[en] Using the Moessbauer spectroscopy method for the ¹¹⁹Sn isotope, the state of tin impurity atoms is studied in silicon, germanium, and silicon-germanium solid solutions over a temperature range 80 to 1000 K. The samples are doped either by means of diffusion annealing at 1200 ⁰C for silicon and 870 ⁰C for germanium, or in the process of crystal pulling from a melt. If tin concentration does not exceed 2 x 10¹⁹ cm^-3, it enters the matrix lattice substitutionally, forming a system of sp³ hybrid chemical bonds. A model, describing tin impurity atom as an isotopic impurity, is discussed. If tin concentration exceeds the above value, associates of tin impurity atoms are formed in the structure of the doped semiconductors. (author)