Compositional analysis of GaAs/AlGaAs heterostructures using quantitative scanning transmission electron microscopy

Abstract

We demonstrate a method for compositional mapping of AlxGa1–xAs heterostructures with high accuracy and unit cell spatial resolution using quantitative high angle annular dark field scanning transmission electron microscopy. The method is low dose relative to spectroscopic methods and insensitive to the effective source size and higher order lens aberrations. We apply the method to study the spatial variation in Al concentration in cross-sectioned GaAs/AlGaAs core-shell nanowires and quantify the concentration in the Al-rich radial band and the AlGaAs shell segments.