Thin Solid Films, Vol.562, 462-466, 2014
Photoluminescence of rare earth ions (Er3+, Yb3+) in a porous silicon matrix
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 mu m and 0.98-1.5 mu m, 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 (Forster 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. (C) 2014 Elsevier B.V. All rights reserved.