Co-mediated nucleation of erbium/silicon nanoclusters in fused silica
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in Chicoine and Francois Schiettekatte Regroupement Québécois sur les Matériaux de pointe, Département de Physique, Université de Montréal, Montréal, QC H3C 3J7, Canada
Federico Roseib) Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique, Varennes, QC J3X 1S2, Canada; and Center for Self-Assembled Chemical Structures, McGill University, Montreal, QC, H3A 0B8, Canada (Received 16 March 2015; accepted 27 August 2015)
We investigate the structural evolution of Er/Si nanoclusters obtained in co-implanted fused silica upon annealing via Raman spectroscopy and transmission electron microscopy. The effect of annealing temperature (900–1200 °C) on the nature and the relative fraction of the formed amorphous-Si, Si nanocrystals (Si-nc), and amorphous Er nanoparticles (Er-np) was determined in this ternary Er–Si–O system, showing a change of growth regime above 1100 °C due to the formation of mixed Er/O/Si aggregates. We observe that the nucleation and growth of amorphous Er-np and Si-nc are mutually affected. The 2-fold increase in the size of Er-np when no excess Si1 is present in the matrix indicates that the formation of Si-nc in the proximity of Er clusters hinders Er diffusivity above 1100 °C. This finding shows the importance of nanoclustering for improving the thermal stability of Er-doped silica systems.
I. INTRODUCTION
Erbium (Er) doped fiber amplifiers (EDFA) have been crucial components for long-range optical fiber telecommunications since the 1990s, due to their emission (Er-4f-shell emission) at a wavelength of 1.54 lm where common optical fibers (SiO2) exhibit minimum loss.1 However, the loss of their optical emission above 900–1000 °C limits their potential use for aerospace applications, in which harsh environments (including high temperatures) are very common. The development of new generation EDFA depends on improving their thermal resistance, which requires an in-depth understanding of the nanostructural evolution upon thermal exposure. After two decades of research on Er-related emission in silica glass, the nature and the relative variation of phases responsible for changes in optical emission are still poorly understood. The beneficial effect of introducing excess Si1 into the Er/SiO2 system on the Er 4f-shell emission at 1.54 lm is Contributing Editor: Himanshu Jain Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2015.277 J. Mater. Res., Vol. 30, No. 20, Oct 28, 2015
well-known and reported in the literature.1–3 The presence of excess Si1 in the SiO2 matrix (upon annealing treatment) results in the formation of Si nanocrystals (Si-nc) that are found to act as sensitizers, thus allowing more efficient Er-related optical emission.1–7 The size variation and inter-particle spacing of Si-nc, as well as the Er concentration are important parameters which affect the efficiency of energy transfer from Si-nc to Er ions and their optical emission.8,9 On the other hand, in recent studies on EDFA for s
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