Identification of EL2 in GaAs

Abstract

Combining electron paramagnetic resonance under optical excitation, deep level transient spectroscopy, electron irradiation, annealing, and quenching on LEC semi‐insulating GaAs and lightly Si‐doped material grown in the same way as the semi‐insulating material, we have shown that (i) the irradiated material contains two types of defects related to the antisite As_Ga, one As^∇_Ga, present before irradiation, identified to EL2 from its characteristic photoquenching behavior and the other As^*_Ga, created by the irradiation, stable under photoexcitation; (ii) As^∇_Ga anneals partially under a 850 °C thermal treatment followed by a quench and the remaining defects are transformed into As^*_Ga; (iii) further annealing around 120 °C converts As^*_Ga into As^∇_Ga, the process being thermally activated (0.5±0.2 eV). From these results and using observations of absorption on vibrational modes of the C‐As interstitial pair in electron irradiated material, we are able to conclude that As^*_Ga is the isolated antisite and As^∇_Ga, i.e., EL2, is a complex of an As antisite and an As interstitial.