Sensitization of the 4I13/2–4I15/2 Er3+ luminescence at 1.54µm in Si-rich silicon oxide was studied in the blue-green range. It was shown that defects due to excess Si in silica acted as luminescence sensitizers. It was also suggested that there existed 2 types of Er centers  (isolated ones and others) which were strongly coupled to defects. In Si-rich silicon oxide, the competition of direct resonant excitation of Er3+ and indirect processes via defects were observed. Enhancement of the Er emission for off-resonant excitation did not seem to compensate losses in the direct channel of excitation to the 2H11/2 state of Er3+. It was suggested that the emission efficiency of Er3+ was limited by distance-dependent transfer rate and little spectral overlap of the interacting states.

Defect-Mediated and Resonant Optical Excitation of Er3+ Ions in Silicon-Rich Silicon Oxide. D.Kuritsyn, A.Kozanecki, H.Przybylińska, W.Jantsch: Applied Physics Letters, 2003, 83[20], 4160-2