The recombination dynamics of defect states in zinc oxide nanowires was studied

by developing a general expression for time-resolved photoluminescence intensity

based upon a second-order approximation to the radiative and non-radiative

recombination rates. The model permitted determination of the parameters that

characterized the recombination from deep defect states (defect concentration,

unimolecular lifetime and bimolecular coefficient) via multi-fitting analysis of

time-resolved photoluminescence measurements. Analyses of zinc oxide nanowires

yielded deep state concentrations of the order of 1018/cm3 and unimolecular

lifetimes and bimolecular recombination coefficient which were comparable to

those typical of interband recombination in direct gap semiconductors. The

consistency of a 'two-channel decay' model (double exponential decay) was tested

by means of a similar analysis procedure. The results suggested that double

exponential fitting of time-resolved photoluminescence data of zinc oxide

nanowires could simply be a phenomenological tool which did not reflect the real

recombination dynamics of the visible emission band.

Recombination Dynamics of Deep Defect States in Zinc Oxide Nanowires.

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

Nanotechnology, 2009, 20[17], 175706