Extremely thin SiGe buffer layers with almost full strain relaxation were obtained by Ar ion implantation into Si substrates before SiGe growth. The amount of strain relaxation was found to depend on ion dose and implantation energy, indicating that ion-implantation-induced defects play an important role in strain relaxation. The existence of a tensilely strained Si layer, observed by Raman spectroscopy, implies that the ion-implanted Si substrate has a compliant effect for SiGe buffer layer growth. (C) 2002 Elsevier Science B.V. All rights reserved.