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-μ-meter spatial resolution, allowing determination of the Al content. NWs consist of GaAs for TG<475°C, but show a two-fold compositional structure for TG>475°C, namely an AlxGa1-xAs core surrounded by an AlyGa1-yAs (y<x) shell, ascribed to the combination of Au-catalyzed (axial) and conventional (sidewall) growth. The cross-sectional shape of AlGaAs NWs changes from triangular (for TG=500÷525°C) to almost hexagonal (for TG=550°C), due to an exchange between {211} and {110} planes as the slowest to grow. The NWs have free-electron concentrations ∼10^18 cm^-3, due to Si contamination of the Al source.
Inner composition, defects and morphology of AlGaAs nanowire grown by Au-catalyzed MOVPE
PRETE, Paola;LOVERGINE, Nicola;
2011-01-01
Abstract
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-μ-meter spatial resolution, allowing determination of the Al content. NWs consist of GaAs for TG<475°C, but show a two-fold compositional structure for TG>475°C, namely an AlxGa1-xAs core surrounded by an AlyGa1-yAs (yI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
