Atomic‐Scale Insights into the 2D Materials from Aberration‐Corrected Scanning Transmission Electron Microscopy: Progress and Future

Abstract

2D crystals are attractive due to their unique atomic, electronic structures, and physiochemical properties, which strongly rely on the synthesis conditions. The atomic structure and presence of defects in the crystal lattice, such as vacancies, dopants, grain boundaries, and edge terminations, significantly influence the properties of 2D materials. Due to its high spatial resolution, aberration‐corrected scanning transmission electron microscopy (AC‐STEM) has become a powerful tool to provide atomic‐scale insights into the crystal structure, defects, heterointerfaces, ferroelectricity, and in situ observations of 2D materials. This review will cover the status of atomic‐scale studies on various 2D materials, including graphene, boron nitride, transition metal dichaogenides, MXenes, and phosphorene using AC‐STEM. The future perspective of AC‐STEM for new findings in 2D materials using machine learning is further discussed.

Two-dimensional materials for future information technology: status and prospects

“…An annular dark-field STEM (ADF-STEM) image is obtained by inserting off-axis annular detectors to collect the electrons with different scattered angle ranges. High-angle ADF-STEM (HAADF-STEM) is the most frequently used mode, which has contrast directly related to atomic number (Z) as Z 1.6−2 and is beneficial to detect heavy elements [160]. Medium-angle ADF-STEM (MAADF-STEM) is less dependent on Z contrast and is usually used for atomicresolution analysis of 2D materials comprising light elements [161].…”