Atomic-resolution annular dark-field STEM image calculations

Abstract

A method based on the three-dimensional Bloch wave description has been developed for the simulation of atomic-resolution annular dark-field (ADF) scanning transmission electron microscopy (STEM) images, which includes the coherent Bragg reflection and the incoherent thermal diffuse scattering (TDS). The contribution of TDS is estimated using two kinds of optical potentials. The validity and accuracy of the method are demonstrated by comparisons in focus dependence between experimental and calculated high-angle (HA) ADF STEM images and in thickness dependence between experimental and calculated ADF STEM intensities. The method reduces the computing time for a HAADF STEM image calculation to about one-tenth of that required for the usual three-dimensional Bloch wave method.