Imaging Negative Charge around Single Vanadium Dopant Atoms in Monolayer Tungsten Diselenide Using 4D Scanning Transmission Electron Microscopy.

There has been extensive activity exploring the doping of semiconducting two-dimensional (2D) transition metal dichalcogenides in order to tune their electronic and magnetic properties. The outcome of doping depends on various factors, including the intrinsic properties of the host material, the nature of the dopants used, their spatial distribution, as well as their interactions with other types of defects. A thorough atomic-level analysis is essential to fully understand these mechanisms.

Assessment of Active Dopants and p-n Junction Abruptness Using In Situ Biased 4D-STEM.

A key issue in the development of high-performance semiconductor devices is the ability to properly measure active dopants at the nanometer scale. In a p-n junction, the abruptness of the dopant profile around the metallurgical junction directly influences the electric field. Here, a contacted nominally symmetric and highly doped ( = = 9 × 10 cm) silicon p-n specimen is studied through in situ biased four-dimensional scanning transmission electron microscopy (4D-STEM).