A first-principles pseudopotential method was used to study transient enhanced diffusion. Electronic degrees of freedom were included explicitly, together with a fully self-consistent treatment of the electron charge density. A large super-cell and a fine k-point mesh were used. The method was shown to furnish a quantitative description of the defect energetics. The diffusion of B was significantly enhanced in the presence of Si interstitials, due to a substantial lowering of the migrational barrier via a kick-out mechanism. The resultant mobile B atom could also be trapped by another substitutional B atom; thus forming an immobile and electrically inactive two-B pair. The diffusion of C was also significantly enhanced; due to pairing with Si interstitials. However, the C bonded to Si interstitials much more strongly than did B; thus removing most of the Si interstitials from B at sufficiently high C concentrations. This led to the suppression of B transient enhanced diffusion. The Fermi level effect played an important role in both Si interstitial and B diffusion.

Ab initio Pseudopotential Calculations of Dopant Diffusion in Si. J.Zhu: Computational Materials Science, 1998, 12[4], 309-18