Si 1Γx Ge x thin films on the Ar + ion-implanted Si substrates with different implantation energy (30 keV, 40 keV and 60 keV) at the same implantation fluence (3 β’ 10 15 cm Γ2 ) were grown by ultra high vacuum chemical vapor deposition (UHVCVD). Various characterization technologies were used to characterize these Si 1Γx Ge x films. Investigations by Rutherford backscattering spectroscopy/channeling (RBS/C) demonstrate that thin Si 0.81 Ge 0.19 films could be epitaxially grown on the ion-implanted Si substrates, although there existed obvious crystal defects. These relaxation extents of Si 0.81 Ge 0.19 films on the Ar + implanted Si substrates are larger than that in the un-implanted case, which were determined by Raman spectra. Atomic force microscopy was used to determine the surface morphology of Si 0.81 Ge 0.19 films. The microstructures of these SiGe/Si hetero-epitaxial materials were investigated by transmission electron microscopy (TEM). All the experimental results demonstrated that a highly relaxed (relaxation extent of 82.3%) Si 0.81 Ge 0.19 thin film (50 nm) growing on the 30 keV Ar + ion-implanted Si substrate is optimal, which is compared to those SiGe films grown on the ion-implanted Si substrate under other implantation condition.