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Excitable Er fraction and quenching phenomena in Er-doped SiO2 layers containing Si nanoclusters Garrido Fernández, Blas García Favrot, Cristina Seo, S.-Y. Pellegrino, Paolo Navarro Urrios, Daniel Daldosso, Nicola Pavesi, Lorenzo Gourbilleau, Fabrice Rizk, Richard Materials nanoestructurats Propietats òptiques Matèria condensada Condensed matter Electronic structure of bulk materials Optical properties This paper investigates the interaction between Si nanoclusters Si-nc and Er in SiO2, reports on the optical characterization and modeling of this system, and attempts to clarify its effectiveness as a gain material for optical waveguide amplifiers at 1.54 m. Silicon-rich silicon oxide layers with an Er content of 4–6 1020 at./cm3 were deposited by reactive magnetron sputtering. The films with Si excess of 6–7 at. %, and postannealed at 900 °C showed the best Er3+ photoluminescence PL intensity and lifetime, and were used for the study. The annealing duration was varied up to 60 min to engineer the size and density of Si-nc and optimize Si-nc and Er coupling. PL investigations under resonant 488 nm and nonresonant 476 nm pumping show that an Er effective excitation cross section is similar to that of Si-nc 10−17–10−16 cm2 at low pumping flux 1016–1017 cm−2 s−1, while it drops at high flux 1018 cm−2 s−1. We found a maximum fraction of excited Er of about 2% of the total Er content. This is far from the 50% needed for optical transparency and achievement of population inversion and gain. Detrimental phenomena that cause depletion of Er inversion, such as cooperative up conversion, excited-stated absorption, and Auger deexcitations are modeled, and their impact in lowering the amount of excitable Er is found to be relatively small. Instead, Auger-type short-range energy transfer from Si-nc to Er is found, with a characteristic interaction length of 0.4 nm. Based on such results, numerical and analytical Er as a quasi-two-level system coupled rate equations have been developed to determine the optimum conditions for Er inversion. The modeling predicts that interaction is quenched for high photon flux and that only a small fraction of Er 0.2–2 % is excitable through Si-nc. Hence, the low density of sensitizers Si-nc and the short range of the interaction are the explanation of the low fraction of Er coupled. Efficient ways to improve Er-doped Si-nc thin films for the realization of practical optical amplifiers are also discussed. 2009-12-29T10:57:58Z 2009-12-29T10:57:58Z 2007 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 0163-1829 https://hdl.handle.net/2445/10634 564621 eng Reproducció digital del document publicat en format paper, proporcionada per PROLA i http://dx.doi.org/10.1103/PhysRevB.76.245308 Physical Review B, 2007, vol. 76, núm. 24, p. 245308-1-245308-15 http://dx.doi.org/10.1103/PhysRevB.76.245308 (c) The American Physical Society, 2007 info:eu-repo/semantics/openAccess 15 p. application/pdf The American Physical Society Articles publicats en revistes (Enginyeria Electrònica i Biomèdica)