Self-organized Si-Er heterostructure nanowires showed promising 1.54 mu m Er3+ optical activity. Si nanowires of about 120-nm diameter were grown vertically on Si substrates by the vapor-liquid-solid mechanism in an Si-Er-Cl-H-2 system using an Au catalyst. Meanwhile, a single-crystalline Er2Si2O7 shell sandwiched between nanometer-thin amorphous silica shells was self-organized on the surface of Si nanowires. The nanometer-thin heterostructure shells make it possible to observe a carrier-mediated 1.53 mu m Er3(+) photoluminescence spectrum consisting of a series of very sharp peaks. The Er3+ spectrum and intensity showed absolutely no change as the temperature was increased from 25 to 300 K. The luminescence lifetime at room temperature was found to be 70 mu s. The self-organized Si nanowires show great potential as the material basis for developing an Si-based Er light source.