The main purpose here was to confirm the conclusion of a previous study that the generation of silicon interstitials was the result of the relaxation of the lattice strain induced due to a thermal gradient. Here, the relaxation of the lattice strain from a different point of view due to impurity doping during float-zone crystal growth was considered. Doping with nitrogen molecules annihilated both the A and D defects, which were the secondary defects of silicon interstitial and vacancy, respectively. The first half of the paper described such peculiar behaviour of nitrogen molecules in crystals doped with both a high concentration of vacancies and nitrogen molecules. The following four important values: the estimated vacancy concentrations, the deep levels at 0.44eV under the conduction band for n-type and at 0.66eV over the valence band for p-type for pure vacancies and the diffusion coefficient of the silicon interstitials,

DI-FZ = 1.3exp[-4.5(eV)/kT]

 were determined. The last half of the paper demonstrated how impurity doping was systematically correlated with the generation and annihilation of point defects. This phenomenon occurred in accordance with Vegard's law as tested with seven kinds of impurities, which had covalent bonding radii that were smaller or larger than that of silicon. Silicon interstitials were generated by doping with impurities that had smaller covalent bonding radii than silicon to maintain the essential lattice constant of silicon at around 1300C, and vacancies were increased above the equilibrium concentration by doping with impurities that had larger covalent bonding radii than silicon.

Generation and Annihilation of Point Defects by Doping Impurities during FZ Silicon Crystal Growth. T.Abe: Journal of Crystal Growth, 2011, 334[1], 4-15