On the origin of 1.5 μm luminescence in porous silicon coated with sol-gel derived erbium-doped Fe2O3 films

Sol-gel derived Fe2O3 films containing about 10 wt% of Er2O3 were deposited on porous silicon by dipping or by a spin-on technique followed by thermal processing at 1073 K for 15 min. The samples were characterized by means of FL, SEM and X-ray diffraction analyses. They exhibit strong room-temperature luminescence at 1.5 mu m related to erbium in the sol-gel derived host. The luminescence intensity increases by a factor of 1000 when the samples are cooled from 300 to 4.2 K. After complete removal of the erbium-doped film by etching and partial etching the porous silicon, the erbium-related luminescence disappears. Following this, luminescence at 1.5 mu m originating from optically active dislocations ("D-lines") in porous silicon was detected. The influence of the conditions of synthesis on luminescence at 1.5 Irm is discussed. (C) 1999 Elsevier Science B.V. All rights reserved.