Time resolved photoluminescence and electrical measurements were made on MeV As, Ga, Si, and O ion implanted GaAs to doses in the range of 1×1014–5×1016 cm−2 and subsequently annealed at 600 °C for 20 min under arsine ambient. Carrier trapping times were found to decrease with increase in implantation dose for all species studied and can be shorter than 1 ps. Sheet resistance values were found to be independent of implantation dose and were of the order of 108 Ω/☒ for As, Ga, and O implantation and ∼2×102 Ω/☒ for the Si case due to its electrical activation. Conductivity activation energies of 0.67–0.69 eV were observed for As, Ga, and O ion implanted and annealed GaAs, which are close to the reported activation energy for annealed low‐temperature GaAs (0.65 eV). © 1996 American Institute of Physics.