Isolated As antisite in GaAs: Possibility of the EL2 defect

A theoretical treatment of the properties of the isolated As antisite in GaAs is presented. The results are compared to recent works of Dabrowski and Scheffler and of Chadi and Chang, which suggested that the As antisite be identified with the EL2 defect in GaAs. A large supercell, an extensive plane-wave basis, and several Brillouin-zone sampling points are used to improve the accuracy of theoretical predictions. We find that the isolated antisite exhibits metastability, which is the most important property of the EL2 defect, but the energy barrier is lower from the experimental value by a factor of 2. Possible sources of the discrepancy are discussed. © 1989 The American Physical Society.