Quantitative HAADF-STEM on heterostructured GaAs nanowires

Abstract

GaAs nanowires are a highly promising candidate for future optoelectronic applications. Here quantitative high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) has been used for studying the Sb content x in zinc blende (ZB) GaAs1-xSbx axial inserts in otherwise pure wurtzite (WZ) GaAs nanowires. Direct comparison of the normalized experimental HAADF-STEM image intensities with simulated intensities displayed a good match for the pure structure. It was discovered that the Sb content in a 20 nm long insert is not uniform but increases from 13 ± 3 at.% at the lower to 21 ± 3 at.% at the upper WZ-ZB interface. Non-compositional effects on HAADF intensity have been identified.