Low Temperature Physics: 33, 192 (2007); https://doi.org/10.1063/1.2718539 (5 pages)
Физика Низких Температур: Том 33, Выпуск 2-3 (Февраль 2007), c. 263-268 ( к оглавлению , назад )
Mechanisms of enhancement of light emission in nanostructures of II-VI compounds doped with manganese
M. Godlewski1,2, S. Yatsunenko1, and V.Yu. Ivanov1
1Institute of Physics Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
2Department of Mathematic and Natural Sciences College Cardinal S. Wyszynski University, Warsaw, Poland
K. Drozdowicz-Tomsia and E.M. Goldys
Division of Information and Communication Sciences, Macquarie University, Sydney, Australia
Microstructural Analysis Unit, UTS, Sydney, Australia
P.J. Klar and W. Heimbrodt
Department of Physics and Materials Sciences Center, Philipps-University of Marburg, Renthof 5, 35032 Germany
Received September 7, 2006
Intra-shell transitions of transition metal and rare earth ions are parity forbidden processes. For Mn2+ ions this is also a spin forbidden process, i.e., light emission should be inefficient. Surprisingly, it was reported that in nanostructures of ZnMnS the 4T1 to 6A1 intra-shell transition of Mn2+ results in a bright photoluminescence characterized by a short PL decay time. The model of a quantum confined atom was introduced to explain the observed experimental results. It was later claimed that this model is incorrect. Based on the results of our photoluminescence, photoluminescence kinetics, time-resolved photoluminescence, electron spin resonance and optically detected magnetic resonance investigations we confirm photoluminescence enhancement and decrease of photoluminescence lifetime and relate these effects to spin dependent magnetic interactions between localized spins of Mn2+ ions and spins/magnetic moments of free carriers. This mechanism is active in both bulk and in low-dimensional structures, but is significantly enhanced in nanostructure samples.
PACS: 81.07.Wx Nanopowders;
Key words: nanocrystals, photoluminescence, magnetic resonance.