Hydride-assisted growth of GaN nanowires on Au/Si(0 0 1) via the reaction of Ga with NH3 and H2 |
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Authors: | Matthew Zervos Andreas Othonos |
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Affiliation: | 1. Nanostructured Materials & Devices Laboratory, Department of Mechanical Engineering, Materials Science Group, University of Cyprus, Kalipoleos 75, 1678 Nicosia, P.O. Box 20573, Cyprus;2. Research Centre of Ultrafast Science, Department of Physics, University of Cyprus, Kalipoleos 75, 1678 Nicosia, P.O. Box 20573, Cyprus |
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Abstract: | High quality, straight GaN nanowires (NWs) with diameters of 50 nm and lengths up to 3 μm have been grown on Si(0 0 1) using Au as a catalyst and the direct reaction of Ga with NH3 and N2:H2 at 900 °C. These exhibited intense, near band edge photoluminescence at 3.42 eV in comparison to GaN NWs with non-uniform diameters obtained under a flow of Ar:NH3, which showed much weaker band edge emission due to strong non-radiative recombination. A significantly higher yield of β-Ga2O3 NWs with diameters of ≤50 nm and lengths up to 10 μm were obtained, however, via the reaction of Ga with residual O2 under a flow of Ar alone. The growth of GaN NWs depends critically on the temperature, pressure and flows in decreasing order of importance but also the availability of reactive species of Ga and N. A growth mechanism is proposed whereby H2 dissociates on the Au nanoparticles and reacts with Ga giving GaxHy thereby promoting one-dimensional (1D) growth via its reaction with dissociated NH3 near or at the top of the GaN NWs while suppressing at the same time the formation of an underlying amorphous layer. The higher yield and longer β-Ga2O3 NWs grow by the vapor liquid solid mechanism that occurs much more efficiently than nitridation. |
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Keywords: | A1. Nanostructures A1. Nanowires A3. Hydride vapor phase epitaxy B1. Nanomaterials B1. Nitrides B1. Oxides |
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