  The annealing kinetics of mobile intrinsic defects is investigated by an ab
initio method based on density functional theory. The interstitial-vacancy
recombination, the diffusion of vacancies and interstitials to defect sinks
(e.g. surfaces or dislocations) as well as the formation of
interstitial-clusters are considered. The calculated migration and reaction
barriers suggest a hierarchical ordering of competing annealing mechanisms. The
higher mobility of carbon and silicon interstitials as compared to the
vacancies drives the annealing mechanims at lower temperatures including the
vacancy-interstitial recombination and the formation of interstitial carbon
clusters. These clusters act as a source for carbon interstials at elevated
temperatures. In p-type material we discuss the transformation of the silicon
vacancy into the more stable vacancy-antisite complex as an annealing
mechanism, which is activated before the vacancy migration. Recent annealing
studies of vacancy-related centers in irradiated 3C- and 4H-SiC and
semi-insulating 4H-SiC are interpreted in terms of the proposed hierarchy of
annealing mechanisms.
