QUANTUM-CHEMICAL INVESTIGATIONS OF ATOMIC-HYDROGEN EFFECT ON FRENKEL PAIRS ANNIHILATION IN SILICON

The SCF MO LCAO method in the valence approach with neglect of diatomi c differential overlap (NDDO) is used to study the effect of atomic hy drogen on the silicon lattice relaxation in the nearest vicinity of a vacancy. It is shown that hydrogen atoms are localized mainly as secon d-nearest neighbours of the vacancies on the Si-Si bond, which results in a significant extension of the vacancy region. The potential barri er height and its dependence on the vacancy charge state were calculat ed for Frenkel pair annihilation with a hydrogenated vacancy in the ca ses of hydrogen localization inside and outside the vacancy. The resul ts substantiate a model of enhanced annihilation of Frenkel pairs in h ydrogenated crystalline Si.