Elaboration et caractérisation de films de ZnO dopé pour des applications optoélectroniques

Abstract : This thesis is part of the development of new monolithic white LED emission. Rare earth(s) and transition metal doped ZnO films were prepared by RF magnetron sputtering. A judicious choice of deposition parameters has allowed us to a better understanding of the influence of dopants on the structure of ZnO:Eu films and their luminescence and electrical properties. We have shown that europium is optically active and that energy transfer occurs between the matrix and the rare earth under optical excitation. However, optimizations of the optical and electrical properties are obtained for antagonist deposit conditions. We have conducted an attempt to optimize these properties by different heat treatments. These were not successful but they have showed a diffusion of Eu3+ ions to the bottom of the film for annealing temperatures of 1173 K, unlike the Eu2+ ions whose distribution remained homogeneous. Correlations between the structural properties and the dopant luminescence have been possible. An Eu/Tb co-doping of ZnO allowed observing both red and green contributions of the rare earth elements and highlighting the energy transfer mechanism between Eu and Tb in ZnO. The weak intensities of luminescence led us to replace the europium by the cobalt. Although the cobalt ion is optically active at 660 nm in ZnO, ZnO:Co films have the same disadvantages as those encountered previously in that they have an optimum luminescence when the electrical conductivity is low and vice versa.
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Submitted on : Tuesday, April 14, 2015 - 6:42:06 PM
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  • HAL Id : tel-01142121, version 1

Citation

Christian Davesnne. Elaboration et caractérisation de films de ZnO dopé pour des applications optoélectroniques. Science des matériaux [cond-mat.mtrl-sci]. Université de Caen Basse Normandie, 2014. Français. ⟨tel-01142121⟩

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