Inner composition, defects and morphology of AlGaAs nanowires grown by Au-catalyzed MOVPE

The inner composition, defect content and morphology of AlGaAs nanowires (NWs) grown on (111)B-GaAs by Au-catalyzed MOVPE is reported. The NWs grow tapered with their [111] axis normal to the substrate. The Raman spectra of single AlGaAs NWs were measured in non-resonant conditions with sub-?-meter spatial resolution, allowing determination of the Al content. NWs consist of GaAs for T G<475°C, but show a two-fold compositional structure for T G>475°C, namely an Al xGa 1-xAs core surrounded by an Al yGa 1-yAs (y