Subgap optical absorption and recombination center efficiency in bulk GaAs irradiated by light or heavy ions

摘要

This letter reports the results of a comparative study on heavy- and light-ion-irradiated semiconductors for fast saturable absorbers. The linear absorption of bulk GaAs irradiated either by Au~(+) ions or protons was measured over a wide range of wavelengths below the gap. Good correspondence was found between the absorption measurements and the calculated elementary defect concentrations. Defect clustering is evidenced in the heavy-ion case. Pump-probe experiments were used to measure the time-resolved absorption variations for weakly irradiated GaAs samples under intense illumination. Much shorter carrier recombination times are estimated for the heavy-ion case.