Synthesis of AlAs and AlAs_GaAs Core_Shell Nanowires

The growth of free-standing AlAs nanowires on GaAs (111)B substrates by chemical beam epitaxy is presented. Nanowire growth was achieved by employing trimethylaluminium and tertiarybutylarsine as metal-organic precursors and Au as catalyst. Different temperature and group III partial pressure values were examined to investigate the growth mechanism. Furthermore, synthesis of a GaAs shell is proposed as a way to protect the AlAs nanowires from rapid oxidization. In situ reflection high energy electron diffraction analysis and ex situ scanning and transmission electron microscopy studies were performed on both AlAs and AlAs-GaAs core-shell nanowires in order to assess crystal perfection and structure of the nanowires.