Recombination dynamics of deep defect states in zinc oxide nanowires

Year: 2009

Authors: Lettieri S., Santamaria Amato L., Maddalena P., Comini E., Baratto C., Todros S.

Autors Affiliation: CNR-INFM Coherentia, I-80126 Napoli, Italy;
Univ Naples Federico II, Dipartimento Sci Fis, I-80126 Naples, Italy;
CNR-INFM SENSOR, Brescia, Italy

Abstract: The recombination dynamics of defect states in zinc oxide nanowires has been studied by developing a general expression for time-resolved photoluminescence intensity based on a second-order approximation for the radiative and non-radiative recombination rates. The model allows us to determine the parameters that characterize the recombination from deep defect states (defect concentration, unimolecular lifetime and bimolecular coefficient) through multi-fitting analysis of time-resolved photoluminescence measurements. Analyses conducted on zinc oxide nanowires gave deep state concentrations of the order of 10(18) cm(-3) and unimolecular lifetimes and bimolecular recombination coefficient comparable to those typical of interband recombination in direct gap semiconductors. The consistency of a \’two-channel decay\’ model (double exponential decay) has been tested by means of a similar analysis procedure. The results suggest that double exponential fitting of time-resolved photoluminescence data of zinc oxide nanowires may be just a mere phenomenological tool which does not reflect the real recombination dynamics of the visible emission band.

Journal/Review: NANOTECHNOLOGY

Volume: 20 (17)      Pages from: 175706  to: 175706

KeyWords: ZnO
DOI: 10.1088/0957-4484/20/17/175706

Citations: 35
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