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Defect induced changes on the excitation transfer dynamics in ZnS/Mn nanowires.

Kaiser U, Chen L, Geburt S, Ronning C, Heimbrodt W - Nanoscale Res Lett (2011)

Bottom Line: The transients of the Mn-related luminescence can be quantitatively described on the basis of a modified Förster model accounting for reduced dimensionality.Here, we confirm this modified Förster model by varying the number of killer centers systematically.The temporal behavior of the internal Mn2+ (3d5) luminescence is recorded on a time scale covering almost four orders of magnitude.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Material Sciences Center, Philipps-University of Marburg, Renthof 5, 35032 Marburg, Germany. limei.klar@physik.uni-marburg.de.

ABSTRACT
Transients of Mn internal 3d5 luminescence in ZnS/Mn nanowires are strongly non-exponential. This non-exponential decay arises from an excitation transfer from the Mn ions to so-called killer centers, i.e., non-radiative defects in the nanostructures and is strongly related to the interplay of the characteristic length scales of the sample such as the spatial extensions, the distance between killer centers, and the distance between Mn ions. The transients of the Mn-related luminescence can be quantitatively described on the basis of a modified Förster model accounting for reduced dimensionality. Here, we confirm this modified Förster model by varying the number of killer centers systematically. Additional defects were introduced into the ZnS/Mn nanowire samples by irradiation with neon ions and by varying the Mn implantation or the annealing temperature. The temporal behavior of the internal Mn2+ (3d5) luminescence is recorded on a time scale covering almost four orders of magnitude. A correlation between defect concentration and decay behavior of the internal Mn2+ (3d5) luminescence is established and the energy transfer processes in the system of localized Mn ions and the killer centers within ZnS/Mn nanostructures is confirmed. If the excitation transfer between Mn ions and killer centers as well as migration effects between Mn ions are accounted for, and the correct effective dimensionality of the system is used in the model, one is able to describe the decay curves of ZnS/Mn nanostructures in the entire time window.

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The experimental data and the fitted curves from Mn PL transients. Two ZnS/Mn wire samples with a Mn concentration 2.8·10-3 at.% which were implanted at temperatures of 400°C and 600°C, respectively.
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Figure 4: The experimental data and the fitted curves from Mn PL transients. Two ZnS/Mn wire samples with a Mn concentration 2.8·10-3 at.% which were implanted at temperatures of 400°C and 600°C, respectively.

Mentions: In Figure 4, the transients of two ZnS/Mn samples implanted at temperatures of 400°C and 600°C during the Mn implantation process (approach 1) with concentrations of 2.8·10-3 at.% are shown. It can be seen that the Mn PL decay from the samples implanted at 400°C is faster than the decay of that at 600°C. This is in agreement with the expectation that with decreasing implantation temperature, the number of defects - thus killer centers - will increase. The curves can be fitted perfectly using the modified Förster model. By fitting with D = 1, n = 0.37 nm-1 or 0.61 nm-1, and keeping all other parameters the same, one obtains volume killer densities of 7.8·1016 cm-3 and 4.7·1016 cm-3 for the samples implanted at 400°C and 600°C.


Defect induced changes on the excitation transfer dynamics in ZnS/Mn nanowires.

Kaiser U, Chen L, Geburt S, Ronning C, Heimbrodt W - Nanoscale Res Lett (2011)

The experimental data and the fitted curves from Mn PL transients. Two ZnS/Mn wire samples with a Mn concentration 2.8·10-3 at.% which were implanted at temperatures of 400°C and 600°C, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211286&req=5

Figure 4: The experimental data and the fitted curves from Mn PL transients. Two ZnS/Mn wire samples with a Mn concentration 2.8·10-3 at.% which were implanted at temperatures of 400°C and 600°C, respectively.
Mentions: In Figure 4, the transients of two ZnS/Mn samples implanted at temperatures of 400°C and 600°C during the Mn implantation process (approach 1) with concentrations of 2.8·10-3 at.% are shown. It can be seen that the Mn PL decay from the samples implanted at 400°C is faster than the decay of that at 600°C. This is in agreement with the expectation that with decreasing implantation temperature, the number of defects - thus killer centers - will increase. The curves can be fitted perfectly using the modified Förster model. By fitting with D = 1, n = 0.37 nm-1 or 0.61 nm-1, and keeping all other parameters the same, one obtains volume killer densities of 7.8·1016 cm-3 and 4.7·1016 cm-3 for the samples implanted at 400°C and 600°C.

Bottom Line: The transients of the Mn-related luminescence can be quantitatively described on the basis of a modified Förster model accounting for reduced dimensionality.Here, we confirm this modified Förster model by varying the number of killer centers systematically.The temporal behavior of the internal Mn2+ (3d5) luminescence is recorded on a time scale covering almost four orders of magnitude.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Material Sciences Center, Philipps-University of Marburg, Renthof 5, 35032 Marburg, Germany. limei.klar@physik.uni-marburg.de.

ABSTRACT
Transients of Mn internal 3d5 luminescence in ZnS/Mn nanowires are strongly non-exponential. This non-exponential decay arises from an excitation transfer from the Mn ions to so-called killer centers, i.e., non-radiative defects in the nanostructures and is strongly related to the interplay of the characteristic length scales of the sample such as the spatial extensions, the distance between killer centers, and the distance between Mn ions. The transients of the Mn-related luminescence can be quantitatively described on the basis of a modified Förster model accounting for reduced dimensionality. Here, we confirm this modified Förster model by varying the number of killer centers systematically. Additional defects were introduced into the ZnS/Mn nanowire samples by irradiation with neon ions and by varying the Mn implantation or the annealing temperature. The temporal behavior of the internal Mn2+ (3d5) luminescence is recorded on a time scale covering almost four orders of magnitude. A correlation between defect concentration and decay behavior of the internal Mn2+ (3d5) luminescence is established and the energy transfer processes in the system of localized Mn ions and the killer centers within ZnS/Mn nanostructures is confirmed. If the excitation transfer between Mn ions and killer centers as well as migration effects between Mn ions are accounted for, and the correct effective dimensionality of the system is used in the model, one is able to describe the decay curves of ZnS/Mn nanostructures in the entire time window.

No MeSH data available.


Related in: MedlinePlus