This study investigates the structural properties of silicon doped with ytterbium (Yb) using Fourier transform infrared (FTIR) and Raman spectroscopy. Silicon samples doped with Yb impurities were analyzed with FSM-2201 and SENTERRA II Bruker spectrometers. The results show that doping silicon with Yb impurities reduces the concentration of optically active oxygen (N_O^opt) by 30-40%, depending on the impurity concentration. An increase in defects leads to a broadening of the amorphous zone. The study also reveals that the relative intensity of three Raman bands in Si-Yb systems in the LTIOS (light and temperature induced ordered state) state changes, with the relative intensity of Si-Si decreasing, indicating that pendant bonds are mainly formed by breaking Si-Si bonds. The light intensity causing this condition is far from that required for laser or solid-state crystallization. Using Raman spectroscopy, a structural transformation was observed, characterized by a densely packed array of nanocrystals with a size of less than 11 lattice parameters. Small clusters were under strong internal stress (up to 3 GPa), which likely prevents the cluster size from increasing beyond the critical value for irreversible crystallization. The study also found that the volume fraction of nanocrystalline nuclei (Vnc) is proportional to the Raman scattering intensity of the first-order TO phonon band. The activation energy for the transition from amorphous to nanocrystalline is estimated at 0.15 eV. The size of the nuclei lies in the range of 8–11 lattice parameters, larger than the size of the threshold for the existence of a stable crystalline diamond-like lattice. When the state of the highest order is reached, it is almost completely filled with crystalline grains. The study concludes that doping silicon with Yb impurities leads to a decrease in the concentration of optically active oxygen by 30-40%, and a reversible ordered state was discovered in n-Si_{1-x}Y_{bx} (0<x<0.38) layers under the influence of a laser beam. The light intensity causing this condition was found to be far from that required for laser or solid-state crystallization. Using Raman spectroscopy, a structural transformation was revealed that manifests itself in a close-packed array of nanocrystals with a size of less than 11 lattice parameters. Small clusters were under strong internal stress (up to 3 GPa), which probably prevents the cluster size from increasing beyond the critical value for irreversible crystallization.This study investigates the structural properties of silicon doped with ytterbium (Yb) using Fourier transform infrared (FTIR) and Raman spectroscopy. Silicon samples doped with Yb impurities were analyzed with FSM-2201 and SENTERRA II Bruker spectrometers. The results show that doping silicon with Yb impurities reduces the concentration of optically active oxygen (N_O^opt) by 30-40%, depending on the impurity concentration. An increase in defects leads to a broadening of the amorphous zone. The study also reveals that the relative intensity of three Raman bands in Si-Yb systems in the LTIOS (light and temperature induced ordered state) state changes, with the relative intensity of Si-Si decreasing, indicating that pendant bonds are mainly formed by breaking Si-Si bonds. The light intensity causing this condition is far from that required for laser or solid-state crystallization. Using Raman spectroscopy, a structural transformation was observed, characterized by a densely packed array of nanocrystals with a size of less than 11 lattice parameters. Small clusters were under strong internal stress (up to 3 GPa), which likely prevents the cluster size from increasing beyond the critical value for irreversible crystallization. The study also found that the volume fraction of nanocrystalline nuclei (Vnc) is proportional to the Raman scattering intensity of the first-order TO phonon band. The activation energy for the transition from amorphous to nanocrystalline is estimated at 0.15 eV. The size of the nuclei lies in the range of 8–11 lattice parameters, larger than the size of the threshold for the existence of a stable crystalline diamond-like lattice. When the state of the highest order is reached, it is almost completely filled with crystalline grains. The study concludes that doping silicon with Yb impurities leads to a decrease in the concentration of optically active oxygen by 30-40%, and a reversible ordered state was discovered in n-Si_{1-x}Y_{bx} (0<x<0.38) layers under the influence of a laser beam. The light intensity causing this condition was found to be far from that required for laser or solid-state crystallization. Using Raman spectroscopy, a structural transformation was revealed that manifests itself in a close-packed array of nanocrystals with a size of less than 11 lattice parameters. Small clusters were under strong internal stress (up to 3 GPa), which probably prevents the cluster size from increasing beyond the critical value for irreversible crystallization.