Mapping Electrostatic Potential Distributions at the Nanoscale in an Electron Microscope.

Because of their high spatial resolution and wide range of signals that can be collected, electron microscopes offer a plethora of possibilities to characterize materials at the nanoscale. This mini-review focuses on a small subset of those, providing an overview of holographic techniques in transmission electron microscopy (TEM), such as off-axis holography, inline holography, differential phase contrast, tilt-corrected bright-field scanning TEM, and ptychography, for mapping electrostatic potentials in thin TEM specimens. We compare their intrinsic strengths and limitations and discuss some of their applications to nanoscale materials relevant to electronics, quantum technology, or energy conversion.