Structural relaxation in pure amorphous silicon (a-Si) produced by ion implantation was attributed to the annihilation of point defects (vacancies and interstitials) introduced during the amorphization process. This problem was studied by using tight-binding molecular-dynamics simulations. It was found that structural defects could be identified in a-Si. They manifested themselves via a strong correlation between the charge and volume of nearby atoms. The relaxation of these defects proceeded via recombination of the dangling bonds. This resulted in an increase in the coordination number at constant density; the relaxation of a-Si therefore resulted from local, rather than global, structural changes, in full agreement with high-precision X-ray diffraction experiments.

Point Defects in Pure Amorphous Silicon and Their Role in Structural Relaxation - a Tight-Binding Molecular-Dynamics Study. X.Urli, C.L.Dias, L.J.Lewis, S.Roorda: Physical Review B, 2008, 77[15], 155204 (6pp)