Journal of Luminescence (2006)

Photoluminescence properties of Co2+-doped ZnO nanocrystals
Petra Lommens, Philippe F. Smet, Celso de Mello Donega, Andries Meijerink, Luc Piraux, Sebastien Michotte, Maria Matefi-Tempfli, Dirk Poelman, Zeger Hens
Journal of Luminescence 118 (2006) 245-250

We performed photoluminescence experiments on colloidal, Co2+-doped ZnO nanocrystals in order to study the electronic properties of Co2+ in a ZnO host. Room temperature measurements showed, next to the ZnO exciton and trap emission, an additional emission related to the Co2+ dopant. The spectral position and width of this emission does not depend on particle size or Co2+ concentration. At 8 K, a series of ZnO bulk phonon replicas appear on the Co2+-emission band. We conclude that Co2+ ions are strongly localized in the ZnO host, making the formation of a Co2+ d-band unlikely. Magnetic measurements revealed a paramagnetic behaviour.


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