Annealing mechanisms of intrinsic defects in 3C-SiC: a theoretical study

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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.