Toward complex observation in electron microscopy using two-dimensional electron detector coupled with phase plate STEM.

A two-dimensional (2D) detector was used to construct phase plate STEM (P-STEM) images. Phase-contrast can be enhanced by the electron intensity inside the hole region of a thin film phase plate. The electron intensity outside the hole region also provides a dark image contrast, which is inconsistent with the weak phase object approximation. We consider that both images have scattering effects that provide a dark contrast. Therefore, scattering contrast was derived by summing these two images, and scattering effects were subtracted from each image to display negative and positive phase contrast. The resultant images are consistent with the weak phase object approximation. These results propose separating scattering (electron amplitude) and phase-contrast (electron phase) using P-STEM, along with a two-dimensional electron detector.