Abstract
New photoluminescence (PL) recovery effects induced by below band-gap excitation have been observed for the fatigued emission bands associated with the deep donor EL2 in undoped semi-insulating liquid encapsulated Czochralski-grown GaAs crystals. The PL intensity quenched by a pre-excitation with a 1.06-µm light is restored gradually by a persistent irradiation of the same 1.06-µm light with a reduced excitation intensity in some samples and by a 1.32-µm light in all the samples. These recovery effects are explained by the occurrence of optical transition from the metastable state to the normal state of the EL2 level.
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