Haranath, D. and Sahai, Sonal and Joshi, Amish G and Gupta, Bipin K and Shanker, V (2009) Investigation of confinement effects in ZnO quantum dots. Nanotechnology , 20 (42). 425701-1-425701-7. ISSN 1361-6528

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Abstract

We report a simple method for the synthesis of Na+ doped and stable zinc oxide quantum dots, using the quantum confinement atom method. An intense broad green photoluminescence (PL) was observed with a maximum located at ~535 nm when excited by UV radiation of 332 nm. The PL peak intensity is found to be highly dependent on the size of the quantum dots (QDs). Electron microscopy observation revealed that the radius of the QD was ~1 nm, which clearly indicated that the QDs are in the strong quantum confinement region (exciton Bohr radius, rB, for bulk ZnO is 1.8 nm). Phase purity of ZnO and the presence of Na+ was confirmed by x-ray diffraction (XRD) and atomic absorption spectroscopy (AAS), respectively. The results are well incremented by x-ray photoelectron spectroscopy (XPS) studies. Intentional ageing of QDs for several days under controlled experimental conditions such as temperature, relative humidity and pH etc, facilitated the formation of various nanostructures with a slight red shift in the PL peak position. Time resolved emission spectroscopy measurements indicated that PL decay time changes from 35 ns for QDs to 1660 µs for nanocrystals. The observed high-intensity and stable green PL emissions have been analyzed and thoroughly discussed.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s Institute of Physics.
Subjects:	Materials Science Physics
Divisions:	UNSPECIFIED
Depositing User:	Ms Neetu Chandra
Date Deposited:	06 Sep 2012 08:11
Last Modified:	06 Sep 2012 08:11
URI:	http://npl.csircentral.net/id/eprint/545

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