The spectroscopic evidence for the identity of EL2 and the AsGa antisite in As-grown GaAs.

EL2, the dominant deep defect in undoped as-grown GaAs has attracted tremendous interest because of its peculiar optical properties and because of its technological importance for the growth of undoped semi-insulating GaAs. This paper first outlines the photoelectronic and optical properties of EL2. The second part describes the optical properties of the As sub Ga antisite defect as inferred from magnetic resonance combined with optical techniques. A comparison of the data demonstrates that EL2 and the As sub Ga antisite as defined by its electron-spin-resonance (ESR) behavior in undoped as-grown GaAs have the same optical properties. At present this fact is the most direct and convincing evidence that EL2 is the As sub Ga antisite seen by and related techniques. Whether this antisite is an isolated defect or a complex with an arsenic interstitial is a highly controversial question