The multiply scanned electron beam method has been applied to annealing selenium implanted gallium arsenide. The conditions necessary to give good electrical activation and mobility have been established for doses from 5×1012to 1×1014ions cm−2. Partial activation was achieved in uncapped samples for doses of 1×1013cm−2and greater. However, to achieve higher activation of these doses, and significant activation of low doses, encapsulation with Si3N4was necessary. It is shown that rapid electron beam annealing lasting only a few seconds gave equivalent results to conventional furnace annealing methods.