The room-temperature diffusion of evaporated Fe atoms into Si and silicon-on-insulator (Sol) materials has been studied by means of the Kelvin-surface photovoltage (SPV) method. The contactless and imaging feature of this technique enabled us to visualize the evidence of the Fe diffusion by using a single sample partly deposited with Fe. The image contrast in the regions between deposited and non-deposited with Fe was clearly observed in the SPV measurements, even after the thin Fe evaporated layer was completely removed off from the Sol surface. In addition, this contrast can be observed down to about 80 nm from the top surface. This result indicates that the Fe atoms can be soluble in the Si layer at room temperature, when Fe atoms are introduced by the vacuum evaporation. Furthermore, the time variation of the depth profile of Fe contamination was also discussed. Our results suggest that the evaporated Fe atoms diffused into the Si layer and dissolved in some form as a recombination center at room temperature.