| Autor: |
Zhou, Shengqiang, Potzger, K., Talut, G., Reuther, H., von Borany, J., Grötzschel, R., Skorupa, W., Helm, M., Fassbender, J., Volbers, N., Lorenz, M., Herrmannsdörfer, T. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; Jan2008, Vol. 103 Issue 2, p023902, 14p, 3 Charts, 17 Graphs |
| Abstrakt: |
Nowadays ferromagnetism is often found in potential diluted magnetic semiconductor systems. However, many authors argue that the observed ferromagnetism stems from ferromagnetic precipitates or spinodal decomposition rather than from carrier-mediated magnetic impurities, as required for a diluted magnetic semiconductor. In the present article, we answer this question for Fe-implanted ZnO single crystals comprehensively. Different implantation fluences, temperatures, and post-implantation annealing temperatures have been chosen in order to evaluate the structural and magnetic properties over a wide range of parameters. Three different regimes with respect to Fe concentration and process temperature are found: (1) Disperse Fe2+ and Fe3+ at low Fe concentrations and low processing temperatures, (2) FeZn2O4 at very high processing temperatures, and (3) an intermediate regime with a coexistence of metallic Fe (Fe0) and ionic Fe (Fe2+ and Fe3+). Ferromagnetism is only observed in the latter two cases, where inverted spinel ZnFe2O4 and α-Fe nanocrystals are the origin of the observed ferromagnetic behavior, respectively. The ionic Fe in the last case could contribute to a carrier-mediated coupling. However, the separation between Fe ions is too large to couple ferromagnetically due to the lack of p-type carrier. For comparison, investigations of Fe-implanted epitaxial ZnO thin films are presented. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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