Izeddin I., Timmerman D., and Gregorkiewicz T., Moskalenko A. S., Prokofiev A. A., and Yassievich I. N., Fujii M.

We present a high-resolution photoluminescence study of Er-doped SiO₂ sensitized with Si nanocrystals Si NCs. Emission bands originating from recombination of excitons confined in Si NCs, internal transitions within the 4f-electron core of Er³⁺ ions, and a band centered at λ≈1200 nm have been identified. Their kinetics were investigated in detail. Based on these measurements, we present a comprehensive model for energy-transfer mechanisms responsible for light generation in this system. A unique picture of energy flow between the two subsystems was developed, yielding truly microscopic information on the sensitization effect and its limitations. In particular, we show that most of the Er³⁺ ions available in the system are participating in the energy exchange. The long-standing problem of apparent loss of optical activity in the majority of Er dopants upon sensitization with Si NCs is clarified and assigned to the appearance of a very efficient energy exchange mechanism between Si NCs and Er³⁺ ions. Application potential of SiO₂:Er, sensitized by Si NCs, was discussed in view of the newly acquired microscopic insight.

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