A model of void formation in Si crystals, from a supersaturated vacancy solution in the presence of N and O, was developed. At the void formation stage, N was represented mostly by dimeric species, but the major vacancy traps were N single interstitials. The trapping was remarkably strong, and yet the voids were easily produced—at a lower temperature and in increased density. These results were in a quantitative agreement with the reported data. A role of the O impurity was to reduce the void surface energy, and also to enhance the pairing/dissociation rate of N.

The Effect of Nitrogen on Void Formation in Czochralski Silicon Crystals. V.V.Voronkov, R.Falster: Journal of Crystal Growth, 2005, 273[3-4], 412-23