Abstract
We have investigated photoexcited carrier lifetimes in arsenic-ion- implanted semi-insulating GaAs by time-resolved reflectivity measurements. Subpicosecond carrier lifetimes (220 to 550 fs) which do not exhibit apparent dosage dependence for samples bombarded with 200 keV arsenic ions at increasing dosages in the range of 10 12 and 10 16 ions/cm 2 are reported. The shortest carrier lifetime was observed for the sample irradiated at 10 13 ions/cm -2 . These are the shortest lifetimes ever observed for ion-damaged GaAs and comparable to those of low-temperature molecular beam epitaxially grown GaAs, which is also nonstoichiometric with excess-arsenic-related, deep-level defects.© 1995 American Institute of Physics.