We studied the influence of energy and fluence of a F+ implantation on the end-of-range (EOR) defects and on B activation in Ge+-preamorphized Si. After F+ co-implantation at either 10 or 22 keV, B transient-enhanced diffusion as well as B electrical deactivation are both reduced. In contrast, 10 keV F+ implantation does not affect the EOR evolution, while defects are stabilized after 22 keV F+ implantation. Our results, therefore, show that the beneficial effects related to F+ co-implantation cannot be explained in terms of a stabilization of the EOR defects. (c) 2007 The Electrochemical Society.