Catalytic role of gold nanoparticle in GaAs nanowire growth: a density functional theory study |
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Authors: | Kratzer Peter Sakong Sung Pankoke Volker |
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Affiliation: | Fakult?t für Physik and Center for Nanointegration (CENIDE), Universit?t Duisburg-Essen, Lotharstrasse 1, 47048 Duisburg, Germany. Peter.Kratzer@uni-due.de |
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Abstract: | The energetics of Ga, As, and GaAs species on the Au(111) surface (employed as a model for Au nanoparticles) is investigated by means of density functional calculations. Apart from formation of the compound Au(7)Ga(2), Ga is found to form a surface alloy with gold with comparable ΔH ~ -0.5 eV for both processes. Dissociative adsorption of As(2) is found to be exothermic by more than 2 eV on both clean Au(111) and AuGa surface alloys. The As-Ga species formed by reaction of As with the surface alloy is sufficiently stable to cover the surface of an Au particle in vacuo in contact with a GaAs substrate. The results of the calculations are interpreted in the context of Au-catalyzed growth of GaAs nanowires. We argue that arsenic is supplied to the growth zone of the nanowire mainly by impingement of molecules on the gold particle and identify a regime of temperatures and As(2) partial pressures suitable for Au-catalyzed nanowire growth in molecular beam epitaxy. |
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