Defect-induced homogeneous amorphization of silicon: the role of defect structure and population

Molecular dynamics based on the environment-dependent interatomic potential is used to investigate the influence of the nature and distribution of defects on solid state, homogeneous amorphization of Si. To this end, different kinds of defects, including single interstitials and vacancies (both uncorrelated and correlated distributions), bond defects, and small interstitial and vacancy clusters, have been considered. It is shown that the threshold defect concentration for amorphization depends on the defect type, and, in the case of single defects, on the degree of correlation between interstitial and vacancy distributions. The threshold varies within the interval [0.18-0.28] atomic fraction, the upper value corresponding to the case of bond defects, the lower to the uncorrelated distributions of single (110) split interstitials plus compensating vacancies.