Author/Authors :
Lettieri, S Complesso Universitario di Monte Sant Angelo - CNR-INFM COHERENTIA, Italy , Amato, L Santamaria Universita di Napoli Federico II, Complesso Universitariodi Monte S. Angelo - Dipartimento di Scienze Fisiche, Italy , Maddalena, P Complesso Universitario di Monte Sant Angelo - CNR-INFM COHERENTIA, Italy , Maddalena, P Universita di Napoli Federico II, Complesso Universitariodi Monte S. Angelo - Dipartimento di Scienze Fisiche, Italy , Comini, E CNR-INFM SENSOR, Italy , Baratto, C CNR-INFM SENSOR, Italy , Todros, S CNR-INFM SENSOR, 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 1018 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.
