Quantitative phase imaging of electron waves using selected-area diffraction

A method for quantitative phase imaging of electron waves was developed based on diffractive imaging. Phase images over field of views of more than 100 nm were reconstructed from pairs of a selected-area diffraction pattern and a transmission electron microscopy image. The illumination wave field was reconstructed uniformly with a phase fluctuation of less than 0.1 rad and a spatial resolution of 2-3 nm. The phase image for wedge-shaped silicon was converted to a thickness map, which agreed quantitatively with electron energy-loss spectroscopy. The present method is also valid for arbitrary-shaped samples even if dynamical diffraction effects are significant.