Defect-induced dissociation of in silicon

Ab initio molecular-dynamics simulations of intrinsic defects and hydrogen in crystalline silicon reveal an unexpected process with considerable implications. The vacancy (Formula presented) and the self-interstitial (Formula presented) both rapid diffusers in (Formula presented) dissociate interstitial (Formula presented) molecules with a substantial gain in energy: (Formula presented) and (Formula presented) The dissociation of (Formula presented) is caused by the lattice strain associated with the defect, and occurs whenever (Formula presented) molecules are in the vicinity of strained Si-Si bonds. After the dissociation, the two H’s may either bind to the defect that caused the strain or diffuse away from it. The calculated Frenkel pair formation energy is 8.2 eV. The reaction (Formula presented) releases less than 0.1 eV, suggesting that (Formula presented)’s in otherwise perfect Si will not generate intrinsic defects.