Room temperature emission from Er-doped silicon-rich oxide microtorus J. Verbert, F. Mazen, T. Charvolin, E. Picard, V. Calvo, P. Noé, J.-M. Gérard, E. Hadji, F. Orucevic, J. Hare and V. Lefèvre-Seguin Eur. Phys. J. Appl. Phys., 34 2 (2006) 81-84 Published online: 25 May 2006 DOI: 10.1051/epjap:2006048