Electron Microscopy Analysis of AlGaN/GaN Nanowires Grown by Catalyst-Assisted Molecular Beam Epitaxy

Abstract

Scanning transmission electron microscopy has been used to investigate the composition of nickel seeds which promote the columnar growth of AlGaN/GaN nanowires deposited by molecular beam epitaxy (MBE) on sapphire. The nickel distribution along the nanowires was investigated by both X-ray and electron-energy-loss spectroscopy. Gallium was observed in nickel seeds at the nanowires growth tips. No aluminium was detected and a minimal presence of nitrogen was observed in the nickel seeds, which exhibit a nickel oxide surface attributed to oxidation following removal from the MBE growth system.