Spatial Distribution of Defect Luminescence in ZnO Nanorods: An Investigation by Spectral Cathodoluminescence Imaging

Publication Type:
Journal Article
Citation:
Physica Status Solidi (A) Applications and Materials Science, 2018, 215 (19)
Issue Date:
2018-10-10
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© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The spatial distribution of ubiquitous green luminescence (GL) in ZnO nanorods is investigated using cathodoluminescence (CL) spectral imaging. The vertically aligned, single-crystal nanorods exhibit a strong GL emission at 2.42 eV at 80 K, attributable to oxygen vacancies. The spectral imaging reveals the GL emission is predominantly located in the surface layer of nanorods; the thickness and intensity of this layer decreases rapidly at elevated temperatures. On the other hand, the near-band-edge emission is weakest near the nanorod edges. The temperature-dependent CL maps are consistent with the properties of a model in which singly ionized oxygen vacancies are stabilized by the surface band bending, which leads to the GL enhancement at the expense of near-band-edge emission. These results demonstrate the utility of spectral CL imaging to map the spatial distribution of defect luminescence in nanostructured materials.
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