Radiative Recombination Mechanism of EL2 Level in GaAs

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Abstract
A clear account is given of the recombination mechanism for deep-level luminescence associated with the midgap donor EL2 in GaAs by photoluminescence excitation (PLE) spectroscopy. The deep-level emission band excited in the photon energy range of 0.8-1.5 eV is shown to consist of the 0.63 and 0.68 eV bands. The 0.63(0.68) eV band is explained as the radiative transition between the conduction (valence) band and the empty (occupied) EL2 level, on the basis of the agreement of the spectral distribution of the PLE spectra with the optical cross-sections of the EL2 level. This assignment is strongly confirmed by the occurrence of the photoquenching effect and by the disappearance of the 0.68(0.63) eV band in n(p)-type semiconductive materials.