Influence of dynamic annealing on the shape of channeling implantation profiles in Si and SiC

The influence of dose rate and temperature on the dose dependence of the shape of Ge depth profiles obtained by channeling implantation into Si and SiC is investigated. A focused ion beam system is employed which enables the application of two widely different dose rates (1011 and 1018 cm-2 s-1). Implantations into Si are performed at room temperature (RT) and 250 0C. SiC is implanted at RT, 225, 450, and 580 0C. The Ge depth distributions are measured by secondary ion mass spectrometry. The shape of the channeling implantation profiles is affected by the formation and evolution of complex defects formed during ion bombardment, since these defects cause significant dechanneling of the implanted particles. The competing influence of dose rate and temperature on the shape of Ge depth profiles is explained in terms of intracascade defect relaxation. The time scale for the reduction of complex defects is estimated. At RT, in Si some defect relaxation occurs within the first 100 s after an ion impact. At temperatures of 225 and 250 0C, in SiC and Si, a considerable defect reduction is found within the first 10 ms as well as between 10 ms and 100 s after an ion impact. The complex defects in Si vanish entirely between 10 ms and 100 s, whereas in SiC some of them survive. At 450 and 580 0C, defects in SiC relax mainly within the first 10 ms after an ion impact. The defect reduction increases with growing implantation temperature. Different mechanisms which may be responsible for the dynamic annealing in Si and SiC are discussed. A phenomenological model is developed in order to treat the dose rate and temperature dependence of the defect-induced dechanneling within the framework of atomistic computer simulations of ion implantation. The simulated Ge depth profiles agree very well with the measured data.