Passivation of shallow acceptors by H in Si: A microscopic study by perturbed angular correlations

The formation of acceptor-hydrogen complexes in silicon is studied via the electric field gradients caused by H atoms at the site of radioactive ${}_{}{}^{11}{}_{}{}^{}\mathrm{In}$ acceptor atoms, and is measured by means of the perturbed γγ angular correlation technique. The identical In-H pairs which are oriented along 〈111〉 lattice directions are found in samples hydrogenated by different methods, well known for the passivation of shallow acceptors. They dissociate around 420 K and are more stable than B-H complexes. There is evidence for an influence of the free-hole concentration on the actual structure of the In-H pairs.