Energy landscape of vacancy-related defects in silicon: a comprehensive picture from DFT and GW

Vacancy related point-like defects are one of the most common degrading centers in silicon-based technology. They have been the subject of extensive studies both experimental and theoretical. However, a comprehensive theoretical model capable of explaining experimental evidence is often missing. By means of first principles calculations we revisit structural, optical and electronic properties of these common point defects in silicon. Guided by simple theoretical models, we are able to perform accurate simulations, including many-body-perturbation corrections based on the GW approximation, in close quantitative agreement with the experiment. Going beyond the common total energy approach allows us to predict the electronic activity and the low temperature dynamics of such centers. At higher temperatures, vacancies become mobile centers, forming more complex systems and/or contributing to the diffusion of impurities. Starting from experimentally proposed mechanisms, we are able to theoretically characterize activation energies of such technologically relevant processes.