100 keV Ar and Xe ions, as well as 40 and 60 keV Ge ions were implanted at room temperature into single-crystalline silicon. The used doses covered the range from slightly damaged to totally amorphized layers for the Xe, Ar and Ge ions, respectively. The relative damage was characterized using spectroscopic ellipsometry (SE) with the Bruggeman effective medium approximation combining the dielectric function of single-crystalline and ion implantation-amorphized silicon. The depth distribution of damage was described by the coupled half-Gaussian model and with an improved model, which describes the damage profile using sublayers with thicknesses inversely proportional to the slope of the profile. The SE results were cross-checked using Rutherford backscattering spectrometry (RBS). The damage peaks were determined from the SE and RBS measurements for different ions and different doses ranging from slight damage to total damage. Comparing the damage peaks (caused by the same doses) determined with SE and RBS, a systematic deviation can be observed: SE measures more damage than RBS for lower and less damage than RBS for higher doses. (C) 2004 Elsevier B.V. All rights reserved.