Sensitization of the 1.54 μm luminescence of Er 3+ in SiO 2 films by Yb and Si-nanocrystals

Abstract

A systematic study of excitation of the 4 f–4 f luminescence of Er 3+ ions near 1.5 μm in SiO 2 layers codoped with Yb and containing Si-nanocrystals (nc-Si) is presented. Layers of SiO 2 were implanted with Er + and Yb + ions at the energies of 800 and 830 keV, respectively, at a wide range of doses (0.5–4.0×10 15 cm −2). Photoluminescence (PL) and PL excitation spectroscopy were applied to study excitation of Er 3+ ions. The Yb 3+ ions were found to play a key role in sensitizing the PL of Er 3+ for pump wavelengths ∼500 nm and 1μm. Models of sensitization processes involving energy transfer from Yb-centers are discussed. Silicon nanocrystals were produced by high dose Si implantation into SiO 2 (excess Si contents ∼7%) followed by annealing at 1100°C. An evidence is presented that transfer of energy from nc-Si is not the dominant mechanisms of excitation of Er 3+ ions. Defect mediated mechanisms seem to be more efficient. It is also found that excess Si in SiO 2 prevents clustering of rare earth atoms.