Local thickness and composition measurements from scanning convergent-beam electron diffraction of a binary...

The nanometer-scale spatial distributions of local thickness or composition of noncrystalline materials are generally measured by spectroscopy with scanning transmission electron microscopy (STEM). Since spectroscopy requires a high electron dose and causes irradiation damage, alternative non-spectroscopic methods are required to measure the local thickness or composition of electron-sensitive noncrystalline materials. Here, we focus on the radial distribution function (RDF) of the electron diffraction of non-crystalline materials. We confirm that the RDF of the electron diffraction obtained by simulation contains information on the thickness and composition. Next, we demonstrate the determination of both thickness and composition from experimentally obtained RDFs. Although some constraints are required, we determine the local thickness and composition of a BaO-SiO2 glass sample by comparing the RDFs of diffraction measured by a high-speed pixelated detector with those of the simulated diffractions. Collaterally, this determination method can improve the quality of STEM images.