Hydrogen-defect interactions in Si

The interactions between hydrogen and intrinsic defects in silicon are studied using ab-initio (tight-binding) molecular-dynamics simulations in supercells and ab-initio Hartree-Fock in clusters. The configurations, electronic structures, and binding energies of H bound to small vacancy aggregates are calculated. The vacancy (V) and the self-interstitial (I)-both rapid diffusers in Si-efficiently dissociate interstitial H, molecules. At low temperatures, this results in the formation of {V, H, H} or {I, H, H} complexes. At high temperatures, one or both H's may be released as interstitials. Preliminary calculations show that H-2* result from the reaction {I, H, H} + V --> H-2*. (C) 1999 Elsevier Science S.A. All rights reserved.