The solid phase epitaxial regrowth (SPER) process of implantation amorphized Si0.7Ge0.3 layers (850± Å thick) grown on (100) Si has been studied by cross-sectional transmission electron microscopy. For amorphous layers produced by 40 Ar+ implantation highly defective three dimensional regrowth was observed in both Si0.7Ge0.3 and Si. Stacking faults were the principle defect formed of both materials during regrowth. SPER after amorphization via 73 Ge+ implantation was also investigated. It was found that the SPER velocity of the 73 Ge+ implanted Si0.7 Ge0.7 Ge0.3 was about twice the velocity of the 40 Ar+ implanted samples; for 73 Ge+ implanted Si it was about three times that of the 40Ar+ implanted samples. The activation energy for SPER in 40Ar+ and in 73 Ge+ implanted Si0.7 Geo0.3 was about 1.6 and 2.6 eV, respectively. The defect density was significantly reduced in 73 Ge+ amorphized Si but not in the 73 Ge+ amorphized Si0.7 Ge0.3. It is proposed that limited Ar solubility inhibits high quality regrowth in both SiGe and Si. Upon 73 Ge+ amorphization and solid phase epitaxy the interfacial strain between the SiGe and Si cannot be accommodated. Thus the epitaxial process is poor in these SiGe strained layers regardless of the amorphizing species.