On the microscopic structures of three different arsenic antisite-related defects in gallium arsenide studied by optically detected electron nuclear double resonance

Three paramagnetic arsenic antisite-related defects have been created in semi-insulating GaAs by electron irradiation at 4.2 K and subsequent annealing. They were investigated by optically detected electron paramagnetic resonance (ODEPR) and optically detected electron nuclear double resonance (ODENDOR) using the magnetic circular dichroism of the absorption (MCDA). The ODEPR/ODENDOR and MCDA spectra are compared and it is discussed what can be said from the analysis of these spectra about possible structure models. Annealing to 77 K leads to an isolated AsGa, to room temperature to an AsGa-GaAs (nnn) anti-structure pair and to 520 K to the well-known EL2 defect, for which an AsGa-Asi model is a microscopic structure compatible with the ODENDOR data. Another possible model is discussed.