First-principles calculation of the interaction between nitrogen atoms andvacancies in silicon

Stability of several states of nitrogen in silicon were investigated by the first-principles calculation. A single nitrogen at a split interstitial si te and bond center site is more stable than that at a tetrahedral and hexag onal site. A nitrogen pair is more stable than the single nitrogen at the s plit interstitial site by 4.3 eV, which indicates that the nitrogen pair ex ists even near the melting temperature of silicon. Binding energy between t he nitrogen pair and two vacancies indicates that a complex consisting of t he nitrogen pair and two vacancies can exist at the temperature of the void aggregation as far as considering thermal equilibrium. Formation of the co mplex can affect the concentration or the diffusibility of the vacancy.