IBS Publications Repository: Surface-Effect-Induced Optical Bandgap Shrinkage in GaN Nanotubes

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Surface-Effect-Induced Optical Bandgap Shrinkage in GaN Nanotubes

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Author(s): Park Y.S.; Lee G.; Holmes M.J.; Chan C.C.S.; Reid B.P.L.; Alexander-Webber J.A.; Nicholas R.J.; Taylor R.A.; Kim K.S.; Sang W. Han; Yang W.; Jo Y.; Kim J.; Im H.

Subject: density functional theory, ; nanotube, ; photoluminescence, ; self-assembling nanostructures, ; semiconductor, ; surface effects

Abstract: We investigate nontrivial surface effects on the optical properties of self-assembled crystalline GaN nanotubes grown on Si substrates. The excitonic emission is observed to redshift by ∼100 meV with respect to that of bulk GaN. We find that the conduction band edge is mainly dominated by surface atoms, and that a larger number of surface atoms for the tube is likely to increase the bandwidth, thus reducing the optical bandgap. The experimental findings can have important impacts in the understanding of the role of surfaces in nanostructured semiconductors with an enhanced surface/volume ratio. © 2015 American Chemical Society