Raman scattering measurements on liquid-encapsulated Czochralski-grown Fe-doped semi-insulating InP(1 0 0) single crystal substrates have been carried out before and after 120 keV N+ implantation for various doses from 1013 to 1015 cm-2 and also after post-implantation rapid thermal annealing of these samples. It is observed that LO phonon mode frequency decreases and full width at half maximum (FWHM) increases with fluence due to implantation-induced lattice damage. Forbidden Raman TO mode in (1 0 0) cut InP is observed at the doses of 5 × 1013 and 5 × 1014 cm-2. This might have appeared due to the polycrystalline and/or misoriented regions created during implantation. TO mode is not observed for high doses in as-implanted samples due to excessive lattice damage induced by the implantation. On rapid thermal annealing at 573 K for 30 s, the implanted samples show a partial recovery of LO phonon mode frequency and FWHM due to partial annealing of the damage. On partial annealing of the implantation-induced defects, TO mode FWHM decreases and area under the peak increases for all the doses from 1013 to 1015 cm-2. © 2002 Elsevier Science B.V. All rights reserved.