Infoscience

Journal article

Ultrafast relaxation dynamics of charge carriers in ZnO nanocrystalline thin films

Ultrafast spectroscopy was used to study the relaxation processes of charge carriers in ZnO nanocryst. thin films. A broad red-IR absorption band linked to shallowly trapped electrons was obsd. by spectroelectrochem. measurements. Femtosecond transient absorption data revealed multiexponential decays of the charge carriers with time consts. ranging from 1 to 400 ps. The decay profile of the signal shows a probe wavelength dependence. This effect is assigned to the trapping (localization) of nonequil. charge carriers which occurs on a time scale of ∼1 ps. The recombination of shallowly trapped electrons with deeply trapped holes, detd. by single-photon counting, mainly occurs in 400 ps.

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