We systematically investigated ion energy and dose dependencies of strain relaxation for SiGe buffer layers using Si+ ion implantation. It was found that for the SiGe grown on Si substrates implanted at the energy of 25 keV and with a dose of 5 x 10(14)cm(-2), relaxation ratio was highly enhanced with very smooth surface. The obtained ratio was 65% higher than that of unimplanted samples. However, strain relaxation ratios were seen to reduce as ion energy increased or ion dose increased. This result indicated that the End-of-Range (EOR) defects generated by ion implantation and post annealing were responsible for strain relaxation and that the depth of the EOR defects from the SiGe/Si heterointerface was very crucial for strain relaxation of the SiGe layers. (C) 2009 Elsevier B.V. All rights reserved.