Damage distribution and secondary-defect formation have been studied in 0.95 MeV 115In+ ion-implanted Si(100) by means of Rutherford backscattering spectrometry and cross-section transmission electron microscopy. The types of defect structures resulting after conventional thermal treatment have been classified as a function of the implantation dose. For low-dose implantation, 5 ×1013 cm−2, we found the formation of “subthreshold” or category I defects at the depth of the projected range, Rp = 4100 rA. This has never been observed before for heavy-mass ion implantation at low energies. A critical dose for amorphization of 1 × 1014cm−2 has been found. For an implantation dose of (1–3) × 10 14 cm−2 a buried amorphous layer is formed. After solid-phase epitaxial regrowth of a buried layer both category II and IV defects were observed. Rutherford backscattering analysis shows that segregation of indium atoms occurs at the depth where the two moving amorphous/crystalline interfaces meet during regrowth of the buried amorphous layer.