A novel growth method to improve the quality of GaAs nanowires grown by Ga-assisted chemical beam epitaxy

García Núñez, C. , Braña, A. F., López, N. and García, B. J. (2018) A novel growth method to improve the quality of GaAs nanowires grown by Ga-assisted chemical beam epitaxy. Nano Letters, 18(6), pp. 3608-3615. (doi: 10.1021/acs.nanolett.8b00702)

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The successful synthesis of high crystalline quality and high aspect ratio GaAs nanowires (NWs) with a uniform diameter is needed to develop advanced applications beyond the limits established by thin film and bulk material properties. Vertically aligned GaAs NWs have been extensively grown by Ga-assisted vapor–liquid–solid (VLS) mechanism on Si(111) substrates, and they have been used as building blocks in photovoltaics, optoelectronics, electronics, and so forth. However, the nucleation of parasitic species such as traces and nanocrystals on the Si substrate surface during the NW growth could affect significantly the controlled nucleation of those NWs, and therefore the resulting performance of NW-based devices. Preventing the nucleation of parasitic species on the Si substrate is a matter of interest, because they could act as traps for gaseous precursors and/or chemical elements during VLS growth, drastically reducing the maximum length of grown NWs, affecting their morphology and structure, and reducing the NW density along the Si substrate surface. This work presents a novel and easy to develop growth method (i.e., without using advanced nanolithography techniques) to prevent the nucleation of parasitic species, while preserving the quality of GaAs NWs even for long duration growths. GaAs NWs are grown by Ga-assisted chemical beam epitaxy on oxidized Si(111) substrates using triethylgallium and tertiarybutylarsine precursors by a two-step-based growth method presented here; this method includes a growth interruption for an oxidation on air between both steps of growth, reducing the nucleation of parasitic crystals on the thicker SiOx capping layer during the second and longer growth step. VLS conditions are preserved overtime, resulting in a stable NW growth rate of around 6 μm/h for growth times up to 1 h. Resulting GaAs NWs have a high aspect ratio of 85 and average radius of 35 nm. We also report on the existence of characteristic reflection high-energy electron diffraction patterns associated with the epitaxial growth of GaAs NWs on Si(111) substrates, which have been analyzed and compared to the morphological characterization of GaAs NWs grown for different times under different conditions.

Item Type:Articles
Additional Information:Research work supported by the Spanish Ministerio de Ciencia e Innovacion (TEC2010-20796 and TEC2013-48350-R).
Glasgow Author(s) Enlighten ID:Garcia Nunez, Dr Carlos
Authors: García Núñez, C., Braña, A. F., López, N., and García, B. J.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:Nano Letters
Publisher:American Chemical Society
ISSN (Online):1530-6992
Published Online:08 May 2018
Copyright Holders:Copyright © 2018 American Chemical Society
First Published:First published in Nano Letters 18(6):3608-3615
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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