Lattice damage in ion implanted silicon-germanium alloys

Abstract

The damage produced in Si 1− x Ge x alloys (0 ≤ x ≤ 1) by implantation of 70–100 keV 30Si + has been measured as a function of temperature and fluence by ion channeling. For all compositions, the damage efficiency decreased sharply as the implant temperature was increased between room temperature and 150°C. Furthermore, the damage efficiency in alloys of intermediate compositions (0.35 ≤ x ≤ 0.5) exceeds that in Ge, especially at elevated temperatures, despite the larger cascade energy density in Ge. It is shown that this behavior can be described based on a model in which the point defect mobility is the dominant factor controlling damage retention, rather than the cascade energy density. This approach provides a framework for understanding other temperature-dependent phenomena related to damage growth in SiGe alloys including dose rate effects and damage saturation in MeV implantation.