Photoluminescence of rare earth ions (Er3+, Yb3+) in a porous silicon matrix

• A simple method to produce rare earth doped materials is represented.
• Photoluminescence properties are investigated.
• Photoluminescence pump power dependencies were simulated using a phenomenological model.

Layers of porous silicon (por-Si) with incorporated rare earth (RE) ions of erbium (Er) and ytterbium (Yb) were prepared by using electrochemical etching of crystalline silicon (c-Si) wafers followed by infiltration with RE ions from solution and subsequent high temperature annealing in air. The prepared samples exhibited room temperature photoluminescence (PL) of both Si nanocrystals and RE ions in the spectral regions of 0.6–0.9 μm and 0.98–1.5 μm, respectively. The PL intensities of RE ions in por-Si layers grown on c-Si substrates with textured surface were stronger than those for the polished ones. The observed pump power dependencies of the PL intensity were non-linear and were explained by a phenomenological model, which accounted for (i) the energy transfer from excitons confined in Si nanocrystals to Er3+ ions located in the surrounding silicon oxide (Förster transfer) and (ii) a cooperative process of the simultaneous excitation of two Yb3+ ions (quantum-cutting like process). The obtained results are promising in view of possible applications of por-Si:(Er,Yb) in light-emitting devices for near-infrared spectral region.