Energetics and diffusivity of atomic boron in silicon by density-functional-based tight-binding simulations

We have applied a density-functional derived tight-binding method (DF-TBMD) to the study of the energetics and the dynamics of boron defects in silico n. This study is motivated by a number of interstitial-driven phenomena obs erved in experiments, as the transient enhanced diffusion of B atoms in imp lanted silicon samples together with the formation of immobile B precipitat es. We discuss first the DF-TBMD results for equilibrium structures and for mation energies of different defect configurations containing a single boro n atom and a silicon self-interstitial. Moreover. DF-TBMD molecular dynamic s simulations at finite temperature allow us to investigate boron diffusivi ty in a temperature range between 900 and 1500 K. We provide for the first time a dynamical picture of B diffusion in silicon characterized by a migra tion energy of 0.7 eV. (C) 2001 Elsevier Science B.V. All rights reserved.