Transmission Electron Microscopy was combined with Time Resolved Reflectivity to study the amorphous–crystalline (a–c) interface evolution during Solid Phase Epitaxy Regrowth (SPER) of Si0.83Ge0.17 films deposited on Si by Molecular Beam Epitaxy and amorphized with Ge+ ion implantation. Starting from the Si/SiGe interface, a 20 nm thick layer regrows free of defects with the same SPER rate of pure Si. The remaining SiGe regrows with planar defects and dislocations, accompanied by a decrease of the SPER velocity. The sample was also studied after implantation with B or P. In these cases, the SPER rate raises following the doping concentration profile, but no difference in the defect-free layer thickness was observed compared to the un-implanted sample. On the other hand, B or P introduction reduces the a–c interface roughness, while B–P co-implantation produces roughness comparable to the un …