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The interaction of hydrogen with shallow and deep level impurities in crystalline semiconductors results in a passivation of their electrical activity by the formation of complexes. Nuclear techniques, like the perturbed γγ angular correlation (PAC) and the channeling of charged particles, have contributed to the understanding of the behaviour and microscopic structure of these complexes. A brief introduction to these techniques will be given. The results on the behaviour of hydrogen, in both elemental and compound semi-conductors, will be reviewed. For the case of Si, the information obtained on the formation, geometry and stability of acceptor-hydrogen complexes will be discussed more extensively.

The Cd-H complex in Cd-111m-doped GaAs implanted with low-energy (150-400 eV) hydrogen atoms is identified and studied by perturbed angular correlation spectroscopy using radioactive Cd-111m as a probe. By measuring the fraction of Cd-H pairs in an isochronal annealing experiment, the stability of the pairs is deduced yielding a dissociation energy of E(D) = 1.35(10) eV. After Cd-111m implantation but preceding the H loading, the GaAs samples have to be annealed at temperatures exceeding 900 K in order to form Cd-H pairs. These temperatures are in agreement with the temperature range required for electrical activation of Cd implants, suggesting that a Coulombic interaction is responsible for the formation of Cd-H pairs in GaAs.

La formation de complexe d'hydrogene accepteur dans Si est etudiee par l'intermediaire des gradients de champ electrique causes par les atomes H dans le site des atomes accepteurs 111 In radioactif

The lattice site of H/D atoms in silicon doped with B and 111In atoms is investigated using the ion channeling and perturbed γγ angular correlation (PAC) technique. The results indicate that at 295 K the antibonding site is occupied by H/D and that this site is easily transformed into a near tetrahedral site under the influence of an analyzing ion beam. Based on PAC results, the population of a second site, possibly a bond-center site, is expected at low temperatures.

The interaction of acceptor atoms with the interstitial impurity atoms hydrogen and lithium in the semiconductors silicon and germanium has been studied with help of the perturbed γγ angular correlation technique at the radioactive acceptor 111 In. The formed acceptor-donor pairs, as characterized by their electric field gradients, show some striking differences in silicon and germanium. In particular, besides the thermal stability of the pairs, the number of formed InLi and InH complexes is different in silicon and germanium. The behaviour of the formed complexes as a function of the carrier concentration will be discussed.