It was recalled that intrinsic interstitials in GaAs were characterized by a remarkable formation energy that made them unlikely to be present in as-grown materials and therefore neglected. However, the role of interstitials had to be considered in implanted GaAs, where collision cascades caused by energetic ions produced a large number of these point defects. A semi-empirical tight-binding molecular dynamics simulation of interstitial defects in GaAs was reported here. The parametrization was initially applied to the simulation of isolated self-interstitials, on the basis of previous state-of-the-art density functional theory results. Di-interstitial properties were then addressed; showing that self-interstitials had a marked tendency to aggregate into bigger structures. The binding energy of these clusters was calculated on the basis of a simple algebraic model that did not require calculation of the formation energy of the compound.

Structural, Electronic and Energetic Properties of Small Self-Interstitial Clusters in GaAs by Tight-Binding Molecular Dynamics. M.Volpe, G.Zollo, L.Colombo: Physical Review B, 2005, 71[7], 075207 (6pp)