Abstract
We studied the defect physics in a prototype chalcopyrite semiconductor. We showed that (i) it takes much less energy to form a Cu vacancy in than to form cation vacancies in II-VI compounds (ii) defect formation energies vary considerably both with the Fermi energy and with the chemical potential of the atomic species, and (iii) the defect pairs such as and have particularly low formation energies (under certain conditions, even exothermic). Using (i)–(iii), we (a) explain the existence of unusual ordered compounds and as a repeat of a single unit of pairs for each 5, 7, and 9 units, respectively, of (b) attribute the very efficient -type self-doping ability of to the exceptionally low formation energy of the shallow defect Cu vacancies; (c) explained in terms of an electronic passivation of the by the electrically benign character of the large defect population in Our calculation leads to a set of new assignment of the observed defect transition energy levels in the band gap. The calculated level positions agree rather well with available experimental data.
- Received 15 October 1997
DOI:https://doi.org/10.1103/PhysRevB.57.9642
©1998 American Physical Society