We combined several atomistic techniques to identify the structure of defects responsible for X and W photoluminescence lines in crystalline Si. We used kinetic Monte Carlo simulations to reproduce irradiation and annealing conditions used in photoluminescence experiments. We found that W and X radiative centers are related to small Si self-interstitial clusters but they coexists with larger Si self-interstitials clusters that can act as non-radiative centers. We used molecular dynamics simulations to explore the many different configurations of small Si self-interstitial clusters, and select those with the symmetry compatible to W and X photoluminescence centers. Using ab initio simulations we calculated their formation energy, donor levels and energy of local vibrational modes. On the basis of photoluminescence experiments and our theoretical multiscale calculations, we discuss the possible atomic configurations responsible for the W and X photoluminescence centers in Si. Our simulations also reveal that the intensity of photoluminiscence lines is the result of the competition between radiative centers and non-radiative competitors, which can explain the experimental quenching of the W and X lines even in the presence of the photoluminiscence centers.
PDF: W and X photoluminescence centers in crystalline Si: chasing candidates at atomic level through multiscale simulations
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