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Surface excitonic emission and quenching effects in ZnO nanowire/nanowall systems: limiting effects on device potential.

Grabowska, J. and Meaney, Alan and Nanda, Karuna. K. and Mosnier, Jean-Paul and Henry, Martin O. and Duclère, J-R. and McGlynn, Enda (2006) Surface excitonic emission and quenching effects in ZnO nanowire/nanowall systems: limiting effects on device potential. Physical Review B, 71 (11). ISSN 1098-0121

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Abstract

We report ZnO nanowire/nanowall growth using a two-step vapour phase transport method on a-plane sapphire. X-ray diffraction and scanning electron microscopy data establish that the nanostructures are vertically well-aligned with c-axis normal to the substrate, and have a very low rocking curve width. Photoluminescence data at low temperatures demonstrate the exceptionally high optical quality of these structures, with intense emission and narrow bound exciton linewidths. We observe a high energy excitonic emission at low temperatures close to the band-edge which we assign to the surface exciton in ZnO at ~ 3.366 eV, the first time this feature has been reported in ZnO nanorod systems. This assignment is consistent with the large surface to volume ratio of the nanowire systems and indicates that this large ratio has a significant effect on the luminescence even at low temperatures. The band-edge intensity decays rapidly with increasing temperature compared to bulk single crystal material, indicating a strong temperature-activated non-radiative mechanism peculiar to the nanostructures. No evidence is seen of the free exciton emission due to exciton delocalisation in the nanostructures with increased temperature, unlike the behaviour in bulk material. The use of such nanostructures in room temperature optoelectronic devices appears to be dependent on the control or elimination of such surface effects.

Item Type:Article (Published)
Refereed:Yes
Uncontrolled Keywords:ZnO; nanostructure; photoluminescence; exciton; surface;
Subjects:Physical Sciences > Physics
Physical Sciences > Nanotechnology
DCU Faculties and Centres:Research Initiatives and Centres > National Centre for Plasma Science and Technology (NCPST)
DCU Faculties and Schools > Faculty of Science and Health > School of Physical Sciences
Publisher:American Physical Society
Official URL:http://dx.doi.org/10.1103/PhysRevB.71.115439
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License
ID Code:5
Deposited On:26 Oct 2006 by DORAS Administrator. Last Modified 29 Jan 2009 16:09

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