Phase imaging and atomic-resolution imaging by electron diffractive imaging

This article reviews diffractive imaging using electron beams, particularly the approach using the selector aperture in a transmission electron microscope (TEM). It proposes experimental setups and reconstruction algorithms suitable for the atomic-resolution mode and the medium-resolution mode. In the medium-resolution mode, the phase distribution of a wave field transmitted through a sample is obtained across a field of view of more than 100 nm with a phase accuracy of 0.1-0.2 rad. Through the phase imaging, a thickness map of the sample and an electrostatic potential map in/around the sample are visualized. In the atomic-resolution mode, its high-resolution ability is confirmed to be better than that of aberration-corrected TEM imaging based on experiments and theory, in which this property is attributed to the lack of direct influence of objective lens chromatic aberration. (author)