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

Published online by Cambridge University Press:  08 July 2011

P. Prete
Affiliation:
IMM-CNR, Lecce Research Unit, Lecce, Italy
B. Buick
Affiliation:
Physics Department, University of Rome ‘Tor Vergata’, Rome, Italy
E. Speiser
Affiliation:
Physics Department, University of Rome ‘Tor Vergata’, Rome, Italy
N. Lovergine
Affiliation:
Dept. of Innovation Engineering, University of Salento, Lecce, Italy
W. Richter
Affiliation:
Physics Department, University of Rome ‘Tor Vergata’, Rome, Italy
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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 (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 and {110} planes as the slowest to grow. The NWs have free-electron concentrations ∼1018 cm-3, due to Si contamination of the Al source.

Type
Research Article
Copyright
Copyright © Materials Research Society 2011

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