Molecular dynamics combined with the nudged elastic band method revealed the microscopic self-diffusion process of compact Si tri-interstitials. Tight-binding molecular dynamics paired with ab initio density functional calculations speed the identification of diffusion mechanisms. The diffusion pathway could be visualized as a five defect-atom object both translating and rotating in a screw-like motion along <111> directions. The density functional theory yielded a diffusion constant of 4 x 10–5exp(–0.49eV/kT)cm2/s. The low diffusion barrier of the compact tri-interstitial may be important in the growth of ion-implantation-induced extended interstitial defects.

Fast Diffusion Mechanism of Silicon Tri-Interstitial Defects. Y.A.Du, S.A.Barr, K.R.A.Hazzard, T.J.Lenosky, R.G.Hennig, J.W.Wilkins: Physical Review B, 2005, 72[24], 241306