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 observers. Thereby, the presence of a point-defect next to the solute atom becomes observable via the altered electronic charge distribution about the solute, giving rise to a defect-specific electric field gradient. Using the perturbed γγ angular correlation technique, this electric field gradient is detected via the hyperfine interaction occurring at the site of the nucleus of the radioactive atom. The sensitivity to solute point-defect pairs is typically in the order of 10¹⁶cm^–3. Several properties of these pairs, such as their chemical nature and 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 semiconductors will be discussed.