Diffusion of fluorine-silicon interstitial complex in crystalline silicon

Based on first principles density functional theory calculations, we identify the structure and diffusion pathway for a fluorine-silicon interstitial complex (F-Si_i) We find the F-Si_i complex to be most stable in the singly positive charge state at all Fermi levels. At mid-gap, the complex is found to have a binding energy of 1.08 eV relative to bond-centered F⁺ and (110)-split Si_i. We find the F-Si_i complex has an overall migration barrier of 0.76 eV, which suggests that this complex may play an important role in fluorine diffusion. Our results should lead to more accurate models that describe the behavior of fluorine co-implants crystalline silicon.