A Story Told by a Single Nanowire: Optical Properties of Wurtzite GaAs

The optical properties of the wurtzite (WZ) GaAs crystal phase found in nanowires (NWs) are a highly controversial topic. Here, we study high-quality pure WZ GaAs/AlGaAs core–shell NWs grown by Au-assisted molecular beam epitaxy (MBE) with microphotoluminescence spectroscopy (μ-PL) and (scanning) tr...

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Bibliographic Details
Published in:Nano letters 2012-12, Vol.12 (12), p.6090-6095
Main Authors: Ahtapodov, Lyubomir, Todorovic, Jelena, Olk, Phillip, Mjåland, Terje, Slåttnes, Patrick, Dheeraj, Dasa L, van Helvoort, Antonius T. J, Fimland, Bjørn-Ove, Weman, Helge
Format: Article
Language:English
Subjects:
Aluminum gallium arsenides
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Cross-disciplinary physics: materials science
rheology
Electron states
Exact sciences and technology
Excitons and related phenomena
Gallium arsenide
Gallium arsenides
Materials science
Molecular beam epitaxy
Nanocrystalline materials
Nanoscale materials and structures: fabrication and characterization
Nanowires
Optical properties
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
Physics
Quantum wires
Scanning electron microscopy
Wurtzite
Zinc
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Summary:The optical properties of the wurtzite (WZ) GaAs crystal phase found in nanowires (NWs) are a highly controversial topic. Here, we study high-quality pure WZ GaAs/AlGaAs core–shell NWs grown by Au-assisted molecular beam epitaxy (MBE) with microphotoluminescence spectroscopy (μ-PL) and (scanning) transmission electron microscopy on the very same single wire. We determine the room temperature (294 K) WZ GaAs bandgap to be 1.444 eV, which is ∼20 meV larger than in zinc blende (ZB) GaAs, and show that the free exciton emission at 15 K is at 1.516 eV. On the basis of time- and temperature-resolved μ-PL results, we propose a Γ8 conduction band symmetry in WZ GaAs. We suggest a method for quantifying the optical quality of NWs, taking into consideration the difference between the room and low temperature integrated PL intensity, and demonstrate that Au-assisted GaAs/AlGaAs core–shell NWs can have high PL brightness up to room temperature.
ISSN:1530-6984
1530-6992
DOI:10.1021/nl3025714