Disorder--recrystallization effects following low-energy beam--solid interactions

Classical MD simulations have shown that thermal-spike-related disorder, including local melting, should be widely expected following high energy ($>$1 keV) recoils resulting from beam-- solid interactions during ion-beam processing. In contrast, the formation of isolated point defects by direct atomic displacement is expected for low energy ($<$1 keV) recoils. Using state-of-the-art dynamical DFT calculations of \emph{c}- Si systems we show that recoils of much less than 1 keV result in highly disordered regions which persist for 100s of fs. Therefore, the production of beam-induced defects, as well as the post-implant yield of active dopants, following low-energy beam--solid interactions is controlled by dynamic recrystallization processes. This work was supported in part by the AFOSR through a MURI grant.