Silicon photodetectors and camera chips are ubiquitous in the visible region of the spectrum and the near-infrared. However, their large bandgap prevents their use at longer, technologically very important, wavelengths. The band-edgemodified rare-earth detectors in silicon demonstrated here, fabricated using standard silicon technology tools, offer a route to these wavelengths and roomtemperature operation. Ion implantation of the usual n-and p-type dopants, arsenic and boron, into commercial silicon wafers is used to fabricate a standard silicon p-n junction. Further implants of the rare earths, either Ce or Yb, are made into the depletion region to enable the extended long-wavelength response. Detectivities up to 1.47 Â 10 8 cm Hz 1/2 W À1 and 2.89 Â 10 7 cm Hz 1/2 W À1 at 1.3 and 1.55 μm have been obtained with these simple planar devices. If integrated as lateral detectors in a silicon photonics platform, responsivities as good as standard silicon photodetectors in the visible and near-infrared will be achievable.