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 As_Ga antisite provides direct evidence that the EL2 absorption band and the As⁺_Ga EPR are induced by the same defect.