PAIRING BETWEEN RADIOACTIVE SOLUTES AND POINT-DEFECTS IN SEMICONDUCTORS

The study of solute point-defect interactions in crystals is performed on an atomic scale by employing radioactive solutes as local observer s. Thereby, the presence of a point-defect next to the solute atom bec omes observable via the altered electronic charge distribution about t he solute, giving rise to a defect-specific electric field gradient. U sing the perturbed gamma gamma angular correlation technique, this ele ctric field gradient is detected via the hyperfine interaction occurri ng at the site of the nucleus of the radioactive atom. The sensitivity to solute point-defect pairs is typically in the order of 10(16)cm(-3 ). Several properties of these pairs, such as their chemical nature an d thermodynamical behaviour are discussed. The point-defects addressed in this paper are intrinsic, such as lattice vacancies, and extrinsic , such as substitutional and interstitial impurity atoms. Results for the elemental semiconductor Si and different II-VI compound semiconduc tors will be discussed.