Structure, optical properties and defects in nitride (III–V) nanoscale cage clusters

S. A. Shevlin; Z. X. Guo; H. J. J. van Dam; P. Sherwood; C. R. A. Catlow; A. A. Sokol; S. M. Woodley

doi:10.1039/B719838H

Structure, optical properties and defects in nitride (III–V) nanoscale cage clusters

S. A. Shevlin,^a Z. X. Guo,^a H. J. J. van Dam,^b P. Sherwood,^b C. R. A. Catlow,^c A. A. Sokol*^c and S. M. Woodley^c

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* Corresponding authors

^a Department of Chemistry, University College London, Gower Street, London, UK
E-mail: s.shevlin@ucl.ac.uk

^b Daresbury Laboratory, Science and Technology Facilities Council, Daresbury Science and Innovation Campus, Daresbury, Warrington, UK
E-mail: h.j.j.vandam@dl.ac.uk

^c Davy Faraday Research Laboratory, University College London, 3, rd , Floor, Kathleen Lonsdale Building, Gower Street, London, UK
E-mail: a.sokol@ucl.ac.uk

Abstract

Density Functional Theory calculations are reported on cage structured BN, AlN, GaN and InN sub- and low nanosize stoichiometric clusters, including two octahedral families of T_d and T_h symmetry. The structures and energetics are determined, and we observe that BN clusters in particular show high stability with respect to the bulk phase. The cluster formation energy is demonstrated to include a constant term that we attribute to the curvature energy and the formation of six tetragonal defects. The (BN)₆₀ onion double-bubble structure was found to be particularly unstable. In contrast, similar or greater stability was found for double and single shell cages for the other nitrides. The optical absorption spectra have been first characterised by the one-electron Kohn–Sham orbital energies for all compounds, after which we concentrated on BN where we employed a recently developed Time Dependent Density Functional Theory approach. The one-electron band gaps do not show a strong and consistent size dependency, in disagreement with the predictions of quantum confinement theory. The density of excited bound states and absorption spectrum have been calculated for four smallest BN clusters within the first ionisation potential cut-off energy. The relative stability of different BN clusters has been further explored by studying principal point defects and their complexes including topological B–N bond rotational defects, vacancies, antisites and interstititials. The latter have the lowest energy of formation.

This article is part of the themed collection: Analysis, manipulation, and simulation on the nanoscale

Article information

https://doi.org/10.1039/B719838H

Article type

Paper

Submitted

02 Jan 2008

Accepted

05 Feb 2008

First published

27 Feb 2008

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Phys. Chem. Chem. Phys., 2008,10, 1944-1959

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Structure, optical properties and defects in nitride (III–V) nanoscale cage clusters

S. A. Shevlin, Z. X. Guo, H. J. J. van Dam, P. Sherwood, C. R. A. Catlow, A. A. Sokol and S. M. Woodley, Phys. Chem. Chem. Phys., 2008, 10, 1944 DOI: 10.1039/B719838H

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Physical Chemistry Chemical Physics

Structure, optical properties and defects in nitride (III–V) nanoscale cage clusters

Abstract

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Structure, optical properties and defects in nitride (III–V) nanoscale cage clusters

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