM probe channeling in a heterostructures crystalline specimen is presented here with a goal to guide appropriate STEM-based characterization for complex structures. STEM analysis of perovskite BaSnO3/LaAlO3 bilayers is performed and the dominating effects of beam channeling on HAADF- and LAADF-STEM are illustrated. To study the electron beam propagating through BaSnO3/LaAlO3 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 BaSnO3/LaAlO3 interface using HAADF- and LAADF-STEM images are provided.