Photoquenching and photoinduced-recovery properties of the EL2 defect in GaAs: Evidence against the identification of EL2 with the isolated AsGa defect.

Abstract

Photoquenching of the stable state and photoinduced recovery from the metastable configuration of the $\mathrm{EL}2$ defect in semi-insulating GaAs grown by liquid-encapsulated Czochralski technique were studied by use of the infrared absorption technique concurrent with monochromatic light irradiation in the energy range of $0.7\ensuremath{\le}h\ensuremath{\nu}\ensuremath{\le}1.5$ eV. The monochromatic light intensity was \ensuremath{\le}2 mW/${\mathrm{cm}}^{2}$. The photoquenching data show two peaks at 1.125 and 1.30 eV while the photoinduced recovery data exhibit a complex structure consisting of a broad band around 0.9 eV and a set of multiple sharp peaks between 1.44 and 1.5 eV. The present results cannot be explained in terms of the available calculations and predictions reported for the isolated arsenic antisite when it undergoes a symmetry-distortion transition.