Enhanced donor activities have been obtained after annealing at 700°C for selenium implants into GaAs by implanting an equal dose of gallium together with the selenium. Donor concentration depth profiles, measured for both single and dual implants of 1×1013/cm2 and 2×1014/cm2 indicated that the increase in activity was mainly due to an increase in peak donor concentration for the dual implants compared with those measured for single implants.