Time response of 1.54 μm emission from highly Er-doped nanocrystalline Si thin films prepared by laser ablation

Er-doped nanocrystalline Si thin films have been controllably prepared over the Er density of 10(19)-10(21) cm(-3) using a prescribed amount of Er in a bulk target by laser ablation. Intense photoluminescence at 1.54 mu m originating from intra-4f shell transitions in Er3+ ions has been observed. The increase of Er density cannot immediately result in a linear increase in Er3+-emission intensity. The time response measurement indicated that the change in the rise time of the Er3+ emission directly shows that Er3+ ions are excited by the energy transfer associated with the recombination of electron-hole pairs generated optically in the Si host. We found that the decrease of the excitation efficiency of Er3+ ions was responsible for the suppression of the Er3+-emission intensity in highly Er-doped nanocrystalline Si thin films. (C) 1999 American Institute of Physics. [S000-6951(99)02703-5].