Direct and indirect excitation of Nd 3+ ions sensitized by Si nanocrystals embedded in a SiO 2 thin film
Résumé
The luminescence properties of Nd-doped SiO x layers containing silicon nanocrystals (Si-ncs) were investigated by steady state, time-dependent and power-dependent photoluminescence spectrometry and photoluminescence excitation experiments. Both direct and indirect excitation processes of Nd 3þ ions have been evidenced. The energy transfer mechanism between Si-ncs and Nd 3þ ions is favored by the overlap between the emission spectrum of confined excitons in Si-ncs and the Nd 3þ absorption from the ground state to 4 F 5=2 electronic level. The more intense Nd-related emission was obtained in samples containing 0.5 at. % of Nd and characterized by an indirect excitation cross section equal to 8 Â 10 À15 cm 2 .
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