First Principles Calculation of Interaction between Nitrogen Atoms and Vacancies in Silicon

摘要

Stability of several states of nitrogen in silicon was investigated using the first principles calculation. It was made clear that single interstitial nitrogen was more stable at a split interstitial site (S-site) or a bond center site than at a tetrahedral or hexagonal site. A nitrogen pair at two adjacent S-sites is more stable than the single nitrogen at an S-site by 4.3 eV, which fact indicates that nitrogen exists as the nitrogen pair even near the melting temperature of silicon. The interrelation between the nitrogen pair and two vacancies results in a strong negative binding energy and this suggests that there is a complex consisting of the nitrogen pair and two vacancies at the temperature of the void aggregation as far as thermal equilibrium is considered. Formation of this complex is presumed to affect the concentration and diffusion of the vacancies.