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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/190

Title: Probing defects in chemically synthesized ZnO nanostrucures by positron annihilation and photoluminescence spectroscopy
Authors: Chaudhuri, S K
Ghosh, Manoranjan
Das, D
Raychaudhuri, A K
Issue Date: 2010
Publisher: Journal of Applied Physics
Citation: S. K. Chaudhuri, Manoranjan Ghosh, D. Das and A. K. Raychaudhuri, Probing defects in chemically synthesized ZnO nanostrucures by Positron Annihilation and Photoluminescence Spectroscopy, Journal of Applied Physics, 2010, 108, 064319
Abstract: The present article describes the size induced changes in the structural arrangement of intrinsic defects present in chemically synthesized ZnO nanoparticles of various sizes. Routine x-ray diffraction and transmission electron microscopy have been performed to determine the shapes and sizes of the nanocrystalline ZnO samples. Detailed studies using positron annihilation spectroscopy reveals the presence of zinc vacancy. Whereas analysis of photoluminescence results predict the signature of charged oxygen vacancies. The size induced changes in positron parameters as well as the photoluminescence properties, has shown contrasting or nonmonotonous trends as size varies from 4 to 85 nm. Small spherical particles below a critical size 23 nm receive more positive surface charge due to the higher occupancy of the doubly charge oxygen vacancy as compared to the bigger nanostructures where singly charged oxygen vacancy predominates. This electronic alteration has been seen to trigger yet another interesting phenomenon, described as positron confinement inside nanoparticles. Finally, based on all the results, a model of the structural arrangement of the intrinsic defects in the present samples has been reconciled.
URI: http://hdl.handle.net/123456789/190
Appears in Collections:2010

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