First-principles total energy calculations were made of the interaction of N with Si self-interstitials. The substitutional N captured a Si interstitial, with a 3.5eV binding energy, to form a <100> split-interstitial ground-state geometry; with the N forming 3 bonds. The low-energy migration path went through a bond bridge state having 2 bonds. Rapid diffusion of N occurred via a pure interstitialcy mechanism in which the N never had less than 2 bonds. A near-zero formation energy for the N interstitialcy, with respect to the substitutional form, explained the low solubility of substitutional N in silicon.

Fast Through-Bond Diffusion of Nitrogen in Silicon. P.A.Schultz, J.S.Nelson: Applied Physics Letters, 2001, 78[6], 736-8