Defect structures created in implantations of radioactive 57Mn + ions into silicon-based semiconductors held at temperatures of 77–500 K have been studied by Mössbauer spectroscopy on the 14 keV γ-radiation emitted in the decay of the 57Fe daughter atoms. For implantations at <300 K, the majority of Fe atoms is located in a specific defect structure, likely within an “amorphous pocket”, which anneals partially at 100–200 K and completely at 300–450 K. The latter is proven to occur within minutes by isothermal time delayed measurements and results in a substitutional incorporation of the 57Mn probe atoms. The atomic structure of the annealing defect is compared to that of Fe in amorphous silicon upon 57Mn implantation.