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Atomistic simulation of Er irradiation induced defects in GaN nanowires

Ullah, M. W. and Kuronen, A. and Stukowski, A. and Djurabekova, F. and Nordlund, K. (2014):
Atomistic simulation of Er irradiation induced defects in GaN nanowires.
In: Journal of Applied Physics, AIP Publishing LLC, p. 124313, 116, (12), ISSN 0021-8979,
[Online-Edition: http://dx.doi.org/10.1063/1.4896787],
[Article]

Abstract

Classical molecular dynamics simulation was used to irradiate a GaN nanowire with rear-earth erbium (Er). Ten cumulative irradiations were done using an ion energy of 37.5 keV on a 10 × 10 nm2 surface area which corresponds to a fluence of 1 × 1013 cm−2. We studied the location and types of defects produced in the irradiation. Er implantation leads to a net positive (expansion) strain in the nanowire and especially at the top region a clear expansion has been observed in the lateral and axial directions. The lattice expansion is due to the hydrostatic strain imposed by a large number of radiation induced defects at the top of the NW. Due to the large surface-to-volume ratio, most of the defects were concentrated at the surface region, which suggests that the experimentally observed yellow luminescence (YL) in ion implanted GaN NWs arises from surface defects. We observed big clusters of point defects and vacancy clusters which are correlated with stable lattice strain and the YL band, respectively.

Item Type: Article
Erschienen: 2014
Creators: Ullah, M. W. and Kuronen, A. and Stukowski, A. and Djurabekova, F. and Nordlund, K.
Title: Atomistic simulation of Er irradiation induced defects in GaN nanowires
Language: English
Abstract:

Classical molecular dynamics simulation was used to irradiate a GaN nanowire with rear-earth erbium (Er). Ten cumulative irradiations were done using an ion energy of 37.5 keV on a 10 × 10 nm2 surface area which corresponds to a fluence of 1 × 1013 cm−2. We studied the location and types of defects produced in the irradiation. Er implantation leads to a net positive (expansion) strain in the nanowire and especially at the top region a clear expansion has been observed in the lateral and axial directions. The lattice expansion is due to the hydrostatic strain imposed by a large number of radiation induced defects at the top of the NW. Due to the large surface-to-volume ratio, most of the defects were concentrated at the surface region, which suggests that the experimentally observed yellow luminescence (YL) in ion implanted GaN NWs arises from surface defects. We observed big clusters of point defects and vacancy clusters which are correlated with stable lattice strain and the YL band, respectively.

Journal or Publication Title: Journal of Applied Physics
Volume: 116
Number: 12
Publisher: AIP Publishing LLC
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Joint Research Laboratory Nanomaterials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 17 Nov 2014 09:00
Official URL: http://dx.doi.org/10.1063/1.4896787
Identification Number: doi:10.1063/1.4896787
Funders: Work was supported by Academy of Finland under the ENIGAZ project. , We also acknowledge support from the German Foreign Exchange Service (DAAD) through a PPP travel grant.
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