Photoresponse of the EL2 absorption in undoped semi-insulating GaAs

Abstract

The response of the EL2 absorption band to monochromatic secondary illumination has been studied in undoped semi-insulating GaAs. Photoinduced changes of the absorption band are spectrally nonuniform. In addition, the changes are nonmonotonic in time similar to the EL2 photocapacitance transients: A fast enhancement in absorption is followed by a slow quenching. These data can be explained in terms of the EL2 properties known from photocapacitance studies. A comparison with recent electron paramagnetic resonance (EPR) results for the AsGa antisite provides direct evidence that the EL2 absorption band and the As+Ga EPR are induced by the same defect.